It comes up now and then, someone asks for brake upgrade suggestions, and someone recommends the Grand Am brake upgrade and then someone else tells them their car will brake WORSE than it did when stock.
While I respect these opinions, I'd like to know where they are substantiated from. I'm not trying to be a jerk about it, but I would like some reasonable explaination as to why this is a BAD decision? The argument against it suggests that by upgrading the front with the Grand Am brakes, and leaving the rears stock creates an imbalanced brake system. I've heard people argue that it will cause the braking to become unpredictable.
I am currently installing the front Grand Am upgrade kit, and then leaving the rears stock. All four rotors are cross drilled, and the rears are slotted.
So my question is, I don't see how it can make a substantial amount of difference in braking. The biggest benefit to upgrading the front with the GA brakes is that they are vented (like the 88 brakes) and this eliminates brake fade (which I suffered from considerably for many years on the front of my 87 before going with cross-drilled).
Comparing the GA brakes to the stock brakes, the rotor sizes aren't that substantially different. I don't have the numbers in front of me, but I seem to recall someone saying the diameter of the brakes were less than 3/4ths larger than an INCH. The braking surface is less than 10% more as well (someone please correct these numbers if I'm not right).
I decided on the GA brakes simply because I wanted slightly better brakes, and I had to replace all the front-end stuff anyway since it was mostly all original and shot anyway. The cost difference was negligeble.
One of the arguments against the GA upgrade is that the brakes are disproportional. Now, I understand that Pontiac set it up a certain way, but I honestly prefer substantially more forward brake bias than stock, and with going poly all around, and tightening up the rear, I'll have less understeer condition in the front as well. I also don't see, really, how if the front brakes did lock up, how that would have ANY effect at all on the rear brakes. They would function just as well, or as poorly as they always have.
In addition to this, I also have stainless steel braided brake lines all around, AND... I have a larger "big bore" Master Cyl which supposedly provides an additional 12% more braking force. I'm keeping the brake booster stock.
If that is still unnacceptable, it's easy to swap in an adjustable brake proportioning valve to get back the stock brake bias (which honestly, will hardly be changed anyway).
So, I thought I'd post it here, in O/T so we can hash it out... since I haven't done the rear brakes yet, I just wanted to get through this discussion early on before I spend the money rebuilding my rear brakes.
EDIT: Here are some gratuitous pics of my new suspension / brakes because I'm so proud of them! heh
I have the grand am brakes on the back of my GT and stock brakes on the front. It stops better than it did before. Plus with the wight of an engine swap it helps to have a little more stopping power in the back.
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12:15 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
I have the grand am brakes on the back of my GT and stock brakes on the front. It stops better than it did before. Plus with the wight of an engine swap it helps to have a little more stopping power in the back.
Do you mean front grand am brakes on the rear of your Fiero? Did you go with an adjustable proportioning valve? Wow... I had never considered that. Does the back-end come around a lot when you're forced to brake and make a steering correction?
Iv got the front grand am upgrade, and stock fiero brakes in the rear, and they work great.. quite a bit better than stock..
If someone is saying they create some kind of balance issue or whatever, maby its just their car, or maby they did a crappy brake job, but they work great if you ask me.
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12:22 PM
bristowb Member
Posts: 745 From: douglasville,georgia,usa Registered: Oct 2009
I have an 87 GT which I did the GA brakes all the way around. Front and rear. with steel braided brake lines and the up graded larger master cylinder. I am very happy with my set up. I dont road race my car at all. But the added stopping power is worth it. I have an automatic trans so the rear parking brake is not needed. My car is a dd. In Atlanta Traffic non the less. I have been very happy with it. I have owned 4 dirrerent cars with Brembo brake packages. Quiet honestly in regular driving even spirited driving(The tail of the Dragon) I could not tell the difference between those and the brakes on some of my other sports cars. In reality the only way you will notice a change in high performance brakes is repeted braking such as a race track. Where heat is the enemy. Even when I raced motorcycles. Standard OEM brake were great with steel braided Lined and Better pads. It has even been proven that Carbon Ceramics brakes only make a difference when heated. But cold or normal driving were actually worse on stopping distances. Compared to there steel counter parts. I am rambling so I will stop here.
I have one car with them all the way around and it stops on a dime, auto-xing they are spot on to what I wanted out of a braking system.
I blew a brake line on my DD on the rear so I did the GA swap on the rear of that and it stops a bit better. You can tell that there is more braking force in the rear for sure, but I tend to like that on a mid-engine.
Last summer, I got sick of fighting with the stock rear calipers ( I don't use the e-brake anyway) and swapped out front stock calipers for rears. However, I'm planning on doing the GA swap on the fronts this winter along with SS brake lines all around and the larger MC.
Glad you posted this. It seems like just as many guys are for as against "front swap only" in Tech so it's been hard to make a decision. This helps a lot.
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01:44 PM
Blacktree Member
Posts: 20770 From: Central Florida Registered: Dec 2001
The stock Fiero brakes are biased to the front, which IMO isn't very suitable for a car with the engine in back. When you upgrade to Grand Am brakes in front, it shifts the brake bias even further to the front. So you're more likely to lock up the front brakes during a panic stop.
That said, the overall braking power does improve. And if you upgrade to Grand Am brakes in the rear as well, the brake balance is a lot more favorable. However, when you do that, you lose the parking brake.
BTW, shouldn't this be in the Tech section?
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01:45 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
Last summer, I got sick of fighting with the stock rear calipers ( I don't use the e-brake anyway) and swapped out front stock calipers for rears. However, I'm planning on doing the GA swap on the fronts this winter along with SS brake lines all around and the larger MC.
Glad you posted this. It seems like just as many guys are for as against "front swap only" in Tech so it's been hard to make a decision. This helps a lot.
Yeah, that's kind of the thing, there seems to be an almost negligeble difference in size between the stock and GA brakes... it just provides for a few moder advancements.
quote
Originally posted by Blacktree:
The stock Fiero brakes are biased to the front, which IMO isn't very suitable for a car with the engine in back. When you upgrade to Grand Am brakes in front, it shifts the brake bias even further to the front. So you're more likely to lock up the front brakes during a panic stop.
That said, the overall braking power does improve. And if you upgrade to Grand Am brakes in the rear as well, the brake balance is a lot more favorable. However, when you do that, you lose the parking brake.
BTW, shouldn't this be in the Tech section?
Well, I put this in O/T because I assume it's going to get heated, but I REALLY wanted to get to the bottom of this.
My experience with rear-engine cars isn't all that much, but I've had a few discussions / aquaintences with people whom owned Porsches because I used to own a 944. Most of them had 911s or some such. They all said they preferred significantly more forward brake bias because having the weight in the rear (like it does) significantly increases the chances of the back-end flying around when in certain situations where a steering correction is required WHILE breaking. I realize the worst thing in the world under performance situations is to brake while you're turning... but let's be honest, sometimes you do this, and sometimes it's necessary when you're going into a turn too fast and simply don't have any other alternative than to make the most use of your time breaking, while needing some steering so you don't fly off the track.
Inertia would dictate that if you're going in one direction, the weight (regardless of where it was on the car, I mean, unless it was cantellievered off the front of the front wheels... it would add down-force to the front wheels under heavy braking.
The possibility of the tires losing contact with the street at this point would have more to do with poor tire adhesion than it would really have to do with brakes that were simple "too much" for the car they're installed on. The same would be said for any brakes you put on the front that are larger than stock.
To put this more simply... under very heavy braking, the rear brakes do very little... as the weight shifts to the front of the car, and off the rear wheels.
I think it's pretty normal for a car to have a 70/40 f/r brake bias... and going with Grand Am brakes would make almost no difference at all in this brake bias.
So... granted, the Fiero is mid-engine... 43/57 weight distribution... and I know the rear brakes certainly are important.
Going with a proportionally larger upgrade all-around would be ideal if you want to keep the factory brake bias, but like I said, this is something you could easily change using an adjustable proportioning valve from JEGS or SUMMIT, would it not?
This is not a subject for non-experienced, theoretical conjecture.
It is like this.
I have driven a GT with GA fronts and stock rears. It sucked along side mine. I found the brakes felt iffy and stopped the car only with real hard brake pressure.
I have driven a stock Fiero and the brakes were adequate, but, not great.
I have driven my current GT with Grand Am up front, Grand Am on all fours, and Grand Am/Seville in the back, and the S10 brake booster. It is perfectly balanced, and like a different car. It stops like it is on fly paper and waaayyyy better than stock with either combination.
There is no proportioning valve issue, and I do have an operational ebrake with the Seville calipers. So far as I can tell a full GA swap is great. The other alternative is the Lebaron swap, however, the bigger rotors mean that stock wheels are out, so you will be upgrading wheels in addition to brakes.
I hope this helps
Arn
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02:00 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
This is not a subject for non-experienced, theoretical conjecture.
It is like this.
I have driven a GT with GA fronts and stock rears. It sucked along side mine. I found the brakes felt iffy and stopped the car only with real hard brake pressure.
I have driven a stock Fiero and the brakes were adequate, but, not great.
I have driven my current GT with Grand Am up front, Grand Am on all fours, and Grand Am/Seville in the back, and the S10 brake booster. It is perfectly balanced, and like a different car. It stops like it is on fly paper and waaayyyy better than stock with either combination.
There is no proportioning valve issue, and I do have an operational ebrake with the Seville calipers. So far as I can tell a full GA swap is great. The other alternative is the Lebaron swap, however, the bigger rotors mean that stock wheels are out, so you will be upgrading wheels in addition to brakes.
I hope this helps
Arn
Sure, understand though that I wasn't born a week ago. I've been working on cars for about 14 years now. That doesn't make me an expert, but by no means does it make me the kid in the Honda with the enlarged, double-walled exhaust tip either.
Are you basing your experiences on simply how your car felt?
Understand that unless you did all these on the exact same car, with the exact same tire and wheel combination, within the same 1,000 miles or so, it's not really fair to say one is clearly better than the other. If the tires and suspension were otherwise somewhat shot on the first car where you did JUST the front (and perhaps the rears had some miles on them too), and then compared it to a new system where everything had been rebuilt / replaced... I don't see how that's really a fair comparison.
Now, obviously, I'd expect the car with the Grand-Am brakes all around to stop better than the car with GA front and stock rears... that just goes without saying.
However, I'm arguing more the claim that I've seen that NOT upgrading the rears makes the car dangerous and the handling unpredictable.
For me... I've upgraded my engine to a 3.2... (3.1 crank / rods w/ .040 overbore). Quite honestly, the stock brakes would be decent enough if they were just vented. So with the GA upgrade in the front, it should work perfectly. And as I said, I personally prefer substantially more forward brake bias and less in the rear (more so than stock). It allows me to brake longer / modulate my speed better going into the corner while not worrying about a twitchy rear-end that's about to break loose because I'm not in a straight trajectory anymore...
I appreciate the conversation though. I just want to get this all out because I want to know really how huge of a difference it's going to make, and I want to determine really if it's just personal preference VS substantiation. Aside from you, I've seen people suggest this, but without any real basis for it. I know you have experience with this, so your input is definitely important to me on this. I have to question some of the other comments I've read in the past (in Tech) because you really don't know sometimes when people are repeating as facts things they've merely heard someone else say, when they don't personally have any experience with it.
If you've already made up your mind, which seems to be the case, then any discussion is basically moot. Go put some Grand Am brakes on the front of your car, and be happy.
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02:22 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
If you've already made up your mind, which seems to be the case, then any discussion is basically moot. Go put some Grand Am brakes on the front of your car, and be happy.
I think you're taking this the wrong way. I'm not "angry" heh...
I haven't made up my mind yet. I have made up my mind that I'm going to put GA brakes on the front, but I really want to understand whether or not the idea that it's BAD for me to leave the rear brakes stock is substantiated or just mere opinion based on driving perception from those who have done it.
Yeah, I started getting the impression that you just want to argue. As the cool kids would say, "my bad".
So, if people's driving experience isn't good enough, then what is? Do you want 60-0 MPH stopping distances, skid tests, etc? Most people don't go through that much trouble.
[This message has been edited by Blacktree (edited 10-30-2010).]
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02:34 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
Yeah, I started getting the impression that you just want to argue. As the cool kids would say, "my bad".
So, if people's driving experience isn't good enough, then what is? Do you want 60-0 MPH stopping distances, skid tests, etc? Most people don't go through that much trouble.
What I would like (in the end), is to see how many people respond and say "Yeah, I just did the front and it was awesome, better braking, no effect on handling." and compare it to how many people say "It sucked! The car was dangerous."
But specifically with your experiences, you say that you think having the brakes biased to the front are not suitable for a car that has an engine in the back. Just curious where you came to that conclusion and why you think that would be the case? I've always understood that the heavier the car is in the rear, the less brake bias you want back there because any braking that occures while in a turn would cause the back-end to fly out.
Has this not been your experience? Why do you prefer more braking in the rear?
Yeah, this IS an argument... but more like one that you have at a bar with friends and alcohol... rather than the kind you have at a political rally with apposing protestors.
The Grand Am calipers have a larger piston bore, which means that they provide a stronger braking force than the factory calipers. This helps move the brake bias to the front when you perform the Grand Am upgrade on the front only.
Putting Grand Am brakes on all four corners keeps the brake bias "stock" front to back.
When you brake hard, the front end dips, the rear end lifts, even with the majority of the weight near the back of the car.
A strong front bias in a hard braking situation, especially when cornering will cause the rear of the car to lift, reducing overall traction in the rear end of the vehicle. This would be caused by less weight on the contact patches of the tires because of the shift of weight towards the front or side of the vehicle in the case of turning while braking.
Try it while driving down a hill with wet surfaces and Grand Am brakes on the front only in a hard braking situation. The moment the center line of the car passes beyond the parallel of the path of travel, the rear end will swing around. Ask me how I know this... :P
I have Grand Am brakes on all four corners of my 86SE, and the braking performance is well above what the factory brakes were. I have not upgraded the master cylinder or the booster, but I do have the braided stainless steel brake lines on all four corners.
The car is stable in all braking conditions, including panic stops. I know this from first hand experience recently.
The upgrade itself is not "bad", but doing front brakes only will shift the front bias considerably forward due to the larger piston bore size, ESPECIALLY if you install the larger master cylinder as it will raise the braking force considerably in the front. A bad situation in driving conditions with the potential for traction loss.
All four corners with the larger bore calipers will maintain the factory bias.
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03:06 PM
Blacktree Member
Posts: 20770 From: Central Florida Registered: Dec 2001
I don't necessarily prefer more braking in the rear, per se, just less braking to the front. For example, instead of 80% front / 20% rear, I think it should be more like 70% front / 30% rear. (That's just an example. I don't remember what the actual numbers are for the Fiero.)
Also keep in mind that a Fiero is not a Porsche 911. The 911's are more tail-heavy than the Fiero.
I personally think the stock Fiero brakes are biased too much to the front. I've actually had the misfortune of experiencing that first-hand on a few occasions. The front brakes lock up first. And when the front wheels are sliding, you can't steer. So you're basically riding in a ballistic missile. There's nothing like skidding helplessly through a busy intersection to get your blood pumping!
Originally posted by 82-T/A [At Work]: Do you mean front grand am brakes on the rear of your Fiero? Did you go with an adjustable proportioning valve? Wow... I had never considered that. Does the back-end come around a lot when you're forced to brake and make a steering correction?
Just replaced the calipers and brake rotors. Everything else is stock. I have had a few emergency stops and the same as my other Fieros just a shorter distance. Eventually I plan on doing the fronts with the same or larger brakes but they are working well as is so I'm not in a hurry.
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03:29 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
The Grand Am calipers have a larger piston bore, which means that they provide a stronger braking force than the factory calipers. This helps move the brake bias to the front when you perform the Grand Am upgrade on the front only.
Putting Grand Am brakes on all four corners keeps the brake bias "stock" front to back.
When you brake hard, the front end dips, the rear end lifts, even with the majority of the weight near the back of the car.
A strong front bias in a hard braking situation, especially when cornering will cause the rear of the car to lift, reducing overall traction in the rear end of the vehicle. This would be caused by less weight on the contact patches of the tires because of the shift of weight towards the front or side of the vehicle in the case of turning while braking.
Try it while driving down a hill with wet surfaces and Grand Am brakes on the front only in a hard braking situation. The moment the center line of the car passes beyond the parallel of the path of travel, the rear end will swing around. Ask me how I know this... :P
I have Grand Am brakes on all four corners of my 86SE, and the braking performance is well above what the factory brakes were. I have not upgraded the master cylinder or the booster, but I do have the braided stainless steel brake lines on all four corners.
The car is stable in all braking conditions, including panic stops. I know this from first hand experience recently.
The upgrade itself is not "bad", but doing front brakes only will shift the front bias considerably forward due to the larger piston bore size, ESPECIALLY if you install the larger master cylinder as it will raise the braking force considerably in the front. A bad situation in driving conditions with the potential for traction loss.
All four corners with the larger bore calipers will maintain the factory bias.
So... what you're saying is that having the bias stock on all four corners would cause the rear to share more of the braking BEFORE-HAND in a panic situation, so as to prevent the rear from lifting (as much) and therefore LESS likely that the contact patch of the rear tires would be compromised, and therefore it would be LESS likely that the rear-end would come around?
Well, this could be a problem for me then. If I upgrade to the GA in the rear, what would I do with the emergency brakes? I'm upgrading to a stick shift... that would mean I would lose the emergency brakes. I guess when you say using grand am brakes in the rear, you're talking about the same calipers? I've owned two Grand Ams, and they both had drum brakes in the rear.
Ok, COULD I get away with simply having an adjustable brake proportioning valve?
The rear brakes act as a rudder of sorts, that keeps the rear end from coming around. I think that's what Synthesis was referring to.
Also, you should never brake hard during a turn... at least not in a tail-heavy car. Regardless of the brake bias, the inertia in the rear end will still cause it to break loose.
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03:38 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
The rear brakes act as a rudder of sorts, that keeps the rear end from coming around. I think that's what Synthesis was referring to.
Also, you should never brake hard during a turn... at least not in a tail-heavy car. Regardless of the brake bias, the inertia in the rear end will still cause it to break loose.
Yeah... sigh... I know. I known it's not good to brake into a turn. But quite honestly, sometimes you just don't have any other options. There have been a few times (a long time ago when I was far more immature) that I would end up in a turn going waaaayyy too fast, and the only hope that I had was to brake and turn at the same time, and just kind of hanging onto that threshold of complete out-of-control-ness while not actually hitting the guard rail.
quote
Originally posted by Blacktree:
I don't necessarily prefer more braking in the rear, per se, just less braking to the front. For example, instead of 80% front / 20% rear, I think it should be more like 70% front / 30% rear. (That's just an example. I don't remember what the actual numbers are for the Fiero.)
Also keep in mind that a Fiero is not a Porsche 911. The 911's are more tail-heavy than the Fiero.
I personally think the stock Fiero brakes are biased too much to the front. I've actually had the misfortune of experiencing that first-hand on a few occasions. The front brakes lock up first. And when the front wheels are sliding, you can't steer. So you're basically riding in a ballistic missile. There's nothing like skidding helplessly through a busy intersection to get your blood pumping!
I know about the 911 having significantly more, but I always presumed most of the front-wheel slide had more to do with massive understeer than it did anything to do with the brakes. But yeah... been there a few times... I've also had a few instances of major oversteer in my Fiero (in ever case, coming out of a turn)... that's actually REALLY fun, and I guess because the car is so understeer prone, when it DOES happen, it's SOOOO easy to control... you know... unless it's raining (ugh).
quote
Originally posted by Jake_Dragon:
Just replaced the calipers and brake rotors. Everything else is stock. I have had a few emergency stops and the same as my other Fieros just a shorter distance. Eventually I plan on doing the fronts with the same or larger brakes but they are working well as is so I'm not in a hurry.
Weird, so all you did really was just change out the caliper mounting bracket? Or perhaps... you re-tapped it? Or did you just use the factory slider bolts? So the rotor fits right on top of the stock rear Fiero hub?
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Ok, so let me ask this... if I really want to keep the emergency brake, what options do I have? When I'm done, my car will be a stick... so I'll definitely need an emergency brake.
I have an account on there because I've owned a couple of Grand Ams in the past. Both of mine had drum brakes in the rear, maybe the new ones have disc?
right now, I have just the GrandAm brakes up front. This ended up giving me way to much front braking. Which is another way of saying I now have LESS rear braking. I have 4 wheels to slow the car with - but only the fronts are doing the work. which - in the end makes my stopping distance LONGER. when I hit my brakes hard - my fronts are near locking, and my rears are just leisurely dragging along.
what I am doing to fix this is adding the Caddy brakes to the rear. there is a guy in the mall who sells the adapters to fit these things inside stock 14" rims. this will allow me to keep the stock hand brake, and the pistons bores match the GA brakes, so once again, the brakes will return to their original/stock brake bias. while the stock bias is not ideal - it is WAY better than 75/25, which is what it feels like now.
the Caddy rear calipers are $$$. as far as stock calipers go, that is. I found a pair at the local u-pull-it. cheap. got a rebuild kit. got a hardware kit. ripped them down, sanded the casting smooth, painted, broke the bleeder...., and am about to start re-assembling. this has actually been going on for awhile now - things keep coming up to take me away from finishing this job....right now, gotta clean up from re-roofing my garage....what fun that was....
this was the first time I've sanded calipers smooth before painting - and - wow! that makes such a difference. I painted my front GAs with the same paint as the rear Caddy calipers. The sanded ones look awesome. almost like they are made of PVC or some kind of plastic. what worked well was a drum bit in my drill motor. the dremel w/drum bit did the tight spots. I will likely repaint the GA calipers next year the same way - sanding smooth.
anyways - the root of problem is the piston bore size. the stocks are equal front/rear. the GA are larger than stock. this creates more hydraulic pressure with the same master cyl push. so, you get much more clamping force up front than in the rear. so, you end up with mainly 2 out of 4 tires doing the work to stop the car. evening up the bore sizes allows the rear to help in the braking pocess again. and, this uneveness is GREATLY highlited in low traction situations, like rain & snow.
so - those who did GA's all around end up with equal pistons bores again + vented rotors + increased hydraulic pressure.
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03:59 PM
WhiteDevil88 Member
Posts: 8518 From: Coastal California Registered: Mar 2007
If you only want opinions of those who had Baretta/GA brakes on the front, then disregard this post. But my most recent Fiero had the front and rear conversion as well as an L67 swap. It still had the original 1986 rubber brake lines so I probably wasn't getting 100%. But I was satisfied with my braking, I drove the car hard on canyon roads, and never stuffed it into anything. That could be due to my driving skill, the quality of.the.brakes, or some yet to be fulfilled destiny that my creator is keeping me alive for. You pick which one sounds most likely.
My main thing that I liked about the Baretta brakes was that the prices for all the parts are significantly cheaper then the Fiero parts and much better quality.
[This message has been edited by WhiteDevil88 (edited 10-30-2010).]
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04:16 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
anyways - the root of problem is the piston bore size. the stocks are equal front/rear. the GA are larger than stock. this creates more hydraulic pressure with the same master cyl push. so, you get much more clamping force up front than in the rear. so, you end up with mainly 2 out of 4 tires doing the work to stop the car. evening up the bore sizes allows the rear to help in the braking pocess again. and, this uneveness is GREATLY highlited in low traction situations, like rain & snow.
so - those who did GA's all around end up with equal pistons bores again + vented rotors + increased hydraulic pressure.
Ok, I see... that makes sense.
Well, I found these on Rock Auto for a 99+ Grand Am.
The mounting holes on these calipers look NOTHING like anything that would fit on the rear hub of the Fiero... but just on the off chance... would this fit with some minor modification?
The grand am front calipers and rotors are a direct replacement for the rear breaks. If you have to have a parking brake then you can buy a spot brake like Archie uses on his brake upgrade. In the couple of years that I have been driving the car it has never had an issue with the brakes. The fronts are stock but they have been rebuilt and new hoses have been installed.
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06:26 PM
84fiero123 Member
Posts: 29950 From: farmington, maine usa Registered: Oct 2004
The slotted and drilled rotors alone would give you more braking power. Without changing anything else. They are supposed to. I would think they wear down the pads a lot faster as well. I wonder how ceramic pads would work with those?
As far as the proportioning valve goes, all brake systems have them and more power is applied to the frt before the back. If I remember right it is 75/25. But you all know how bad my memory is. Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't. Detroit iron rules all the rest are just toys.
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06:32 PM
BobJones97 Member
Posts: 186 From: Madison, IN, USA Registered: Jan 2002
I have (front) Grand Am rotors all the way around, as well as the S10/Blazer MC. My tires are fairly soft Nitto 225s. It brakes excellently, but not surprisingly my wife's 2200lb MR2 Spyder stops better. Haven't tried any of the other options, but I'd bet this one is the easiest as it requires absolutely no modification. I certainly don't have any complaints about braking anymore at all.
Don't remember who it was, but someone on here that started with swapping the master cylinder, did the GA conversion, then moved onto the (I think Vette) big brake conversion said the MC swap hands down made the biggest improvement of anything. By the time he made it to the Vette brakes improvement wasn't especially noticeable.
In my case I may eventually do something else later on, but only because my 17's still look a bit silly since the GA rotors are the same diameter as the Fiero.
[This message has been edited by BobJones97 (edited 10-30-2010).]
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07:59 PM
Gridlock Member
Posts: 2874 From: New Westminster, BC Canada Registered: Apr 2002
The problem...you get a bunch of weekend warrior mechanics taking 20 year old parts off a 20 year old car, then testing the mods and saying they felt a huge difference.
Yeah! No **** .
Replace all the stock parts...lines, pads, calipers and rotors with new stock parts, and go and test it.
Guess what? It feels like a new car!
I've seen pictures of people doing some wonky **** on this forum..and others regardng modifications and it gets scary.
I really don't understand what is so hard about understanding that if you add a front caliper with a bigger piston on a stock system, and it requires more pedal travel to fill the piston, but, the rear piston is still stock and smaller, that the pedal pressure will have to go way up to stop the car.
I think I know the difference between scary soft stomper and strong hard pedal.
The GA front with stock rear calipers makes the pedal have to travel farther and makes it softer. The larger pistons both fore and aft, whether GAx4 or GA/Seville, with the S10 booster, maintain correct balance and give you a much superior braking package than stock can achieve with its smaller brake booster and smaller caliper pistons.
I agree, if you want cheap, then do just GAx2 and forget the x4. But, please don't kid yourself. Mis-balanced brakes are not a good idea. They aren't particularly safe, and they could land you in the ditch or on a tree in the right circumstance. But, it's your call.
Arn
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09:26 PM
82-T/A [At Work] Member
Posts: 25714 From: Florida USA Registered: Aug 2002
I really don't understand what is so hard about understanding that if you add a front caliper with a bigger piston on a stock system, and it requires more pedal travel to fill the piston, but, the rear piston is still stock and smaller, that the pedal pressure will have to go way up to stop the car.
I think I know the difference between scary soft stomper and strong hard pedal.
The GA front with stock rear calipers makes the pedal have to travel farther and makes it softer. The larger pistons both fore and aft, whether GAx4 or GA/Seville, with the S10 booster, maintain correct balance and give you a much superior braking package than stock can achieve with its smaller brake booster and smaller caliper pistons.
I agree, if you want cheap, then do just GAx2 and forget the x4. But, please don't kid yourself. Mis-balanced brakes are not a good idea. They aren't particularly safe, and they could land you in the ditch or on a tree in the right circumstance. But, it's your call.
Arn
Why is the brake booster such a big deal? The brake booster doesn't have anything to do with the volume of brake fluid going to the brakes... all it does is provide braking support by means of a vacuum diaphram so you don't have to push the pedal as hard. Are you sure you're not talking about the brake master cyl? I already have a larger bore brake master cyl... although I plan to rebuild it anyway since it's already about 5 years old now.
1. It illegal to use front brake on rear axle and not use a separate parking brake. Any business sell or working on illegal part needs a vary good lawyer if/when business get sued. see cave, link section under main menu. look at USCODE and FMVSS.
This is Federal rule and law... Cops/DA/etc can enforce FMVSS and USCODE even if state doesn't have state rule/law. Insurance Co. uses any law/rule it can decline payment and cancel policy when car is in a wreck.
2. "Good" option: GA front, https://www.fiero.nl/forum/Forum2/HTML/083566.html in back, and bigger MC. Main improvement is vented rotors. Hydraulic and mechanic is about the same as OE system. Do the math on your time... Most math in cave article...
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
1. It illegal to use front brake on rear axle and not use a separate parking brake. Any business sell or working on illegal part needs a vary good lawyer if/when business get sued. see cave, link section under main menu. look at USCODE and FMVSS.
This is Federal rule and law... Cops/DA/etc can enforce FMVSS and USCODE even if state doesn't have state rule/law. Insurance Co. uses any law/rule it can decline payment and cancel policy when car is in a wreck.
2. "Good" option: GA front, https://www.fiero.nl/forum/Forum2/HTML/083566.html in back, and bigger MC. Main improvement is vented rotors. Hydraulic and mechanic is about the same as OE system. Do the math on your time... Most math in cave article...
Ogre, I appreciate your advice, and agree, I definitely want to have the use of the emergency brake.
So, I read through Arns85GT thread, and came across a comment that you made:
"This means that even before anyone messes with prop valves, the car has a little less brake on the back and therefor less likely to spin out etc."
Are you suggesting here that having less rear brake bias than on the front would help eliminate the chances of the rear wheels coming around? This is what I thought initially as well, but it's been explained to me now that this is not the case. Is that what you meant, or am I mis-reading you?
most people think rear brake lockup is good... wrong. Almost all cars are bias to front.
Lockup in back can spin the car. GM etc set brake so the car will not spin out for back brake lockup. (Look into "unsafe at any speed" by Nader... GM Corvair (sp?) screwed up brake bias in some settings and end result, Nader wrote a book.)
Think: Car weight shift to back in burnout. Need bigger tire in back... Car weight shift to front when stopping. Need more brake in front.
And Higher speed = more weight shift to front when stopped!
Doesn't matter vehicle involve. Car, even a bicycle, get weight shift toward front in stopping. (You can tell nube cyclist. Uses back brake only or over brake in front and goes over steering bar...)
Think Mid engine Fiero has different rule? Not. Is a Physic Rule... Even Porsche mid/rear engine have front bias on most models.
Most OE prop valve doesn't work in most stopping, only use in panic stop settings. Most people think all bias is done by a valve but their wrong most times. Prop valve think regulator and activate until 800-900PSI from MC. Prop valve doesn't activate in normal use. Many other way to give you Bias, Fiero and most GM models included. If only valve give you Bias then when valve is dead, Bias is dead... and likely only warning is car get spinning around.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
most people think rear brake lockup is good... wrong. Almost all cars are bias to front.
Exactly correct. A rolling tire develops more traction (i.e. friction force) than a sliding tire, and it has a strong tendency to roll straight ahead..
Front brakes lock first: Loss of steering control, but rolling rear wheels cause the car to travel more or less straight ahead. (Physics: With the front brakes locked the car's center of traction is behind the center of gravity. => positive stability)
Rear brakes lock first: Car swaps ends ... kinda' the ultimate loss of steering control. (Physics: With the rear brakes locked the car's center of traction is ahead of the center of gravity. => negative stability => unstable)
In a street-driven car, positive stability under all conditions is more important than absolute maximum braking deceleration. In a race car, stability margin may be traded for slightly higher peak braking performance, but that is under controlled conditions with a presumably skilled driver, and even then you will still not see a competitive race car with significant rear brake bias. You will definitely not see a race car where the brakes are intentionally set up to lock the rears first.
[This message has been edited by Marvin McInnis (edited 11-01-2010).]
most people think rear brake lockup is good... wrong. Almost all cars are bias to front.
Lockup in back can spin the car. GM etc set brake so the car will not spin out for back brake lockup. (Look into "Safe at any speed" by Nader... GM Corvair (sp?) screwed up brake bias in some settings and end result, Nader wrote a book.)
Think: Car weight shift to back in burnout. Need bigger tire in back... Car weight shift to front when stopping. Need more brake in front.
Higher speed = more weight shift to front when stopped.
Doesn't matter vehicle involve. Car, even a bicycle, get weight shift toward front in stopping. (You can tell nube cyclist. Uses back brake only or over brake in front and goes over steering bar...)
Think Mid engine Fiero has different rule? Not. Is a Physic Rule... Even Porsche mid/rear engine have front bias on most models.
Most OE prop valve doesn't work in most stopping, only use in panic stop settings. Most people think all bias is done by a valve but their wrong most times. Prop valve think regulator and activate until 800-900PSI from MC. Prop valve doesn't activate in normal use. Many other way to give you Bias, Fiero and most GM models included. If only valve give you Bias then when valve is dead, Bias is dead... and likely only warning is car get spinning around.
I have a small block in the back of my Fiero and a Norms flipper hood in the front so I put a wight in the back and took wight out of the front. I have yet to lock up the brakes and spin out, the Fiero is pretty nimble and I have drove out of all of the close calls so far. I wouldn't suggest anyone just bolt up different brake parts that are not made for the car or balanced. What I have seems to work but it may be a one in one million.
The problem...you get a bunch of weekend warrior mechanics taking 20 year old parts off a 20 year old car, then testing the mods and saying they felt a huge difference.
Yeah! No **** .
Replace all the stock parts...lines, pads, calipers and rotors with new stock parts, and go and test it.
Guess what? It feels like a new car!
I've seen pictures of people doing some wonky **** on this forum..and others regardng modifications and it gets scary.
When we rebuilt Jezebel (85 GT) She got "new" rebuilt brakes all around, as well as new braided lines, and the system cleaned to perfection.
She stopped nicely. Now that she has the Grand Am upgrade she stops very nicely*.
Jezebel got the best of everything when being rebuilt, no "crap" parts, no modifications. At the time I was wanting pure stock, no cheap aftermarket, no shortcuts.
I however have not mixed my brakes so I cannot join the current discussion.
Brad
*Jezebel had a heart attack a while back, and is awaiting funds for the 4.9 transplant.
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12:35 PM
Black Lotus Member
Posts: 340 From: Washington State USA Registered: Jan 2010
most people think rear brake lockup is good... wrong. Almost all cars are bias to front.
Lockup in back can spin the car. GM etc set brake so the car will not spin out for back brake lockup. (Look into "Safe at any speed" by Nader... GM Corvair (sp?) screwed up brake bias in some settings and end result, Nader wrote a book.)
Thanks Ogre, I appreciate it. That's pretty much what I thought, but was just getting a little bit confused. I'd rather beat a fake horse to death 10 times and do it right the first time, than spend money on a whim, and then have to re-do it again.
quote
Originally posted by Black Lotus:
Hope you're not going to use this CRAP tire. The rubber is probably hard enough to use as a file. It will end up killing you.
Dude, I don't know what you're talking about, those tires are just fine... seriously. You realize these are Firestones, right? They have an impeccable record for safety and reliability. I don't change out my tires until I start to see metal bands exposed.
Hah... no, I'm just kidding. Yeah, I know... they're awful. My car hasn't been driven, except in and out of my garage in something like 6 years. And honestly, the last 2 years before then, I only drove it about 6 miles at about 35mph on a back road while moving it from my dad's house to my house that I bought 6 years ago. So really, I haven't driven the car in 8 years. Those tires are on there while I'm rebuilding my car. I'm going from front to back, replacing and rebuilding every single component. All new hoses, all new brake and suspension components, repainting everything except the body panels, new rubber seals, brake lines, clutch lines, it's being converted from an auto to a manual, and a bunch of other stuff. I'll get new tires before I get it registered, but for right now, it's enough to keep the car supported off the ground.
They are actually Firestones though! haha... I bought them like 10-11 years ago I think.
EDIT: They are REALLY hard too... and all four of them have a very pronounced crack running along the interior diameter (as you can see in the picture). The front tires are much worse (almost bald) than the rear from all the understeering I used to get 9-10 years ago when I used to drive like a stupid kid. I also have to refinish the wheels too.
The one thing that I remember reading about the Grand Am brakes on the front was regarding the cut down Fiero hubs and the tolerances in the GA rotors.
As the story goes, if the center hole and the stud holes in the rotor were just a bit too big, it would allow the rotor to move "off center" relative to the hub and the wheels, and cause the assembly to be out of balance. (I can believe that even a little bit of movement here would be "bad"TM.)
This, and some other items, are also covered in The Ogre's article. A worthwhile read.
