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My brake conversion and parts, please correct me if I'm wrong by way2qik4u
Started on: 02-01-2019 12:12 PM
Replies: 13 (362 views)
Last post by: fieroguru on 02-02-2019 09:38 AM
way2qik4u
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Report this Post02-01-2019 12:12 PM Click Here to See the Profile for way2qik4uSend a Private Message to way2qik4uEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm doing a brake conversion on my 86gt ......I wanted to pass my parts list by the many who have had experience in this swap to make sure I'm getting the right parts. It's a LeBaron conversion. First off is the purchase of (4) rear, 89-94 Chrysler LeBaron rotors. I will be using 85 Camaro front calipers up front and rear 85 Seville calipers in the rear to preserve the ebrake. Now going down the list and after reading extensive views on the subject I have decided to go ahead and install the larger master brake cylinder along with the larger vacuum brake booster, but here is where I go astray I'm getting conflicting answers on the years of those parts to use. Some say use the MC and booster off a 1997 s10 part number on the booster is 54-71061. While others say to use the MC and booster off a 1994 s10. I have run the part numbers and between the years the parts carry different numbers........So I would say my biggest question is will both these setups work the same as each other?

I have read that Rodney and one other gentleman are offering the booster part number 54-71061 already has or ready to accept the longer brake rod adapter for the booster. The reason why I mention the 54-71061 1997 booster is that I have access to one for free new in box!.........please anybody with anything to say on this subject respond.. answers, questions all welcome!..............lengthening the push rod is really no big deal being one of my trades is that of a welder

What I do know is the LeBaron swap will fit my aftermarket 15-inch wheels, the 15-inch wheels are why I had to go LeBaron and not corvettes 12 inches, that one would not fit into the wheel

The reason why I decided to do all replacements of the mc and booster is that of time. We already know that after the larger calipers are used the stock mc will offer a softer longer travel so that is why the mc change. We also know a change to a larger MC would give a harder feel to the pedal yence the booster change. I wanted to make all steps in a single work period and brake bleed.......It has come to my attention that some of you have gone to using the Master Cylinder 10-2352 that comes on a 2000 cadillac for its quick take up and use in 4 wheel disc setups, anybody using one of these or have more information on its use?

[This message has been edited by way2qik4u (edited 02-01-2019).]

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Report this Post02-01-2019 02:11 PM Click Here to See the Profile for wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
I did the same swap about 10 years ago. I did not change the master cylinder nor did I do the booster upgrade. To me the pedal did not feel much different than stock. From everything I have read, the booster upgrade helps a lot if you are running stock brakes. Once you go with the bigger calipers and rotors you get more braking without the extra vaccuum boost. The real problem with bigger brakes is premature wheel lock up when you really have to stomp on them. Almost always the right front. Using smaller calipers on the front helps but they cost a lot more money than the calipers you are going to use. It helps to understand what is really going on with your brake circuitry. This is a good thread : //www.fiero.nl/forum/Forum4/HTML/064690.html
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way2qik4u
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Report this Post02-01-2019 02:17 PM Click Here to See the Profile for way2qik4uSend a Private Message to way2qik4uEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for the link...........Now thinking on what you said do you think I may end up with a system that is too powerful and prone towards lock up? I would go through step by step, as in, first the big brakes then see if the MC needed changing and then the booster but I wanted to save time with doing it all at once.
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Report this Post02-01-2019 02:25 PM Click Here to See the Profile for wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
I would just do it starting with the front brakes, try it out, do the rears try it out etc. Easier to see what problems might develop. The right front lockup is a known problem with the LeBaron swap though. This used to be available to solve the problem: //www.fiero.nl/forum/Forum4/HTML/064690.html
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way2qik4u
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Report this Post02-01-2019 03:25 PM Click Here to See the Profile for way2qik4uSend a Private Message to way2qik4uEdit/Delete MessageReply w/QuoteDirect Link to This Post
I did move my battery to the front right in order to offset this lockup tendency.........can you tell me more about the system you did have and your thoughts on it. Nothing comes close to talking to a guy who has actually done the swap, I assume it was worth it?..you did both front and rear and kept the stock MC and booster right?

Correct me if my figures are wrong but couldn't the front lockup be contributed to the front caliper being a piston of 2.5 versus the backs 2.125 ? so what would happen if I used the same piston diameter caliper both front and rear wouldn't that switch more bias back towards the rear? I realize I might have to use an aftermarket caliper to do that such as a Wilwood.
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Report this Post02-01-2019 05:34 PM Click Here to See the Profile for wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
I initially installed the front and rear LeBaron system, virtually identical to what you are going to do. It does give better stopping power but the right front lockup problem was there right away. I already had my batterry in the front. The problem was not as bad with the stock 2.8 engine in the back vs going to the lighter ecotec 2.2 motor. I never did get the kit parking brake to work. So to save weight I went to Willwood aluminum calipers, 2.5" single piston all the way round with no parking brake. The problem was still there. I went back to the stock rear setup to further save weight and to gain back a parking brake.
The problem got worse. Changed the front calipers to some 2 piston Willwoods with a smaller total bore size. Problem got much better but still there. At the time the calipers I had just bought were the smallest bore area you could get from Willwood in a GM metric style caliper.
Still determined to get rid of the problem, I did some some research in to disabling the stock prop valve and putting a brake adjusting valve on the front brakes. The Fiero brake system puts too much braking on the front and not enough on the rear of the car. The cars that the brake adjusters are designed for (60's and 70's muscle cars mostly) have too much braking on the rear brakes. So these adjusters are designed to reduce rear braking, not increase it.
So disabling the prop valve and putting an adjusting valve on the rear brakes was not going to help. So then I put an adjusting valve on the front. Although on Wilwoods web site the valve I used is called a proportioning valve, it really isn't. There is no interaction between the front and rear brake circuits like happens while pushing harder and harder on the pedal with a stock Fiero prop valve. The Willwood valve just restricts the flow on whichever brake circuit it is on. With the stock prop valve disabled it then just becomes a fluid junction, so I have my adjuster valve on the front circuit.
I tested it by first giving the front brakes full power and then slowly closed the valve until I could get the rears to lock up slightly. Then I gave slightly more power to the fronts until the rears could not lock up any more.

So the way my brakes work now both fronts can be locked up but only at less than 15 mph and I have to stomp on them. Stops from high speed with no lockup at all, just push as hard as I want. I have tested the system on the track and I am very happy with it.

If you go to member Blacktree's thread in the construction zone, you will see that he is using a single piston Willwood caliper with a bore of 2" on the front and I think a Seville caliper on the rear. And a very specific stock prop valve (not all years are the same). He claims that this will cure the lock up problem but he has not posted much about his brakes lately.

The front calipers Blacktree is using are the ones that were not available to me. If you use those calipers and the stock prop valve he recommends, I think you would have a pretty good setup, and much easier than the way I did it. And I do not recommend that anybody copy what I did because it is just too far off the wall for people with limited experience with brake systems.
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Report this Post02-01-2019 06:27 PM Click Here to See the Profile for way2qik4uSend a Private Message to way2qik4uEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for putting in so much of your time putting into detail your brake system. One thing I did not mention is it no longer has the v-6 in it, in place, there is a very warmed over LS1 v-8 . I'm not sure if that will help or hurt the front brake lockup problems. I run a rather large tire both front and especially in the rear. It does sound to me that I should try and run the same caliper piston size in the front as in the rear......do you mind me asking what was the problem you were having with dealing on the ebrake? I would just get rid of it but the laws here are pretty tight concerning safety and needing an ebrake setup. I did hear from a few in this forum that like you, they also used a proportionating valve in the front but they never came back to tell if it worked or not.

I will follow up on reading blacktrees posts in the construction zone....thanks again
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Report this Post02-01-2019 06:39 PM Click Here to See the Profile for wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
The problem with the kit ebrake was the flimsy bracket that held the cable in place. Pull up on the ebrake handle and the bracket bent and no brake engagement. I am sure something better could be fabbed up but I did not try. I just went through Blacktree's thread and I noticed he has stock 88 rear brakes. So somewhere he has done a cradle swap as well. I could not find where he mentioned what prop valve he used. Maybe just a stock 88? They are closer to a 50/50 split if I understand correctly. I enjoy posting all this stuff so you are welcome.

I would think that the heavier motor and the large tires would help reduce the lock up problem. I have 205/50/16 front and 245/50/16 rear BFG comp2 AS tires now. I wanted to go to a 215/255 setup but not available for 16" rims. But I am really happy with my new tires, for all season tires they are really grippy.

[This message has been edited by wftb (edited 02-01-2019).]

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Report this Post02-01-2019 07:57 PM Click Here to See the Profile for way2qik4uSend a Private Message to way2qik4uEdit/Delete MessageReply w/QuoteDirect Link to This Post
Reading what you have taken the time to post has raised a new thought process for me. I think now I can make a system that will be a little rear bias then use a valve to get it right on the money, figuring it out right now and will post my results right here as soon as I see any.......this is all on paper of course
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Report this Post02-01-2019 09:07 PM Click Here to See the Profile for way2qik4uSend a Private Message to way2qik4uEdit/Delete MessageReply w/QuoteDirect Link to This Post

way2qik4u

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WFTB what do you think of this all........since we used rear Seville calipers with a piston area of 3.55 along with front Camaro calipers with an area of 4.83 it is no wonder the fronts are locking up. When taking the piston areas into account we are way front bias in our braking and that is why you going to a smaller Wilwood piston made some difference.

So if we take all this into account why don't I start with a rear Seville one as before but this time try and match it with a similar piston area in a Wilwood front caliper. So once again the Seville one is 3.55 area and looking into Wilwood calipers they have a Dynalite dual piston that has an area of 3.00. All else being equal that should put us a little rear bias don't you think? So on my 15 inch wheels, I can only fit a stock rotor of the lebarons 11.26 but in taking measurements in the front I can put a Wilwood 11.75-inch caliper to replace the lebarons thus moving the bias a little more to the front due to increase leverage on the rotor. Now taking into account the stock fiero has a piston area of 2.81 and now we have a larger piston area the pedal should travel a little bit more do to increase volume needed for larger calipers but should have close to the same feel in hardness. When talking of this if a person wanted overall more power from the braking system then all they would have to do is go to a larger MC and brake booster.....so what we have here at least on paper is a braking system that by itself would be close to a 50/50 bias

If you can shoot holes in the theory then please do but in my mind, at this time this is what we get.
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Report this Post02-01-2019 10:45 PM Click Here to See the Profile for wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
The only Wilwood caliper that fits the LeBaron brake brackets is the D154 replacement type. The Wilwood 2" single piston caliper gives an area of 3.14" in a d154. Pretty close to what you are looking for, for front calipers. Dynalites won't work without a custom bracket. And if you go with an 11.75" rotor there may be clearance issues on 15" wheels. I think you are on the right track otherwise with this combination.

[This message has been edited by wftb (edited 02-01-2019).]

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Report this Post02-01-2019 10:55 PM Click Here to See the Profile for way2qik4uSend a Private Message to way2qik4uEdit/Delete MessageReply w/QuoteDirect Link to This Post
yes the spacing for the bracket would be smaller 5 1/4 for the dynalight., so the d154 might be a better choice.I have a friend around me who has Wilwood 11.75 rotors and I borrowed one of his to test fit in my wheel and it just makes it if I went to the 12 inch it would not clear. ...... Turns out Wilwood makes a hat that is just about the right offset and has the fiero bolt pattern

Since we are basically right around the same area of pistons as a stock fiero the pedal should be around the same as stock and stock to me requires too much force for lockup if desired. So back to one of my original questions and that is what brake booster and what master to use?

[This message has been edited by way2qik4u (edited 02-01-2019).]

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Report this Post02-01-2019 11:11 PM Click Here to See the Profile for wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
Do a search in the mall but if I recall right Sardonyx? makes up an S10 booster kit that seems a popular choice. Can't answer about what MC to use because mine is stock.

//www.fiero.nl/forum/Forum4/HTML/060500.html

[This message has been edited by wftb (edited 02-01-2019).]

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Report this Post02-02-2019 09:38 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by way2qik4u:

yes the spacing for the bracket would be smaller 5 1/4 for the dynalight., so the d154 might be a better choice.I have a friend around me who has Wilwood 11.75 rotors and I borrowed one of his to test fit in my wheel and it just makes it if I went to the 12 inch it would not clear. ...... Turns out Wilwood makes a hat that is just about the right offset and has the fiero bolt pattern

Since we are basically right around the same area of pistons as a stock fiero the pedal should be around the same as stock and stock to me requires too much force for lockup if desired. So back to one of my original questions and that is what brake booster and what master to use?




When you move the caliper further from the wheel center to accommodate a larger brake rotor, you increase the leverage the caliper has on stopping the car (as well as improve fade resistance). This works very well and allows an otherwise stock brake system an increase in braking potential.

Simply put, adding the larger rotors will improve your ability to lock up the tires with less pedal effort, without changing anything else in the brake system.

Note: lockup isn't a sign of good brakes or something you should aspire to, as when you lock the wheels up, stopping distance increases and you lose the ability to control the direction of the car. For example, put crappy tires on the car and you will be able to lock then up easily, but stopping power will be poor. At the other extreme, put crappy pads on and you won't be able to lock the tires, nor will the car stop well.

What you should aspire to is maximizing the ability to stop the car as fast as possible while retaining the ability to modulate the brakes to the verge of lockup w/o going into lock up.

Start with the best tires for your application (something close to 200 treadwear), use the best pads for your application, then focus on increasing the braking potential. The 3 primary methods to do this are:
1. Increase caliper leverage - larger rotor upgrade

2. Increase clamp force at caliper by using calipers with a slightly larger piston area - be careful here as if you go too large, then you need a larger master for proper fluid flow and will partially negate the benefit of the larger piston area.

3. Increase brake line pressure by using a "smaller" master or by installing the S10 brake booster. Note, this gain happens before the Fiero combination valve, so the gains front and rear will not be the same, nor will they linear.

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