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Brake upgrades by Daryl M
Started on: 02-18-2021 05:22 PM
Replies: 21 (442 views)
Last post by: BillS on 02-23-2021 11:52 AM
Daryl M
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Report this Post02-18-2021 05:22 PM Click Here to See the Profile for Daryl MClick Here to Email Daryl MSend a Private Message to Daryl MEdit/Delete MessageReply w/QuoteDirect Link to This Post
When you all consider brake upgrades, how often is unsprung weight considered? It would seem that going from small, relatively light disks to 12 or 13 inch vented rotors would add a bunch of weight.
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DimeMachine
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Report this Post02-18-2021 06:09 PM Click Here to See the Profile for DimeMachineSend a Private Message to DimeMachineEdit/Delete MessageReply w/QuoteDirect Link to This Post
Unsprung goes up further if you go from the stock aluminum calipers to steel..
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Daryl M
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Report this Post02-18-2021 06:15 PM Click Here to See the Profile for Daryl MClick Here to Email Daryl MSend a Private Message to Daryl MEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by DimeMachine:

Unsprung goes up further if you go from the stock aluminum calipers to steel..


88s already have calipers that are half steel. Bigger diameter trims also weigh more than stock, not to mention bigger tires. All of that changes handling. Not sure how much though.
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cvxjet
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Report this Post02-18-2021 06:43 PM Click Here to See the Profile for cvxjetClick Here to Email cvxjetSend a Private Message to cvxjetEdit/Delete MessageReply w/QuoteDirect Link to This Post
I switched my 85 SE V6 to 88 brakes- In the rear I switched the subframe/suspension to 88 and the brakes came with that.....Up front I bought Sluppy123 adapters and ALUMINUM hubs, so although I had to go up to 12" Vette discs the weight overall stayed the same.

On the tire/wheel problem, I installed 16 x 7" wheels that only weigh 14 lbs each and General G-Max tires which are lighter than most other tires (By 2-4 lbs) in sizes 205/55 and 225/55 which were sizes very common on a number of cars back in the 80s and 90s so are available from a number of manufacturers.
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thesameguy
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Report this Post02-18-2021 07:12 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Roughly the same approach - added a little brake weight, took away a little wheel/tire weight.

If the choice comes down to reliable, repeatable stopping and a little extra weight, I'll take that deal every time. I found the stock brakes ... inadequate for how I like to use the car.
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Report this Post02-18-2021 07:57 PM Click Here to See the Profile for pmbrunelleClick Here to Email pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
If fade resistance is a metric you wish to improve with a brake modification, weight gain is intrinsic to the mod.

You need rotor mass to absorb heat, and you need rotor size to dissipate it.

My consideration for unsprung weight with regards to a brake modification is that yes, it will increase, do it anyway.
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Report this Post02-19-2021 04:45 AM Click Here to See the Profile for FrenchrafeClick Here to Email FrenchrafeSend a Private Message to FrenchrafeEdit/Delete MessageReply w/QuoteDirect Link to This Post
My experience with this is that our cars are not highly lightened race cars!
We are not driving prototypes!

A little more unsprung weight is more than compensated by better heat dissipation and better brakes.
I race against Lotus and while I can never handle in the turns like they do, I can brake a little later and with my power I can accelerate out of the turns harder, so keeping up and even overtaking a better handling but lower powered Lotus.

As well, our brake upgrades use cost effective off the shelf parts. Try doing a big brake upgrade on something more exotic! Loads of money!

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. Sticky tyres. Driven hard!
https://www.youtube.com/cha...1wZvWQlkYxTjivW_0XNg

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Report this Post02-19-2021 09:36 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
As mentioned above, this is a case of "give and take". You want good brakes? That will usually involve more unsprung weight. You have to decide for yourself if being able to stop the car safely is worth the small impact on handling.

That said, you can do things to counteract some of the weight gained. Mentioned above was the lighter tire & wheel combo. That's especially effective, because it also reduces rotating mass. And I used Wilwood aluminum calipers (instead of iron) in my front brake upgrade, to minimize the added weight. Stiffer shocks will help to control the extra unsprung weight.
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Will
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Report this Post02-19-2021 11:41 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
Two piece rotors with aluminum hats drop a little weight as well. They don't even have to be expensive... I'm looking at 12 3/16 x 1.25" units that are $85 each from Wilwood.
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fieroguru
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Report this Post02-19-2021 09:48 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
It is all about balancing your goals with your pocket book and optimizing the benefits of your decisions.

Increasing rotor diameter improves the mechanical leverage the calipers have to stop the car. They also have more surface area for air to cool them to reduce brake fade.

Increasing rotor width helps with air flow and cooling (fade resistance), but normally adds even more weight than the same diameter rotor that is thinner.

With the 88s, the bang for the buck is larger rotor, but keeping the thickness close to the stock width. This keeps weight down, and also saves $$$ as the stock calipers can be retained.

When I developed my 13" brake kit, I was looking for the largest/lightest rotor with the proper offset and ended up with a rotor that is about 6.5 lbs heavier than stock per corner. The 13" rotor gives 33% more mechanical advantage with the stock 88 calipers, which is a very noticeable improvement.

The 12" C4 rotor is only about 3 lbs heavier than stock 88 and provides a 21% increase is mechanical advantage. This is a very good compromise of benefit vs. weight, but fitment and needed clearance work are the two main drawbacks and why after running it for 8 years I developed my own brake kit. Since this rotor is for a Vette, lighterweight 2 piece rotors are available and could keep the weight gain near zero, but it will cost about $1000 for the hats and rotors.

The rotor diameter change also impacts the wheels and tires you can run.
12" C4 rotor requires 16" wheels on an 88.
My 13" rotor kit requires a 17" wheel (but I have installed it in 16x7 35et wheels with some caliper and brake hose bolt clearance work)

Larger/wider wheels adds more weight, but you get stiffer sidewalls and wider tires which allows you to run softer/stickier compounds with good tire life - even with 200 or less treadwear.

Having ran a 205/245 stagger in a stock weight fiero with 3x the stock power and 33% more brake leverage, I found the front tires and rear tires lacking... 225/285 is what I wanted, but couldn't find both widths from the same mfg and model tire with 200 treadwear so I settled for 235/285.

The issue with wheel width is that it sometimes forces you to upsize the diameter as well.. to go much over 8.5" on an 88 requires an 18" rear wheel to clear the knuckle clamp flange on the strut. So I had to have an 18" rear to get to 9.5" width, but didn't want the extra weight of the 18" wheel up front, so I focused on a 17" wheel. Finding a 17/18 with 8"/9.5" widths in a 5x100 pattern is a challenge by itself, but keeping weight to a minimum and cost down... took quite a bit of research.

For comparison,
Stock 14" wheel with a 215/60/14 tire - it weights 32 lbs. Pretty light, but sloppy performance... light or not, I would never enjoy driving my car with this combo.
Stock 15" wheel with a 215/60/15 tire is ~ 40 lbs. This is really the benchmark of wheel/tire weight for performance.
16x7 35et Millie Miglia MII with 205/50/16 tire weights 41.2 lbs. Little heavier, but allows 12" brakes and stiffer side wall.
18x9.5 Enkei Kojin w/ 285/30/18 weighs 45.2. So about 5 lbs heavier but can fit 13"+ brakes and 285 wide tires.

So 33% better brakes and 285 sticky rear steamrollers for a 12 lb (less in front) weight penalty per wheel/tire... For a stock powered Fiero the car will accelerate slower, with 3x the stock power the added weight is is easily overcome.

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skywurz
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Report this Post02-19-2021 11:15 PM Click Here to See the Profile for skywurzClick Here to visit skywurz's HomePageSend a Private Message to skywurzEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:


Stock 15" wheel with a 215/60/15 tire is ~ 40 lbs. This is really the benchmark of wheel/tire weight for performance.



Technically on 88 the front should be 205 with a narrower wheel so the front weight would be less. But im nit picking great layout!
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fieroguru
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Report this Post02-20-2021 07:08 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by skywurz:
Technically on 88 the front should be 205 with a narrower wheel so the front weight would be less. But im nit picking great layout!


Yes, the stock 88 15" wheels have a staggered width and the fronts are narrower, but the overall weight is the same.
The difference in tire weight between the 205/60/15 and the 215/60/15 is about 1 lb. The narrower 88 front 15" wheel weighs about 1 lb more than the 15" rear wheel due to having a wider flange on the inside surface of the wheel.

I chose to focus on the rear 15" wheel as it is virtually the same across the 88s and non-88s (main difference is placement of the valve stem) so a good comparison could be made with the weight difference between it and some really large/wide wheels/tires.

Here is a picture of this wider inside reinforcement on the 88 front (it also makes fitting larger rotors front/rear more of a challenge as things fit the rear, but won't fit the front due to this wider rib).


Here is the rear for reference:

[This message has been edited by fieroguru (edited 02-20-2021).]

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skywurz
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Report this Post02-20-2021 01:12 PM Click Here to See the Profile for skywurzClick Here to visit skywurz's HomePageSend a Private Message to skywurzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for that ***The more you know*** My front's just always felt lighter to me i never actually weighed them.
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cvxjet
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Report this Post02-20-2021 03:49 PM Click Here to See the Profile for cvxjetClick Here to Email cvxjetSend a Private Message to cvxjetEdit/Delete MessageReply w/QuoteDirect Link to This Post
You need to balance between added weight and performance- If you are on a flat track and doing multiple laps, then BIG brakes will help you. But if you are driving on streets and every so often do a little performance driving, then the stock brakes are ok.


I have 88 calipers front and rear with 12" and 10.5" vented discs.....I go up Mines road or Redwood road and crank thru some curves, of course using the brakes but I only drive hard for maybe 5-10 minutes at a time. Never noticed any fade- even with the original solid disc brake system.

My wheels are 16 x 7 and my tires are the aforementioned General G-Max 205/55 and 225/55.......Weight is 36 lbs for each front and 38 lbs for each rear. The FEEL of the car is much better than when I had the heavier 15 x 7 wheels and 215/60 and 225/60 BFG tires (approx' 42 front and 43 rear)....The car used to feel club-footed but now feels very good- agile....And a professional driver tested my car and was actually impressed.

We tend to always think "BIGGER is BETTER!!!" and sometimes that is true- but remember what Colin Chapman (Of Lotus) used to say; Add Lightness

Think of the really dumb guys nowadays that install "dubs" on their cars....I have seen a couple of these sitting on the side of the road because an axle/spindle broke- They don't drive worth a crap! Or how about those guys who don't just lower their car- they LOWER!!! their car, until the tires are rubbing, the suspension bottoms all the time, and their wheels stick out at 30* angles...Anyone who knows suspension knows that those extremes are absolutely idiotic.

Here is a pic of my car as it looks now.....It could have 12" discs all around but I kept the 10.5" Fiero discs in the rear to save some weight (Even Porsche 911s have smaller disc in back)

[This message has been edited by cvxjet (edited 02-20-2021).]

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Daryl M
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Report this Post02-20-2021 09:22 PM Click Here to See the Profile for Daryl MClick Here to Email Daryl MSend a Private Message to Daryl MEdit/Delete MessageReply w/QuoteDirect Link to This Post
My project car was purchased in pieces, so I was missing brakes to begin with. I don't know how much a stock 88 rotor weighs, but the Chevy Terrain 13" rotors I am considering are about 17 pounds each. Add the caliper adapter plates and the weight goes to about 70 pounds for 4. How does that compare to 4 stock rotors?
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fieroguru
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Report this Post02-20-2021 09:51 PM 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 Daryl M:

My project car was purchased in pieces, so I was missing brakes to begin with. I don't know how much a stock 88 rotor weighs, but the Chevy Terrain 13" rotors I am considering are about 17 pounds each. Add the caliper adapter plates and the weight goes to about 70 pounds for 4. How does that compare to 4 stock rotors?


Stock 88 brake rotors are about 11 lbs. So a 17 lb rotor is 6 lbs heavier per corner.

I suspect you are looking at the 13" Traverse rotor (my 13" kit was developed using this rotor - GM Lambda platform) as the Terrain rotors are only 12" in diameter and the rears are too deep to be used on the 88s and the fronts are too thick to work with the stock 88 calipers.
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Daryl M
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Report this Post02-20-2021 11:35 PM Click Here to See the Profile for Daryl MClick Here to Email Daryl MSend a Private Message to Daryl MEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:


Stock 88 brake rotors are about 11 lbs. So a 17 lb rotor is 6 lbs heavier per corner.

I suspect you are looking at the 13" Traverse rotor (my 13" kit was developed using this rotor - GM Lambda platform) as the Terrain rotors are only 12" in diameter and the rears are too deep to be used on the 88s and the fronts are too thick to work with the stock 88 calipers.


You are correct. I ordered and drilled the rotors and they seem to fit nicely. My tire/wheel combo weighs 49 pounds R 255-45r18, and 42 pounds F 225-45r18. I don't know how that compares to stock wheels/tires.
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fieroguru
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Report this Post02-21-2021 08:08 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
The stock 15" wheels and tires are about 40 lbs. per corner.
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cliffw
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Report this Post02-21-2021 07:38 PM Click Here to See the Profile for cliffwClick Here to Email cliffwSend a Private Message to cliffwEdit/Delete MessageReply w/QuoteDirect Link to This Post
I don't usually weigh in here nor offer advice, and rarely ask for it.

From our "Mall", years back.

Bigger Brake Booster ($100 brake upgrade)

I forget the exact user name of this forum that made me aware of it FieroSE I think, no, ? "Darkrams" I dunn know.

He had a North Star mod and he swore by it. How much weight and balance could a brake booster cause ?
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Daryl M
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Report this Post02-22-2021 01:54 PM Click Here to See the Profile for Daryl MClick Here to Email Daryl MSend a Private Message to Daryl MEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by cliffw:

I don't usually weigh in here nor offer advice, and rarely ask for it.

From our "Mall", years back.

Bigger Brake Booster ($100 brake upgrade)

I forget the exact user name of this forum that made me aware of it FieroSE I think, no, ? "Darkrams" I dunn know.

He had a North Star mod and he swore by it. How much weight and balance could a brake booster cause ?


The brake booster doesn't really improve braking. You still have stock brakes, you just have more help pushing the pedal. If you want to actually improve braking and reduce brake fade, you have to disapate heat and increase the diameter of the rotor or increase the pressure without increasing stored heat. That is why performance cars have larger diameter vented rotors .

[This message has been edited by Daryl M (edited 02-22-2021).]

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cvxjet
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Report this Post02-22-2021 02:50 PM Click Here to See the Profile for cvxjetClick Here to Email cvxjetSend a Private Message to cvxjetEdit/Delete MessageReply w/QuoteDirect Link to This Post
One thing that hasn't been discussed is ducting air to the hub centers to give more cool air flow for cooling the brake discs......Attach ducts to the radiator side flashing and then run them in (To clear turned wheels) and aim the air at the center of the hub.....same in the rear (No- not from the radiator! What do you think I am....Stupid? (Don't answer that!)
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BillS
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Report this Post02-23-2021 11:52 AM Click Here to See the Profile for BillSClick Here to Email BillSSend a Private Message to BillSEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by pmbrunelle:

If fade resistance is a metric you wish to improve with a brake modification, weight gain is intrinsic to the mod.


Well not completely. The first mod everyone should try entails zero weight addition - finding a pad material that is optimal for the car and the way they drive it. If you are still experiencing fade after that, then I agee - you'll have to incur a bit of added weight to make any additional difference. BTW, FWIW, I found the 88 brakes to be considerably better than my 87s. Unfortunately the 88 is a bit of an orphan in terms of aftermarket parts availability.....

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