quote Originally posted by pmbrunelle: I am speaking from a brake bias point of view. Normally, brakes from a front-engine car are not suitable for a rear-heavy mid-engine car. Brakes taken directly from a front-heavy car swapped into a rear-heavy car will result in the rear brakes doing less than their share of work, and premature front wheel lockup. Best results (stopping distance) are obtained with approximately the same hardware at all 4 wheels; that is: Identical discs (same diameters) Identical calipers (or similar piston areas) I was unhappy with my LeBaron swap until I changed the front 2-1/2" calipers for 2-1/4" ones. They are a better match for the 2-1/8" rears - not perfect, but I'm satisfied now. It really is worth the research to find well matched calipers. If you're intent on using Nissan calipers, you will probably have to mix and match between different models. Another alternative is to use 4 identical calipers all around, with mechanical spot calipers for the parking brake.

Absolutely it makes it easier to balance your braking systems front-rear bias by using calipers with identical or very similar bore size/piston surface area[multipiston calipers] for a Fiero braking system. If you can get your bore ratios to be the same or very near the factory setup it will be much easier to achieve proper front rear bias balance and you should definitely strive to build your system this way.

Clamping force, and front to rear bias, is not solely dependant on caliper bore ratios. Your opinion I'm assuming [correct me if I'm wrong] is based on the assumption that the same composition of pads of equal proportions are used on each corner. Alot of bias, front or rear, can be added or subtracted depending upon pad selection by changing things up with different pad compositions, and different pad dimensions, on the front vs. rear. In simple terms the swept area of the rotor, and what pad said rotor area is swept with, along with rotor diameter, play a part in determining bias. Even pad thickness has some effect on how a pad grabs the rotors.

You can balance the lebaron setup, or a similar setup, through trial and error by changing up the pads front to rear and/or setting an adjustable prop valve properly. Modern braking systems are hydraulic so you have to think about how a basic hydraulic system works. A smaller piston area will give you more clamping force over a larger piston area. Think about it, that smaller piston is going to move farther and press harder with the same volume of fluid moving into the caliper. There are other issues like boiling the brake fluid in the smaller bores that can come into play, but that would only be an issue with very heavy roadrace use where there is alot of heat in the brake system over a long period of time[see any roadrace car and all its brake ducts and fans]. For a street setup, you're most likely not going to have this issue. With a smaller piston area on the rear if everything else is balanced [identical] you'll have rear bias. With an adjustable prop valve and/or different pads you can balance your system.It may take a little more work but it's not impossible as some would have you believe. When you take ALL the variables into account it's not as difficult as it seems.

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88blackchopv8

[This message has been edited by av8fiero (edited 02-07-2010).]

Yes, playing with pads is another option to affect the bias.

It's rare that I have ever seen the coefficient of friction published for a pad, which makes pad selection somewhat of a trial-and-error guessing game. The front/rear coefficient of friction could be affected differently by temperature depending on the pad, thus making the bias temperature-dependent. With the same pads at all four corners, at least they're fading (relatively) the same.

It might be worth considering for many, but I personally don't consider it worth the headache.

I disagree that the pad area changes much in terms of braking torque - for things like pads, the frictional force is the product of the coefficient of friction and the clamping force. It's a simple linear relationship. (tires are completely another story, because their contact patch area does determine the traction, but they're rubber and deform to the road surface)

You have it backwards on the piston area.
When you step on the brake pedal, you have the master cylinder producing a fixed pressure. Lets say 500 psi.
(this depends on how hard you're pressing, the contribution from the vac booster, and the bore size)

That means the brake fluid is pressurized to 500 pounds, per square inch. The fluid literally exerts 500 lbs of force on every square inch of tubing, or whatever it is that may be containing the fluid.

If you have a caliper with a piston area of 1 square inch, its piston will exert a 500 lb force.
If you have a caliper with a piston area of 2 square inches, its piston will exert a 1000 lb force.

Lower piston area causes lower clamping force on that brake.

That's why I *reduced* my front bore size - to reduce the front clamping force relative to the rears, which remained the same. For what it's worth, I could have increased the rear bore size (to help avoid boiling), but bores larger than 2-1/8" were not available with parking brakes, and at the end of the day, I'm just a casual driver.

[This message has been edited by pmbrunelle (edited 02-07-2010).]

quote Originally posted by Brembo-Fiero: Hi GS Jon, it is very difficult to get this information in "good old Germany"

www.brakewarehouse.com

www.rockauto.com

both are very good resources for finding specs on calipers and rotors. the centric line usually publishes the caliper bore, bleeder screw size, inlet size, whether the caliper is leading or trailing the axle, etc. they also publish the rotor diameter, thickness, total height, bolt circle, hub bore and minimum thickness.

it's nice if you can find rotors from the same manufacturer so that you don't need hub rings, but it all depends on the manufacturer. there are a few decent calipers out there- the lexus LS430 has some nice monoblocks 4 pots on it for relatively cheap (43mm pistons). the sumitomo 4-pot (nissan R32/300ZX/later model WRX) are decent calipers as well, and pretty cheap (40mm pistons). FC and FD RX7s have sumitomo 4-pots up front with 36mm pistons, but they are for a pretty narrow disc (20-22mm).

my MR2 is getting porsche 996C4 calipers up front with supra TT discs, and 88 fiero rear calipers on 96-01 rav4 front rotors. the bias will move about 2.5% to the rear, which is fine considering the extra tire i have back there now. i'd rather have too much rear bias than too little, since you can use a prop valve to reduce rear brake bias- you can't increase rear bias way other than changing calipers (never ever ever ever ever use a prop valve on the front brake circuit!)

quote Originally posted by pmbrunelle: Yes, playing with pads is another option to affect the bias. It's rare that I have ever seen the coefficient of friction published for a pad, which makes pad selection somewhat of a trial-and-error guessing game. The front/rear coefficient of friction could be affected differently by temperature depending on the pad, thus making the bias temperature-dependent. With the same pads at all four corners, at least they're fading (relatively) the same. It might be worth considering for many, but I personally don't consider it worth the headache. I disagree that the pad area changes much in terms of braking torque - for things like pads, the frictional force is the product of the coefficient of friction and the clamping force. It's a simple linear relationship. (tires are completely another story, because their contact patch area does determine the traction, but they're rubber and deform to the road surface) You have it backwards on the piston area. When you step on the brake pedal, you have the master cylinder producing a fixed pressure. Lets say 500 psi. (this depends on how hard you're pressing, the contribution from the vac booster, and the bore size) That means the brake fluid is pressurized to 500 pounds, per square inch. The fluid literally exerts 500 lbs of force on every square inch of tubing, or whatever it is that may be containing the fluid. If you have a caliper with a piston area of 1 square inch, its piston will exert a 500 lb force. If you have a caliper with a piston area of 2 square inches, its piston will exert a 1000 lb force. Lower piston area causes lower clamping force on that brake. That's why I *reduced* my front bore size - to reduce the front clamping force relative to the rears, which remained the same. For what it's worth, I could have increased the rear bore size (to help avoid boiling), but bores larger than 2-1/8" were not available with parking brakes, and at the end of the day, I'm just a casual driver.

You know what, you may have me in theory here. I'm sure all your calculations are spot on. I'm so confused that I feel I'm talking in circles [probable]. All I can say is I have balanced my lebaron setup through trial and error to my liking playing with all the variables [prop valve and pads, my rotors are the same front to rear]. I have the blazer master cylinder. I'm using the s10 calipers on the front and the standard caddy calipers on the rear. I have an adjustable prop valve installed on the rear brake line. I have ebc greens on the front and ebc reds on the rear[same pad dimensions]. I feel I have excellent brake bias front to rear with little fade. I'm faster on a roadcourse than I was with stock brakes. They feel great to me. Maybe they're not optimal for the street in every situation and condition, but they sure are awesome on a roadcourse.

I've had zero problems running this setup on the street. Maybe I'm not the average driver out there and maybe this setup won't be the "best" for everyone. I will say my car rarely even sees wet conditions, but even when it has a little pedal modulation has kept me easily out of trouble [loss of control]. To me they feel way better than a stock setup and I reduced my stopping distance by 20 feet from 100 mph over the best I could do with a Stock 88 system with the best pad combo I could come up with. To me that is a big difference.

I don't have all the calculations and formulas down pat, all I can say is that my setup works for me and that I would take it over any other system that I've tried [most of them]. I'm speaking from my real world experience of using this setup on roadcourse track days and street use. My car and it's braking performance is real, it isn't a mathematical calculation on a piece of paper. I agree my system may not be perfect for every condition. Your system with the smaller front piston area may even be better than mine as I personally haven't tried what you're running, but in my opinion you cannot say that the standard lebaron setup is less effective than a factory setup, which seems to be what you're implying.

At any rate the ssbc setup should be a very nice setup AS LONG AS IT'S SET UP PROPERLY. Get the bore ratios to be as close to the factory setup as you can. this will make balancing the system as easy as possible. The reduced unsprung mass with these calipers will be great for braking as well as handling

edited for spelling
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88blackchopv8

[This message has been edited by av8fiero (edited 02-08-2010).]

pmbrunnelle I'm just curious, have you done any actual testing to back up your claims that this setup will be unbalanced and dangerous bias wise? Or are you merely basing your opinion on your calculations and formulas? I agree that the lebaron setup may not be perfectly balanced bias wise, but I disagree that that it is less effective than a stock fiero braking system. It is an excellent brake upgrade. From the results I've seen on my car I don't think this system is unsafe for a street application or is as unbalanced as your calculations would suggest it to be. IF setup properly, most, if not all of the potential imbalance can be eliminated, as it has been on my car. I will say I have done alot of trial and error to get my brakes as balanced as they are, but anyone could easily get the same results as me with a little effort. I do agree with you that you should try to get the bore ratios as close yo factory as possible, especially if you're going to use the factory prop valve.

What do you think? If my system is so imbalanced why does it work so well for me in dry conditions as well as wet? Any feedback you have to offer would be greatly appreciated.

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88blackchopv8

I base my opinion on the balance of a LeBaron setup using combination of numbers, and practical experience consisting of daily driving my LeBaron-swapped Fiero for about a month. This is when it had the Cadillac/Blazer 2-1/2" front calipers just like everyone else.

I drove my Fiero like this, rain or dry, for about a month. The daily driving routine included threshold braking on highway exits. Experience confirmed the predicted premature front lockup in all conditions.

I can't substantiate the poor performance of the standard swap with scientific (same tires, same driver, same car) before/after stopping distance testing.

Lets not get into your modified system, it's another story completely, when you play with the pad compounds - it's effectively doing the same thing as playing with caliper bore ratios (albeit more of a guessing-game band-aid that may be temperature affected). Playing with pads/calipers affect bias throughout the entire range (rain + shine) while prop valves only affect high traction bias (sunny weather). I don't doubt your system works rain or shine, because you run different pads front/rear.

[This message has been edited by pmbrunelle (edited 02-09-2010).]

quote Originally posted by pmbrunelle: I base my opinion on the balance of a LeBaron setup using combination of numbers, and practical experience consisting of daily driving my LeBaron-swapped Fiero for about a month. This is when it had the Cadillac/Blazer 2-1/2" front calipers just like everyone else. I drove my Fiero like this, rain or dry, for about a month. The daily driving routine included threshold braking on highway exits. Experience confirmed the predicted premature front lockup in all conditions. I can't substantiate the poor performance of the standard swap with scientific (same tires, same driver, same car) before/after stopping distance testing. Lets not get into your modified system, it's another story completely, when you play with the pad compounds - it's effectively doing the same thing as playing with caliper bore ratios (albeit more of a guessing-game band-aid that may be temperature affected). Playing with pads/calipers affect bias throughout the entire range (rain + shine) while prop valves only affect high traction bias (sunny weather). I don't doubt your system works rain or shine, because you run different pads front/rear.

Ok fair enough, I do agree the standard lebaron or any other system with similar bore ratios does have more front bias than what it needs. I will also say that most if not all factory braking setups [no abs] will lock the fronts well before the rears in order to keep the average person from spinning out in a panic stop every time it rains [stupid driver beyond threshold braking]. All I'm saying is that running a standard lebaron setup with the same pads all around with a factory prop valve isn't as bad as you're making it out to be. I can substantiate the performance of the swap with scientific (same tires, same driver, same car) before and after stopping distance testing. I've tried it, unbalanced as it is, and it still outbrakes a stock 88 setup wet or dry. Is it ideal? most likely not. Is it unsafe? a definite no. Does it work? yes. Will the average person with this setup be happy with it's performance? probably. Can you make it better? absolutely.

Now on my system I did do some things to make my system more balanced. I messed with the pad compounds and I messed with an adjustable prop valve. If you would like to call this a band aid fix I'm fine with that, my only response to that is my system works, and it works quite well. Also I don't have any temperature related bias issues, I've run my car hard on road couse track days and casually on the street, it seems pretty consistent to me.

For the average person who is going to perform this swap, it's much easier [cheaper, i.e. the fiero community as a whole] to change up pad compounds than to get replacement aftermarket calipers. I'm sorry but the average guy doing this swap just isn't going to change out the calipers. All I'm saying is that you can make this setup work the way it's supposed to using my band aid fixes. There's more than one way to make this setup work effectively. You just can't flat out say the setup has no chance of working properly.

If someone is just performing this swap now they should try to build it with the front calipers you used if they can afford them as it will take out some of the setup and tuning required to make it work. If someone already has this setup with the s10 blazer/camaro front calipers and caddy rear, or calipers with a similar bore ratio, you can make it work as it's supposed to without changing out the calipers with some trial and error experimentation by playing with pads and an adjustable prop valve.

Is there a right way and a wrong way? Who cares? I only care about how it works. If my system is wrong but works I'm ok with that. If your system is right and works I'm fine with that too. It's nice to know there is more than one way to make things work properly. This whole forum is all about using ingenuity to reach your fiero performance goals. Wouldn't you agree? Now let's smile, have a nice day and build something cool!!

Let me know what you think!

edited for spelling
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88blackchopv8

[This message has been edited by av8fiero (edited 02-09-2010).]

I want to thank all you guys for so much good info. I was considering this for my Fiero, so I'm glad to see this.

I'm not surprised you don't have temperature related bias issues. Especially because you have a big brake kit - the pads never really get super hot. It's more of a concern for small stock brakes that are being run hotter. This is also going to be quite dependent on the particular pad combination. It's good that you found an effective combination.

I'm wondering - you installed LeBarons on an 88? (It's unusual, the readily available brackets I've seen were all for 84-87)
I'm quite surprised about the standard LeBarons outbraking the stock 88 by a mile. I don't doubt that you did that, but I doubt the conditions were equal. As they say, tires stop the car, not brakes.

About the front biasing of the standard LeBaron or similar being safe for the average driver... well this is going to be subjective. I have had white-knuckle moments related to stopping distance - yet I never got scared from fishtailing under braking.

I'd consider myself an average driver who is budget-conscious. I couldn't put up with the standard setup. I suggest closer to stock caliper bore ratios from the start, because it's just a waste of money to buy 2-1/2" calipers only to replace them two weeks later with 2-1/4" calipers.

On the other hand, maybe I really am just anal...

Here's my writeup on the 2-1/4" cast iron reduced bore calipers I used:
https://www.fiero.nl/forum/Forum2/HTML/103925.html
I kept the factory proportioning valve, and used the same off-the-shelf plain pads all around.
The calipers cost $80 each + shipping.

Regardless of whether someone already has the standard LeBaron setup, or is just in the planning stages, I'm not convinced that the adjustable valve + aftermarket pads is the cheaper route.

Anyway, the diversity is nice!

[This message has been edited by pmbrunelle (edited 02-11-2010).]

Hi Eric,

how about your brake bias? Theoretically it´s a little bit rear biased, but how does it perform?
Do you have a manual or a automatic transmission? I am asking this because the automatic transmission
is havier than the manual transmission and it can handle a little bit more brake force on the rear.
Did you have the issue of the dragging brake pad on the drum of the brake disc on the rear?

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Jürgen Martin
white GT 87
Germany

quote Originally posted by pmbrunelle: I'm wondering - you installed LeBarons on an 88? (It's unusual, the readily available brackets I've seen were all for 84-87) I'm quite surprised about the standard LeBarons outbraking the stock 88 by a mile. I don't doubt that you did that, but I doubt the conditions were equal. As they say, tires stop the car, not brakes. About the front biasing of the standard LeBaron or similar being safe for the average driver... well this is going to be subjective. I have had white-knuckle moments related to stopping distance - yet I never got scared from fishtailing under braking. Regardless of whether someone already has the standard LeBaron setup, or is just in the planning stages, I'm not convinced that the adjustable valve + aftermarket pads is the cheaper route. Anyway, the diversity is nice!

Yes I have them on my 88. The brackets are available from Archie and probably others. It's less involved than the earlier chassis as you don't need to make front hubs for the rotors. Just some different brackets besides that. I've tested the swap on the same car, same tires, same driver vs. the factory 88 brake calipers and rotors. The only thing that was different was the day, and about 10 degrees ambient temp. All I can say is it will out brake the factory stuff. I didn't say it was a day and night difference over stock. The 88 stuff is pretty good and would be more than enough brakes for most people. The lebaron swap is better [averaged 8 ft better dry from 100mph, about 4ft better wet], not much of an improvement, that is why I played around with my system to balance it as best I could. I have ALOT of time in my brakes [track days will do that to you] trying to make them better. I picked up another 12 ft of improvement for 20ft better over stock. 20ft is a big deal. You may even do better with the calipers you used.

Too much front bias isn't going to make it fishtail, it's going to make the car plow straight ahead once the fronts lock up. Yes the lebaron setup makes this worse, but if you can keep the car at or a little below the threshold to lock the fronts [keeping from panicing] it will stop better even though it's imbalanced. Playing with the setup as I did or playing with the bore ratios as you did will certainly improve the balance.

As for the cost difference you're probably right, it would pretty much be a toss up as to which is actually cheaper.

The aluminum ssbc brake upgrade to this swap can be made to work one way or the other. It will give you a nice reduction in unsprung weight. If you can afford it go for it. If the caliper bores are like the standard lebaron swap you have to fiddle with it to make it balanced better.

You can make the standard lebaron swap well balanced with some work if you want to, or you can find those aftermarket front calipers with the smaller bores. I'm done arguing this, the difference between my setup tweaked the way it is, and your setup with the aftermarket calipers is probably trivial. Good luck whatever you build
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88blackchopv8

[This message has been edited by av8fiero (edited 02-12-2010).]

quote Originally posted by PaulJK: If this is the 11 and 1/4 inch upgrade, i have a brand new set of the adapters i'm not using - if anyone needs them, PM me.

PM sent

I have found a new caliper on the wilwood website. It´s called GM D52 Dual Piston. It´s like the SSBC calipers
a replacement for the factory calipers on 1968-96 GM passengers vehicles. It uses the same brake pads and
mounting assembly. Has 2 stainless pistons. Different Piston diameters (1,25"/31,75mm and 2"/50,8mm) are
available. Unfortunately they don´t offer a rear caliper.

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Jürgen Martin
white GT 87
Germany

D52 Wilwood caliper does not have a dust boot. Isn't that a no-no for a street car? Or am I wrong?
Any aluminum calipers for the 84-87 front brake? How about anybody finding a 2", 2 1/8" or 2 1/4" piston front caliper?
Anybody try the seville calipers on all four corners?

Related threads:
https://www.fiero.nl/forum/Forum2/HTML/109042.html
https://www.fiero.nl/forum/Forum1/HTML/048271.html

Do you mean using the REAR Seville calipers on all four corners, with parking brake function disabled for the front?

I haven't used this master cylinder but planning to. http://www.ssbrakes.com/com.../index.cfm?nPID=8810 http://www.ssbrakes.com/com.../index.cfm?nPID=6177 http://www.ssbrakes.com/com.../index.cfm?nPID=6178 I've already purchased the A181 front calipers and A182 rear calipers, still need the rotors and master. http://www.ssbrakes.com/com...index.cfm?nPID=8679. they do not show a listing for the A182 rear calipers, SSBC only did a small production of those rear calipers with a parking brake lever, I purchased them from Joe at Team Race-Tech and he told me that he had a difficult time getting them a few years ago, they were special order.

[This message has been edited by rourke_87_T-Top (edited 04-27-2011).]

quote Originally posted by rourke_87_T-Top:

about brake bias... you could always remove the prop-valve and pick calipers based on their piston size and the calculations I assume you have all done :-)

About the volvo calipers mentioned earlier. The 4-pot calipers used on the 240 series (4x36mm if memory serves me right) fit the fiero front upright (84-87) with no modification. However, this will limit your choice of rotor and there is very little space between the hub and the caliper. To get around this, you could design a new hub where the rotor mounts from the rear like on some old opels. The other option is to use a larger rotor, but keep in mind that the inlets of these calipers (they use two inlets, each inlet providing 2 opposing pistons with fluid) are situated so they are pointing towards the hub centerline. Which means that it's likely that an adapter to move the calipers will get in the way of the inlet fittings. Or at least that's what I experienced when investigating the volvo 240 caliper combined with the volvo 740 rotor. Would have been a very nice combination if it had worked out so I'm thinking I should have another look at it. As it is, I went with half a vette upgrade (rear vette calipers with e-brake function weren't available at the time, so I'm now considering removing the prop-valve to get the bias closer to what my calculations tell me I need)

[This message has been edited by PerKr (edited 07-05-2012).]

I finished the fronts today,

All I can say is Wow ! Unbelievable. I have C4 upgrade with EBC green stuff on my '88 Formula but this upgrade blows that out of the water.

[This message has been edited by rourke_87_T-Top (edited 07-05-2012).]

quote Originally posted by rourke_87_T-Top: I was pricing these out the past week and was suprised to see them advertised in the Mall by a member that lives in my area. QUOTE]Originally posted by Team Race-Tech: What I have are brand new front SSBC dual piston calipers with hard ware and pads, rear SSBC calipers with e-brake hard ware and pads, plus only the front caliper brakets powder coated black for 11.25" disk conversion. I would like to see if there is any intrest out there. When I bought them I had great difficaulty in just getting the rear calipers. I recall paying $695 each one. these are some pictures of the calipers. Front: if anyone has any questions please feel free to ask. These calipers can be used on any 11.25" or 12" brake kit or for those who already have a kit and want to upgrade the calipers, these are it. regardless I have to charge shipping and I'll add insurance since these are not your ordinary wrecking yard find.....Joe

.
http://myfiero.oceanmoon.co...80%99s-brake-upgrade

[/QUOTE]

[This message has been edited by rourke_87_T-Top (edited 07-06-2012).]

Sent Sardonyx247 PM about the S10 booster, swap needs a bit more boost. Payment sent for the new modified S10 booster, Also have so many more pad options with the GM D52 style pads.

[This message has been edited by rourke_87_T-Top (edited 07-16-2012).]

quote Originally posted by pmbrunelle: It's rare that I have ever seen the coefficient of friction published for a pad, which makes pad selection somewhat of a trial-and-error guessing game. The front/rear coefficient of friction could be affected differently by temperature depending on the pad, thus making the bias temperature-dependent. With the same pads at all four corners, at least they're fading (relatively) the same.

Willwood,
who also makes GM Metric Calipers of varying designs (and cost much less than the SSBC units) publishes their coeffecients for most of their pads according to temperature, they make the Metric pads in all of thier available compounds as well.
Compound Flyer:
http://www.wilwood.com/PDF/Flyers/fl227.pdf
GM Metric Pads:
http://www.wilwood.com/Brak...st.aspx?padtype=D154

EDIT: typos and bad links

[This message has been edited by FieroWannaBe (edited 07-16-2012).]