quote Originally posted by imacflier: Mark, Check out AutoZone rotors, p/n 5344 (11 1/4 diameter, 61 mm bore, 5x100 bolt circle): http://www.autozone.com/aut...810_172993_2708_6348 Centering rings at 60mm to 57.1mm are available here: http://www.ebay.com/itm/60-...em484430d318&vxp=mtr I believe that that 1mm difference in the size of the centering ring and the rotor is tolerable. This combination would result in NO machining of wear parts required, just the caliper adapters and (maybe) a spacer for the caliper to deal with the increased rotor thickness. Whatcha think? Larry

I like this! I do everything in inches yet so mm don't really say much to me until I convert... .040 is more slop than I want since the key to this vehicle is light weight and handling.... (complete suspension rebuild as well) and for $ 17.50 I will make my own since I have other machining to do.... But for a regualr driver.....

Fierobsessed,

Is it worth increasing rotors for '88's from 10 1/2 to 11 1/4? Well, I think it is since it give about an 8% increase in braking torque for any amount of pedal pressure. In a previous thread I published this chart comparing the various brake conversions:

code:

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			84-87	Grand Am	88	LeBaron	12" Vette	13" Viper
Rotor Diameter			9.68	9.68	10.43	11.26	12.01	13.03
								
84-87								
Rotor Weight			13.85	10.8	11.25	13.7	20.4	17
Vented?			N	Y	Y	Y	Y	Y
Torque Factor			1.00	1.00	1.08	1.16	1.24	1.35
W/ 9" S-10 Booster			1.27	1.27	1.36	1.47	1.57	1.70
								
88								
Torque Factor					1.00	1.08	1.15	1.25
W/ 9" S-10 Booster					1.27	1.37	1.46	1.58

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Looking at the last three lines (88 only): The S-10 booster is slightly better than the 13" conversion and is clearly the very best upgrade.

I believe that the difference between a torque factor of 1.27 (stock rotor with S-10 booster) and a torque factor of 1.37(Lebaron rotor with S-10 booster) IS a significant difference. YOUR mileage my vary, of course.

I have the S-10 booster on my '88, and still attempted to do the 12" 'Vette conversion. Although quite a few folks have reported success in fitting the rotors, I was unable to find clearance. I believe it is because of differences between the bracketry available. It is close though. I believe the 3/4" reduction in package diameter in going from the 12" to the 11.26" will allow the rotors to clear. Combined with the ability to use unmodified rotors (a wear part), I believe it will be a good modification to make, so I am still pursuing this conversion.

With regards to the total height of the rotor, higher will be better so as to move the rotor and caliper inboard to better clear the curve of the inside of the '88 front wheels.

Larry

[This message has been edited by imacflier (edited 03-24-2013).]

quote Originally posted by Justinbart: EBC street race pads would be the best bang for the buck.(No, they do not require heating up) Yellows if you want all out performance, Reds if you are concerned with dust. You do not need larger heavier rotors that increase the rotating mass, killing performance. They are purely for looks.

100% agree with Justin on this. EBC Yellow pads are perfect! They made my car stop like a whole new beast.

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quote Originally posted by imacflier: code: 88 LeBaron 12" Vette 13" Viper Rotor Diameter 10.43 11.26 12.01 13.03 88 Torque Factor 1.00 1.08 1.15 1.25 W/ 9" S-10 Booster 1.27 1.37 1.46 1.58

The 88 information in this post for the various 88 upgrades isn't accurate. What you are doing is using a ratio of the rotor diameter to determine increased braking torque, but that approach isn't correct. The torque lever arm is the radius between the center of the rotor and the center of the brake pad. The 88 pads are 1.6" in height and the stock 88 caliper mounting position has the pad inset from the edge of the rotor .18" as well. The other inaccuracy is not stating the different gains Front/Rear for the S10 booster (my #'s are from actual caliper fluid pressure measurements). So the real numbers are:

code:

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						Stock 88	Lebaron	C4 12"	fieroguru 13"		S10 (11" booster
Rotor Diameter					10.43		11.27	12.01	13.03		
88 Pad height					1.6		1.6	1.6	1.6		
Radius to center of caliper pad			4.235		4.835	5.205	5.715		
Edge of pad inset from rotor			-0.18		0	0	0		
						
% Improvement vs. Stock with pad inset		0		14%	22.9%	34.9%			29%F/11%R
% Improvement vs. Stock w/o pad inset		0		9.5%	17.9%	29.4%		

---

As you look at the numbers above, the stock 88 brake setup has the edge of the brake pad inset .18" from the rotor edge. When you use this actual pad placement, each upgrade is actually worth about 5% more as people normally place the edge of the pad at the rotor's edge.

The S10 booster does a very good job increasing the caliper pressure 29% in the front but the rear only sees an average gain of 11%. I am not a fan of brake upgrades that change the front/rear brake bias, which is what the S10 booster does, but my real concern about S10 booster upgrade is that it instills more confidence in braking ability (you can feel the improvement when cold/warm under limited use) but it does absolutely zero to improve brake fade resistance which is what normally gets people in trouble... false confidence in your brake system is quite dangerous.

The other concern is overlooking the common trends that require your brakes to work harder on a daily basis:
Larger wheels/wider tires - both add weight and increase rotational inertia that your brakes have to overcome.
Larger tire OD - decreased the leverage ratio between the caliper position and OD of the tire - again making your brakes work harder.
Common upgrades that add weight to the car (engine swaps, 4 speed autos, body mods, stereos) - curb weights 100+lbs heavier take more energy to stop.
Increased speed/aggressive driving - both require more work from the brakes.

I am looking forward to seeing what smaller rotor options people come up with.

Edit: here is the chart for the pressure changes front/rear with the S10 booster install.
https://www.fiero.nl/forum/Forum2/HTML/121747.html

[This message has been edited by fieroguru (edited 03-24-2013).]

The other incorrect information is the weight of the 12" Corvette rotor. At rock auto.com they show f/r at 14.0 / 13.5

Combine that with 88 calipers for minimal weight gain and complexity, while keeping factory bias.

Dave

quote Originally posted by imacflier: ...if you can lock your brakes up currently, NONE of the upgrades will reduce your minimum stopping distance....that is limited by your tires. Larry

That's not always the case.
A cheap brake pad may work well when cold, but will contribute to fade very quickly.
Better pads (like the Hawks mentioned earlier) will work better even under abuse.
Better fluid (DOT 4/5) is a HUGE deal for reducing fade as well, if you're working your brakes hard.
Finally, quality braided lines will help with pedal feel and line longevity.
If you're not upgrading other hardware, this is the best formula.

That said, the S10 kit posted earlier looks amazing.

------------------
~Michael
'85 GT 4sp white - SOLD | | '85 2M6 Auto red - SOLD | | '84 2M4 bare chassis - SOLD
Crap, I'm out of Fieros! Time to buy another!!

Daveg,

interesting....but I used all data from AutoZone: see AutoZone Part Number: 55009
Weight: 20.824 lbs

Different manufacturers? Data entry error? Who knows?

Larry

quote Originally posted by imacflier: Daveg, interesting....but I used all data from AutoZone: see AutoZone Part Number: 55009 Weight: 20.824 lbs Different manufacturers? Data entry error? Who knows? Larry

That's the wrong rotor...
The C4 12" kit for the 88's is based on using the front rotor from the 88+ C4 Vette with the lighter duty brakes. The right part # is 55011. Which is a 12" rotor with rotor thickness of 20mm and weighs 13.53lbs.
The one you list is a 13" rotor (heavy duty) with a rotor thickness of 26.4mm (1.04") and weights 20.82 lbs.

My 13" rotor weights right around 17lbs.

Thank you, FieroGuru

quote Originally posted by imacflier: FieroGuru, Actually, although I neglected the pad offset in my calculation, there is no difference between using the radius and the diameter. Example with 6" and 4": 6/4=1.5 (diameters) and 3/2=1.5 (radii) Out of curiosity, why did you use the center of the pad width? You may be quite correct, but my (admittedly limited) knowledge of mechanics does not make that obvious to me? I really do appreciate your insight. Larry

They are engineering fundamentals. Lever arms are measured from the point of pivot (in this case the center of the wheel/rotor) and the location of the applied force. In this case there isn't a single point force, but rather a mostly uniform frictional force across the height (1.6") of the pad surface. Since the total frictional force is proportional to the area of the friction material, you can use the midpoint of the friction material as the midpoint of the total force across the pad as a general approximation (but pad shape does come into play). For brake upgrades that only move the caliper, the gain in braking leverage is solely based on the placement of the caliper not the change in the rotor diameter (although they do track closely with each other).

Correct.

Larger rotors when combined with the stock caliper/pad really only offer 2 things:
* Slight advantage in leverage
* Added swept area giving you better heat dissipation and therefore less heat-related fade.

[This message has been edited by TRiAD (edited 03-25-2013).]

Actually, not correct. Friction in not dependant on area for sliding friction.

quote Originally posted by imacflier: Actually, not correct. Friction in not dependant on area for sliding friction.

Not understanding your post. Try again?
Try reading this. Esp. p48.
http://www.sae.org/events/bce/tutorial-limberg.pdf

[This message has been edited by TRiAD (edited 03-25-2013).]

quote Originally posted by imacflier: Actually, not correct. Friction in not dependant on area for sliding friction.

Correct (pad wear is dependent on area), but the approximation of using the area to define the point of the load is a good approximation. A more precise measurement would be to the center of the caliper piston, but the pads are pretty well centered on the piston.

I turned my rotors today. Tomorrow is busy all day. Friday I am buying the convertible top from a junk caviler. Soon I will get pictures and post them with the caliper mounts... Little by little progress, but it looks like it will turn out well! I will post all pictures I promise.

OK, I promised pictures. While not quite done yet, here is a start.


We are using rear 91 - 93 lebaron brakes on the front, and front 91-93 Lebaron brakes on the rear. Unfortunately both have to be modified.
I do not have a before picture, but the brake drum section on the rear/front rotor must be cut off for clearnace. The hub diameter must also be slightly increased to fit over the Fiero front hub. Just bore out something like .020". On the rear a spacer ring must be made.






Spacer for the caliper halves were made from SS Fender Washer from Menards.This allows the thicker rotors to work with stock calipers.




This is the start for the new brackets.





The brackets still need a taper put on the back side and the new holes and nuts welded to gain back the ofset. When done I will post more pictures....
And oh,,,, Couldn't resist...

Well this is a 2nd try. The last one did not post !!! Well here goes again. We need to start with the brackets. Here is a blank.

The nuts are welded then a clearance chamfer is added.







The rear brackets are much simpler,



Then when I went to assemble the bridge, I about had a heart attack! It would not fit!!!



Is this a 6000 caliper that they gave me by mistake???



It is at the outer most limit on the rotor.




I do not have dimensions. But I have patterns.

Can anyone supply the part number or a more specific description of the brake power booster that is the good improvemnt to the 88 Fiero?
I hear "96 Blazer, and I hear S-10...but what is best? What year and model please?
Is there a master cylinder that should be changed also? Or is the stock 88 Fiero master cylinder OK?
Thanks.

dander10,

Here is the link to the $100 upgrade (all EIGHT pages of it!)....everything you might need to know is in it. https://www.fiero.nl/forum/Forum2/HTML/072173.html FYI check the mall for a member who supplies converted boosters at a quite reasonable price....I seem to have forgotten his name at the moment.

Do NOT change out the master, the stock master works just fine.

This is a GREAT upgrade, BTW.

Larry

To fit inside factory rims I was forced to trim the outer caliper bridge.

Is PIP down? I have tried to post pictures for an hour....

quote Originally posted by TRiAD: Better fluid (DOT 4/5) is a HUGE deal for reducing fade as well, if you're working your brakes hard.

Isn't DOT 5 the synthetic and you cant use it with stock components designed for non synthetic? Thanks

Well the brakes are done. The only real advantage of this swap is that they completely fit behind the stock lace wheels. It is a fairly cheap but labor intensive swap. I kept a pattern for the adapters. It was necessary to grind some clearance onto the stock caliper brackets front and rear. I personally would go with the 04 cobra brakes since the adapter is so easy, but that would require different wheels. I currently do not have the emergency brake hooked up, but that is only due to the fact that I didn't take the time to modify the bracket holding the cable. Since I have an automatic, I wasn't too concerned. All in all, I am happy with the swap, and now I can use my new tires that I already had.













Now back to work on this!

quote Originally posted by darkhorizon: Sliding in some EBC race pads will increase your braking more than a 13 inch upgrade kit assuming you are using some garbage pads right now.

Please quantify the increase in brake torque resulting from the change in coefficient of friction of EBC pads vs. that of switching to 13" rotors.

quote Originally posted by Justinbart: EBC street race pads would be the best bang for the buck.(No, they do not require heating up) Yellows if you want all out performance, Reds if you are concerned with dust. You do not need larger heavier rotors that increase the rotating mass, killing performance. They are purely for looks.

Please quantify how badly performance is "killed" by larger brake rotors.