1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

12a Brake Upgrade

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Old 05-25-05, 04:14 PM
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Question 12a Brake Upgrade

I posted a thread a while back asking if I could replace the brakes in my 12a 85 GSL to that of the 13B 84-85 GSL-SE. I was told the spindles where the same and the rotors, calpers etc should all work. Well I got bad news - I tried it and it didn't work out - everything seemed to fit fine except for the rotors. I strongly feel it has something to do with them being Beck Arnley's the center where the bearings go were bigger and therefore the bearings weren't secured properly - is it that these rotors require different bearings that are bigger? I looked at the rotors from a junked 13B GSL-SE and the bearings where the same as the ones on my car - the difference was that the rotors where stock and not Beck Arnley's - would buying some rotors that aren't beck arnley's solve my problem?
-Thanks, Manuel
Old 05-25-05, 04:38 PM
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the gsl-se has a different lug pattern than the gsl... go to cpracing.ca and look up they're turbo two upgrade it is fairly cheap. or change to a gslse suspension
Old 05-25-05, 06:12 PM
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Probably that is the problem if you look the spindels on the GSL and the GSL-se are exactly the same part that is why the bearings are the same part go to a local bearing shop and they should be able to give you some.
Old 05-25-05, 06:31 PM
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They probably gave you the wrong rotors. The SE uses the same bearings and spindles as the 12A cars.
Old 05-25-05, 09:33 PM
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You were told wrong, the rotors and calipers won't work. As stated above the bearings and spindles are the same.

Save your money on something that will really help performance. People are flogging the stock 12a brakes on the track every day of the year. They stop the car just fine. Upgrade the brake pads and flush the fluid.
Old 05-26-05, 01:08 AM
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Sorry but have to disagree cpa7man. In Spec and IT classes they have no choice but the stock rotors to remain legal. The rotors are typically overstressed and develop heat cracking that destroys them. The last two sets I pulled off were still in usable spec apart from the cracks that radiated all the way from the hub to the outside edge of the disk, and all the way through. One of them was cracked this way in three different places! SE brakes are legal as soon as you get to EP and most guys use them because you get slightly better brake performance, and greatly improved rotor life.
Old 05-26-05, 11:09 AM
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they gave you the wrong rotors like said above. the mounting bracket may be differant but should work with work.
Old 05-26-05, 06:39 PM
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As stated above, the spindles are the same on all the 84-85 cars - they are the big bearing spindles. Everything brake-related bolts to these spindles and therefore, everything is transferrable from the SE cars to the non-SE cars, assuming you have the correct parts in your possession.
Old 05-26-05, 07:51 PM
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Old 05-26-05, 08:18 PM
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Originally Posted by Boswoj
Sorry but have to disagree cpa7man. In Spec and IT classes they have no choice but the stock rotors to remain legal. The rotors are typically overstressed and develop heat cracking that destroys them. The last two sets I pulled off were still in usable spec apart from the cracks that radiated all the way from the hub to the outside edge of the disk, and all the way through. One of them was cracked this way in three different places! SE brakes are legal as soon as you get to EP and most guys use them because you get slightly better brake performance, and greatly improved rotor life.
I agree with you to a point. For an EP car the stock brakes are too small . For a street application the brakes work fine. How hot are you going to get these things anyway.....back to the EP car, then you gotta go with KC Raceware, or the Sevensonly setup.

After 2 full seasons and a 6 hour enduro we replaced my little tiny ITA 12a car's brake rotors, yes they were worn but not cracked as you describe. I think a lot of it depends on the tracks you run at as well. Boswoj the truth is the 13b's (GSL-se) brakes are more problematic than the 12a's. Check out this thread. http://www.coloradoscca.org/prodcar/...pic.php?t=3291
have you ever seen these type failures in 12a brakes. The SCCA passed a last minute rule change that make alternate rotors/hubs legal for the Runoffs last year. I'm not saying that the 12a rotors don't fail but to think you have solved your race car brake issues by going to the GSL-SE rotors is a mistake.

BTW - I'm going to KC Raceware's setup before the Runoffs..


Originally Posted by cpa7man
You were told wrong, the rotors and calipers won't work. As stated above the bearings and spindles are the same.
This was somewhat of a misstatement. The rotors and calipers will work with all the other SE stuff.

Last edited by cpa7man; 05-26-05 at 08:25 PM.
Old 05-26-05, 09:24 PM
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I was under the impression that the spindles were not the same, slightly shorter on the non-SEs.. However, you could use the SE caliper mount plates, rotors, and calipers on 84-85 NON-SE spindles.
Another difference as I understand it has something to do with the strut cartridge mount. Small difference in ride height, I believe..
Old 05-26-05, 11:09 PM
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All SE front brake stuff (rotor,caliper,backing plate)will bolt right up if you have an 84-85 spindle,period...been there done that.All 84-85 cars have the short,fat spindles and take the same bearings.

The 79-83 cars all have longer,thinner spindles with smaller outer bearings.The small outer bearing is a common failure,especially with race guys,so many people upgrade to 84-85 struts/brakes,to get those larger spindles and bearings.When you do that,might as well go full SE if you can/want.
Old 05-27-05, 07:17 PM
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Okay, it must have been the previous year spindles I was getting confused with.
But there is a ride height difference between the SE and non-SE? Or no?
Old 05-27-05, 07:31 PM
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cpa7man

Some of that is true, some not. The idea that SE rotors were not available or a safety issue was more related to trying to make sure that the two-piece hub/rotor assemblies that you noted were approved than anything else. The same two piece setups were run previous years and a strong debate was going on in the production community as to whether they were legal before the runoffs. That ruling came down becasue there was a protest-fest scheduled in Mazda Production (oops - I guess thats E Production) if the issue wasn't cleared up beforehand. I have followed several threads about the problems with the whole SE hub separating from the rotor allowing things to come apart in a fairly spectacular way, but I'm not sure there was enough evidence that it was an epidemic of any kind. Anyway, I've been putting off buying the Sevens Only setup until I use up my pile of 13" slicks, so I can buy all new wheels and tires AND brakes - there goes the budget! I personally wouldn't walk across the street to **** on KC Crapware if they were on fire because of a very unsatisfactory business dealing that I had with someone involved, and of course I would warn everyone else to do the same.

You may very well be right about differing tracks. We have several local tracks and some seem to affect the brakes not at all, while others seem to eat a set of pads and rotors in a week-end! It was the same when I had an overprepared Pro-7 car, an underprepared ITA car, and now in EP trim. They just seem to be a bit underbraked which is exaggerated by how difficult it is to get a reasonable amount of bias dialed to the rear.

Last edited by Boswoj; 05-27-05 at 07:39 PM.
Old 05-27-05, 10:24 PM
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Boswoj, I don't think we disagree much, just different tracks, you might push it a little deeper into the corners than I do. At the tracks I run at most you only stop hard twice per lap.

I was following that brake debate as well. The boys (Prather et al) were pitching it as a safety issue, and it obviously was to some degree. They played down the performance enhancement part. Anyway.....KC racewares setup was the only legal setup from what I heard. The rule change as the SCCA proposed made the Sevensonly setup illegal. I understand they have since corrected it. It seems most of the EP guys here run the KC parts. I have never heard anything negative until now. Sounds like we have the same racing background. I came from IT to EP this year. Having a blast.

FWIW: I called a guy today that advertises in the back of Sportscar Mag, he sells slicks with 80% or so thread left for around $350 shipped. (set of 4) He can do Goodyears or Hoosiers. He had a good set of Goodyears in stock. I've gotten all my tires off the prod forum. I'm on my last good set now.

Anyway back on track...sorry to thread jack. Check out these links: http://www.sevensonly.com/

http://www.kcraceware.com/

both companies make upgraded brake kits for the first gen, using the stock (GSL-SE) or aftermarket calipers. Both companies will make it fit whatever bolt pattern your running. Kind of pricey in the $700 range.
Old 05-30-05, 09:26 PM
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cpa7man

Ya - I was wondering about 7's only. When they made the two-piece setups legal, they also stipulated that they had to be the same weight as the stock setup, and I know they were originally lighter. I'm sure they jumped right into compliance with the new rules, as they are a reputable shop. $700+ is pretty stiff for the front brake setup, but I'm guessing that if the rotors are as cheap and long lasting as I think they are then they might actually pay for themselves fairly quickly. Too bad we have to stick with the stock caliper because their GT system with the Wilwood calipers and big pads would make for a really nice low maintence, long lasting, fade free brake system!
Old 05-31-05, 10:37 PM
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go to cpracing for BIGBRAKES you can use the brakes of the 88rx7 [ www.cpracing.ca]
Old 06-11-05, 02:04 PM
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Originally Posted by Boswoj
Sorry but have to disagree cpa7man. In Spec and IT classes they have no choice but the stock rotors to remain legal. The rotors are typically overstressed and develop heat cracking that destroys them. The last two sets I pulled off were still in usable spec apart from the cracks that radiated all the way from the hub to the outside edge of the disk, and all the way through. One of them was cracked this way in three different places! SE brakes are legal as soon as you get to EP and most guys use them because you get slightly better brake performance, and greatly improved rotor life.

Im with you..half the fun of racing the 7 is packing junkyard rotors on free weekends for track spares.
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