why not more choices?

[iwantawd]

how come there arent better brake kits for dsm's. why cant there be 12.5 inch FRONT AND BACK rotors and all four calipers have 2 pistons or more. its not a good idea to have 13 inch rotors in the front and 10 inchers or whatever in the back with better rotors only in the front, it throws the whole balance off. is there any word of anything coming out?

 

[NDgsx]

Because there aren't any two pistons calipers that will go on the back and have provisions for a parking brake/cable. AEM does sell larger rear rotor kits for 1Gs, part number 29-631. They don't list the size on their site though.
TCE does make a larger rear rotor kit with wilwood calipers, but you loose the parking brake. http://www.tceperformanceproducts.com/

 

[Blizz92tsi]

I have the Baer Track Upgrade on my 92 awd. They are for the front only. The kit comes with everything: huge 13" rotors, corvette zo6 (if i'm not mistaken) four piston calipers, stainless steel brake lines, and performance brake pads. These babies are awesome. For the rear I bought a set of powerslot rotors, new pads, and ss lines. My abs isn't working for some reason but they don't lock up until you're almost stopped. As far as balance goes your front does a majority of the work. I think I have a little over a grand invested in my brakes for all four. I hope that helps. Sorry for the long post.

 

[snox135]

well, because your front brakes should do most of the work. If you had the same brakes all the way around your car your cars back end would come around VERY easlily when braking if you did not have a front to rear brake balancing valve If you did then you would not be using most of your braking power in the rear of the car. Then you just have extra rotating weight back there slowing you down.

 

[iwantawd]

not true. if you make huge upgrades to only your front brakes then it will be unbalanced and thats not good. you should keep your upgrades even all around.

 

[2-0turbo]

Originally posted by iwantawd
not true. if you make huge upgrades to only your front brakes then it will be unbalanced and thats not good. you should keep your upgrades even all around.

No, actually you don't know what you are talking about. STOCK AWD DSM's have about 60% of the cars static 3150 lbs on the front axle. When you step on the brakes, you get a phenomenon called weight transfer. On softly sprung cars and cars without "anti-dive" geometry, this is evidenced by the front bumper scraping the ground and the tail-end of the car stuck way up in the air (not really, but bear with me) under aggressive braking.

When you cram on the brakes, that 60% static weight distribution goes to maybe 75% (let's assume, I don't have time to figure it out). That means that only 25% of the cars weight is on the rear axle during hard braking. Since you want the front to be able to lock first, that further reduces the requirements of the rear brakes. So, not taking into account the requirement of the front locking first, the rears can have approximately 75% less capacity than the fronts and do their job just fine. (editor: Stoptech's website claims that under OEM conditions, the rear brakes only contribute 15-20% of the braking force generated, so I am being liberal).

Now, this assumes a lot, but for discussion purposes it is adequate. If you move up to stickier/larger tires and further increase your front braking capabilities, that further increases the dynamic weight transfer and further reduces the requirements of your rear brakes.

The only time you see larger brakes on the front than the rear is on cars that have a higher rear weight bias: Porsche's are a great example. They often have static weight distributions that are 60R/40F. Now, as I said before that changes due to the weight transfer during braking.

This has been a very generalized discussion of what happens. Brake "torque" is acutally what is at work here and its interaction with the tires. The tires are what acutally stop the car. The brakes just provide the torque to slow the wheel/tire. In fact, the only reason to go with bigger rotors is enhanced modulation (more torque with equivalent line pressures) and heat capacity.

All that said, there are some rear brake upgrades. I believe that AEM makes some rear upgrades. Read this article from Stoptech's site and check back. Try their root directory of their technical white papers for additional information.

EDIT: The paragraph that states: The only time you see larger brakes on the front than the rear is on cars that have a higher rear weight bias: SHOULD READ: The only time you see larger brakes on the rear than the front is on cars that have a higher rear weight bias....

Typed too fast.

Regards,

 

[Turbo Guru]

Matt,
That is one of the best answers I have seen thus far. I commend you on the explaination and offer my support to your answer being the correct one. Well done!

Joe

 

[larryd]

i remember this discussion coming up on DSMtalk back in the day when the wildwood kit from TCE came out.. people were up in arms about wether or not upgrading the front would be defeating the purpose when doing nothing to the rears

 

[snox135]

2-0turbo is right assuming you don't change your spring rates. If you go to stiffer spring rates you will then need a brake balancer or upgrade the rear brakes, because you will have less weight transfer.

 

[NDgsx]

I was one of the beta testers for the 1G TCE kits. The billet superlight calipers have a slightly smaller piston area than the dsm 2 piston "big brake" calipers. This offset the additional torque created by moving the lever arm outwards. I can't remember everything off the top of my head now, it's been well over a year; but I believe that the bias was only slightly moved frontwards.
You can always go to a rear pad with a higher coeficent of friction to get more torque and help even the balance if you feel you have to much front bias.