TimeAttackR

On my integra type r racecar I felt that the rear brakes weren't doing enough. I tried pulling slightly on the ebrake while slowing from high speed and I found it settled the rear end down alot. This is a powerful turbo car with a bbk on the front so it would unload the backend while high speed braking and make it want to come around on corner entry. At this point the setup was all stock except wilwood 6 piston and 12.9" rotors on the front with ht10 pads and stock rear with hp plus pads. So then to add rear bias adjustment and replace my corroded stock lines I bought the chase bay booster delete and brake line kit with bias adjustment. It's pretty bad, the pedal feel is brutal and the front brakes stick a little bit. Now I'm looking at buying a non abs 1" master cylinder, reinstalling the booster and teeing off the front brakes from the front port and running the rear port to the bias adjuster and then teed to the rear brakes. I know people love the itr abs but the back brakes didn't seem to be doing anything. Any advice on what to do with the brakes on this car?

killerpenguin21

stop spending money on brakes and fix/modify the suspension setup so that the front can handle the weight transfer sand not unload the rear of the car so much, your chasing the wrong system on the car

TimeAttackR

There are no rubber bushings left on the car, all spherical or some pcl bronze bushing in a few spots. The coilovers are AMR 900lb fr and 1000lb rear. The car doesn't dive it just depends on the front brakes too much. It's been corner weighted and aligned last week. It's likely just something I have to live with like the massive amount of torque steer.

TheShodan

iTrader: (14)

What have you done to address the torque steer, thus far?

TimeAttackR

0.04 toe in on the front, all the solid bushings as mentioned and I bought different wheels to improve scrub radius. Now 17x9 ×35 with 255/40/17 r88r in the front and 235 in the back. Its definitely better but I'm still using the itr diff. Upgrade this off season.

iwannarace

I've had great success with using two different pads front and back. HP+ in back. They have great bite until temps get up there, but since they are in the rear, temps never seem to get hotter than their optimal range.

TimeAttackR

0.04 toe in, higher offset wheels to improve scrub radius and the bushings as mentioned. The diff is still a stock itr gear type, but I broke the transmission during practice today so maybe its upgrade time.

killerpenguin21

the car absolutely does dive, thats vehicle dynamics 101. i dont know anything about amr dampers, but i can tell you your front spring rate is a little light depending on tire. have you done shock adjustment testing? adding rear rebound would be a good idea.

the problem is only solvable to an extent, we have tiny rear brakes and a tiny bit of weight in the rear. i can tell you that the majority of guys i race with put a stock type rear pad in and forgot about it, i know of racers who have literally clamped off rear brake lines to try and stop lifting/rear lockup and even that wont do it. adjustable bias will help, but the majority of the answer lies in fine tuning the front spring rate and rear rebound and a good spherical compliance bushing like the ones from kingpin.

ross2004

I thought about removing my rear brakes all together: less weight and no more square rear tires.

Kidding...(kind of).

TimeAttackR

yes of course the weight transfers to the front but it doesn't stand on its nose like some cars I've seen. The AMR shock is only 1 way adjustable and I have tried to adjust it and it's setup pretty well. This is pretty fast car, I run 550whp in 4th and 5th gear, I have to brake from 230km/h down to 100km/h in one particular corner so I'm experiencing different forces than a 180whp setup. I may try the 1000 pound spring in the front just to see how it performs, also yes the kingpin compliance bushing is on the list, I have the PCI right now.

killerpenguin21

the speed and horsepower dont change the amount of weight transfer/force only the amount of time/distance it spends transferred. what tires are you using?

bias adjustment can only be so helpful before it becomes problematic. you have nice big wilwoods in front yet you are moving braking force to the rear that cant handle the heat as well, will screw with handling characteristics and extend stopping distance. i have adjustable bias on my car, i was able to go 1 full turn towards the back before things got funky. i wound up with like a half turn just to ease some lockup.

what are your corner weights?

ross2004

What are your rear alignment specs?

TimeAttackR

Toyo R888R 255/40/17 fr 235/40/17 rear
the car weighs 2480lbs and was balanced to 50.2% but I can't find my pic of the exact weights
0.03 toe out and 1.7° camber

ross2004

I had a little toe out in the rear as well (more than you) and she was all sorts of wiggly under braking. I brought it to "in" an 1/8" and it made a dramatic difference in stability under braking.