lowering car and braking
10-17-2005, 10:25 AM
#4
It depends on what kind of a braking system you have. On an LS1 fbody, the brake proportioning is done by the ABS computer and would be self adjusting for this. For something else, you may need to install an adjustable brake proportioning valve.
And yes, there are better handling forums than this one.
And yes, there are better handling forums than this one.
10-17-2005, 12:25 PM
#5
TECH Fanatic
Originally Posted by FastKat
So from what I undersatnd, lowering your car slows and reduces the weight transfer to the front of the car under hard braking. Does that mean you adjust your system to safely use more rear brake?
With more AD you can adjust the bais towards the rear to increase its percentage and NO....... the ABS controller doesnt have anything to do with changing or controlling the bias. The ABS has other controlling functions off of actual, individual wheel speed that are independant of bias. Close in theroy but not the same animal.
To really answer your question, I need to know more of the suspension in which you are questioning. Not all suspensions are created equal and even small changes to geometry or even alignment can effect handling and/or braking characteristics.
But to answer your last question simply....... yes you can safely increase your brake bias towards the rear, which will improve your overall braking by having somthing closer to equal load (in theroy) at each wheel. Its like having a 70\30 and then going to 60\40....... the work is being displaced to four corners more evenly than the majority just to the front.
Last edited by chicane; 10-17-2005 at 12:31 PM.
10-17-2005, 11:57 PM
#6
chicane, I know the LS1 ABS system and a brake proportioning valve are not the same thing, but guess what, the ABS system is all you get, no mechanical proportioning valve. GM engineers reasoned that the ABS could just take care of the rear wheels when they start to lock up before the fronts. Again, as you say, not the same animal, only works in theory. Throw a set of race slicks on all four corners and go SCCA racing and you find out you have a ton of wheel hop if you use the brakes much. I was able to tame it by running an adjustable proporting valve upstream from the ABS, and using more agressive brake bads on the front than the rear.
So back to FastKat, it also depends on how you use the car and what kind of tires it will have, street tires vs. slicks. No easy answer, need more information.
So back to FastKat, it also depends on how you use the car and what kind of tires it will have, street tires vs. slicks. No easy answer, need more information.
10-18-2005, 10:57 AM
#7
Car is a street car and I am buying new calipers for it. I am trying to decide what size pistons to get. I really don't want to install a proportioning valve but if I absolutely have to then I will. I planned on keeping the piston area of the front pistons to the rear pistons proportional between the new and old setups... in other words, if the stock area of the new pistons was 3" and the rear was 2", I would buy calipers with a 4.5" area of front piston and the 3" area of rear piston.... I know I will not be able to make a perfect match, and I want to know if I should give the rear calipers more or less clamping force.... I think the clamping force is proportional to piston size.
9.5" street tires on the fronts and rears, biggest concern is emergency stops and occasional hard braking. Street only! I will probably go with a taller rotor as well.
9.5" street tires on the fronts and rears, biggest concern is emergency stops and occasional hard braking. Street only! I will probably go with a taller rotor as well.
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10-19-2005, 12:55 AM
#8
TECH Fanatic
Originally Posted by Cal
chicane, I know the LS1 ABS system and a brake proportioning valve are not the same thing, but guess what, the ABS system is all you get, no mechanical proportioning valve. GM engineers reasoned that the ABS could just take care of the rear wheels when they start to lock up before the fronts. Again, as you say, not the same animal, only works in theory.
Originally Posted by Cal
Throw a set of race slicks on all four corners and go SCCA racing and you find out you have a ton of wheel hop if you use the brakes much. I was able to tame it by running an adjustable proporting valve upstream from the ABS, and using more agressive brake bads on the front than the rear.
The noted problem could / is related to your suspension, on your chassis. There was no explaination of any specific suspension, in question....... so thats is where my comments were being directed. I just didnt want to assume FastCat was meaning a stock F-body and redimentry suspension.
BTW, the fix we found for the F-body and its possible wheel hop when lowered was a change in shock valving and the LCA angles, which effect the IC of the rear suspension.
Originally Posted by Cal
........... it also depends on how you use the car and what kind of tires it will have, street tires vs. slicks. No easy answer, need more information.
