944S2 Brake Lockup Right Front Wheel
02-28-2004, 02:46 AM
#1
2nd Gear
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944S2 Brake Lockup Right Front Wheel
Can anyone suggest a cause for premature brake lock-up on the front-right wheel of my 944S2 - non-ABS.
The car has been corner balanced. The left/right bias is fine on the Porsche Centre Melbourne brake dyno, but on the road the right front wheel locks up too early. Porsche Centre Melbourne acknowledge that there is a problem, but don't know the cause! The say that it might be a problem with the suspension.
Could the brakes behave differently on the road to on a brake dyno? Is it worth while fitting a new master cylinder?
Modifications conducted to the brakes/suspension include:
Big red callipers, 993TT rotors, 928 front/rear bias valve, steel brake lines, 993 OWM front pads, rear 968CS pads. Suspension has been modified with 200lb springs/torsion bars, koni yellow adj shocks, M030 sway bars and lwr control arms, height adjustable springs.
The car has been corner balanced. The left/right bias is fine on the Porsche Centre Melbourne brake dyno, but on the road the right front wheel locks up too early. Porsche Centre Melbourne acknowledge that there is a problem, but don't know the cause! The say that it might be a problem with the suspension.
Could the brakes behave differently on the road to on a brake dyno? Is it worth while fitting a new master cylinder?
Modifications conducted to the brakes/suspension include:
Big red callipers, 993TT rotors, 928 front/rear bias valve, steel brake lines, 993 OWM front pads, rear 968CS pads. Suspension has been modified with 200lb springs/torsion bars, koni yellow adj shocks, M030 sway bars and lwr control arms, height adjustable springs.
02-28-2004, 11:06 AM
#2
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Is it a factory ABS delete, or has the system been disconnected?
When was the last time the brake fluid has been flushed? I have had cars lock wheels if the system is not bled properly. Especially in an ABS equipped car, if air gets in the hydraulic/pump unit.
For a master cylinder problem: Since both front brakes work off of the same piston in the master cylinder, I would think you would have a problem with the function of both front brakes, not right or left. And usually it would be reduced stopping power if the piston seal is failing.
I cant think of a suspension problem that would cause the brake to lock up, unless the shock is failing to rebound and brakes are chirping the tire going over bumps. But I doubt that. And you would also see other symptoms in the ride.
When was the last time the brake fluid has been flushed? I have had cars lock wheels if the system is not bled properly. Especially in an ABS equipped car, if air gets in the hydraulic/pump unit.
For a master cylinder problem: Since both front brakes work off of the same piston in the master cylinder, I would think you would have a problem with the function of both front brakes, not right or left. And usually it would be reduced stopping power if the piston seal is failing.
I cant think of a suspension problem that would cause the brake to lock up, unless the shock is failing to rebound and brakes are chirping the tire going over bumps. But I doubt that. And you would also see other symptoms in the ride.
02-28-2004, 11:13 AM
#3
Drifting
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On the road, when you're braking you get massive weight transfer to the front tires... I don't think it happens on a brake dyno. So maybe for some reason the weight shifts more on to the left side (=resulting in more grip on that corner) ... could be the suspension, dunno really. When the car was corner balanced, were you sitting on the driver's seat or not? I'd imagine that could be enough to throw the balancing off just enough for this to happen....
02-28-2004, 03:03 PM
#4
Rennlist Member
Does it pull to one side at all when you brake? When was the last time (if ever) that you had the brake lines changed? Sometimes one side will swell internally as the lines get old, causing uneven pressue to be applied. I would think that you'd also feel the car pull to the right if this were your issue, though.
Perhaps there's an issue with your left side caliper, and the problem is really that you're not getting adequate braking at the limit on the left side rather than that you're getting too much from the right?
Perhaps there's an issue with your left side caliper, and the problem is really that you're not getting adequate braking at the limit on the left side rather than that you're getting too much from the right?