steering rack rebuilt but 246 still pulls to left under braking

The problem would be opening the bleeder valve EXACTLY the same amount on the two sides. Basically impossible.

 

Caster and camber is changed on these cars by adding and removing shims, no? So unless something is bent those will not change.
I did not hit any curbs or anything to cause this problem to come up.

Also, I can't imagine an alignment problem that would allow the car to go straight down the road with the steering wheel centered but jerk strongly to one side under braking.

 

Actually the teflon -SS lines are cheaper than the rubber ones from Ferrari vendors.
I got teflon-SS lines for my Pantera for $15 each from Jegs.
The cheapest I've found for rubber ones from the vendors is $60.

The only rub so far I've found is that I will need 2 AN-metric adapters per wheel at $20 per adapter-- so it still ends up about the same and I'll have a better part..

 

That's a good idea- I'll have to call around and see if any shops are not just "R+R" places but can actually make their own hoses.

 

I'm going to pull the right front caliper apart just to be sure a piston isn't binding, but the flexible lines are going to be replaced too.

I find an assistant (my wife doesn't complain too much) and the "push down-close valve when pedal is at bottom--let up--open valve-- push down--system is best.

 

I think it is logical to concentrate on the right front brake first.
I had my wife press lightly then more firmly on the pedal (with the engine off, so no power boost) while I compared how hard it was to turn the front wheels, and the right was slightly easier to turn. Both pistons are pushing the pad against the rotor, but I have no way of measuring how hard.

Last time I drove the car I took my hands off the wheel and stabbed the brakes on a smooth road. The wheel jerked 90 degrees to the left at like lightning speed before I grabbed it.

So this is not a subtle problem.

I looked at the a-arms and bushings and they look OK. The bushings show cracks in the rubber but there are no missing pieces (like there were in my rear bushings before I replaced them.)

I'm going to replace all the flexible lines and disassemble the right caliper to check it and we'll see if the problem goes away.

 

I think I found the problem. I took the right front caliper off and found that while the inboard piston could be pressed inward some by hand (the pads are basically new so the pistons were basically all the way back in the bores) the outboard piston would not budge. When I applied compressed air to the caliper the inboard piston came out and the outboard barely moved. I had to reinsert and restrain the inboard piston with C-clamps (to keep pressure in the system) to get the outboard piston out.

The portions of the pistons and bores deep to the pressure seals look good but the outboard piston bore has some rust superficial to the seal (the inboard piston has some too)-- so at the opening of the bore.

A Scotchbrite pad seems to do nothing-- what should I use on the rusty metal there? Steel wool? A Dremel tool with wire brush?
I'm thinking I'll leave the old pressure seal in to protect the deeper part of the bore while I work on the opening area.

Jim

 

I thought it was the obviously worn steering rack carrier bushing that was causing this, but rebuilding / replacing everything and curing that obvious problem made no difference in the braking pull.

 

I think there's over a 90% chance it was that stiff piston causing the problem. It shouldn't take 50psi of air pressure to get a piston out of a bore.
It had an area of dark corrosion where the surface was pitted and my theory is that it was binding / stuck to the pressure seal.
I have ordered a rebuild kit, new SS brake lines, and an SS piston from superformance UK.