Sud Brake Balance

[slackmanor]

I am having brake balance problems on my 83 Sud Ti. The rear brakes are locking up on heavy braking well before the front does. This makes it very interesting sometimes with a few unexpected 360 deg spins( in the wet). I understand the proportioning valve in not adjustable and you don't seem to be able to buy a replacement. Any assistance or ideas would be apprecaited.

Slackmanor

[PSk]

If this is a track car then add a ball bearing in the rear brake line so that you effectively are disconnecting the rear brakes. People inspecting the car will still see brakes so you will pass the pre-race test. You might have to do something to your master cylinder to.

I'm fairly serious and did speak to a guy driving a very fast Sud when I first visited Australia and that is what he did ... but ofcourse no liability, please do the required thinking and testing, etc.

I did on my racing Sud add 2 bias adjuster thingies (one came from a 105 series Alfa) and the other an adjustable lever thingie, and eventually I had the balance right and still with the original master cylinder. Now if I had more than 10% rear brakes I'd be surprised.

Best
Pete

[77SudTi]

sounds to me as though the balance valve is not working as it should be. Have a look under the car to see if the rod coming off the panhard rod is sitting in the correct location so that it actuates the valve correctly.
If it is a defective balance valve and you decide you cant rebuild it (I seem to think you can if you take it to a good brake specialist and select the appropriate parts and seals - it could be a case of the bore of the valve having some corrosion in it and the piston is jammed)

Aside from all that, you can plumb the rear brake lines so as to bypass the original valve and install an adjustable brake bias valve from a manufacturer like wilwood and dial in the braking effort you want from the rears yourself.

Many people believe the rear brakes do nothing on a Sud, but infact rear brakes do help with braking in many circumstances, particularly when cornering. A sud with well set up rear brakes will behave very differently to a sud without rear brakes, particularly noticeable when driving in wet conditions.