LS3 swap brake problems
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Teching In
Joined: May 2017
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LS3 swap brake problems Recently had an LS3/4L80E tranny swapped into my 1977 olds cutlass supreme. At the same time I had the brakes upgraded to 4-wheel disks from a newer caddy, with a proportioning valve. Ever since that the brakes work decent but the pedal goes almost all the way to the floor with little resistance before they engage. The shop that did the work says it's a vacuum problem but most mechanics I've talked to say that if it didn't have enough vacuum it would have a rock-hard pedal. SOMEBODY HELP!
Sounds to me like an adjustment problem. If there is too much pedal free play before starting to move the master cylinder piston then the shaft between the pedal and the M/C must be adjusted. Without actually seeing the installation this is only a SWAG.
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Teching In
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Thanks for the reply. That's one of the suggestions someone else told me just haven't had the time to try that yet. Do you know if the rod is adjustable? or does it need to be replaced with a longer one?
Brakes The rod from the pedal to the booster is the easy adjustment and should have about an inch of freeplay. The pin between the booster and master cylinder is a whole different game. Usually the pin is mounted in the booster and is adjustable. The problem is that the clearance between the pin and the M/C should be about 1/32" (better look this up). A very small adjustment of the pin will result in so-so brakes to paste to the windshield results. Adjusting the pin is a pain because it requires removal of the M/C and lines so you only want to do this once. My experience has been the pin adjustment won't affect the pedal travel as much as you indicated.
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Joined: Sep 2007
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From: Kansas City, MO
Is this the solid mounted 4 piston caliper? If so there are two bleeders per caliper to bleed. But you may have to get a different size master cylinder for it to work right depending on the piston surface area and travel.