Help, no brakes on the race car!

[zracer22]

I replaced everything on the MK2 GTI brakes this winter. New master cylinder, vacuum booster, brake lines, rotors, calipers and pads. The front rotors and calipers are from a 93 Passat (they are bigger than the Golf's) I've used the power bleeder, vacuum bleeder, and the old fashioned 2 man bleeding methods. Pedals feels semi firm, but as soon as ai start the car and the pedal goes soft and very little braking. I swapped in another master cylinder and booster, still no change. Feels like there is a ton of air in it somewhere. Is there some trick to bleeding these damn things. It does not have ABS. Before you rule nerds point out the illegal passat stuff, I race in GTS Challenge, not IT. :P

Thanks in advance, Mark

[Sandro]

is the booster and mc from the golf or the passat the calipers came from?

[racer14itc]

Mark,

Us old timer VW guys have seen this before. Usually the fix is to do BOTH master cylinder circuits at the same time. This will give a full piston travel in both circuits and get all the air out . If you just do one wheel at a time, the other piston will keep the one you're trying to bleed from getting getting full travel and forcing all the air out of the master cylinder.

If you still have the diagonal braking circuitry, try doing both fronts at the same time. Then both rears at the same time.

This is the same sort of thing that stumps people when they put in dual Tilton/Wilwood master cylinders at first. . On my GP Scirocco, which has Wilwood master cylinders, I bleed a front and a rear at the same time so both master cylinders get full travel of the pistons.

Let us know what happens, OK?

MC

[zracre]

I also bench bleed the master before it goes in...you can bleed the lines at the master in the car...

[zracer22]

Thanks guys....I'll try this tonight and let you all know how it goes.

[JimLill]

try this........

get a clean squeeze oiler.... remove the squirt end and add a foot of plastic tubing that also fits your bleeder. Fill the oiler with brake fluid, open the bleeder and pump fluid slowly "uphill" to the M/C. The air, being lighter than fluid will move to the M/C. Do not let your M/C overflow. (old motorcycle racing trick)