Changed out my CMC from SSP to Magnus. Put everything back together (with no spare parts at the end ), bled the clutch and brakes, tightened up the ports. Go out to do a test drive and I don't have brake pressure. Pump the brakes and i get pressure again. I didn't do anything for about 10 seconds. Checked again to make sure my brake work, and again I lost pressure. If I pump them, it comes back along with my car RPM's going up then back to normal.

Anyone have any idea what it may be? There's a gasket that I made sure was there that goes between the brake booster and master cylinder. If it slipped, would that cause the problem? I'm done working on it for today, but I really don't feel like taking everything apart if i don't have to.

 

I would take it apart and check the oring(gasket if you call it that). When I did mine I swore I got it right but it had slipped and gotten pinched. Caused a similar thing to what your describing. The second go at it I used vasoline all over the oring and opening to hold it in place and make the seal not pinch the ring out of place. Seems to have worked, that was over a year ago. Good luck.

 

sounds more like a bleeding issue---so what was the order you bled in?

 

Three things off hand I can name that will cause the loss in brake pressure.

1. O-ring not seated properly
2. Brake Booster not tightened far enough. Check the stoplight switch and pedal stopper for specified distance. .5mm-1.5mm
3. Air in the brake lines.

 

bled the clutch, then the brakes

I didn't know about the stoplight switch distance. I'll check that out before i start taking stuff apart again. Thanks


Funny you said that cause after I made this post, I realized I said the wrong thing when I meant O-Ring If it did come off, hopefully it didn't get pinched.

Thanks for the help everyone

 

O-ring was where it needed to be. Clearance on the stop light switch was good. That didn't fix it. So I bled the lines again, including the inboard ports on the calipers and it finally fixed the problem!

 

You don't even need to remove the brake master cylinder to change out the CMC....