Cascade Crew

Al Hasse · Posted: Sat May 10, 2008 1:21 pm Post subject: Excessive brake pressure

What could cause this? I was driving the 89 home from the junkyard after looking for some spindles and started to smell something hot. Almost home and rolling downhill, I shifted into neutral and coasted, well almost, I slowed to a stop. There was so much pressure in the lines that all four wheels were smoking a bit, also the pedal was very hard at the time, also the driver's side rear caliper squirt some fluid past the bleed screw (maybe that just needs tightened). I made it home OK, but don't want to drive it until I know what's going on.

Master cylinder perhaps??

chevymad · Posted: Sat May 10, 2008 2:40 pm Post subject:

Brake booster problem, incorrect pushrod length in the booster for the master cylinder you're using, master cylinder itself. If its all 4 brakes acting up at once then its the master/booster. When I converted my velle to power brakes way back when, I had a mismatch between the master and the booster. Did the same thing you're talking about.

Al Hasse · Posted: Sat May 10, 2008 3:09 pm Post subject:

Just got that same info from another source, thanks B. I was informed that the pushrod on the booster may be a hair too long for the new master cylinder and might have to adjust that (or do some cutting).

Had a look at the pushrod. Apparently not adjustable and I didn't want to go through the trouble of shortening it. I thought maybe a couple of approximately 1/8" washers on the master cylinder would effectively do the same thing, and it's not permanent. There's no seal there for fluid that I could see, so I thought it worth a try. We'll see what that does after I check everything else out.

blue89 · Posted: Mon May 12, 2008 7:32 am Post subject:

So you think its too long causing the mc to keep some line pressure? Did you upgrade your mc to a larger one Al?

Al Hasse · Posted: Mon May 12, 2008 7:39 am Post subject:

Not sure about larger, but it came from a 2002 SS Camaro. The piston is actually smaller in diameter than the original master cylinder's is. I either need to find a shorter pushrod (from same model as the master cylinder) or machine this one down a bit.

blue89 · Posted: Mon May 12, 2008 7:55 am Post subject:

Weird. When swapped mine over I took note of the pushrod length and mine were the same. 89->94. But after 94 they upgraded the brakes again so maybe they changed the MC as well. Do you have the old setup still or did you buy a new MC?

Al Hasse · Posted: Mon May 12, 2008 8:17 am Post subject:

I still have the original master, but I'd rather not go through the trouble of bleeding the system again if I don't have to. I still need to make som JY trips, so I'll be looking for a 95+ model to pull a push rod from. Or maybe if someone knows how long it is, I can have mine machined down to match.