How to adjust brake pedal?

[nac593]

I just switched to disc brakes. I'm pretty sure I bled all the air out. The brakes work good but the pedal almost touches the floor. Is there any way to adjust it?

[big_al_71]

HHHmmmmsomething does not sound right, I think you need to double check the brake hoses make sure there are no leaks, top off the fluid and re-bleed the brakes. Once you bleed the brakes correctly the pedal should not move more than just about an inch or so. just my .02...

[neonlarry]

Did you change master cylinders? If so you might not have the correct lenght brake rod.

[cdowns]

master cyl and prop valve is different for disc brakes do you have the right ones? did you clamp the piun onnual?

[LONGHAIR]

If the brakes are firm and work well and the pedal is just too low, it is probably just the linkage (rod). There is a short rod that pushes from the pedal to the back of the master cylinder. There should not be much "slack" between them. Simply adjusting this to take out the slack will raise the height of where the pedal "works".

[nac593]

So I can adjust the rod from brake pedal to brake booster to fix? I bought front and rear discs from ECE with new brake booster, master cyclinder, and prop valve. I asked them about the prop valve for disc/drum or disc/disc and they said it was ok, might just want to add inline adjuster. I just did the rear discs. When I did the fronts I couldn't get it to bleeed right so I took it to a abrake shop. When they were done, my brakes were about the same. worked good but the pedal went far to floor. When I asked the shop they said it was just because I had to get used to the way disc brakes feel compared to drum. They also said I should add a canister for vacuum for the brake booster. Something about the cam in my truck. Thanks for all the help.

[nac593]

Also when I installed the brake booster, the rod was a litttle to long. ECE said it was ok to cut. I cut alittle. When I went to the brake shop I asked them to check it out but they didn,t. I cut just enough to make it fit. 1/2" or 3/4".

[orgalmeister]

Does the pedal have more travel with the engine running as opposed to not running?
Also are the rear discs adjusted properly? I'm guessing they have parking brakes.

I'm going thru this with my '56. Have less pedal travel with the engine off. Brakes work with the engine running but the pedal goes almost to the floor and won't return upon release. Not trying to hijack, I hadn't posted about this yet until I tried all avenues to fix. So far no change.

Steve

[nac593]

Yes, its a little better when running. I guess that's what the vacuum canister would help according to the brake shop. The parking brake is another issue i'm having. I can't get it to start grabbing.

[orgalmeister]

Get the parking brake adjusted first. I'm guessing that the caliper pistons are too far retracted causing no parking brake and having to move too far to engage the disc thus causing the low pedal.

[hchad18]

We've did the same conversion and the pedal did the same thing. I've found these articles that explain the brake system really well. I believe one explains why the pedal went away. Two small diameter bore master cylinder= high press not so good pedal, big bore = low press better pedal. All components have to match. Very good reads.

http://www.mpbrakes.com/uploads/documents/optomize.pdf
http://www.hot-rod.com.au/builder/brakes.html

[nac593]

Good articles. So what did you do to fix your problem?

[hchad18]

Was a friends truck. My guess is you need a master cylinder/ prop valve designed for 4 wheel disk systems. It would probably be a larger diameter bore. I am getting a master cylinder from performance online which either has a 1" or 1-1/8" bore. The stock one being used with disc and drum probably has two different size bores. Larger one for front discs smaller for drums, which would explain why you lose part of the pedal when you converted to 4 wheel disc. My guess, I'm not an expert.

[hchad18]

I just re read, if you switched to just discs in the front, my guess would still be the same. You've changed the system balance.

[orgalmeister]

Bore size in a master cylinder as far as I know, does not change. The reservoirs may be different sizes for a disc/drum setup the larger size for the disc portion.

[PanelDeland]

I would call ECE since that's where you got the conversion.Get the part #'s off of the MC and prop valve before you call.They may have sent a disc/drum MC by mistake.Or there may be a problem that needs to be addressed that they did not mention in the instructions.The Vac canister is probably because you cam does not allow enough Vacuum to operate the brakes.I think adjusting your park brake will make a difference but it may not cure all of your problems.