Pedal cluster rebuild?, No pressure on braking Options

[brooks944]

just got my car back from the shop after major rear end rebuild of the wheel bearings and most brake parts to the wheels. The PO had front calipers on the rear so put the correct rear calipers on-hey I have a parking brake now! Also had A new master cylinder installed. But now it takes a bunch of pressure to get the car to stop. Brakes have been bled so no air, the shop says the pedal cluster needs rebuilding. What do the experts here at 914 World think? I also have installed a complete FI system purchased form a member which was outstanding so I greatly respect the advice here.

Thanks,
Rick

[ThePaintedMan]

If they put in anything larger than the original 17mm master cylinder, it's going to take more force to get the pedal to depress - assuming all else is kosher. Worth taking a look at both the pedal cluster for a rebuild to be sure. Bdstone914 (Bruce) sells rebuild clusters that are beautiful.

[bandjoey]

Pedal bushings gone I don't think would effect brake pressure. Eric will tell us straight on that.

[bdstone914]

Rick

Ask your mechanic if the pedal will depress easily if a bleeder valve is opened. If it does the problem is not in the pedals. If the bushings are binding they will make the pedal stick moving both up and down.
Glad to sell you a pedal set but I doubt that is causing the hard brake pedal.
Bruce

[barefoot]

I'd only suspect the pedal cluster if the brake pedal is stiff to move thru it's free play stroke. Just push in & out by hand to see if it's hard to move.
just had mine apart as part of general restoration and it had been upgraded to bronze bushings at some point and was fine except for minor corrosion.

[brooks944]

Thanks guys. The pedal is easy to push, not hard at all. Is that a bleeding problem? There is actually about a couple inches before there is any pressure.

[Nate]

While my experience isn't as vast as some of the other guys who have replied, I have to agree that the problem doesn't seem pedal based. Like previously mentioned, a different size master cylinder can wreak havoc on brake feel and pressure. Did you source the replacement master cylinder or did the shop? I'd verify it is the correct one. Also, sometimes even after lots of bleeding, air can remain in the system and require more bleeding. I'd probably try bleeding using at least two different methods as my first resolution. I.e. Use a pressure bleeder and bleed as much as possible, then use the assistant method and have them pump the brake pedal and do that quite a bit as well.

Hope this helps.

[mgp4591]

You may have too much clearance on the rear pads making the mc and the rear caliper pistons having to make up the gap. If there's no air in the lines that's what I'd look for.

[DRPHIL914]

You may have too much clearance on the rear pads making the mc and the rear caliper pistons having to make up the gap. If there's no air in the lines that's what I'd look for.

(IMG:style_emoticons/default/agree.gif) this was my issue

[Dave_Darling]

I recommend using half of the factory spec for rear pad clearance.

But it really sounds to me like there is still air in the system.

--DD

[brooks944]

Appreciate everyone's advice. The shop got the master cylinder. Would having the larger one (19 mm versus 17 mm, I think) installed cause this? You really have to push hard to brake and it doesn't seem to brake at all until the pedal is almost to the floorboard.

Thanks,
Rick

[a few loose screws]

A larger master will shorten the distance the pedal travels. Yes, you have to exert a bit more force due to the increased size of the piston in the master. I wouldn't jump around the system and try to diagnose random parts of the brake system. Start with the rear brake adjustment. Set it up to half the factory spec as stated previously, then bleed the brake system real good, take your time, get all the air out. Double check the free play of your brake pedal, adjust the pushrod if its too sloppy. If you have a 19mm master it will be pretty obvious at this point. you should definitely notice a slightly firmer pedal with less travel, but you shouldn't have to push it to the floor to get it to stop. If it still feels wrong, your master may not have been properly bench bled, and you could still have some air in it. Lots and lots of posts on here of people having a tough time bleeding these things. Take your time, diagnose the system properly and you'll get it sorted. Good luck.

[DRPHIL914]

Appreciate everyone's advice. The shop got the master cylinder. Would having the larger one (19 mm versus 17 mm, I think) installed cause this? You really have to push hard to brake and it doesn't seem to brake at all until the pedal is almost to the floorboard.

Thanks,
Rick

No the 19 mm would not cause that. I have a recently installed 19 mm m.c. and I replaced the previous one because it needed rebuilding. I would have to do what you are saying as well at first because of 2 issues. #1 was even after I bled them there was still air in the system and #2 the rear venting clearance was not set yet so it took more pressure and more pedal travel to get the inside pad in contact with the rotor. I will bet they have not set this rear clearance. Look on Pelican tech pages the have a step by step on this. When I installed mine I didn't know that the gear thing that has to go in there to adjust the setting had not been put in when they were rebuilt. When Eric at PMB does them they assumed I had kept mine but I had left them in the old ones and they did not switch them out as I expected they would so we had to have them send me thise.
Bottom line is my 19 mm feels no different that the previous on now. My braking is awesome!! Pedal is firm and the pads grab right away. You might still have air too though. If the m.c. was not bench primed then it takes a lot to get all the air out of the system.
Good luck.