Bouncing brake pedal

[leftoflefty]

Hey there. I have a '77 CJ5 . My brake pedal is bouncing a lot (when I hit a bump the brake lights come on). There is a spring connected to the top part of the pedal. I was wondering if there is supposed to be another spring to counter balance the pedal assembly to keep this from happening?

Ricky

 

[73CJ]

Check out this thread: http://www.jeep-cj.com/forums/f49/brake-pedal-8375/

There is a spring in the master cylinder that helps as well.

 

[al2ride]

Hey there. I have a '77 CJ5 . My brake pedal is bouncing a lot (when I hit a bump the brake lights come on). There is a spring connected to the top part of the pedal. I was wondering if there is supposed to be another spring to counter balance the pedal assembly to keep this from happening?

Ricky

Mine used to do the same thing, but when I changed to PBs I fixed it. Not sure what the PO did, but there are no springs on mine. There is a plastic shim that goes between the brake rod and brake pedal's pin. The shim takes out any play since the diameter of the rod is larger than the diameter of the brake pedal 's pin. My shim was worn out. I had to fab another piece to take out the play.

 

[leftoflefty]

Thanks guys. I just gutted the interior so I could por15 the floor pans. I'll get up under there and see if I can get down to the root of the problem.

 

[Niedhogg]

Can I ask a similar question about mine? I don't mean to hijack, but I just finished my brake system, completely new front to back, top to bottom, I have an automatic tranny but have a similar problem, no return spring on mine. Not only that, I used a YJ tub that had the exact brake pedal assembly in it as my CJ, with no spring, so I just figured this is how it's supposed to be. I am having trouble bleeding the brakes, well not really trouble, just having soft pedal issues, which is just exaggerated while the jeep is running and the vacuum attached.. I physically have to pull the pedal up with my foot to pump the brakes.. am I supposed to have a spring??

 

[Torxhead]

You might have some air in the proportioning valve, sometimes its tough to get the air all the way out. There is a procedure to properly bleed the system,and that valve, if you didn't already know that. Since you swapped out the pedal assembly and it sounds like you have a loose pedal, you might need to install an adjustable pushrod coming out of the master cylinder to fine tune it. Stopping a CJ with 35s and a stock power brake system, if that is what you have, is a real bear, at least from my point of view.

 

[Niedhogg]

You might have some air in the proportioning valve, sometimes its tough to get the air all the way out. There is a procedure to properly bleed the system,and that valve, if you didn't already know that. Since you swapped out the pedal assembly and it sounds like you have a loose pedal, you might need to install an adjustable pushrod coming out of the master cylinder to fine tune it. Stopping a CJ with 35s and a stock power brake system, if that is what you have, is a real bear, at least from my point of view.

How do I adjust the rod? It's an aftermarket, 8" dual diaphram system and has the adjustable rod, but how do I know how far to adjust this? And I've bled several times, and I figured it would take some patience, but man, I've used a whole bottle so far and it just seems like I should be done, lol.. I've tried starting with the closest wheel and worked my way out to the farthest, I guss I'll just keep bleeding..

 

[BajaEdition]

did you do a bench bleed of the master cylinder?

 

[Torxhead]

As I recall, the rod gets adjusted out just so to remove excess play in the pedal. There is a pin valve at the front end of the proportioning valve that should be held open during the bleeding process, some guys use a small vise grip. According to the M.R.252 factory service manual, the brakes should be bled in this order: right rear, left rear, right front, and left front. Its nice to know that you have clean fluid in your system. Oh yeah, X2 on the bench bleeding.

 

[al2ride]

How do I adjust the rod? It's an aftermarket, 8" dual diaphram system and has the adjustable rod, but how do I know how far to adjust this? And I've bled several times, and I figured it would take some patience, but man, I've used a whole bottle so far and it just seems like I should be done, lol.. I've tried starting with the closest wheel and worked my way out to the farthest, I guss I'll just keep bleeding..

I just recently upgraded to PBs and used an 8" aftermarket set. Did you prime the master cylinder? I adjusted the rod (one that goes through the firewall) so that it links to the brake pedal when the brake pedal is in the far back position. The rod just turns in or out.

 

[Niedhogg]

As I recall, the rod gets adjusted out just so to remove excess play in the pedal. There is a pin valve at the front end of the proportioning valve that should be held open during the bleeding process, some guys use a small vise grip. According to the M.R.252 factory service manual, the brakes should be bled in this order: right rear, left rear, right front, and left front. Its nice to know that you have clean fluid in your system. Oh yeah, X2 on the bench bleeding.

Ok on the rod, that's exactly what I thought and did. I turned it out so that the pedal was all the way out... I did not bench bleed the master cylinder, but the entire system was dry to begin with, being totally new, so would that really matter?... And last but not least, I bled my brakes completely the opposite of that recommendation, lol... I have another brand new bottle, so I guess we'll try again tomorrow. Any other suggestions??

 

[Torxhead]

Since your system is completely installed, I would say keep bleeding. Although when I bleed brakes, the engine is'nt running, so I can be in a warm garage. I would think by the time you go thru that next bottle all the air would be out. Also when I bleed brakes I use a clear drain hose and bottle so I can see the bubbles come out. All that air has to come out sooner or later.

 

[Niedhogg]

Since your system is completely installed, I would say keep bleeding. Although when I bleed brakes, the engine is'nt running, so I can be in a warm garage. I would think by the time you go thru that next bottle all the air would be out. Also when I bleed brakes I use a clear drain hose and bottle so I can see the bubbles come out. All that air has to come out sooner or later.

I never bleed brakes when the engine is running, and no warm garage for me here... snow on the ground and 20 degrees outside.. so then, I guess this question was never really answered, there is no return spring on the brake pedal, right?? It's pushed, or held back by whatever spring is in the master cylinder, correct?

This will be the last thing I'll be doing to it before we leave for home Tuesday afternoon. It gets loaded on the trailer tomorrow and tied down for the long trip home.

 

[Torxhead]

As far as the brake pedal return spring goes, I would say it depends on the vehicle. Looking at the inside brake linkage, do you see holes for a return spring? My '86 never has that I know of, but the fsm does show one. The return spring in the mc on my rig seems to work just fine. So, if you think you need one install it.

 

[Niedhogg]

As far as the brake pedal return spring goes, I would say it depends on the vehicle. Looking at the inside brake linkage, do you see holes for a return spring? My '86 never has that I know of, but the fsm does show one. The return spring in the mc on my rig seems to work just fine. So, if you think you need one install it.

I'll have to look again, but I don't think there are holes for the spring. I'll try bleeding again and see where I'm at..