Brake Pedal Question

[Case500D]

This weekend I installed a brake vaccuum booster and master cylinder on my '92 truck. The brakes work 100% better. The problem is that the pedal is a little slow on its return and the brake lights (tail lights) keep coming on while driving down the road. I have tried to slide the little swith down so it would contact the brake pedal arm, but it still isn't enough. While driving home I reached down and pull the pedal up and it came up 6 inches. So, I got to drive for the next hour and a half holding the bloody brake pedal up. My question is, can I put some type of spring on the brake pedal to help it return better and to help it make contact with the brake light swithch? Or is my vaccuum booster junk? Also has anyone had there brake pedal come up 6-8" off the floor? Thanks for the help. I think this is a simple problem, but figured I would ask for a bit of help/advice/experience first.



Jeremy

 

[Tim1]

Hey Jeremy, don't add a spring to fix the problem, find out why this pedal is not returning. My suspicions would lean towards the master cyl or possible a bind some place. A spring may be a temp. fix, but may surprise you when you least expect it. Just my 2 cents. Tim

 

[Case500D]

I looked through my service manual but still can't figure out why the brake pedal doesn't come back as far as it used to. When I first put the new booster on, the pedal had about an inch of free play that it never had before. I think the reason I can lift the pedal up so high is because the brake light switch moved up allowing the pedal to travel more. If I can get the switch moved down, then I think everything will be okay. Although the 1 to 2 second delay in the brake pedal returning baffles me. BTW I got my parts from NAPA. Thanks.

 

[CrewCabDiesel]

SEND IT BACK !

The master cyc. and booster have return springs. DON'T short cut brakes, get new booster and master cyc. on there you got at least a 5K lbs truck, complete brake failure would be a bad thing . As for NAPA I have sent back 2 master cyc. /boosters for defects and the third booster is starting to leak . My next one is coming from the dealer

Kyle

 

[Case500D]

I just called NAPA and they are going to get me another master cylinder/booster assembly. Before I go to the work of changing everthing again are there any adjustments or anything to look for? The guy at NAPA said to make sure nothing was binding, but I am not sure what could be binding unless it was something internal that I can't see. With the brake pedal in its normal position, the arm misses the light switch by 1/4" of inch (that is with the switch adjusted all of the way down). I have never felt brakes hesitate or hang on after you let off the pedal like this does. Oh well, I want to fix it right. I am really happy with the way it stops right now. I sure can tell the 1 ton brakes are back there I won't be able to fix it till this weekend, so I guess I have to ride with the wife to work. Thanks for all of the help. TDR is the BOMB

 

[paccool]

Jeremy,



This is one of those" been there, done that" answers. There are a couple of things you need to check. I had a similar problem when I changed mine and ended up cooking the rotors.



Between the master cylinder and the booster there is a threaded rod. You will need to unbolt the master cylinder to get too it. You can leave lines hooked up if you are careful. This must be adjusted for your truck and will affect pedal height. After you do this and put it back together, pop the top off the master cylinder and look at the ports. Make sure they are open 100% when the pedal is all the way up. if not, the brakes are not releasing all the way. Mine came as an assembly and foolishly I figured things would be set up correctly- WRONG!!!



The brake light switch must make contact with the pedal or the cruise control won't work right. The cruise control won't stay on or even engage if too far from the pedal and the brake lights will be on also. Is real touchy to get things set right. I finally took a cable tie and secured the switch in position because the darn thing wouldn't stay where set with the dumb plastic ears they were designed with.



Hope this helps. Doesn't answer all your questions but may be at least part of the problem.

 

[Case500D]

Paccool,



After reading your post I had a revolation/brain fart. When I put everything together I split the master cylinder from the booster and put the brake line bracket in between. I wonder if the added space (1/8") has cause the pedal to fall down which might intern cause the brakes to come back slowly. Also, thanks for the idea on holding the brake light switch in place. Is there anything special on adjusting the rod, or just lenghthen it until the ports are 100% open? Is there a lock nut or anything on the trheaded rod? Thanks so much. If I get lucky maybe I won't have to do another install.



Jeremy

 

[paccool]

Yes, moving the master cylinder outboard will allow the pedal to drop. Don't know if it will drop as much as you said though. Will cause the system to not work right.



It seems like there is a barrel nut setup in the cylinder with a lock nut. Can't remember for sure(thats a "getting old" thing) but you will see as soon as you open things up how it works.



I suspect the master cylinder is not releasing good and that is why the pedal is not returning all the way like it should. I'm a little surprised that you didn't have a brake drag problem like I did. I sure hope I'm right and you don't have to redo things again. Doing things once isn't so bad but twice sucks!



Good Luck

 

[Dfeland]

Been there done that also. That bracket just wants to slip in behind the master cylinder doesn't it! You need to move it in front of the master cylinder for the rod not to bind. Next the threaded rod must be adjusted for your truck. It fits serveral applications and is not the same for all. If you still have the old one match it if not you have to play with it all day like I did.

 

[Case500D]

I just went out and checked the truck in the snow and I did put it together right after all. The bracket is in front of the master cylinder. Its been a long day. However, I am going to adjust the rod and fortunately I do have the old booster to measure. Things are definitely looking up. All I have to do is get less an inch of slp out of the pedal and everything will work, or so I hope. I think a proper adjustment will fix the delay. Anyway, now that I am repeating myself, I will look tomorrow evening and see what happens. Thanks so much guys, your experiences are priceless.

 

[Cummins Cowboy]

i had the same prob with the brake light switch last summer after i changed my booster seemed though the switch would stay in place for a little while then work its way back. i think they used some kind of metal clip or something orginally, here is what i used i couldn't find nut to go on there to save my life, i went to my hard ware store and finally in the electrical section i found a small brass nut one of those really thin ones that threaded on perfact. I think they thread on those hollow threaded shafts used in lamps. i put some plastic washers on before the brass nut and all has worked flawlessly for the last few months. it really holds the switch tightly in place against the pedal.

 

[paccool]

Cowboy, they didn't use anything to hold them in place. I bought a new one thinking it would take care of the problem. Instructions said to push switch in all the way then pull up on the brake pedal. It was supposed to set itself at the correct positon doing that. Well. that didn't work and the switch still moved out of the housing whenever I bumped the pedal getting out of the truck.



Your idea of the thin switch nuts is a good one. I'll have to try that.

 

[Case500D]

I got to work tonight and found out several things. I measured the length of the threaded rod on the old vacuum booster and it was turned out 1/4". The new vacuum booster was only turned out 1/8". So I made the adjustment. The pedal came up and I got the brake lights to go off when the are supposed to. I don't think the brakes are dragging because the truck will coast and doesn't grab or jerk just coasting to a stop. When I looked inside the master cylinder, there are 4 holes, 2 in the front compartment and 2 in the rear copartment. On each rear hole in each compartment I can see what appears to be a shiny rod, but can't tell for sure. Anyone have any advice for checking for brake drag or anything else being wrong. I am going to go to the hardware store and get a nut to keep the brake light switch from moving. Thanks for all of the help guys.



For reference, it takes a 9/16" to remove the master cylinder. It takes a 3/8" wrench and a small pair of vise grips to adjust the rod on the vacuum booster.



Jeremy

 

[paccool]

Great! Sounds like you got it fixed. If you can see the holes and they are clear and open all the way, you should be OK. Mine were not opening fully. If the brakes are dragging, you will know it in the first 3 or 4 miles - you will feel jerking as the rotors heat up and go out of round and they will be cherry red. I first thought I had a flat when mine did it.



Guess my experience with this actually helped someone else. Thats the way its supposed to happen as I have recieved lots of help on this site from others and it feels good to be able to help others in return.

 

[Case500D]

Update again

I drove 7 miles to work today and the front rotors were nice and cool. The only thing I dislike is the way the pedal returns if I just feather the brakes. It takes it up to 3 seconds to release. But if I come to a complete stop, it releases instantly when I take off. Who knows? I believe it is good enough for now. The point of engagement is now withing the top inch of travel and the brakes are fully engaged by two inches. Thanks for the help guys, I appreciate everbodies $. 02 because it is worth millions.



Jeremy

 

[JLEONARD]

So what you have done effectively is adjust the amount of "freeplay" in the brake pedal?

Now a question..... where should the brake pedal engage?



Mine is about half way down , the brakes feel great, and the stop light comes on if I just touch the pedal. I replaced calipers, rear cyls, drums, and master a few months ago.

But I do have the intermittent brake warning light problem that seems to have no common cause, judging from the situations when it comes on.

Is pedal "freeplay" be a factor other than how it affects the stop lights?

 

[Tim1]

Hey bud, I get that intermidiate brake lite also, but if i tap the emergency brake release, it always goes out. Just my . 02. Tim

 

[JLEONARD]

Yea, that was the first thing I tried too... actually several times but I wasn't that lucky.

I have the Mitchell book that covers my truck. It has an 8 or 9 step proceedure to diagnose the brake light thing. I guess I'll have to go thru it one by one.

 

[Case500D]

I know that you can adjust the rod between the master cylinder and vacuum booster incorrectly as Paccool has stated in previous posts. So I am not sure about changing the length of the rod to change brake engagement points. I used to have intermitant brake warning light and ABS light problems and a new vacuum booster seems to have fixed that. However, I tested for a vacuum leak first and found one. I have also had the problem with the emergency brake causeing the brake warning light to come on. I finally got it to stay up by adjusting the e-brake cables a bit. As for my the point of engagement, I tried to set it up the same way it used to be. My measurements are just guesses. But by halfway down, I am completely stopped or at least squalling tires. Hope this helps.



Jeremy

 

[paccool]

Push the brake light switch down and secure it. Like I said above, this will cause intermittent light as well as possably screwing up the cruise control.