Team Camaro Tech banner
Cancel
Create thread New Garage Forums

Rod too long ? Brakes locked up

1 reading
Jump to Latest
1 - 16 of 16 Posts
P

plum_crazy_purple

· Registered
Joined
·
69 Posts
Discussion starter · #1 ·
Hello,

After installing from discs, new master cylinder, new lines all around, proportioning valve and the longer of the two rods that came in the kit ( that i think i ordered from Matts - - it was over a year ago that i ordered it and just go to installing it a month ago). The brakes locked up. I was about two miles away from my house with a 2yr old and wife in the car and i needed to get home so i kept on driving eventhough the brakes were definitely on pretty hard. when i got home smoke was pouring out from all 4 wheels. it was bad.

I never replaced the rear brakes, just bled them after installing the new lines. After installing all the new parts the brake pedal never really felt right. It would only go down about 2 inches and then it would stop as if i were hitting something. From the instructions i could has sworn i was supposed to use the long rod but now i am begining to think i was wrong. I can't imagine why else the back breaks would lock up ( or drag to such extremes) when all i did was replace the lines.

I am nevervous to take off the wheels to see what damage i may have caused by driving it home. Unfortunately - it was better option that getting stuck on the side of the road and missing the wedding we had that day.....trust me.

Is there anything i can do / check before pulling the brake pedal off, the MC out, popping off the lines, and switching the rods ( it will take me 3-4hrs). I have never done anything with the proportioning valve. Should I ?

Thanks
Brian
 
#2 ·
I am nevervous to take off the wheels to see what damage i may have caused by driving it home. Unfortunately
Click to expand...
Damage...replace all the gease in the bearings and check the bearings
May have to get the drums/discs skimmed

The search button is your best friend.....
just back the MC bolts off and the brakes should release....depending on if nothing has 'welded ' due to very hi temps.
 
Discussion starter · #3 ·
unbolting the the MC bolts will just release the brakes and not solve the problem. i can't imagine what else other than the rod being too long that would cause the rear brakes to lock up as well - when i never did anything to them other than to replace the lines and bleed them.
 
#4 ·
If backing off the mc releases the brakes then that is most prob the issue...
Older threads tell you how to measure the depth in the back of the mc (there are several depths) and the pin.
What can happen is the rears drag after 1st use due not being able to return get hot, espec if newly adjusted up also, and expand lock on a bit tighter...we are talking thous of an inch here and that is all it takes.
If replacing a mc, always measure distance and pin never assume it is right.
 
#5 ·
I know its too late, but for everyone who is getting the repro MC kits, it is very important for you to check the rods, besides choosing long or short. Test fit the MC to the booster with the rod of your choice. If you have a gap between the MC and the booster, you need to grind the rounded end of the rod. I had to take about 1/8 in off, in multiple tries. You should be able to put the mc on the booster without nuts and have it fully seat without any pressure. If you have a gap or can still rock it gently by hand, you need to grind some more. I just took a 4" grinder and kept shaping the rounded end. After that the brakes are working fine.

Also make sure the pedal rod is in the LOWER hole!

Hope there is not permanant damage.
 
#6 ·
KevinW said:
I know its too late, but for everyone who is getting the repro MC kits, it is very important for you to check the rods, besides choosing long or short. Test fit the MC to the booster with the rod of your choice. If you have a gap between the MC and the booster, you need to grind the rounded end of the rod. I had to take about 1/8 in off, in multiple tries. You should be able to put the mc on the booster without nuts and have it fully seat without any pressure. If you have a gap or can still rock it gently by hand, you need to grind some more. I just took a 4" grinder and kept shaping the rounded end. After that the brakes are working fine.

Also make sure the pedal rod is in the LOWER hole!

Hope there is not permanant damage.
Click to expand...
Thanks for this advice, Kevin! I have a brake swap coming up and this is what I need to know.
 
Discussion starter · #7 ·
After doing a lot more searching and reading through these posts, i am left to believe that there could be two possible causes of sustained fluid pressure to all 4 brakes ( which has to be the case since i never touch the back brakes and they had sever drag and smoked just as the front ones which i did replace). I know that i am using the correct lower pedal hole.
After completing the brake conversion i noticed that it was strange that i could not press the brake pedal to the floor or even close to it. I would get about a 1/3 a push and then it felt as if the brake pedal was pushing up against something rigid like metal and would go no further.

A. When i replaced the booster and MC, i arbitrarily set the clevis lenghth ( i just turned it and turned it until i could get all the parts to fit: Booster to clevis to pedal). Perhaps unscrewed it too far ( making the rod too long) so that in effect the brakes were on almost all the time. Then if the brake fluid heated up from excessive drag, it expanded putting more pressure on the brakes.

B. I am using the short rod with the adapter/receiver in the MC. Maybe the combined length of the long rod without the adapter in the MC is actually shorter than the short rod and the adapter thing in the MC. Perhaps i need to switch from short rod and adapter to long rod and no adapter.

Because i am an amature and because i bought the MC and booster in a kit with two rods etc, i believe that i am doing somehting wrong rather than having received the wrong or mismatched parts. Something is causing there to be sustained pressure in the brake lines....
 
#8 ·
Bri, When the booster is at rest the rod sticks out a set amount and the lower rod with clevis is only adjusted for pedal height. Nothing should be pressing on the MC. BUT if the rod sticks out too far from the booster at rest and you installed the MC, you would have had to use the nuts to tighten the gap. that is what puts pressure on the MC.

I would remove the nuts for the MC (you dont have to undo the lines, they have enough flex if you remove the lower clamp) and examine the rod and MC back. the difference between the rods in over an inch, so you should be able to see which MC you have. Luck!

BTW, the repro MC comes with both rods. And did you Bench bleed the MC before installing?
 
Discussion starter · #9 ·
Thanks for your reply. Yes, I did bench bleed it the MC before installing.

I will try what you suggested. The kit came with a receiver of some sort ( a metal rod about an inch or two long that fits in the MC --- which is different than the two push rods that came with the kit. Perhaps this is what is causing the problem. I had been using it but perhaps i shouldn't be).

I really believe that because i was getting a "hard stop" when i pressed the brake pedal down only two inches ( as if it was hitting something metal), that i must have done something wrong with the rod.

Thanks again - I hope i can fix it and will get back as to what i found.
 
#11 ·
Here's a pict of the tool used to measure the rod gor the master cylinder.
J-34783-A Kent-Moore U.S.A. (stamped on tool) the center rod slides
back and forth, measure the depth od the M/C then how far the rod
stisks out should have a small clearance.
 

Attachments

Discussion starter · #13 ·
so the idea is to make sure there is 1mm of clearance between the tip of the extending from the booster and the receptor thing in the mc. ( nobody ever seems to talk about the receptor thing that fits in the mc in these kits. in the kit that i have there is an inch-and-half to two inch receptor rod thingy that fits right in the MC that extends back to the back of the MC - - this is different than the rod that fits in the booster and reaches out to the MC).

i do appreciate the help,i know it sound as if i couldn't change a tire. I will take some pictures and post them.
 
#14 ·
If it's an aftermarket booster, you'll likely need to grind some length off the little push rod. I've used two of those repo boosters, and they work and look fine, but both needed adjustments (grinding) to the little rod; usually about 3/16".

Also, has the master sat, with fluid in it, for a long period of time? They can lock up.

Laslty, are you sure your pedal linkage is correctly installed and has the needed room?

Since all 4 corners locked up, you're looking in the right place; from the pedal to the master.

FWIW
 
Discussion starter · #15 ·
I compared the old MC rod length to the one i am currently using and they were the exact same length. I think what might have been happening is that the other rod, the one that goes from the pedal to the Booster was too long and then when i tightened the booster to the firewall it made it so that there was constant pressure on the brakes ( still not sure though because the problem didn't start until about 3 driving days after installing the disc upgrade). The new and the old MC looked exactly the same to me ( when i bought the car it had power drums on all 4).

This weekend i re-installed the old booster ( the one with the shortened pedal rod) thinking that it they looked exactly the same why not install the old one with the shortened pedal rod instead of cutting the pedal rod on my new booster. The results were disappointing. After bleeding the brakes again, its not working correctly. There is way too much play in the pedal now and i can get the pedal down the floor and it can't stop the car in a reasonable amount of distance. It also pulls to the left.

Because the rear drums are toast, i was going to replace them to eliminate that as a potential cause of my problems.

When i hit the brakes the nose does dive telling me that the front brakes are doing work so i don't think the proortioning valve is set wrong.

Am i correct in saying that if the brakes are correctly bled and the MC has been bench-bled, and if there are no leaks, that if i can press the pedal to the floor, the Booster pedal rod is incorrectly adjusted ? ( because brake fluid doesn't compress). There is about 3 inches of travel when i press the brake pedal before i feel any real type of resistance. I think this may be my problem.
 
1 - 16 of 16 Posts
About this Discussion
15 Replies
6 Participants
Last post:
Steptoe
Team Camaro Tech
posts
2.4M
members
90K
Since
1998
A forum community dedicated to 1st generation Chevy Camaros owners and enthusiasts. Come join the discussion about performance, builds, restoration, modifications, classifieds, troubleshooting, reviews, and more!
Full Forum Listing
Explore Our Forums
Bench Racing Engine Body Shop Performance Brakes, Suspension & Steering