Is this a disc/drum set up?
if so, Residual valves installed - 2lb for disc; 10lb for drum?
if so, Residual valves installed - 2lb for disc; 10lb for drum?
brakes still problematic
- Thread starter 56chevtrk
- Start date
His M/C is higher than the wheel cylinders/calipers, so residual valves aren't needed.
Thanks, forgot about that little tidbit.
Good job all - kicking around these ideas may eventually get my problem solved.
I am going to try to see if the different booster I have will fit and make any difference.
After removing and bench bleeding the M/C again I had visible fluid flow into both reservoirs with no air bubbles. So feel that the M/C should be good. Also had no leaking out the back of the M/C.
Next as said above will examine the booster closer and maybe see if I can swap it out!
Also as previously said I have great pedal feel until I start the engine and once started a very clear swoosh or hiss when stepping on pedal and significant loss of pedal. Not sure if I had that sound with the other booster and M/C. The other M/C and booster I had sat a long time - like 15 years - and it leaked brake fluid out the back almost immediately.
On line research has me a bit confused, as usual, but some places mention a swoosh or hiss when pressing pedal can be problematic. Booster may be leaking somewhere!
I am going to try to see if the different booster I have will fit and make any difference.
After removing and bench bleeding the M/C again I had visible fluid flow into both reservoirs with no air bubbles. So feel that the M/C should be good. Also had no leaking out the back of the M/C.
Next as said above will examine the booster closer and maybe see if I can swap it out!
Also as previously said I have great pedal feel until I start the engine and once started a very clear swoosh or hiss when stepping on pedal and significant loss of pedal. Not sure if I had that sound with the other booster and M/C. The other M/C and booster I had sat a long time - like 15 years - and it leaked brake fluid out the back almost immediately.
On line research has me a bit confused, as usual, but some places mention a swoosh or hiss when pressing pedal can be problematic. Booster may be leaking somewhere!
Canuck
Active Member
Hey 56 chevtrk, 1st have to say love your truck,, nice build.
Know how frustrating it is trying to troubleshoot problems like this. Saved some info years ago relating to a similar problem incase it showed up on the 94 truck I was driving, Summary disc of article " In this article, we are going to take a close look at one group of vehicles that tends to experience low brake pedals more than most others. The vehicles in question are General Motors trucks built from 1980 to 1999. This includes the C-, K-, M-, R-, V-, G-, S- and T-series platforms. I think you recognize by this list the chances of you being impacted by these vehicles on a regular basis are pretty high".
If this sounds like yours, if there is a way I could send it to you, about 14 pages of Word document, located on my computer.
Let me know.
Jim
Know how frustrating it is trying to troubleshoot problems like this. Saved some info years ago relating to a similar problem incase it showed up on the 94 truck I was driving, Summary disc of article " In this article, we are going to take a close look at one group of vehicles that tends to experience low brake pedals more than most others. The vehicles in question are General Motors trucks built from 1980 to 1999. This includes the C-, K-, M-, R-, V-, G-, S- and T-series platforms. I think you recognize by this list the chances of you being impacted by these vehicles on a regular basis are pretty high".
If this sounds like yours, if there is a way I could send it to you, about 14 pages of Word document, located on my computer.
Let me know.
Jim
Just in case get one of these and keep it in the bed of the truck..might come in handy.
Yes absolutely you could email it to me: barrywood@xplornet.com
My frame and brakes are 1980 Chev C10. Fits nicely in that group.
Thank you so much.
There you go.
Got any of those laying around out there by the Great Lakes. None at all around here in the foothills!!!
Make sure the pushrod from the booster to the master cylinder is adjusted correctly. If it's too long it can keep the read MC chamber from getting any fluid. here is a tutorial https://techtalk.mpbrakes.com/how-t...forget-the-booster-pin-to-master-cylinder-gap
I am going to look into this also. But I have to wonder that because I purchased them as a pair from Performance Online I was kind of hoping that they would be a matched pair.
Thanks.
Barry
Right ! A guy in our car club was building a rat rod and at the Radium Car show was a complete chassis with running gear for sale from a merchant, ... he bought it. A year latter he could not get the brakes to work right no matter what he did, finally called the seller who said that they had just put it together for display purposes and the calipers could be upside down, ... he was right! ( Have you met Mr. Murphy, ... he works overtime. )
Who would put calipers upside down, even just for display purposes. That is just odd.
Someone that did not know better, ... the kid that swept the floors I think, ... but I can supply the name of the company and you can ask them if you like.
(Mitch should have caught it sooner too.)
Any update on the problem? Did you find the issue?
Well I have done a lot of research on this problem!
After talking to several people and an internet search I arrived at the conclusion that I do not have enough volume of fluid to push out the big GM C10 1/2 ton front callipers.
The frame and brakes I am using are from a 1980 C10. That truck usually has a 1 1/8" diameter bore master cylinder. The two previous master cylinders I have had in the truck were smaller bores.
So I bought a 1 1/8" bore master cylinder and got all excited when it arrived. The instructions that came with it to bench bleed it were a bit different then what I have been previously doing. This time it said simply to block off the front and rear lines and fill with fluid and pump it up with short strokes until I could not move it any more. Previously I had built some short pieces of brake line that I fed back into the master cylinder and pumped till no more bubbles. I think both methods work.
Anyway I got it pumped up and then went to mount it on the booster. The only problem was the rod between the booster and master cylinder would not fit in this new master cylinder. I was totally bummed...
So after a bunch more research this turns out to not be a new problem. I was glad that I was not the only one in the world who ran into this problem. It was however hard to locate the proper diameter and length little rod to fit in there. I was going to build one but low and behold I found one from a distributor in California. Ya...
So I emailed him and said yup he knew exactly what I needed and we made the deal. With the border still closed I bit the bullet and told him to just mail it. Shipping was as much as the part but what another $60.00 bucks total to get my truck running and stopping!
Just a 2 week wait for it to get here after they ripped it apart at the border. Don't they know its legal in Canada now!!!
So it came and I raced out to the shop, ripped the package apart - man those border guys use good tape!
And once it was opened it was plain to see that they sent me some sort of rubber brake part the likes of which I have never seen before.
I was again bummed out.
I emailed the guy and admit I had a bit of an attitude. He immediately phoned me and could not say enough times how sorry he was.
So some one some where has my little rod.
He said he was immediately going to send me the right part.
It has not arrived yet but I am expecting it any day.
When I told my mechanic - the one who came out to set my timing - he said he had previously told me that that was the problem. I don't remember him saying that but hey maybe I was not listening close enough to him.
So I am really hoping that I have figured it out. People I have talked to are saying if I was using a multi-piston Wilwood system I probably would be okay as the calliper pistons would be smaller and basically not bottom out before actually grabbing the rotor.
Heres hoping!!!
After talking to several people and an internet search I arrived at the conclusion that I do not have enough volume of fluid to push out the big GM C10 1/2 ton front callipers.
The frame and brakes I am using are from a 1980 C10. That truck usually has a 1 1/8" diameter bore master cylinder. The two previous master cylinders I have had in the truck were smaller bores.
So I bought a 1 1/8" bore master cylinder and got all excited when it arrived. The instructions that came with it to bench bleed it were a bit different then what I have been previously doing. This time it said simply to block off the front and rear lines and fill with fluid and pump it up with short strokes until I could not move it any more. Previously I had built some short pieces of brake line that I fed back into the master cylinder and pumped till no more bubbles. I think both methods work.
Anyway I got it pumped up and then went to mount it on the booster. The only problem was the rod between the booster and master cylinder would not fit in this new master cylinder. I was totally bummed...
So after a bunch more research this turns out to not be a new problem. I was glad that I was not the only one in the world who ran into this problem. It was however hard to locate the proper diameter and length little rod to fit in there. I was going to build one but low and behold I found one from a distributor in California. Ya...
So I emailed him and said yup he knew exactly what I needed and we made the deal. With the border still closed I bit the bullet and told him to just mail it. Shipping was as much as the part but what another $60.00 bucks total to get my truck running and stopping!
Just a 2 week wait for it to get here after they ripped it apart at the border. Don't they know its legal in Canada now!!!
So it came and I raced out to the shop, ripped the package apart - man those border guys use good tape!
And once it was opened it was plain to see that they sent me some sort of rubber brake part the likes of which I have never seen before.
I was again bummed out.
I emailed the guy and admit I had a bit of an attitude. He immediately phoned me and could not say enough times how sorry he was.
So some one some where has my little rod.
He said he was immediately going to send me the right part.
It has not arrived yet but I am expecting it any day.
When I told my mechanic - the one who came out to set my timing - he said he had previously told me that that was the problem. I don't remember him saying that but hey maybe I was not listening close enough to him.
So I am really hoping that I have figured it out. People I have talked to are saying if I was using a multi-piston Wilwood system I probably would be okay as the calliper pistons would be smaller and basically not bottom out before actually grabbing the rotor.
Heres hoping!!!
Thanks for the update, hope you get the rod soon and get to sort your problem. Keep us up to date.
Its close to a 100% a master cly problem, I have installed a lot of these on cars that I have built. These work great 99% of the time but a couple have been troublesome for me even after a couple of miles driving. The way your describing your problem my guess is the master is bypassing one of the sides (front or rear with the fluid never leaving the master).The master should be bench bled, which is simply clamped in the vice, filled and pumped until no air bubbles are seen in the reservoirs, however the "new" way is to block off both ports, rather than running plastic tubes back into the reservoirs, then the push rod is only pushed in a 1/4 inch at a time. Continue this way until no bubbles are seen coming up. Doing it this way the air comes up until the seal covers that hole the air bleeds out of that's why only a 1/4 inch at a time until no bubbles are seen. Another trick I have done for years is not to pump the pedal to bleed the system but to gravity bleed. Pumping the pedal will make lots of little air bubbles out of a few small ones. Your truck is a good example for this way because the master is a lot higher than the wheel cylinders. With the lines on the master tight start with the right rear and ending up with the left front.(farthest from master first) Dont get in a hurry sometimes this takes a long time to start then you will see bubbles then a steady flow maybe a few more bubbles then flow because all the lines fill or bleed slowly, after right rear the other three wheels will flow faster. Leaving the cover off the master so it can be topped up as the fluid goes down and so the fluid can drain. Then after your happy all the air is out don't fill the master to the top leave it down a 1/2 -3/4 inch so when the lid is put on no fluid will not spill out. My last tidbit is the fluid itself, I only use dot 4 fluid for number of reasons, I'm sure there are going to be some comments about this lol. Third of all dot 3 really absorbs water causing a lot of rust from the inside and this is seen in the fluid turning black, second it has a high tolerance to heat. After being on my brothers Players Challenge Camaro racing team, where we run everything as close to stock as possible, we were allowed to run the high temp brake pads and steel braided hoses in the name of safety. Dot 3 boiled almost on the first lap so in went the dot 5 this is very good for heat but gives the pedal a spongy feeling so I use the dot 4 in my street cars.The number one reason, you guessed it, it don't wreck the paint if some is spilled, just wash it off with water. I hope this helps even if I did get rattling along like an old man talking to the kids at the park!
Randy
Good information there Randy, I’m sure that many of us will get something out of it.
Yes really good information. Im just waiting for the little rod to come in the mail and then I will be back at it.