Rusty Bowtie
General Category => Early Chevy/GM Discussion => Topic started by: 39delux on July 04, 2021, 09:18:25 PM
-
Doing general maintenance on the '39 I discovered the right front wheel would hardly rotate (car off the ground). Left was not nearly as bad but still does not spin freely. The front end is a MII style with GM 11" rotors and early GM metric calipers. Master cylinder is located under the floor with a 2 lb residual valve. I suspected the caliper puck was not retracting and replaced the caliper. After bleeding and getting a firm pedal the wheel was still locked up as before. Next in line is to replace the rubber hose. Have one on order and also ordered a new residual valve just in case. During my investigation I cracked the bleeder and several drops of fluid came out and the wheel would then turn which means (to me) something will not release the pressure. Visual inspection of the hard line yields no damage that I can see. Rubber line looks good but can't see inside. If the residual valve was faulty both wheels would be locked up. While driving the car did not pull to one side even when applying the brakes. Any ideas?
-
Well it really sounds like a rubber hose problem. Had that happen on a barely 2yr old hose, collapsed in the inside. It was just one, but re-replaced both. This new rubber anything these days are just junk in short order it seems😡
-
I believe your on the right track. I would replace the lines with the steel braided type as they have Teflon tubing inside the SS braid
-
I'm with the other guys. Because it is specific to one wheel you have to look at the parts that affect that wheel. You already replaced the caliper. In my experience, I have only ever seen steel lines crack or rot through, that really doesn't leave much more than you hose. And, like 62131 says, a braided line might be worth the investment.
-
Quick question...If the pin between the M/C and booster were to long would that cause the brakes not to fully release?
-
Yes it could, but problem would have been there long time. Also i would think both frt brakes would be effected. My '59 Elcamino had a problem like that after year after disc brake conversion. Effected both front brakes and i had to crack line at m/c to relieve pressure. Checked rod adjustment, was ok. It ended up being a hung up m/c piston return, replaced m/c and solved problem.
-
Problem solved. Got a pin adjusting tool and tried to set the pin clearance between the booster and M/C but ran out of adjustment. The pin was just to long. Ordered and new 8" duel diaphragm booster and M/C combo but went from 1 1/8" bore to a 1" bore. Set the pin clearance to .020" and everything works fine now. Better brakes than I had before. Don't understand why the right was almost locked but the left was a bit more free. Didn't pull when braking. Can't stress enough on proper clearance of that pin. Tool to set it is worth the price on line.
-
Glad you got it fixed and it is good to know what the problem was.
-
Nice that things worked out for you, but a little perplexed why one front wheel would lock up........
-
Yeah buying separate components like that can be a PIA
-
Glad you figured it out. Great info!
-
Good to hear you got it👍
-
Well, well, well, the plot thickens. Went to a small show in El Paso, on the way back developed a vibration. Got home and jacked the front up and they were locked up again. Took things apart, open the bleeders but no fluid came out, sill locked. Figured the caliper mounting brackets were cocked causing binding but they were true and parallel with the rotors. Noticed the rotors were worn on the outside but NEW on the inside. Upon further investigation I discovered I didn't have Camaro rotors but Ford Granada 11" rotors. Also found out the Granada rotors moved the wheel out about 1/4" and require different brackets for the Camaro (GM metric) calipers to work properly on the Granada rotors. I didn't even know that Granada rotors would work with a MII setup. New brackets on order from welderseries. If it wasn't for the article in their catalog I would never have known this. Turns out the larger rotors are a cheap upgrade for MII brakes.
-
Glad you figured that out....if it helps any I used rotor Part # GH8810 on my son's 37 Chevy with Mustang II, they are 11", 5 on 4-3/4". Not sure who makes them...I just wrote the part number down for future needs.
-
Glad you figured it out. Just knowing what the problem is and how to fix it is a big deal. These things happen when we change stuff. ::)
-
I purchased all my front end parts from one location made it easy
-
The plot thickens (sickens) again. Every time I think I've solved the problem the same symptoms pop up. Got in touch with Trevor at Master Power Brakes and he told me to look at the booster. Took the new booster off, hooked up my vacuum pump to it and it was hard to operate and the M/C side pin would only retract with some coaching!!! Cycled it a bunch of times and it would retract to random depths. Took the old booster and tried it. Worked much smoother but at first it would also need coaching but did return to where it should be. Light grease, more cycles and it started to act normal. Trevor at MPB said he had seen this with the 7" and 8" duel diaphragm booster. Rare on the 9" boosters.
My stupidity did not stop there. Decided to use the vacuum pump to activate the booster and bleed the brakes. That worked well. Then I set the free pedal using the vacuum pump...mistake. Went for a short ride to test the brakes. Good firm pedal and then I noticed the car downshifted. Tested the brakes and the pedal was AT THE TOP. Got the car home under full power and the brakes were smoking big time. Temp on the rear was over 400 degrees. Vacuum pump puts out 28 lbs plus and engine about 18 or so. See the difference? Readjusted the pedal and all seems well on a 15 mile test.
House now smells like a NASCAR pitbox at Darlington.
Overlooked the booster every time. Never thought a new (make that 2) booster would malfunction.
-
I hope that's it for you. I think at some time we've all had new parts that did't work right but that is certainly not where we look first. We just assume ............ ::)
-
I got my fingers crossed for you, Rattiac. This problem has been a journey