Brake Questions - Jamar brake/clutch assy.

[Skulptorchaz]

Hey Gents, I am getting this rail finished up and the gentleman I bought it from bought a Jamar brake/clutch assy. and I'm having trouble getting brake pedal.
We bled the system and got the air out but I can't get any pedal. It just goes all the way to the floor.
I have the brakes adjusted down to a slight rub so they are good but still no pedal.
Could it be that he bought the wrong size bore master cylinder? I took it apart and everything inside looked perfect - o-ring, cup, plunger. It is a 3/4" bore and I have stock drum brakes. Is that the appropriate size??
One thing that is interesting is when I leave the cap off and push the pedal, I see very little movement of fluid inside, as opposed to the clutch master cylinder, which shoots out fluid. I've always known for master cylinders to shoot out fluid. This could be a different animal, I don't know.
Anyway, any thoughts appreciated!!!

[JWHracing]

3/4" bore should be just fine.

Are you running a residual pressure valve? Drums call for a 10 psi residual valve if used.

I would double check all your line connections. Make sure everything is tight and leak free. What's the condition of the wheel cylinders and flex lines?

In my situation, I have been able to lift the front of the buggy up to make the master cylinder the highest point and can bleed most of the air that way. If I can't make it bleed, it usually means one of my connections isn't as tight as it should be and sucking air.
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65 Baja - Class 5 Unlimited Race Car

2021 STORR Pro Air Cooled Buggy Champion
2019 AZOP Unlimited Buggy Champion
2017 SADR 1300 Class Champion
2016 AZOP Limited Buggy Champion

Currently "retired" from racing

[Skulptorchaz]

Thanks for the info on the bore.
I have never had to run a residual valve before. I have the brakes adjusted to the knat's ass. (Maybe I'm just lucky.)
This is a new build. All new stuff.
Connection are tight and no fluid on ground.
I have heard about the "lift the front end" and altho that seems like a possibility, it seems more like a bad master. I still think the master should shoot fluid like the clutch master but, I've never had one of these.
We did find a paper this piece of rubber in the master cylinder when we pulled it and drained it, just now. It came from the center of the rubber -boot/plunger, whatever it is called- in the cap. How and why, I have no idea. Maybe that caused the issue but, I doubt it.
Thanks man!!!!!

[Dale M.]

IS there any free play of brake pedal pushrod..... Maybe the port for cylinder is not being uncovered when you release the pedal.....
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“Fear The Government That Wants To Take Your Guns"
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
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All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[Skulptorchaz]

Thanks Dale. It's a kinda self contained unit. There was enough play. I'm taking it back to the store to swap it out. They seem to be good about it.
I appreciate it.

[Skulptorchaz]

Sorry to be bothersome guys but I'm still struggling.
To recap - stock brakes all the way around, parking brake lock switch for the rear, 3/4" Jamar master cylinder. All brake shoes are slightly rubbing the drums. All lines are tight and no drips anywhere.
I replaced the Jamar with another 3/4" Jamar master cylinder but no luck. I replaced it again with a tall EMPI 3/4'' master cylinder and still no luck. It will push fluid thru to bleed the lines but not enough "pedal" to lock the brakes up.
I measured the bore of the stock two reservoir master cylinder I have, and it is a 1'' bore. Could it be the extra 1/4'' in the bore is what it needs to make the brakes lock up? Or is that extra 1/4'' for it being a two reservoir?
Also, I have not put in the residual valve but, since it is stock brakes, I wonder why I would have to now? I'm fine with that if I have to but, just not sure why with stock brakes.
Guys, I am getting to the end of my rope. I must say, I'm not a 65 y.o. rookie. I have built cars (Mainly hot rods) and between me and another car guy buddy of mine, we are completely perplexed.
Any help and time on your part is GREATLY appreciated. Truly. Some of you guys have been awesome with your time and help over the years and I would gladly pay you back if there was something I could do for you. If you were close, you would not have to worry about a welding bill!
Thanks again!!!

[JWHracing]

Drips or no drips from the fittings, run your finger under all of them. You'd be surprised.

I installed the same pedal setup on my sand rail recently. Could not get the brakes to hold pressure or stop bleeding air. No leaks or issues under the car. Reach behind the seats where my line from the pedals goes into the T fitting near the frame horns, and the adapter fitting i used to convert the the 10mm vw bubble flair fitting was not as tight as it should have been. It seemed tight, but it definitely needed to be more tight. Soon as i fixed that i had brakes in just a few pumps.
_________________
65 Baja - Class 5 Unlimited Race Car

2021 STORR Pro Air Cooled Buggy Champion
2019 AZOP Unlimited Buggy Champion
2017 SADR 1300 Class Champion
2016 AZOP Limited Buggy Champion

Currently "retired" from racing

[Skulptorchaz]

Thanks JWH. I'll look again.

[Skulptorchaz]

OH, just another quick note, we could not even pump up any "pedal" so it was not just a little air in the line.
Thanks guys.

[BFB]

Doesn’t seem anyone asked if this thing has a cutting brake ?
_________________
"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't.

[Wulfthang]

[rayjay]

I came up with a "reverse flow" system for bleeding front brakes on motorcycles which are basically impossible to bleed using conventional means. I used a high quality lever operated oiler [ oil squirt can ] and about 24" of clear hose that was a tight fit on the oil can nozzle and the brake bleeder screw.

Pump the brake fluid through the hose before putting it on the bleeder so you get all the air out of the hose. Form a loop in the hose so if any bubbles exit the pump you can contain them at the top of the loop. Then just pump the oil can lever until the master cyl is full and no bubbles. I used paper towels to absorb excess brake fluid in the reservoir.

I used this set up multiple times to quickly bleed new brake systems on cars. You would still need to do a few conventional pump and release on the brake pedal to get the last bit of air out of the calipers or wheel cylinders.

[rayjay]

Another thing you could do is verify that the master cyl will actually pump up hard. A short section of hose or tubing attached to the MC and the other end with some sort of cap that would allow bleeding. Just an appropriate fitting you can loosen to expel air. You should be able to get a rock hard pedal. Then you KNOW the MC isn't the issue although at this point it's pretty apparent it's not the MC.

[BFB]

agree, and to add to that Buggys master cylinders are lower mounted than a typical passenger vehicle making things more complicated.
_________________
"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't.

[Skulptorchaz]

Thanks guys.....VERY much!!!
In answer - No cutting brakes. Just a park lock.
In my many years of playing with cars, and occasionally having to do the brake system, if there was just some air in the line, I could still pump up pressure. Not the case here.
Man this is hurtful and I'm stumped.
Thanks again.

[rayjay]

Some more brainstorming. Pull the rubber plugs from the backing plate and watch for brake shoe movement. #2- adjust the shoes so they are in hard contact with the drums. If the pedal is now hard you must need the inline residual pressure valves. I've never used them but maybe the OEM master cyls I used had them in the rear circuit. I always had disc brakes at least at the front. Weird problems like this can drive you crazy.

[Skulptorchaz]

Well, rayjay gets the win.
What he suggested led to me finally getting the brakes to work.(I hope, so far).
This is one for the books in case someone else runs into it. I gotta wonder if it is inherent to VW's. It has never happened to me before but.......here it is.
I disconnected the line to the rears. I adjusted the front shoes all the way tight on the drums as I could. I mashed the pedal a few times and it was hard. I went to loosen the shoes - here's the good part - and the drums were "almost" free. It only took a couple "clicks" on the adjusters and they were set right. I reconnected the rears, bled them and they did the same thing. Same results. It only took a couple clicks on the adjusters. I now have brakes.
OK, so................. what had to "seat", or "set-up", or whatever in the wheel cylinders for them to now work? I have done plenty of brake "jobs" on American cars, mainly Hotrods, but have never seen this. Typically, you put them together, adjust them, bleed them and go.
Anyway, thanks a ton guys!!! I DO appreciate your time and help. Kudo's!
Chaz

[rayjay]

I think what happens is that when the brake shoes are very loose they are not concentric with the drum. You adjust them until you hear them rub and then back them off a click. The problem is that the shoe is still not concentric with the drum and just the lower edge was rubbing. The rest of the shoe is far from the drum and the wheel cyl doesn't have enough travel to touch.
.
Once you adj them hard into contact then the shoes are now concentric and now the brakes work normally. That's my theory and I sticking to it.
.
Nowadays my knee jerk reaction is discs all around. Soooo much simpler too deal with especially on a VW where the drum and the hub are one piece.

[Skulptorchaz]

Your theory sounds very plausible. Let' go with that...... and thank you for helping me. Hopefully, it may help someone else in the future as well.