LF advice on M/C

[Richard]

I bought a brake master cylinder from a junkyard just to get the plastic reservoir and cap but I have a few issues with it.

1. It came with black gunk inside. I've got limited access to the inside through the cap so I need a solvent to clean it out. I tried mineral spirits and that didn't work. Any ideas?

2. I need to get the reservoir off the m/c. I got the pins out but I can't pull it off and I'm afraid I'll break it if I apply more force. What is holding it in and what's a good...

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[chunkytrunks]

I would imagine once you get the reservoir off you can use brake clean with the straw to get the gunk out.

As for removing the reservoir, put it in a vise and try to wiggle it off. It should come off but they can be a PITA to get off.

 

[Richard]

I tried that already, but like I said I'm afraid to break it as it's old. I'm only doing this because I can't get a new m/c with reservoir and remanufactured ones don't come with it...cheap bastids issed:

 

[Mitko]

2. I need to get the reservoir off the m/c. I got the pins out but I can't pull it off and I'm afraid I'll break it if I apply more force. What is holding it in and what's a good method to take it off?

Put it in the wise and try (gently) prying it out with a big flathead screwdriver or small pry bar. Nothing holding it inside except the rubber gromet.

 

[Richard]

I did, I got a new one but the rear seal leaked. Called to get a replacement and no one has any, they're all back ordered. I just want to get my Jeep running!

Got the reservoir off, so scratch #2 off. And I'll need lots of brake cleaner to get that gunk out. Still need a good way to patch the reservoir.

 

[handsomeDave]

Got the reservoir off, so scratch #2 off. And I'll need lots of brake cleaner to get that gunk out. Still need a good way to patch the reservoir.

What about a fiberglass patch?

 

[Richard]

I have some cloth, but no resin. Was going to try epoxy with the cloth.

 

[Dirk]

Looks like the reservoir is plastic....

plastic is weldable. I have seen, forget where, actual plastic weldding rod. Used like in Oxy/Acetyline welding. Just use a hot soldering iron instead of the flame.
Another option would be using a piece of the same type of plastic as a filler and a hot iron to melt it in.

Other than that, epoxy maybe....

 

[handsomeDave]

I have some cloth, but no resin. Was going to try epoxy with the cloth.

I got a fiberglass kit at CT with cloth, resin and hardener for like $15. Not sure about epoxy, but I doubt brake fluid will do anything to resin.

As far as the gunk goes, maybe let it soak with engine degreaser in it

 

[chunkytrunks]

Found this on Jeepkings http://www.plastex.ca/

Here is the thread:
http://www.jeepkings.ca/forums/showthread.php?t=93371

This stuff looks pretty cool. And you can get it in clear too.

:beer:

 

[Richard]

OK, a quick update on the reservoir:
Carb cleaner and q-tips: GOOD
Epoxy and fibre tape: GOOD
Pry bar and wiggling with hands: GOOD

Got the MC all setup last week but then spent several hours trying to bleed out the system as the pedal was always soft and could barely stop the Jeep. Even got Matt to come over to help beer::beer but after 4 hours we still couldn't figure out the problem.

Finally got some progress today Plugged both M/C ports and got a hard pedal proving it was fine and free of air. Connected the rear brakes only and pedal was good and hard. Connected the front brakes only and pedal was soft. Connected the rear brakes to the front port and pedal was hard again. Tried the front brakes on the rear port and soft again. So now it really seems to be the front brakes.

I took out the linelock and put in a coupler, no help. The combo block is also gone so all that's left is brake lines and calipers. So what could it be? This started when I replaced a front pinched hard line and a caliper. I figured it was the m/c so I replaced/upgraded it. Maybe it was something else all along?

I'm using the 3 pump bleed method, and yes the bleeders are at the top :flipoff:

Anyone ever have a strange problem like this? Rubber hose to the caliper? Damaged caliper? There's not much else.

 

[chunkytrunks]

You can try those steel braided lines i have if you want. If it fixes it then you know it's one of your flex lines.

 

[J33P]

Kinda sounds like you aren't moving enough fluid. Phil J had something similar with his D60 and Corp 14 swap in his TJ, his brakes were REALLY soft.

I think he removed the residual valve from the combo block entirely and he got brakes, they weren't firm at all. I remember going for a test drive and a bit white knuckled.

IIRC there is a corvette MC swap that is common for the larger calipers, also using a cherokee one is similar to the corvette as it has a larger bore.

 

[Richard]

Have you ever used vice grips on the rubber line? You may have broken the core and are getting some brake fluid getting into the lines core. it doesn't take much room to loose a peddle. Try replace both soft lines. Cheap and easy . and it it does nothing, you have spares....hehehehe.

:beer:

I did just this spring, so I guess I'll try that next.

You can try those steel braided lines i have if you want. If it fixes it then you know it's one of your flex lines.

If they fit I'll try them.

Kinda sounds like you aren't moving enough fluid. Phil J had something similar with his D60 and Corp 14 swap in his TJ, his brakes were REALLY soft.

I think he removed the residual valve from the combo block entirely and he got brakes, they weren't firm at all. I remember going for a test drive and a bit white knuckled.

IIRC there is a corvette MC swap that is common for the larger calipers, also using a cherokee one is similar to the corvette as it has a larger bore.

This is why I'm upgrading m/c and took out the block, the brakes should be better than last year.

Thanks all.

 

[chunkytrunks]

Yeah, try them and see if they will fit your big callipers. I will drop them off tomorrow or sat.

:beer:

 

[Richard]

So I replaced the 4 rubber lines and still the same. This all started after I replaced a front caliper, any chance that's causing it? I just can't figure out how since it's not leaking anywhere.

 

[Richard]

The brakes were fine last December which was the last time I drove it. While doing maintenance I noticed a stuck caliper and a pinched hard line to that same caliper so I replaced both. I didn't let the system drain. I didn't change anything else and went for a test drive, and didn't have as much brake power as last December and before.

Figuring it was the m/c I decided it was a good time to upgrade. The new m/c has a larger bore, 1" vs 15/16" or 14% area, so it should provide same or better brakes which so far it hasn't. As part of the upgrade I changed to a dual diaphragm booster, removed the combo block and got a manual prop valve (which is now removed). Unless the residual pressure from the prop valve was helping me removing it shouldn't be a problem.

I did bench bleed the m/c, and Matt helped me bleed it again with lines to the reservoir on the Jeep.

As stated before I did have a new m/c that had the soft pedal but it was leaking so I replaced it with a re-manufactured one. So that's 3 m/cs that have been giving me trouble.

Before putting in the first new m/c I pushed in all the caliper pistons to drain out old fluid, anyone think this may damage one?

 

[Richard]

Well I got partial success this week and it's now driveable .

Even though it seemed to measure OK I extended the booster pushrod into the m/c about 1/16" and cut 1/8" off the firewall bracket to pull the pedal back. With this 3/16" extra travel into the m/c I have the same braking power as last year where I can just lock the rear and stop pretty quick, about as quick as a 4,700 lbs top heavy Jeep can stop

I was expecting a better improvement, but maybe I just compensated for whatever problem I've had since the spring that I still haven't found, or something else is going on. Matt and I did notice that the booster flexes out when pressing hard, but his TJ does the same.

I'll be working on it tomorrow putting things back together and back in place and should be good for a trail run next weekend and I'll try to improve it again next year.

Oh yeah, and I moved the line lock to the rear so now I can dig, and I didn't need the adjustable prop-valve (it'll be up for sale soon), the difference in brake size is really close to perfect balance.

 

[Root Moose]

Glad to hear you've had some success. I'm kinda dreading getting mine dialed in to be honest.

 

[chunkytrunks]

CONGRATES!!!!!!! Thats awsome. At least it wasn't something stupid and right infront of our faces like we figured. Wanna do the gorge next weekend?