A3 master cylinder removal tips please

[mactiredearg]

ok before we start, yes I have read the TMs. repeatedly. And I've tried both the site and google search of the site, but no joy for specific tips. And yes, I am well aware of how much some folks hate the A3. But thats what I've got sitting broken in the backyard and thats what I need help with.

I have an A3 (M109A4 actually), with an issue where the brakes will not release. This was a sudden onset issue, the brakes worked fine for the self-recovery from Nellis to Denver and for several events and then started the no-release issue between one drive and the next. I have done everything short of pulling the master cylinder trying to get this solved (airpacks multiple times, full fluid flush, etc).

I've read that the release valve on the master cylinder can cause this issue so now I'm trying to pull that and I need advice. I have the driver side airpack, etc pulled already. But now I cannot for the life of me figure out how in the world to get the master cylinder out from underneath the truck. I can see how easy it would be if I could pulled the cab, but that is NOT an option. From underneath, with how the mounting is tucked into the frame, I cant even figure out how to get a wrench on the outboard bolts holding the thing in place.

So, if anyone has managed this feat could you please share your tips/advice on how to pull this thing from underneath the truck? Specialty wrench? A larger assembly to pull to bring it all out? Anything? Thanks in advance.

 

[goodguyzy]

I've never had to pull mine but ive looked at it and its similar to an A2 which I have pulled. I cut a 9/16 wrench in half to get to that last bolt that is a pain. A few bloody knuckles and a few cuss words help.

 

[SCSG-G4]

I managed to get to the last (frameside) upper bolt using a 9/16 deep well, pushed by a 6" extension, with a universal on top of that and another 6" extension to get it out far enough for the ratchet handle to work. But mine was a single circuit brake master. I went in through the round hole behind the Master and it is a tight fit. I still think they built the rest of the truck after installing that cylinder!

 

[moving chicane]

I managed to get to the last (frameside) upper bolt using a 9/16 deep well, pushed by a 6" extension, with a universal on top of that and another 6" extension to get it out far enough for the ratchet handle to work. But mine was a single circuit brake master. I went in through the round hole behind the Master and it is a tight fit. I still think they built the rest of the truck after installing that cylinder!

+1 I used 2 universals to get a straighter shot at the bolt though.

 

[steelandcanvas]

Mactiredearg, Now I see why you couldn't come out and play. Gimme a call this weekend sometime.

 

[rtk]

Just a dumb question , but has anybody thought about cutting a square out of the floor and remove the bolt and/or MC from above . While I was hoeing and mowing today , I wondered about a floor cut , remove the bolt or MC and either weld the panel back in or make a hinged panel , if nothing else it would make it easier to get to the LUBE FITTING on the brake shaft .

 

[mactiredearg]

steelandcanvas, yeah, between working 70+ hours the last three weeks with no end in sight and this truck driving me nuts in what little free time I've got I'm wiped out.

Need to get this thing rolling for the mini-rally next weekend and so I have enough time to redo the triple bunk (going quad) for the girls before the airshow display next month...

Oy'vea...

 

[steelandcanvas]

I still have to find the source of my drive-train rattle, so I'll be working on that this weekend. I should have my axle gaskets in the mailbox today. Good luck Bro!

 

[peashooter]

I think I know the problem since my truck had it and I've read about it a few times now. You don't even need to pull the mc. Very likely the brake pedal pushrod has come out of the master cylinder piston pocket behind the boot and doesn't let the piston fully retract home and return fluid. Check this out: http://www.steelsoldiers.com/showth...nder-failure&p=1361461&viewfull=1#post1361461

or it could be the plugged return like you said but the pushrod can pop out of the pocket and cause the identical problem

Here is another thread that shows some pictures of what happened when the pushrod popped out: http://www.steelsoldiers.com/showth...ter-Cylinder&p=1158552&viewfull=1#post1158552