MGB & GT Forum

Welcome! Sign In Register
Please Sign In or Register to Search

Master cylinder rebuild

Posted by Jim Adams 
Springfield, MO, USA   usa

I am going to try to rebuild my brake M/C next week. Does any one have any words of wisdom? And while we're on brakes, why does everything seem to say DON'T SPLIT YOUR CALIPERS!!! It almost seems like I will end up in the DPO hall of fame if I do. Why?

Jim A.

'76 B
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info
Tulsa, OK, USA   usa

I think the general concensus is NOT to try rebuilding the M/C. I re-did my brakes a few months ago and wound up buying a new M/C after receiving that advice from several posters on the board who know a lot more about it than me.





Bill
1973 MGB GT

rcedward Avatar
Rob Edwards
Raleigh, North Carolina, USA   usa
1951 MG TD MkII "TDC6000"
1969 MG MGB "182608"
1969 MG MGC GT "8806"
1969 MG MGC GT "8651"
1970 MG MGB GT "Donor"   → more

>I am going to try to rebuild my brake M/C next week. Does any one have any words of wisdom?

I've never done it myself. One parts catalogue I saw said something to the effect of, "Usually, rebuilding a master cylinder is a wasted effort, but we understand that you may need to prove this to yourself."

I think the deal on the calipers is that the bolts are single-use, special bolts, i.e. they are not standard hardware and should not be reused once they have been torqued. That said, back before I knew any better, I split my calipers and reused the bolts. I'm still here (for now... ;-)





--
Rob Edwards
Raleigh, NC
http://www.mgcarz.com

If you're in NC, check out the North Carolina MG Car Club!
http://ncmgcc.org
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info
Springfield, MO, USA   usa

I guess my logic is, the rebuild kit costs 10 bucks. The new M/C costs something like 280 bucks. I am willing to try the rebuild and if it turns out a dud, I am out 10 bucks and have to buy a master cylinder anyway. Unless it will be dangerous (can't immagine immediate danger, maybe progressively worse and finally dangerous), then I will probably try.

Are the MGB master cylinders so much different from other vehicles? Like say my old '79 ford F-150. As long as the M/C wasn't bad, it could be rebuilt with no problem.

Just trying to pick up a little bit of the HUGE amount that I don't know.

Jim A.

'76 B
Springfield, MO, USA   usa

I talked to another guy on the phone who has apparently split several sets of calipers with no ill effects. I hope that if the need arises, I will be able to do the same for just one set.

Jim A.

'76 B
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info
Gerry Avatar
Gerry Masterman
Prairieville, Louisiana, USA   usa

Forget rebuilding your M/C. Been there, done that and been suscessful only about 25% of the time. A MGB M/C is a real PITA to get apart. I have had some that came apart easy, some are still not apart. Spliting calipers is not the problem that some folks protray it to be. Just make sure that you replace the special o-ring. I would not try to rebuild a caliper without splitting it. The seal retainer is sometimes a bear to get in without bending it out of round, so I reccomend that you buy at least one more kit that you need. Even better yet, is to buy already rebuilt calipers, loaded for around $70 each





Signature removed at Skye's request
Springfield, MO, USA   usa

As far as the calipers are concerned, I've already got the o-rings. What is the story on the bolts? Rob said they are single use. Where can I get more. I don't seem to remember seeing them in the Moss catalog, or in Brit-tek (or in Victoria British for that matter). Are they available? If not is there an acceptable replacement?

Jim A.

'76 B
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info
Gerry Avatar
Gerry Masterman
Prairieville, Louisiana, USA   usa

I have always reused them without any problems





Signature removed at Skye's request
Tom Bedenbaugh Avatar
Memphis,Tn, USA   usa

Your waisting your time and money trying to rebuild an MGB brake master cyl. That's all I'm going to say about that. As far as splitting the calipers. I would guess I have built well over 100 MG calipers, and I have NEVER had a problem. I split them, reuse the O ring and bolts. Matter of fact I save the old steel retaning rings and if I bend a new one trying to put it in, and I always bend at least one, I use the old one. I do replace the pistons with stainless ones.





http://www.importandsports.com/
Gene Avatar
Gene Johnston
Ridgeland, MS, USA   usa
1971 MG MGB "Ole Red"
1973 MG MGB GT "Morrisey"

The master cylinders are a PITA to get out also.

I'd pay the bucks.

I've had best luck with Apple Hydraulics 601.369.9515. They offer brass sleeved rebuilds or stainless if you want to pay extra.

Last brass sleeved I purchased was in '02.

$125.00 + shipping + $45.00 core charge.

While your at it if your going to hang onto the car I'd replace the clutch master. They do those also.

See 1st line....PITA to get in/out.



Post Edited (11-10-04 19:33)
Gerry Avatar
Gerry Masterman
Prairieville, Louisiana, USA   usa

This will make the job easier next time http://www.shadetreemg.com/master_cyl.htm





Signature removed at Skye's request
Gene Avatar
Gene Johnston
Ridgeland, MS, USA   usa
1971 MG MGB "Ole Red"
1973 MG MGB GT "Morrisey"

Another excellent plan Gerry!
Thunder Bay, ON, Canada   can

I'm going to have to say it even though I everyone went against this, but I rebuit all the hydraulics on my car. The brake was a pain to get apart, but it wasn't that bad. That is as long as there is no rust or scratches in the the cylinder bore. I have split my calipers as well. The pistons were stuck, and I couldn't get them to budge using the pedals. So I had to split them and put some compressed air through them. That got them undone in a hurry.

Would I rebuild them again, yes, assuming the cylinder itself is fine.

Kurt
Tom Bedenbaugh Avatar
Memphis,Tn, USA   usa

His is mounted on the brake booster, Gerry. All he has to fight is getting the hard lines started with out crossthreading them.





http://www.importandsports.com/
Tom Bedenbaugh Avatar
Memphis,Tn, USA   usa

Trust me you got lucky. Then again,how many miles have you put on the brake master?





http://www.importandsports.com/

I rebuilt my master cylinder due to a continuous leak I was having, found out the DPO had gauged the piston. This is definetly something to watch out for if you are doing it yourself. I had to find a replacement piston at the local junkyard. With the repair kit it is really easy, I highly recommend noting the order of each part that comes out and investing in some long needle nose plyers. Also, do both the brake and clutch cylinders since you have them out.
rcedward Avatar
Rob Edwards
Raleigh, North Carolina, USA   usa
1951 MG TD MkII "TDC6000"
1969 MG MGB "182608"
1969 MG MGC GT "8806"
1969 MG MGC GT "8651"
1970 MG MGB GT "Donor"   → more

>Rob said they are single use.
I guess I should amend that to say that I've been told that they're single-use....





--
Rob Edwards
Raleigh, NC
http://www.mgcarz.com

If you're in NC, check out the North Carolina MG Car Club!
http://ncmgcc.org
Springfield, MO, USA   usa

I already replaced the clutch hydraulics (M/C, slave and hose) since the slave blew out almost as soon as I bought the car. It was a PITA until I discovered the little square rubber panel on the firewall. After I removed that, it was pretty much a breeze to replace the clutch M/C.

I will hopefully start the front half of the brake system on Mon. (M/C and calipers) After the feedback I'm getting I don't feel too concerned about the calipers. The M/C however is another issue. To the Mrs. ($$$) I will try the rebuild just so I can tell her that I tried everything else. If the M/C is anything like the rear wheel cylinders, it will be complete junk and have to be discarded. The rear wheel cylinders were frozen solid, no choice but to replace them. Gene, I appreciate the info about Apple hydraulics, I will call them. That is about half of a new M/C from any of the suppliers that I could find.

Thanks for all the help.

Jim A.

'76 B
Mark Jones Avatar
SW, Ontario, Canada   can
1970 Triumph Spitfire MkIII
1995 MG MGF "Barney"

Jim;

I rebuilt the brake m/c's on both of my lbc's with 100% success to date, but you have start off with a m/c that has a good bore, ie no pitting (rebuildable). I rebuild the m/c in my 73 GT about 5 years ago and it is still working fine.

I understand why Tom doesn't rebuild; not worth the aggrivation of a customer returning when a rebuild fails. For me, I had a good m/c bore to start with and the price difference made it worth trying. I know I'm talking about a very important parts of the car; the brakes, and I would have bought a new m/c, or reslieved if I would have been concerned about the bore.

Good luck,

Mark
Gene Avatar
Gene Johnston
Ridgeland, MS, USA   usa
1971 MG MGB "Ole Red"
1973 MG MGB GT "Morrisey"

Jim,

Good luck. As indicated it's a matter of balancing time/money/frustration tolerance. At this point I have little time, some money, low frustration tolerance.

It's a very fluid equation.......
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info

Reply to this topic or post your own questions!

Members Sign In if you've already registered, or

Register a New Account

Registration is free and takes less than a minute

Having trouble posting or changing forum settings?
Check the Forum Help File (FAQ) or contact the webmaster.


Join The Club

Sign in to ask questions, share photos, and access all website features

Adjust Text Size

Larger Smaller
Reset Save