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MG MGB Technical - Frozen Rear Brake Adjuster

Does anyone have any experience freeing up a frozen rear brake adjuster? I've got penetrating oil on it now, and sure don't want to use heat given its close proximity to the fuel tank!

Thanks,
Greg
Greg Van Hook

Heat may be your only solution. However, first try tapping the end of the adjuster with a hammer - trying to hit it squarely so as not to damage the head. Otherwise, you can use a snowshovel or piece of plywood between your torch and fuel tank. It's not the heat so much as the flame that's a problem. You can have a fan blow air at the tank so that any fumes are blown away from the area you're working.

Wayne
Wayne Pearson

Thanks Wayne. I'll try giving it a whack.

My snow shovel is plastic.... yuk yuk

Seriously, I might also try heating it from the other side with the brake drum off.

FWIW, I came across this adjustment technique that seems to make sense:

http://www.templeoftriumph.org/tech01.html

Greg
Greg Van Hook

Greg, they have to be replaced periodically. I wouldnt go with the adjustment technique advocated. Too many variables in elderly cars.
Roger
Roger

Assuming you can get the drum off, it is best to take the adjuster off the car and use lots of heat and oil - however it is not unusual for the ally casting to corrode to the steel peg and even if you do free it off, it will have damaged threads.

I have successfully rescued damaged adjusters by cutting a 3/8" UNF nut down to half height and pressing it into the casing inside the adjuster.
Chris at Octarine Services

Like Cris says, these can be unscrewed from the back-plate, and hence can be replaced. In my experience once siezed and released they can become very slack and strip. It's lack of attention over many years that causes the problem, this should be dismantled and lubricated annually for daily drivers, you can leave it for longer with mainly summer cars, but I do mine annualy anyway. I unscrew mine fully (a screwdriver slot cut in the little square end facing outwards helps this) then lubricate the threads with copepr grease. Screw it all the way back in then put a little more copper grease on the threads that are now sticking out the back. The when you turn the adjuster to adjust the brakes it builds up a 'collar' of grease where the threads in the adjuster body start which helps to keep water and corrosion out. Remove, clean and give a smear of grease to the 'cam followers' between the adjuster and the shoes as well.

The handbrake levers inside the drum are another thing that can sieze solid. But after spraying with PlusGas or similar and banging about it's amazing how sloppy they get, i.e. just how much gunge and crud build up round the pivot. Press a little copper grease into the angles the two bars make to lubricate the pivot wiping off any excess, and also clean and lubricate where the clevis pin joins the cable to these levers, and the compensation lever on the diff (where provided).
Paul Hunt

They're $24.95 each from Moss (complete adjuster assembly). The pistons and adjustment screw are likely in good shape if you get it apart, but the metal alloy used for the adjuster body is probably corroded and you'll find the passages for "pistons" will be oversized if and when you get it all cleaned up. Basically, it's unrepairable and not worth the effort. I had to replace one on my Limited Edition and it's scheduled for UPS delivery today. I'll let you know if it's not built to exact factory specs.
Rick Penland

Hi Greg,
The adjuster usually seizes on the outside threads as the get a bguild up of dirt on the thread so on the FIRST sign of getting stiff UNDO the adjuster & clean up the thread. Attempting to screw it in will damage the thread as you are trying to wind the seized up bit further into the adjuster.
Garth
Garth Bagnall

OK, so far, it's still stuck. I'll try backing it out. Was ready to order a replacement from Moss, but I'll wait and see.

Thanks,
Greg
Greg Van Hook

Greg,

Good to have a square drive that you might find at Sears. Believe Moss offers one. Obtained mine from tool dealer. Square drive helps!! Usually try and move small portions at a time. Back and forth while spraying WD40 or some other lube on front and back. Would be good to pull shoes off adjuster and pull out pistons on either end while going through this exercise. You do not have to remove shoes and all. Just put shoes on outside edge of adjuster and pull pistons out of either side. Do not be surprised to see pieces of aluminum housing on adjuster screw if you do get it out. Just clean off with metal wheel and tap inside of adjuster before reassembly. Also add some kind of Antiseize material from local auto store before reassembly. Will never have this problem again!!! Don't spend too much time because lots never come apart. You can drill nuts off back or just break them and get old unit off the car to aid in adding heat or replacement. I may have a good used unit I can sent to you. Send email to wright22@bellatlantic.net. CHECK THE OTHER SIDE BEFORE GETTING TOO FAR if you haven't already. Not unusual for both to be in same condition.

HTH

Fred
Fred Wright

If you can't find a 1/4" square or octagon socket, you can make up your own very easily, just use a couple of same size 1/4 drive sockets and a cut off allen wrench that will fit in them and glue it all together. Use a small 1/4 drive ratchet wrench to do the adjustments (when you get the adjuster working or replaced). See below. Cheers - Dave

David DuBois


FRED,
There is NO WAY I would use an adjuster after winding it out IE: all the way through. the thread in the alloy will be 'buggered' throw it away. We had an A50 with a hot MGB motor in it about 30 years ago & when my wife was going down a hill and applied the brakes her foot suddenly went right to the floor. The adjuster had stripped. Thankfully she had enough time to pump the brakes & stop before sailing right through the intersection. SO BE WARNED. If there is any doubt about the condition of the thread bin it.
Garth
Garth Bagnall

"There is NO WAY I would use an adjuster after winding it out"

Overstating the case, surely. Maybe if it were seized and you had to use some force to get it to turn you might get stripping subsequently. But if it screws freely from the bottom to right out and back again then it won't. That is what it is designed to do.
Paul Hunt

Garth,

As I said earlier, if this happens simply cut a 3/8" unf nut down to half height and press it into the ally casing so that it sits just under the piston bore - then you have strong steel threads for the adjuster to work on.

Alternatively Helicoil the thread.

The reason it is worth reclaiming the original units is that new ones seem to be made of some strange French cheese...
Chris at Octarine Services

Greg, as mentioned above, I got the Moss replacement and installed. It's almost identical to the original with a slight difference in the casting (rounded a little different on a couple of corners than the original). The original adjuster screw and pistons will interchange, but comes all new anyway.

The casting is likely "Britannia Metal" which is an alloy of over 90% tin, about 5% antimony and a little bit of copper. Basically, it's a soft metal (softer than the adjuster screw and pistons) and about the same as Pewter. It's not likely to survive your efforts to free up in good shape.

It's not "French Cheese" and the alloy appears to be the same in both the original and the replacement from Moss. I suspect there is a slight difference since early Britannia Metal included a couple percent lead which most manufacturers have eliminated due to environmental requirements.

As Garth mentioned, you certainly don't want to risk a brake failure and it's only $25 plus shipping.
Rick Penland

Thanks everybody. I ordered a new adjuster today.

Cheers,
Greg
Greg Van Hook

Far more likely to be aluminium.
Chris at Octarine Services

OK, when I tried to remove the brake drum on the wheel with the frozen adjuster, I was able to pull it outward (toward me along the studs) about 1/16 inch or so, then wouldn't come out any farther.

I know the shoes are not contacting the drum because it spins freely, and there is still too much slop in the hand brake (it's at its limit on the ratchet before it actually engages enough to hold the car), despite turning in the hand brake cable nut as far as it would go as a stop-gap measure to compensate for the lack of brake adjustment. So, I don't know what's holding the drum.

I'm thinking I need to open the bleed nipple and let the shoes come in a little more? Maybe there's a ridge on the drum behind the shoes?

And Dave, I like your 1/4-inch socket thingy. I already made myself a tool out of old/extra unused tools that I'll just keep in the MG tool kit.

Thanks,
Greg

Greg Van Hook

It could well be a ridge in the drum - I sometimes get that with more modern cars that have automatic adjusters. The trick I use for those is to reattach the wheel and rock it from side to side as I pull - the extra leverage is usually enough to get the wheel and drum over the shoes.
Miles Banister

Worn drums do develop a ridge, which is when you have to back off the adjusters a certain amount before you can get the drum off. But that would be causing the drums to bind on the shoes if you try and turn the drum *while it is pulled forwards*.

Don't open the bleed nipple, there shouldn't be any fluid pressure holding the shoes out, you will just let air in. It will be the handbrake levers holding the shoes out, remove the clevis pin on the back between cable and and lever and that will fully release them (only neccessary with a siezed adjuster).
Paul Hunt

This thread was discussed between 29/04/2009 and 14/05/2009

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