Rear Brake Adjustment

Hi all,

Firstly, thanks for all your help in the past. This site is superb.

Having converted the front brakes to disks, I am now replacing the rear wheel cylinders on my BN6 with BJ8 wheel cylinders. Its all gone together pretty well, but I am almost out of adjustment on both rear brakes. I have the adjuster screwed so far in so its difficult to get at it, as its wound fully into the rear plate yet the drums still turn freely.

I have replaced the shoes at the same time, and they (and the cylinders) appear to be the same size as the originals.

Is it unusual to run out of adjustment? Is it possible to adjust the handbrake cable to compensate?

Hello guy, I have never had that problem with a Healey but I have had the problem awhile back when rebuilding the brakes on an MGTD. I believe the problem is because the drums have been turned too far and are now of a larger diameter. I had a real problem with the TD because it was a disk wheel car and there are no longer any new drums available for the disk wheeled TDs. You don’t want to use the emergency cable as the adjuster. There would be a chance that the piston in the wheel cylinders would get pushed too far out of the cylinder. After much investigating and some wild ideas offered up that I didn’t want to trust, I decided to weld a good bead of weld on the mating edge of each shoe and then file it to the VERY EXACT profile needed make it ride smoothly on the end of the wheel cylinder. This took up the clearance that needed to be removed. I would get new drums if possible.

vette said:

... After much investigating and some wild ideas offered up that I didn’t want to trust, I decided to weld a good bead of weld on the mating edge of each shoe and then file it to the VERY EXACT profile needed make it ride smoothly on the end of the wheel cylinder. This took up the clearance that needed to be removed. I would get new drums if possible.

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That's a clever solution, but I wouldn't be comfortable with it. By effectively elongating the shoes, aren't you changing the profile of the shoes; i.e. the braking surface of the shoe will not align evenly with the drum (not a terrible thing, since front disks do 70-80% of the braking, but not ideal)? If the drums have been turned so far the shoes can't be adjusted normally--in California, I believe it's a felony for anyone to exceed manufacturers' maximum ID for drums, and minimum thickness for rotors*--then I say new drums are in order (about $90/ea. and some Moss retailers give a discount). Given what the disk conversion kits cost--and assuming better braking is what you sought from front disks--that's a no-brainer. I know some owners are concerned enough they have new shoes 're-arced' to the drums for maximum contact between both surfaces, but I think it's all but a 'lost art' these days.

Edit: Using the handbrake to 'adjust' the rear brakes is a non-starter, IMO.

Edit2: I just saw that Guy is in France, so the Moss pointer may not be helpful, but I think Moss has a warehouse in England so, unless Brexit screwed cross-border shipping it might be doable.

* I tried to have a local parts house that I favored turn my front disks, but they wouldn't touch them because they couldn't find an 'official' min. thickness (they may have been misinformed, but I just sprung for new rotors since I was installing new pads anyways).

Bob, you are probably right on all of those counts but desperate times sometimes require desperate measures. Your point about the geometry of the shoes to drum contact surface is relevant but I did consider that seriously and decided that the amount of change in the geometry wasn't going to be serious. The small change in length of the brake shoe wasn't very much. Also it must be considered that just the wear of the shoes especially in association with a turned drum gives variable geometry to begin with. The complete brake job I did also involved new shoes which did not resolve the problem. Yes no reasonable shop will turn a rotor or a drum past its designed limit but once it is done and no new drums available it leaves very limited choices, hence my delemma and my ad hoc resolution. I was very careful to ensure that the geometry would work. Here is a resolution that a very well known MG shop suggested. They said that they insert a penny into the brake cylinder bore to allow the piston to push the 'foot' out further. WOW !!!!! I couldn't believe it. Can you imagine the scenario if that penny cocked and jammed in the cylinder upon applying the brakes. Can you imagine the liability if that car was involved in a serious accident and then the car was impounded and inspected for cause. So I believe I chose the least risk best path to fix the problem. I'm sure there are many slightly ill conceived fixes floating around the world of automobiles. It's not a perfect world in spite of the legislators. And it never will be. Also, as I said the best solution is new brake drums if they can be had.

I'm surprised no one has drums for a TD; they probably made at least as many as early Healeys. I (barely) recall somewhere that someone had a fix where they pressed new liners into a drum, them turned them down to original ID (or this could be my non-perfect memory misfiring). I never could find anybody that would re-arc shoes; guess there aren't enough drum brake systems around to make it worth buying the equipment and learning the skill; I figured the shoes would 'self-re-arc' as they got run in.

Anyway, I understand you do what you have to/can sometimes. As an aside, I am amazed there are several companies that still sell parts for my dad's early 1950s Ford tractors, but they made and sold millions of them. You can get a full engine overhaul kit--the bores are sleeved--for about a grand.

I was surprised that I couldn't get new drums as well. Seems drums are not available for just the disk wheel cars. I was in email contact with suppliers from all across the USA, UK and and Australia.

Or, you can do what I did - install rear discs.

Thanks for the replies. More careful examination shows the new shoes all have a slight smaller diameter than the old ones.



So the choice is spend more money on new drums which may or may not fit the shoes better or stump up for a disk brake conversion as John did.

Decisions, decisions...

Guy Marshall said:

....or stump up for a disk brake conversion as John did.

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The 100-6 being the only Healey with a 4-wheel disc brake option. Conversion's a non-trivial undertaking, though.

I know in the US there are shops that reline brake shoes for most any thing. I worked as a Elevator repairman for 40 years and replaced many brake shoes that shops relined or I riveted the same. Sometime you have to look outside the box. As for arcing shoes I sand to about 70 % for fit with paper in drum Must be to old school for todays shops Madflyer

steveg said:

Conversion's a non-trivial undertaking, though.

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In what way, please Steve. So far it just looks expensive Is there more to it than simply fitting the rotors/caliper mounts, calipers? A proportioning valve makes sense but are there other traps?

I'm not sure what you mean by "disc wheel cars" but the following vendors offer hub and wire wheel rear drums for MGTD/TF's on their UK websites:-
the MG owners Club, The MG Octagon Car Club or MGbits4U

Guy Marshall said:

In what way, please Steve. So far it just looks expensive Is there more to it than simply fitting the rotors/caliper mounts, calipers? A proportioning valve makes sense but are there other traps?

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I have galleries on this - see the link in my sig below.

Thanks Steve - an eloquent argument

Make sure the linings are correctly positioned - leading and trailing - so that the unlined areas are equal. One shoe can only go on one way - the other one fits either way and often is installed incorrectly.
Good luck,
Bob

mgtf328 said:

I'm not sure what you mean by "disc wheel cars" but the following vendors offer hub and wire wheel rear drums for MGTD/TF's on their UK websites:-
the MG owners Club, The MG Octagon Car Club or MGbits4U

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"disc wheel cars" means MGTDs with disc wheels, obviously. See pic.
I repaired this car for an owner about 2 years ago. I could get no new drums for it. See the link to Moss Motors on their Brake section, scroll down to items 70 and 71 and you will see that the drums for disc wheeled MGTDs is N/A. Also, I was in contact with other suppliers that gave me the same answer. Another example was Abingdon Spares in Connecticut who told me the best they could do for me was to sell me some USED drums but that they were probably no better than the ones I had.
Drums and hubs are obviously different for disc wheels than they are for wire wires.
https://mossmotors.com/mg-tc-td-tf/brakes/td-tf-brakes

Guy Marshall said:

Thanks for the replies. More careful examination shows the new shoes all have a slight smaller diameter than the old ones.

View attachment 66649

So the choice is spend more money on new drums which may or may not fit the shoes better or stump up for a disk brake conversion as John did.

Decisions, decisions...

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I believe this picture demonstrates the variables found in the geometry of many drum brake systems. Not much different than the little bit of metal that I added to the shoes to make the repair. As a matter of fact the repair I made probably improved the geometry.

British_Recovery said:

Make sure the linings are correctly positioned - leading and trailing - so that the unlined areas are equal. One shoe can only go on one way - the other one fits either way and often is installed incorrectly.
Good luck,
Bob

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Also check that the linings run true to the inside of the drums. There are 'steady posts' under the shoes to adjust the angle of the shoe to the drum; they can be moved in or out to effect changes. The shoe lining should be orthogonal to the backing plate--and parallel, obviously, to the drum interior--it's an 'eyeball' setting, but I've used a small carpenter's square to get pretty close. I've also used a large caliper to ensure both linings are parallel to each other.

Edit: There are also small 'felts' that go on the steady posts, to which a bit of grease should be added to facilitate the shoes' movement. They usually mostly disintegrated quickly, but Tom Monaco sent me what looks like cloth/fiber tubing that should hold up better.

vette said:

I was surprised that I couldn't get new drums as well. Seems drums are not available for just the disk wheel cars. I was in email contact with suppliers from all across the USA, UK and and Australia.

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What other wheels were standard on a TD?

Roger said:

What other wheels were standard on a TD?

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Well, I have seen TDs with wire wheels and disc wheels. That seems obvious. And Moss list both types but the drums for disk wheels are not available.