Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Rear Brake Shoe Question

The leading end of the leading shoe in mine is worn pretty thin, should be okay till next tyre change but since it is in bits thought I would ask a couple or three questions of those with more experience of drum brakes than me. The other end of the leading shoe is not much worn and the trailing shoe looks bedded in and not really any more worn than that so;
1. Is it okay to just swap the two shoes over?
2. If not okay, what is the problem?
3. If not okay, anyone know what the fitment is to get a new set from a local factor?
I expected uneven wear but didn't expect it to be quite so pronounced.

Some pairs of shoes come with different thickness of lining - one thick, one thin. This is a modern development which is hard to fathom. You might not know for sure until you get a new pair.

If it's a single cylinder set up then the shoe which faces direction of travel at the hydraulic cylinder, will take most wear.

If the shoes are identical then I would try swopping over. Note if there's an auto adjustment - sometimes not obvious, and punp the pedal well and operate the handbrake to take up the slack before you drive off.

Thanks Dave.
Now back in the garage, and on closer examination it turns out that the shoes are not identical so it is a bit of a moot point whether it's okay to swap them over.
There certainly is an adjustment mechanism behind the shoes but I think I will leave it till the next tyre change to fit new shoes and I'll work out how that works then.
Never do today that which can be put off till tomorrow!
Cheers
Calum

Calum,
Please don't swap the shoes over!When down at the factory in the 3wheeler shop I asked about the thin shoes and it turned out from new one of the shoes has about half the lining material than the other one.
Looks very odd to me but a pal of mine bought a pair of new shoes which looked exactly like the ones he took out.
The factory couldn't give me a reason for one thick and one thin shoe!
Regards David

The front shoe is called primary because acts first ( going forward ) when it contacts the drum it gets forced down which causes it to also push the secondary shoe (rear) through the self adjuster. The rear shoe applies the most force due to being pushed by the primary shoe, rotation of the drum and the anchor/pivot point being at the top. Due to this design thats why you should have more material on the rear shoe because it is doing more work than the front shoe.

Simples..

According to the parts manual, there is only a lower centering block that holds the two lower shoes points. Usually there is a manual adjuster on drum brakes that the part brake or self adjusting mechanism click into and automatically adjusts up the opposite end of the shoes from the wheel cylinder.

I don't see anything in the parts breakdown that looks like a self adjuster.

Also as others have said, because of the way the cylinder pushes out and operates in series the two shoes, they are self-energizing. A lot like strap brakes on the old cars with a leather strap. The strap works best with one direction of the drum versus the opposite direction. The shoes do the same in that the more they push out the more the brake drum friction grips harder and "adds" pressure to the shoes against the drums.

I'm still at a loss though on what keeps the shoes out within first striking distance of the drums.

You "should" be able to adjust the lower centering block to re-arc the shoes, so to speak to the diameter of the drum. Maybe the park brake has a part in this adjustment. But that would eventually get you out of park brake pull on the lever if you didn't readjust the cable periodically as normal maintenance.

Drums should "just" slide on over the shoes when properly adjusted. There will be some drag until they seat into place.

I also didn't see any residual valves in the plumbing pages. Usually with lower mounted master cylinders, they use a 2psi on the front for rotors and a 10psi on the rear for drums. The residual valve hold that amount of pressure in the line against the wheel cylinders do they don't retract as far from the rotors/drums. Without residual valves, sometimes you have to pump the pedal too far to get the first bit of braking force.

I used them on several of my street rods with lower frame mounted master cylinders.

So I'm not sure what MMC uses to hold the pads and shoes close to the friction points.

Good luck with your swap out on your next tire change.

I'm used to seeing disc pads about 6mm to 8mm thick, but on my new Harley with disc and ABS, the pads are only about 2mm to 3mm thick. I thought they were worn out until I saw a new set at the stealership.

Has anyone sussed out yet if these pads and shoes are unique to the three wheeler or common with another car / bike ?

Best option is to take them off go to your local motor factor and match them up with something. These people usually have loads of catalogues with full sized outline drawings even if nothing on the shelf.

Did you know....
S1 Elise front pads also fit formula Ford and some 1970's Rolls Royces.

Have now stripped, cleaned and re-assembled the rear brake and here's some useful information;
1. I had it back to front - apologies - the leading shoe is the one with the thicker lining and has lots of material on it (3.5mm minimum). It also has the auto-adjust mechanism.
2. The trailing shoe once cleaned actually has more material left on it than I thought and no doubt started much thinner than the leading shoe. It's got a minimum of 2mm left.
3. The shoes are made by Caparo and they appear in their classic car catalogue; an abridged version is here on Dropbox. .The shoes are Caparo part number HF206. Don't know if they are available from factors, haven't asked.
4. I took a series of photos of the mechanism as I took it apart, There is a pdf of photos with minimal captions here on Dropbox. Might be of use to people.
5. The adjuster mechanism is easily re-set to retract the shoes as far as possible for refitting into the drum; it then ratchets out when the brake pedal is pressed.

Well done Calum.

That does look remarkably similar to the Trad rear brakes......

Roadster rear brake:


Plus 4 Rear Brake: