Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Stuck rear brake?

Headed off to an car event early this morning. About a mile out there was a clunk (an unusual one, not one of the many normal ones) from the rear as I pulled away from a stop. At the next stop I noticed there was rolling resistance. Checked/cycled parking brake and that all seemed to engage and disengage normally. Traffic light turned and I headed down the highway but as shifted to third I noticed some odd heavy vibration from the rear and backed off. Since I was close to home I drove it back. In the garage could confirm something was dragging. I could still, with some effort, manually push it. If I set the parking brake it won't roll at all, so it's still functioning.

I switched cars and headed to event and am writing this at the event in hopes of good ideas to look at when I'm back home. My first and current thought is that the rear drum is somehow not fully releasing. No friction material smell when I got back home, but it's not that much resistance that would overheat the shoes in under 5 miles. Any other ideas as to what could be causing the drag? Very bummed not to be able to drive the car today.

Many thanks!
Phil

I had similar happen on my Plus 8 and it turned out to be a shoe steady spring hold down cup washer that had poor registration and let the shoe break free locking the wheel up in my case. I don't think the rear brakes are that different to a 4 wheeler which the diagram is from. It was a real PITA levering off the drum with a bolster and lump hammer very gently so as not to damage the backplate. I don't have a puller that big.

It's the one you turn through 90 degrees to lock. Part of No8 on the diagram, good luck.

I had an odd vibration from the rear once, it turned out to be a stone embedded in the rear sprocket. Once I had the car jacked up you could rotate the rear wheel and feel the extra resistance as the belt went over the embedded stone.

Another possibility is that you could have a seized rear brake slave cylinder. There have been several occurrences of this on M3W's and it seems that it is common on 4 wheelers that use the same set up. That is assuming your car is not "new". The parts to replace are listed in the Alternative Parts List here: https://www.dropbox.com/s/o9sokmoxizjosmf/Updated%20list%2012%2016%20Aug%202019.pdf?dl=0 Not sure how available Leyland LDV 200 or Ford Transit parts are in the US but that is what they are from.

Had the same experience and it was as planenut describes, a seized rear brake slave cylinder.
PM me your email address and I'll send you some reference photos if you need them.

While virtually all manufacturers suggest a full brake fluid bleed/replacement every 1-3 years (primarily to remove accumulated moisture), my experience with older machines without disc brakes really should have their fluid changed every two years maximum. I do a comprehensive bleed (about a pint through the system) on all my machines at least every two years, and find I don't have issues, assuming I'm starting with a fresh rebuild. My oldest drum brake job (Singer roadster) is going on 14 years without hydraulic issues.

Thanks! PM sent.

Thanks for the replies and ideas.

When I got home I tinkered a minute with it. I could roll it back easily but forward was more difficult. I worked it back a forth a few times and everything seemed to loosen up. I took it for a quick drive and noted that the new vibration was still there around 3200rpm. At 6:30 this morning my brain had let me down and I attributed it to the rear end, but it's definitely associated with the engine pulses under acceleration and clears up by 3500rpm. It's strong enough to feel it coming through the drive shaft tunnel in the cockpit, hitting my leg.. Happens only under load and only around 3200 rpm. Maybe the brake is still dragging and the engine is working harder. I drove about 5 miles and smelled what seems like hot rubber in the cockpit. Came home and sniffed the car (must have looked odd) and the smell definitely was coming from the back. Tire and belt aren't rubbing anything so can't imagine where that smell is from.

Promptly gave up for the day and went in for a beer. Will look again tomorrow. I've never pulled that rear wheel assembly out so I may be in for some fun.

If this problem isn't related to the rear brake try looking further forward. I assume your car has a Centa type compensator? There should be a hole about 2" diameter cut in the underside of the compensator housing, have a look inside it with a torch and a small mirror and see if there are any chunks of rubber in there. If the rubber rollers break up the lumps of rubber often jam in the housing and rub against the rotating internal parts, hence the burning rubber smell. When they break up you rarely loose all drive but there is an increase in vibration. If you chose to ignore these signs you will eventually loose all drive but that is very extreme.

If it is the Centa rollers breaking up the good news is that a new set is only about £25, the bad news is that the engine has to come out to replace them. Hopefully your Centa is fine and it's a binding rear brake. Also agree that it is a very good idea to change the brake fluid every other year, don't forget the clutch fluid as well.

Good advice 👍🏻