Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Rear Wheel Cylinders BTR Axle

I've been trying to find time to replace my rear wheel cylinders over winter, and had set aside two days, expecting trouble. As it turned out, I did both in two and a half hours yesterday morning.

So here's how.......

My Roadster was built in late 2004, so the rear brakes are original, and sixteen years old. I treat the drums as regular service items, and remove them once or twice a year to clean out the dust and clean the shoes and backplate (without dismantling). Although some owners have trouble with leaking or sticking cylinders after a few years, mine have remained operational, although last autumn I saw they were getting crusty, so pencilled in a change over winter. I also do a full fluid change every two years and I strongly believe that this makes a huge difference, especially to see the fluid emerging from the rear as a dark grey liquid. So after this job, the brakes are fully refreshed with new discs and calipers, new stainless flexibles, and new rear cylinders.

First remove the four small bolts, and with the handbrake released, the drum will wiggle off.



The inside of the drum was in pretty good shape, but with a slight hint of rust in the six o'clock position. I think that condensation gathers at the bottom, so a good reason to roll the Morgan to a different parking position occasionally, as well as preventing flat spots on the tyres. I blow over the paint if necessary, and give the contact area a rub with emery paper, which controls the rusty lip which sometimes emerges on the edge.



The inside looks pretty good for sixteen years and twenty thousand miles, OK, not a high annual mileage I grant you.



I figured that I could get the cylinder off without dismantling the brake shoes and although its a fiddle, I managed it. First remove the shoe keepers...see four o'clock and eight o'clock in the image above. I use pliers on the washer head.........push hard, while holding the back of the pin, twist 90degrees, and the fastener releases. Replacing is the reverse but you need strength and good light!

Next I removed the clip behind the cylinder on the backplate using a screwdriver. Access is very tight. It basically pings out of a groove. I've never used a special tool to replace these clips, but because access is so tight, I bought one, from MG Owners Club, and this easily put the new clip in the groove on reassembly.

Next I removed the brake pipe, taking care not to twist the pipe along with the union.A squirt of lubricant helps. The brake pipe can't be refitted until the cylinder is secure with the clip in place, so the pipe must be bent carefully out of the way. Refitting need a bit of force to line the brake pipe up, and to ensure it goes in square and not cross threaded.

With a bit of leverage on the brake shoes, the old cylinder can be persuaded out. It's tight, but does not foul the hub. The rubber glove keeps the splines clean.



As you can see, there is a single shaped hole for the brake pipe and bleed nipple, and a smaller hole for a roll pin which locates the cylinder in the right place.

The new brake cylinder slides into place! Haha......it takes resolve to part the brake shoes, and a home made tool to do this would make this part easier. But better than unhitching the springs.



These are the cylinders for the 2005 BTR axle:



This is the nearside, crusty but not leaking..........the leading shoe piston was seized though, and hard to free off.



When dismantled.....not too bad for sixteen years.



The offside was slightly better......



So that's how it's done............

Nice one Dave, I do like to see the outside of the drum painted satin black

Same cylinder on the 1999 4/4.

Didn't know there was a tool for refitting the circlips, it would have made life a lot easier when I did mine a few months ago.

What is the tool and how does it work?

Is it only available from MGOC or is that as good a place as anywhere to get it from?

Here Bob

Circlip fitting tool 17H7949T
Suitable for MGB, C, V8 & Midget models, a wheel cylinder circlip fitting tool designed to make fitting of the wheel cylinder retaining clip simple. Benefitting from a hardened steel cone for years of reliable service.

Price: £14.95 / €17.79 / US $16.57 (Including VAT at 20% except $ price)

https://www.mgocspares.co.uk/cgi-bin/sh000001.cgi?WD=cylinder%20tool%20brake&PN=Tools%2dsafety_equipment%2ehtml#a36781W_2d17H7949T

Also on E-Bay and elsewhere.

So the cone acts as a spreader as you tighten the nut then just pops the circlip over the boss on the cylinder and into the groove.

Is it really that simple?

Good pics and task description, thanks for posting Dave.

Yes....two minutes

Dave, I sell my car....

Or I will never again read your posts...


Each time I see pictures of your clean car

what you call a circlip we used to call them jesus clips

David Byrne

Having 'lost' a few to Saint 'ping', I think I know why