Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Seized brake cylinder?

Hi all,


Car is my 1960 +4, has drum brakes in the rear and Girling disc brakes in the front. I just replaced the master cylinder and remote brake fluid reservior with new and rebuilt the front calipers. Didn't touch the hydraulics of the rear end, I just took the drums off and cleaned out the rear assemblies well and made sure the bleeder screws were patent. I haven't messed with any of the lines. Brakes were working to some degree before I tore everything apart (not sure if the rear brakes were ever working?), but the calipers were looking worn and the brake fluid was 50 years old.

Today I had a friend over and figured we'd bleed the brakes. Filled up the reservior and started bleeding (starting at the rear driver's side as this is the furthest from the m/c). We can't get any fluid out of the rear bleeders on either side. The front calipers bled with no difficulty. At the same time, the pedal got a nice firm pressure as we were bleeding the front calipers, but then all of the sudden lost all pressure. Tried bleeding the rears after the fronts and still no fluid. No leaks noted anywhere in the car.

I'm wondering if the one line that runs to both rear brakes could be clogged? what else could cause the rears not to bleed? And why did the pedal loose pressure all of the sudden? Does this sound like frozen brake cylinders in the rear and I blew out the m/c?

You could try and loosen the brake line to the rear drums initially at the rear hubs and see if any fluid drips out, or at the t-piece on the read axle.

This would show if there was a blockage.

I guess if you have duel circuits there may be an issue with the master cylinder?

Sometimes you have to go around each bleed nipple a few times.....

Does a 1960 car have:

1. A front /rear bias valve, they can stick so clsing off th rear...
2. Split circuits? Again added complications!

53 year old hydraulic pipes will always be suspect and any flexible parts highy suspect.

I think a full replacement of all lines and parts would be prudent, especialy the rear cylinders. All cars with fromt disc and rear drum brakes are prone to suffer stuck cylinders ans they get so little use.

Check the flexible rubber brake hose at the rear axle. A common failure mode is when the rubber swells with age and squeezes off the lumen making a check valve out of the hose or just blocking it completely. It is very common for the rear cylinders to freeze up due to corrosion and they are usually too far gone to rebuild. Also, bleeding can be frustrating with that model master cylinder-vigorous, rapid pumping will often expel a trapped air bubble

Take the nipples out completely and clean them out or replace. Try a gentle pump with the nipple out.Not sure about loss of pressure - it points to a leak somewhere - the m/cyl should be man enough to take the punishment.

Thanks all, I just got done replacing all the hard lines and soft lines (with braided stainless). The one thing I have yet to tackle is the rear wheel cylinders. They are on order. That said, I have never putzed around with drum brakes much since they were before my time haha. Does anyone have a good guide on how to do this, if not I'll just start wrenching and I'm sure I'll figure it out.

Looks like those C-clips could be a pain.

Mine ('76) did not have the c-clips (I thought these were only post '93). The cylinders are held with two c-plates that interlock and are held in place with a third "sprung" one. I removed the outmost sprung one and then lifted the tags with a pick and pulled out with long nose pilers.

After that quite easy. I used the HoE fitting and rubber boots on reassembly (also re-useable). Much better protection than the Morgan default.

Best tip is do one side at a time and then you can view the other side.

Hub comes off with the four small bolts (do not turn the screws!). May need a sharp tap or two to brake any rust (as if you are hammering it on). Also you may need to wind in the brake adjuster (square peg on the inside of the back plate) - if you turn it the wrong way you can not rotate the wheels).

Did mine for the first time a few weeks ago, all quite straightforward. Remember to adjust the brakes with the square peg on reassembly (or you'll struggle to adjust the handbrake).

Best to connect the springs and then pull the shoes in to the cylinder and adjuster...or that's how I did it.

Hope that this helps,

R.

Thanks Richard, that helped a great deal. I've already pulled off the hubs. Now I'm just staring at the cylinder, springs, and shoes going "where do I start?" haha.

Man, those clips are a pain! Got the cylinders off, both were frozen. Also the soft line running to the rear brakes was not patent.

http://www.talkmorgan.com/ubbthreads.php/topics/62276/Rear_Brake_Cylinder_Replacemen

I'm not sure if your car's the same but there's a thread here from when I did mine with some very useful links.