Lotus Elan

Tandem master brake cylinder fixed finally

PostPost by: lotocone » Mon Aug 27, 2012 1:44 pm

After getting my tandem master brake cylinder resleeved in brass and rebuilt, I had a no luck in getting a firm brake pedal. There was a problem with an internal wave washer. Maybe others can watch out for this during a rebuild and prevent frustrating rework and rebleeding of the system.

I tried lots of ways of bleeding the system after the rebuild and just couldn't do so. The pedal couldn't even be pumped up, so I decided to remove the MC have it checked.

The shop that did the work found that a little wave washer inside was broken. They said it pushes a seal in place to seal the bore from the front section of the brake fluid reservoir when the pedal is applied. When I was pushing the pedal, some fluid was just going back into the reservoir from the bore. No wonder I couldn't get any pedal feel. The washer is shown in the parts manual, but it's not numbered. It is located near the end of the bore of the MC.

The shop said that a rebuild kit normally doesn't even contain the wave washer. The new washer in my MC came from another Girling kit the shop had. I suggest that if you are rebuilding a tandem MC, either replace the wave washer somehow or inspect it carefully. The shop told me they are usually okay being reused. It is a thin little washer that appears to be brass and only about 0.0015 in thick based on my measurement. It seems like they should be replaced to me considering that most of them are old.

By the way new tandem master cylinders haven't been available in a long time I'm told, so I couldn't take that route when I started this project.

Bob
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Wave washer in MC (2).JPG and
Bob
1969 S4
lotocone
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