Lotus Elan

Pressure bleeding tandem master cylinder

PostPost by: crannyr » Thu Jun 09, 2011 1:47 pm

I have recently completed restoration of a Federal 72 Elan Sprint with dual master cylinder and no servo, standard pads. After many attempts to bleed the brake lines I find that I still have only marginal braking with long travel and significant pedal effort. The system was initially pressure bleed, then manually bleed, and finally the pedal was put under pressure over night. Still only so so preformance.
So here is the thing. It my owners manual there is a single line that says "WARNING: Under no circumstances must the tandem master cylinder be bleed under pressure." (I found this only after my pressure bleed). This statement does not appear in any of the workshop manuals I have. I have not a clue why this should be a problem, what damage it might have caused, or whether it has any significance to my poor braking. At this point I am about to go and rebuilt the master once agian and avoid the pressure bleed.
Has anyone had any experience wit problems related to pressure bleeding tandem masters?
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PostPost by: Tahoe » Thu Jun 09, 2011 2:51 pm

I don't know if this is your problem or not, but when I bleed a system when installing a new master cylinder, I always bench bleed the master cylinder first to remove any air from it before bleeding the rest of the system. This can be done outside the car or installed in the car before attaching the brake lines and bleeding the rest of the system. You do this by attaching fittings to the outlet ports and bleeding the air out and access fluid back into the reservoir. After getting all that air out you attach the lines and bleed per the manual.

Not sure if this is the issue but worth mentioning.
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PostPost by: collins_dan » Thu Jun 09, 2011 7:17 pm

Last time that I rebuilt the master cylinder I found that I had to bleed the master cylinder (in car) prior to bleeding the whole system, in order to get good pressure. It's a federal S4, so the same set up as yours, dual with no servo. Dan
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