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Girling Supervac brake servo


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Hello guys,

A bit of an odd question. I'm rebuilding the brake system on an '83 Lotus Excel and found the brake servo is broken internally. Not just the diaphragm, but the actual plate pushing against the diaphragm. I suspect someone stepped on the brakes while the master was disconnected and forced the plate beyond the normal travel thus causing it to break.

New parts are unavailable from Lotus specialists, and rebuilding is only possible if all parts are intact. However, the Girling Supervac was also used by Land Rover on the Series 3 and early 90/110 I believe. Problem is, there are several variants out there... The manual states the Excel used a Supervac 50. However, looking at pictures, the servor looks more like the Supervac 38, with 90mm square mounting pattern.

Does anyone have a spare servo he could look ar and measure? It could be an NRCSTC1816 or NRC4775/STC2878. I'm not too worried about the dimensions of the vacuum pot, as long as we get some brake assist. But the 90mm mounting pattern has to be the same, as well as the length and type of the input rod (with a fork, not an eye), unless that's easily changeable. I've found the servo from a Triumph TR6 would also fit, but I can't get the input rod connected to the pedal properly...

Any info welcome!



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  • 2 weeks later...
  • 1 year later...

Just realized I never finished this thread. :blush:

I got an STC1816, for a Series 3. We did have to change the input as it came with an eye instead of a fork. Luckily the Excel has a fork with threads for adjustment, so we cut off the eye and welded on a short stud was welded on (with the rod removed so there was no risk of heat damage to the seals). Been working as it should for about a year now, though I fear the master may be leaking again as the pedal isn't always as firm as it should be.

A bit late, but thanks for the info Marc!


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