Lotus Elan

Plus2 with no servo: best master cylinder size.

PostPost by: TonyA » Fri Sep 30, 2022 7:51 pm

Just discovered where all my brake fluid was going: the servo was full..! I have removed it and want to try to live without it. Question: I'd like to hear the views of plus2 drivers who have deleted their servo: which is best: retain the original M/C with 0.7 inch bore or buy a 5/8 inch bore M/C. Also, small capacity 5/8 inch master cylinders are widely available (the plus 2 clutch master cylinder for example) but is there a 5/8 inch M/S on the market with the same large capacity as the plus 2's original 0.7 inch M/S. Or do I have to re sleeve mine. I want to keep things simple so no digressions on remote reservoirs nor tandem/dual circuit solutions please ! Cheers. Tony
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PostPost by: mbell » Fri Sep 30, 2022 8:54 pm

There are various options for single circuit masters. Wilwood do multiple options with 5/8" or 0.7, including girling clones. I don't think they do one with integral large capacity, but they have screw in reservoirs. I've used a 5/8" on my car and it was fine. I suspect any of the parts supplier will have an option.

I just switched to a spitfire 0.7 dual circuit master thou. I think either 5/8" or 0.7 master is fine TBH, I found 5/8" pedal travel was slightly too long, 0.7 is touch too firm. Its a personal thing.

If you have a 0.7" master already then just try that and see how it is. I would recommend making sure you have right high friction brake pad compound as being critical when not having the servo.

Personally I'd strongly suggest considering the dual circuit master on safety ground....
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: alan.barker » Sat Oct 01, 2022 8:29 pm

Buy a kit to recondition your servo.
Alan
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
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PostPost by: alanr » Sat Oct 01, 2022 9:10 pm

Better than just fitting a kit in a 50year old servo in my opinion is to have the servo cylinders resleeved with stainless steel liners.
Pastparts Ltd are one of the few who do stainless cylinder servo resleeving with a quick turnaround.
https://www.pastparts.co.uk/

Alan.
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PostPost by: Baggy2 » Sat Oct 01, 2022 11:50 pm

FWIW Early in my recent restoration project I sent my servo to Past Parts for re-build. As happens the project took longer than expected and it was between a year and 18 months before it was fitted to the car and used. It was immediatly obvious that it was leaking fluid . To be fair I spoke to Past Parts and they said to send it back but I had just got the car back on the road and couldn't cope with a few weeks not driving it so I bought a kit and re-built it myself. In doing so I was surprised to find evidence that at least one part that I would have expected to be renewed - the main piston - its in the kit - had not been. After my rebuild the servo still leaks but only a tiny amount. I'm not sure specifically where the leakage takes place in the servo but I guess Alan is probably right that the only 100% solution involves machining rather than just a new set of seals.

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PostPost by: alan.barker » Sun Oct 02, 2022 5:22 am

+1 you're right fitting a sleeve looks the best way to go.
Alan
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PostPost by: TonyA » Wed Oct 05, 2022 7:12 pm

I am now running my +2 with servo removed and the original 0.7 brake master cylinder.Brakes feel fine: a little firmer push needed than before but braking power is the same . One less thing to go wrong , : having the servo suck my master cylinder dry was no joke; and hearing one of our contributors being equinanaimous about a rebuilt servo stil sacking brake fluid after spending £400 quid ! Makes ,me wonder why Chappers fitted a servo, given his famous 'add lightness' philosophy and infamous cost cutting meanness..!
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PostPost by: Tim » Thu Oct 06, 2022 1:49 pm

Hi - I deleted the servo in my Plus 2S 130/5 and replaced the master cylinder with a tandem one from Caterham with a 0.625" bore (i.e. smaller). I know that opinions will vary, but my logic was this:

1. I felt nervous about the reliability of the Girling remote servo, particularly as it don't use my elan as a daily driver (sadly) ans i don't have the skills to overhaul the servo every 1-2 years.
2. Failure of the remote servo can lead to total loss of braking, with the brake fluid being drawn into the inlet manifold, which might only become apparent when braking (not a great time to find out).
3. I wanted dual circuit brakes for redundancy but not by having to have 2 remote servos, or even the very clever dual remote servo that Car Building Solutions sells.
4. The smaller bore 0.625" tandem m/c gives slightly more mechanical advantage than the original 0.7" single m/c.
5. The servo wasn't essential, so why not just simplify and add lightness?

Without doubt the lack of servo is noticable and the smaller bore m/c does not compensate for it. But it is certainly enough to stand the car on its nose if I press hard enough. Brake feel so connected and progressive and now matches the feel of the steering, suspension, chasis etc that define the driving experience. EBC Greenstuff pads on the front, but they will be changed this winter to Mintex. I reinforced the GRP bulkhead with a bespoke steel panel/flange where the pedal box connects to compensate for my heaviler right foot, but the orginal connection is so dodgy my advice would be that everyone should make that mod, servo or no servo. Dual circuit (front/rear) also gives confidence. Most of all I am re-assured that a have the simplest and most relaible braking arrangement, if not the most powerful.

That's been my experience and I've got no regrets, but I completely respect the fact that others would not make this mod.
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