Lotus Elan and Lotus Elan Plus 2 Forums

1970 Elan +2S, Dual Servo System, Tandem Master Cylinder
Master Cylinder (Girling 64676717)
Reservoir (Girling 64476296)

Earlier in the year I had some issues with my rear brakes. In the process of repairing the system, the mechanic rebuilt the master cylinder. A few months later the master cylinder started leaking from below the reservoir for the rear chamber only. The leak went from taking a week or so before requiring a top-up, to virtually emptying itself in a day.

I?ve read through the archives about this particular master, and realize the reservoir and gasket(s) are unobtainable and the repair has typically been to go to a single system or with a modified aftermarket setup. However, I don? think I?m ready to go either of those routes if I can fix my current one.
A few days ago I finally built up the nerve to squeeze myself into the footwell and remove the offending unit. What I discovered is that the reservoir itself seems intact, and that the leak is coming from where the reservoir inserts into the master. It looks as though this may be something I can repair, however I?m a little confused by the setup and how it is supposed to go together.

With reference to the pictures below:

1) When I removed the reservoir, the little rubber seat (B) came out ON the end of the nipple (as opposed to staying in the master.
2) When I looked in the groove (in the master) I could see the little metal ring (A), but it was not fully seated in the groove. I have since removed it, as it did not want to snap back into the groove easily.
3) Looking down into the master, there seems to be a location for the rubber seat (B) to insert into loc?n (E).


Questions:

a) Is the little rubber seat (B) supposed to ?press? into loc?n (E), instead of sitting on the end of the reservoir nipple loc'n D? Referencing the step in the seat in the pictures, which end of the seat is up?
b) Is the metal ring actually supposed to be there, or is it supposed to be an o-ring? which I do not have?
c) Does the metal ring (B) (or o-ring if that?s what?s required) sit in the reservoir groove loc'n (C), or live in the groove of the master loc'n (F)?
d) If it is what I need, where can I get another metal ring?

I?ve looked in the workshop manual, but the copy I have is not clear enough to show exactly what the setup is. It also does not provide a removal/reassembly procedure. The parts manual (also not clear) seems to show a much larger sleeve which presses into the master... which does not look to be my setup.

With what I currently have... I THINK that the little rubber seat (B) is supposed to press into the master cylinder loc?n (E). The metal ring lives in the groove loc?n (F). When the reservoir nipple is inserted, it snaps into place with the grooves lining up (by way of the metal ring) and pressing the end of the nipple into the rubber seat creating the seal.

I?d like to get this all confirmed, as I?m really not looking to remove the Master cylinder from the car again. Plus, the metal ring is a little warped and I don?t want to waste my time trying to repair it if I don?t need to.

Brandon

Hi,
Have up loaded some images which might help - not sure how clear they will be

One of the photos is of a complete master cylinder - I have three of these to sell but only suitable for parts and are nor vertical mounting

Regards
Steve

brandon wrote:1970 Elan +2S, Dual Servo System, Tandem Master Cylinder
Master Cylinder (Girling 64676717)
Reservoir (Girling 64476296)

With what I currently have... I THINK that the little rubber seat (B) is supposed to press into the master cylinder loc?n (E). The metal ring lives in the groove loc?n (F). When the reservoir nipple is inserted, it snaps into place with the grooves lining up (by way of the metal ring) and pressing the end of the nipple into the rubber seat creating the seal.
Brandon

I think you're right, the seal is suppose to seal between E/MC and the tank

lotus-suspension-f42/elan-federal-brake-master-cylinder-t36306.html?hilit=tandem#p248816

My guess is that age making the tank less flexible, the groove and ring get worn some, then the pressure between the nylon cone decrease and the seal does not seal well (esp. since there is a large lever when one inadvertently hit the tank to that rear section). I've read some people use a o-ring in addition / replacing the seal... one has to source the proper size and material o-ring (depending on where it is supposed to seal both on the nylon tank tip and the cast MC, and the upward force it will exercise, to be taken by the circlip).

If the old seal is still usable, clean everything well and snap the reservoir back into place. If you ever find a source for the snap rings, please let us know. I have tried to source these for many years, but never managed to locate any.

I have 2 new front seals for the reservoir nipple, and believe I can have more made if necessary. [The 2 that I have were made last year; I used a third one and it does not leak.]

Steve in Ohio

Thank you... exactly what I needed.

Patrics, Where did you find that diagram (I haven't read through the other thread in it's entirety yet)?

I'll put things back together and see how it goes. I got a new seat from a brake re-manufacturer which looks to be similar, but no circlip. If I find an alternate source for the circlip I'll certainly post it back.

Steve, are those seats for sale? If so how much would one or two be?

Brandon

Hi Brandon,
Pictures are from the Lucas Girling G202 book - standard book for rebuilding Girling braking products

Regards
Steve

I've just got my hands on a .7" MC for my car and was trying to get it apart to rebuild and found that I can't get the nipple out of the hole, and it will spin quite freely in the hole- which leads me to wonder if it will leak. I've pulled it by hand to no avail, then tried to pry it out with a screwdriver but didn't fight too hard with that method as I don't want to break the plastic.

Any suggestions?

I'd be interested in that seal too if available.

I just thought I'd give a quick update...

After looking at the diagram I decided to try putting things back together with the new seat. The circlip was a little bent, so I straightened it out and put in back into the groove. I've since fitted it into place, reconnected the brake lines and filled the reservoir. It's been 4 days now and not a drop has leaked out. I'm feeling confident enough that I'm going to finish installing the master cylinder, bleed everything and give it a go.

My suspicion is that the circlip partially popped out of the groove when it was rebuilt, so the reservoir was never properly fixed in place. With the vibrations of the car/engine/road it would have continued to work itself out of place until it started leaking, and continued to get worse. It may also have just been time for the rubber seat to be replaced, which does not seem to be all that difficult to get.

The Veg,
My reservoir spins like you're seeing (don't take that the wrong way ). If the rubber seat is good then it shouldn't leak, but that is of coarse the big unknown. I'm not sure how much force is required to get the nipple out, but as you can see in my pictures and the diagram, the reservoir groove needs to pop out of the circlip. I would make sure to try to lift it straight out though, otherwise the nipple might bend and crack. Maybe one screwdriver on each side to try prying it??? Or perhaps a brake rebuilder would have some type of special tool.

When I was looking for bits I noticed that RD Enterprises is now carrying new reservoirs, but they're rather pricey. Their pictures look like it comes with an o-ring rather than a circlip though, and I haven't had a chance to call them about it.

Brandon

a couple year later my quick fix of the -to my knowledge - NLA front port seal had started to develop a small seeping again... so before winter I got around to solve that source of irritation.

The original seal looked like a foamy (from age?) cylinder about 2mm thick, 15mm ext. diameter and 5mm tall, possibly with a recess at the bottom (o

r one that was imprinted by years of sitting). I replaced that with two EPDM O'rings , 11mm internal diameter 2mm ring diameter, stacked on top of each other, so that the conical output of the nylon reservoir exerted a bit of pressure when back in place. One was not pressing enough to my taste, possibly because the grove where the wire circlip has been widened some from removal. I had sourced other O'rings for trying out while at it if need be (slightly thicker or wider), but I figured that this combination provided a good seal at the bottom and to the side of the MC port (cylindrical recess), and the stack offered a good sealing to the reservoir. I understand that two O'rings rather than one is *not* (typo edited) an ideal solution, but I had the feeling that they would seal reasonably if lightly pressed together as they both are guided by the wall of the MC drilling - and it's a non pressurised circuit.

Not tested on the road yet, but the static seeping did not come back after refilling the reservoir - so far so good...

------ edit : photos of the stock seal

I wound up using needle-nosed pliers wedged under it to pop it loose.