I decided to reseal my master cylinder after I found that the “moisture” in the jute driver’s footwell padding was in fact brake fluid (which I should have figured out given the flakes of red primer and paint that were lifting off.) I was wondering what the mystery drops of fluid in the lift catch-trays was, all confirmed by bone-dry brake reservoirs…
Waiting to get a genuine seal kit from SNG Barratt, I disassembled the master cylinder and found no corrosion at all in the bore or on the piston. This confirmed my decision to re-seal. In fact, the cylinder looked like a replacement rather than the original 52 year old part, with no signs of iron corrosion. Just black carbon patches.
Upon disassembly, I noted some differences between my original and the seal kit parts (sourced from Liberty Vehicle Technologies, which appears to be the descendant/purchaser of AP (Automotive Products) OEM line.
The spring retainer on my original is metal instead of plastic. I understand the Jaguar/AP/Lockheed originals were made of plastic too, as described in the Jaguar service manual. So somewhere along the line a metal one was developed. I think I’ll keep the metal one.
More importantly, the new seal is thicker with a “flange” at the base accounting for the increased thickness. It’s a major difference. I don’t know what the Jaguar originals looked like (the replacement or my original.)
When I pried out the secondary seal, the recess holding the seal had what looks like dried glue in it. Were these glued in? I have no idea why this would be necessary if so, and there’s no mention of it in the manual.
That seems like the most logical explanation. It dried hard, and seems to have corroded the aluminum piston. The corrosion in the 1st pic was underneath the “glue/grease” sections, scraped off with a plastic tool.
I’m not sure how grease or even glue would attack the aluminum like that. I’m using silicone grease instead for this reassembly, just in case the “red” stuff has this effect.
Now for more mysteries - my master cylinder guts have more differences than what the factory manuals show.
1st, I seem to lack a 2nd “small” bearing (#12 highlighted in the diagram pic.) The pic (on the blue towel) is the internal assembly just as I withdrew it from the cylinder - pic taken for reassembly reference, and am I glad I did. I would have gone nuts thinking I had lost that part.
2nd, my “big” piston (#22 highlighted) was reversed from the factory diagram, and the seal #13 fits into the recess on #22 facing the opposite direction vs. the diagram. (towards the pushrod instead of the reaction valve.)
3rd, the “original” type factory main cup (#24) in the rebuild kit seems to fit far better than what my cylinder had. (see 3rd pic of reassembled internals on black background.) Could the thin cup have been for a different cylinder internal?
I don’t know if AP changed the design of the internals or I got a unit built on a Friday after the workers had a bunch of pints for lunch. I’m going to hope it was a changed design and go with this, but then would the old-style cup be appropriate…
The exercise of writing this all out made me think further. The big bearing #22 shouldn’t face the rubber seal towards the pushrod, because then the return spring would press against the rubber, not a hard metal or plastic surface. And then I looked at the diagram included in the rebuild kit, and it is different to the manual!
It points the #22 bearing as my cylinder had it, but with the “missing” small bearing interposed between the spring and the rubber seal, which would provide a firm base for the spring to act against.
So either somehow I lost that small bearing extracting the spring, or I never had one (which might explain why a new-looking master cylinder was leaking.)
I would say that the design did change from what was represented in the original factory manual, but when or if in the E-type production time frame I can’t say. But the rebuild kit instructions seem to suggest this (unless the illustrator that day also had a few too many pints…)
Dave, since you got no other responses, I will give it a try, and maybe prompt some others. I have rebuilt my m/c in the past, but have no memory of how it went together. I am curious, you seem to indicate that your 52 year old m/c is original with the original parts inside. Why do you believe that? I would think that would be unusual to have been original after all those years. Or has it been sitting for years?
But that is not important. To your questions. The fact that your new primary cup fits snugger in the groove, IMO, is not overly important. But it does seem to indicate it is probably “more” correct part. I believe it should do just fine.
As to the arrangement of the other seal. I do not think it matters. Other than I would not want the spring directly pressing on the cup. I would assemble it as it came apart, but again, I do not think it matters. That seal is to do two things. Keep the fluid from running out the back of the m/c and onto your feet. And to keep a solid supply of fluid behind the primary cup to prevent air in the system. Assuming after you rebuild everything and use it a few times that you do not get air back into the system, I would think you are fine.
Tom
Hi Guys
This topic does come up regularly.
whilst repairing my S3 master, which is identical to your S1, I pulled two master cylinders apart, they both had the seals as per the seals diagram shown in your picture from brake house, and agrees with your photo showing your seal as removed.
However this is at odds with the repair and operations manual, but on balance with 3 units pulled apart and the repair kit diagram agreeing I would go with this orientation, I have.
You should have the part no 12 which is a plastic washer for the spring to push against, rather than push on the seal.
the important thing with the secondary rubber seal, part 13, is that the lip faces inwards in the cylinder to keep the fluid in.
I used heaps of red rubber grease on reassembly as others have pointed out that the modern brake fluids are not as lubricating as earlier ones.
check the spring in the nose of your reaction valve, as some have found this gets tired over the years and leads to faulty operation of the reaction valve. Indeed some have fitted a stronger spring in the reaction valve to guard against this failure mode. Also use plenty of red rubber grease on the little piston that operates the reaction valve, part 31 in your diagram. It may also be worth checking the bore of the MC where it operates, I gave mine a polish with 1500 grit wet and dry paper.
cheers
Mark
No, I don’t think this is the original cylinder as produced in 1967. By “original” I mean what my car had vs. the rebuild kit. There are no signs of brown iron corrosion on the outside. Just black carbon-like speckles on a gray finish that looks just like it had been sprayed with Eastwood Brake Gray paint. Very slick and shiny.
Combined with the fact that so many of the internals parts diverge from what most people report on their originals (no plastic parts at all - just rubber and metal) I’ve of the opinion that AP etc. made design changes along the line in the past 50 years and revised things. But no proof, just what I see from the parts and diagrams.
I found the answer to my own question about the “small” bearing - what the manual appears to call a bearing, I would have called a “washer”. It’s a cadmium plated steel item that has no apparent smooth machining or finish usually associated with a bearing. It’s what the spring thrusts against. It also is the only item that shows signs of corrosion, but I’ll just clean it up a bit and reuse it.
I didn’t take apart my reaction valve since I didn’t order rebuild parts for it, and as far as I know it is not giving problems. There can’t have been many miles on it - the car has sat largely undriven since the late 70’s as the original owner set it aside for refurbishment and… well, we know what happens so often after that.
I’m sure this is a replacement cylinder installed some time after the layoff (either back then or in 2008 as part of a refurbishment that got the car assembled and drivable again.)
What you also call a “washer” (part 12) is the small bearing I was wondering about earlier. Placed over the seal, it is the thrust surface for the big pushrod spring.
I’m concerned that the red grease is corrosive to aluminum. The dried stuff inside the big bearing had to be grease - can’t think of anything else - and it attacked the surface of the bearing (luckily, on the inside where the seal goes, not on a friction or sealing surface.) I’m using silicone grease instead.
As I just mentioned, everything in my master cylinder is metal or rubber. No plastic parts at all - no plastic bearings that I hear mentioned in passing, spring retainer is metal instead of plastic even as supplied by the rebuild kit, no plastic washer/bearings.
I’m assuming/hoping the metal parts are an upgrade.
Well, this saga ended like so many others who’ve attempted a reseal - I ended up buying a new (from original supplier) one. The resealed one leaked.
I don’t regret attempting the reseal - the kit was not expensive and the bore was completely clean with not a spot of corrosion. I suspect this item leaked from new, and was some unknown vendor’s attempt at remanufacturing worn master cylinders.
The substitution of metal bearings and retainer caps might be explained by the idea that the plastic types aren’t available from the aftermarket, so possibly a company attempted to instead have them machined from metal, which is more economical in small quantities. But at least in my case, it wasn’t successful, probably from the very beginning.
One last pic showing the IMHO inferior quality of aftermarket parts (the rubber pushrod boot) vs. the OEM original that came in the AP/920/Liberty rebuild kit. The aftermarket boot is much softer and seems less resistant to abrasion. (note wear around the boot hole.) If rebuilding, I feel the OEM rebuild kits are the way to go at only a $5-7 price difference.
BTW regarding the original question on the diagram and assembly differences - I read at least one other thread here describing this, and Chris Rooke describes this in his “E-type Jaguar DIY” book (which I’d missed before creating this thread.) It seems that all say follow the later diagrams instead of the factory manual, so likely there was a change sometime along the way.
