71 replies to this topic

[Lplus]

Thanks. This helps...i checked inside the chamber and can see the one O ring is still in there.

The kit came with 2 big and 2 small O rings.

What came out looked like 1 big and 1 small and that's what I did when I replaced it but the small somehow seems to have come off.

So to confirm it's just the two O rings and the spacer on the end?

I just rechecked the bits that came out of mine and they look like the same size, two small o rings, with the spacer at the end.  I wonder if yours had the wrong size at the spring end?

 

The diagram above for the newer type of piston is confusing because it shows two small o rings at the end, but one of those is the "installation position" and the other shows the same ring in the "operating position"  The o ring next to the spring should also  be a small o ring. 

 

At least that's how I read it based on what came out of my old cylinder and the statement that "the smaller pair of O rings are fitted to the new piston assembly"

Edited by Lplus, 23 June 2024 - 07:32 PM.

[miniGTS]

I changed the seals to 2 smaller ones. It still leaked and while I was checking the leak and kept the EZ bleed connected... POP went the master cylinder reservoir.

I take this as a sign from the universe that I should get a new master cylinder. I'll probably get the single line AP with the plastic reservoir.

Unless there's a reason I shouldn't?

 IMG_20240624_151933_edit_618072183628084 (1).jpg   39.72K   0 downloads

Edited by miniGTS, 24 June 2024 - 02:24 PM.

[Lplus]

I changed the seals to 2 smaller ones. It still leaked and while I was checking the leak and kept the EZ bleed connected... POP went the master cylinder reservoir.

I take this as a sign from the universe that I should get a new master cylinder. I'll probably get the single line AP with the plastic reservoir.

Unless there's a reason I shouldn't?

IMG_20240624_151933_edit_618072183628084 (1).jpg

Guess why I had to change my old cylinder to a yellow tag.....  BOOOMMM.  Serves me right for using a tyre at running pressure on the EZbleed - 26 psi is far too much.

 

I went for a dual circuit to keep some semblance of safety, but fitted a servo to the front line only as per the Innocenti cooper.  Works quite well.

[miniGTS]

I used around 20psi...according to the gauge on the bicycle pump that I used to inflate the wheel.

Either the gauge is inaccurate or the reservoir was old and plastic is brittle. Either way, it was still leaking after changing the seals so maybe it is a sign to get a new one. Just feels like a waste having spent on getting this one resleeved.

Anyway, I've heard from a few people that a single line is the way to go as it's less complicated and gives a slightly less spongy pedal.

I'm just wondering if I should get the plastic or metal can one. Also, I see the GMC167 master is still available from MS but a bit pricey.

[Spider]

That's a bummer that it's now come to this, however, by the looks of that break in the reservoir, I'd say the plastic has gone brittle.

 

As for going Single Circuit vs Tandem, I'd suggest looking in to your local Registration Laws. I'd say off hand, if it came with a Tandem Master, you'll likely need to stick with it.

[miniGTS]

That's a bummer that it's now come to this, however, by the looks of that break in the reservoir, I'd say the plastic has gone brittle.

As for going Single Circuit vs Tandem, I'd suggest looking in to your local Registration Laws. I'd say off hand, if it came with a Tandem Master, you'll likely need to stick with it.

Our local registration laws are not that strict. For roadworthy, as long as it works... so there's no issue here.

Though, I will get a price for the Gmc167 dual master from my local supplier. I will probably end up getting a new one to replace what will come out. Since I already did the new lines for that setup. Besides, a new one will probably last many years without issues.

Edited by miniGTS, 24 June 2024 - 08:30 PM.

[miniGTS]

The price I got from the local supplier is pretty high for the dual master.. Over 200GBP and he also recommended to change to the single line AP master with the plastic reservior instead which will be just over 70GBP... so quite a big price difference.

 

Since there's no local regulation around what master cylinder I use, I'll likely go the single line route. 

[miniGTS]

I removed the master cylinder this evening and checked the piston behind the plastic switch and the lower of the 2 seals came out broken. That explains the leak. The previous time I took out it was also damaged. So that explains the leak through the switch both times. I do remember it going in tight but didn't think it broke the seal.

Now, I assume it's the wrong size seals? I'll try to source a good condition reservoir to replace my broken one, clean that chamber again and try this one more time

[sonscar]

Not being familiar with your type of cylinder so could be poor advice but I would check the surface finish of the new sleeve and check for a decent taper leading into it the help fitting the seals,Steve..

[miniGTS]

Not being familiar with your type of cylinder so could be poor advice but I would check the surface finish of the new sleeve and check for a decent taper leading into it the help fitting the seals,Steve..

I have the GMC167 that has the built in PDWA valve. That chamber wasn't resleeved and that is where the seal broke when I reassembled.

[Spider]

You mentioned earlier that PDWA had also been stainless sleeved. When sleeves are fitted, various ports for fluid that are already in the cylinder need to be drilled through the sleeves to maintain the ports and fluid flow. Following drilling, which is nearly always done from the outside in to the sleeve, there'll be a burr in the sleeve that needs to be removed and than after that, the port is then dimpled, usually using a hard ball (ball from a bearing is what's commonly used). The dimpling is to make a smooth transition for the seals to slide over as they pass the ports.

 

I'm just wondering if this process was done when you had your sleeves fitted ?  The PDWA being such a small bore would make this process a real fiddle.

[miniGTS]

Oh, I meant I changed the seals in the PDWA bore. That one wasn't resleeved. The main bore was resleeved.

It's also possible that I didn't clean it up well enough before I assembled it and the seal got caught in some dirt going in causing it to pinch perhaps.

I think I will clean it up again and reassemble with more care.

I just need to find a replacement reservoir.

Edited by miniGTS, 25 June 2024 - 08:32 PM.

[miniGTS]

I managed to source a reservoir that looks to be in good condition. I'll clean it up and inspect.

When I rebuild the master, should I be using a small amount of silicone paste on the seals when I assemble?

[Spider]

Nice one !

 

When I rebuild the master, should I be using a small amount of silicone paste on the seals when I assemble?

 

Rubber Grease or Brake Assembly Grease or at the very least, Brake Fluid is what to use on assembly.

If you have an old 1 thou feeler strip, you could cut a thin strip off that and rub it on some 600 wet & dry or similar to smooth off the edges. Then when assembling the PDWA Shuttle / Piston, put the feeler strip down the bore to cover over the ports, insert the Piston, then remove the strip. This should avoid damage to the I Rings if there's an edge on the ports in to this bore.
 

[miniGTS]

Cool, thanks. I'll see if I can get some rubber assembly or brake assembly grease.

Thanks for the tip using the old feeler strip. I should have some loose ones around.

I also scored a plastic switch that I hope will come out without breaking... Otherwise I still have my original one though the thread is not perfect.