Morris Minor Owners Club

I have just checked the brake fluid level in the master cylinder. This check is because I did a lot of work on the brakes and I am now up to the 350 mile mark since that work. All good. Level exactly as it was. Anyway, the point is I confirmed that no harm was done to threads in the mc from fitting the unvented cap and the normal vented cap behaves normally when screwed back on.

Stephen

The unvented cap I purchased from ESM (see link in my earlier post) fits perfectly without any stiffness or tightening of the threads.
The cap is plain aluminium not painted or coated.
The only problem I can find is that the hexagon head is too high and I will have to machine a smidgen off the top otherwise my heel will be catching on the head as I do not have carpets in my Minor.

It must be a different batch Phil. Both my cap and George's cap are recent purchases from ESM and neither of them fit properly. I was aware that nobody had ever mentioned an issue with the threads in older postings on here.

It's complete pot luck with parts. Like the Wild West. You cheerfully go to fit something as simple as a cap and then instantly there's trouble......

Stephen

That may be so.
The threads are 1 1/8" x 20TPI which appears to be British Cycle (BSCY).

Thank you Phil but I have no means to check what the thread is on my unvented cap. Perhaps George does....Or perhaps I might run down your way at some point because I am doing trips just for the sake of running-in miles on my engine.

Stephen

Folks,
I'd been unable to get onto the website as there were internal server errors. Looks OK today.
I received a replacement cap from ESM and this too only goes in half it's thread depth in both fitted and extracted Master Cylinders.
Note that both caps are coated black.
I sent the following photos to ESM of the 2 caps "fitted" in the MC that is actually in the car This is as far as they both go in without forcing the socket beyond what I felt was "reasonable force".
I've also taken pics of the caps fitted in the extracted MC as it is easier to see the thread depth The 2nd cap has some sort of thread damage (silvery colour).

ESM have now tried a 3rd cap, at their end, and fitted it to a brand new MC and this fits and they sent me an image I was offered a refund or to try this 3rd cap - I've opted to try the cap.
I suppose an alternative would be to fit a number of fibre washers, to the cap, to take up the depth of thread that doesn't screw in.

Phil, thanks for giving info on the thread size - I can confirm that both caps are 20TPI, but the thread shape doesn't look right (have not been able to take an image of the screw gauge placed against the threads).

Please note that this cap will be drilled and tapped to take the Gunson's Eezibleed system and would then be removed after brake bleeding.

Unfortunately, this 3rd cap did not arrive on this morning's post, so the Low-light will not be going to the local Fayre on Monday

Have a great Bank Holiday weekend,

George.