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MG MGA - Thread type size Rear wheel Cylinder

Gday Could someone tell me the correct size type and TPI of the thread in the wheel cylinder please. I have been to Barney's site but have been unable to look in the right place. Thanks Bob
B WALKER

I believe all of the hydraulic cylinders on the MGA have 3/8-24-UNF thread (although the banjo bolt on front calipers might be different).
Barney Gaylord

Thanks Barney, that is what the wheel cylinder that came off the car is(3/8-24 UNF) but the parts supplier says it should be 3/8-20 BSF . Both the Mgas I have are 3/8-24 (The same banjo bolt fits on any rear cylinder) Thanks Bob
B WALKER

I have still in my possession (I think) one MGA rear wheel cylinder Classic Gold from Moss (from a few years past) that has a different thread, and the bolt of brake line will not fit. Moss didn't have any explanation for it, other then one fluke in production. Since there were not a rash of complaints and returns, I didn't list it as a faulty part. At the time I thought it may have been a metric thread.
Barney Gaylord

I have a vague 45 year old memory of very early MGA having some BSF threads in the brake system, It was an anomaly then. The Magnette's pipe fittings are mostly BSF and the brakes are otherwise the same. There were similar oddities in various replacement master cylinders back then; adaptors were usually but not always supplied. At this point, the recommendation is measure and use appropriate parts; few if any cars can be counted on as "original".

FRM
FR Millmore

Very interesting. I just changed the slave cylinders on my sidevalve minor. Was going to use new pattern ones but on the fronts the nuts from the originals I took off would not fit the new cyls so in the end I used NOS cyls I had been hoarding. I could not find a BSF or UNF but which would fit the new ones. Same story as on that MGA. Maybe mine are metric too!
H L Davy

I have recently fitted a set of the Classic Gold cylinders to replace the Lockheed ones I installed when restoring the car 20+ years ago. The threads were all identical, and there was no deed for any adaptor - in fact they dropped in simply and quickly so the job was done (including bleeding) in less the an hour for both sides.

I can also confirm that the banjo bolt on front disc brakes is larger, but couldn't specify the thread.

dominic clancy

I've just replaced the rear wheel cylinders(Lockheed) of my 1957 Roadster and they definitely are NOT 3/8-24 UNF. My replacement cylinders(Classic Gold) ARE 3/8-24 UNF. Since I'm in the beginning stages of frame off resto and will be replacing all the brake tubing it won't be a problem for me but what a surprise for those of us just wanting to replace cylinders and finding out that the lines, or at least end fittings need to be replaced, too. UGH!

Somewhere in my research prior to starting the restoration, I remember an article concerned with the change over to UNF fittings on our MGAs. Naturally, can't find the reference now but I think the change occurred after 1957 which flagged the issue for me. I think the '58 model year was changed to 3/8-24 UNF.

John
JR Alexander

Does the BBS readers think it would be better to send the wheel cylinders back to parts supplier or buy banjo bolts that fit from them? Bob
B Walker

Apparently (from Clausager) the threads on brake line fittings, including the rear brake cylinders, were changed to UNF from car number 27989 - March 1957 (disc wheels) or 28540- April 1957 (wire wheels). . Doesn't say what they were before the change but almost certainly BSF..................Mike
m.j. moore

M.J.Moore is correct except the wheel cylinder GWC1111 And Banjo Union Bolt 7H7847 have always been 3/8" BSF 20tpi Never UNF or Metric
THe 180% double Brass Banjo & Bleed screw on the early
1500 MGA were also threaded 3/8"BSF 20tpi
then they Changed to 3/8"unf 24tpi on all the brake pipe
ends
P G BEADLE

Yup - early cars (my Jamaican chassis was built in late 1956) had the oddball threading.
Bill Spohn

This thread was discussed between 26/04/2012 and 17/05/2012

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