The 'E' Type Forum

I am interested in replacing the brake bleeding nipples of my E Type Series III by non-return valve bleeding nipples. One supplier claims metric thread size for front brake bleeding nipples: M10x1x16mm. Is this correct?
Thanks and best regards
Holger

I can't speak with certainty about S3 cars but I would expect that they are 3/8" 24tpi UNF like earlier cars.

Be aware that M10 1mm is very similar. A 3/8" fitting will screw into a M10 hole quite convincingly. M10 is slightly larger in diameter and I don't think an M10 fitting will go into a 3/8" hole.

Hi Holger,

Andrew is correct. The thread of most Girling calipers on UK cars at the time (including the Series 3) was UNF and the bleed nipples are 3/8 UNF. Aftermarket units often differ - you can check by running a bolt into the caliper, the vast majority of 3/8 UNF bolts have a 9/16" head.

UNF 3/8" thread has 24 tpi.

Regards,

Simon

Just for info Jaguar used M10 on the brake fittings on the later S3 XJ6 models..so possibly some confusion there....Steve

mgcjag wrote: ↑

Thu Nov 26, 2020 11:36 pm

Just for info Jaguar used M10 on the brake fittings on the later S3 XJ6 models..so possibly some confusion there....Steve

I found out about this when installing Volvo 244 calipers on my E Type. Even though they are Girling all the holes and threads are metric. So when I tried to fit 3/8 UNF fittings they went in but leaked.

The only sure way to tell them apart is by measuring them with a vernier. From memory the 3/8" are about 9.35mm in diameter, the M10 are around 9.8mm. There's only one TPI difference in thread pitch and it is very hard to differentiate them by this.

Hi Andrew, Simon and Steve
Thanks; I understand: I will order non-return bleeding nipples with both thread sizes to make sure that I can install them directly after removing the old nipples. The supplier has already agreed to take the non-fitting parts back.
Regards
Holger