Clutch master and slave thread sizes

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discomania

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I have been researching this all morning and I am fairly sure this is the case for me, but can someone confirm or add their thoughts.

I have it as master (550732) is 3/8 24 UNF and slave (591231) is 7/16 20 UNF

I am going to do away with the rigid line, flexi and jump pipe and just have a SS braided pipe from master to slave.
 
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I have been researching this all morning and I am fairly sure this is the case for me, but can someone confirm or add their thoughts.

I have it as master (550732) is 3/8 24 UNF and slave (591231) is 7/16 20 UNF

I am going to do away with the ridged line, flexi and jump pipe and just have a SS braided pipe from master to slave.

The bottom end of the solid pipe is definitely 7/16 UNF, as we replaced the nut for a SS version doing a rebuild. The top I can’t remember what size it was as we used a standard line, but it was different to the brakes that used M10 x 1.
 
The bottom end of the solid pipe is definitely 7/16 UNF, as we replaced the nut for a SS version doing a rebuild. The top I can’t remember what size it was as we used a standard line, but it was different to the brakes that used M10 x 1.

Thanks, so we are going to be 50% sure. AFAIK there is only two options for the slave, 3/8 UNF and M12x1 - it won't be M12 as this is an early Defender and I think the threads changed with the 300.

Just ordered a TRW slave and TRW master and a stainless steel braided pipe to replace all the existing bits.

I will let you know how I get on!

Thanks
 
Right, I decided to go and work it all out for certain.

The master is drilled and tapped for 3/8 UNF. Into this screws an adapter face to face with a copper washer. The adapter takes it from 3/8 to 7/16 UNF and I believe a JIC flare.

20210218_143651.jpg

Technically you could get a 7/16 UNF to 7/16 UNF pipe made up and keep the adaptor but I have opted to get rid of the adaptor and make it as simple as possible.

Hopefully it all works!
 
Right, I decided to go and work it all out for certain.

The master is drilled and tapped for 3/8 UNF. Into this screws an adapter face to face with a copper washer. The adapter takes it from 3/8 to 7/16 UNF and I believe a JIC flare.

View attachment 231195

Technically you could get a 7/16 UNF to 7/16 UNF pipe made up and keep the adaptor but I have opted to get rid of the adaptor and make it as simple as possible.

Hopefully it all works!

Where have you ordered it from? Are all the fittings on the braided hose SS too?
 
Where have you ordered it from? Are all the fittings on the braided hose SS too?
A motorsport company, I will post full details once it arrives, I cannot remember their name. Looks like it will be tomorrow or Monday now it arrives, hopefully the master and slave too so I can build it all up on the bench and photograph.

The fittings and pipe are all stainless.

I think once it all comes together (I accept that first time it might not all work spot on but I will get there) it will be a really nice solution. It was going to cost me about £15 for a new slave jump pipe, then about £10 for a branded non-bluebox clutch flexi, this worked out about £3 more and has so many advantages I can see.

I am thinking that it would make it possible to undo the slave and just pull it up into the engine bay for maintenance or what not. I also think it will make bleeding easier as I could actually fill from the slave in an elevated position back to the master, refit the piston and then lower it down into the engine bay and fit etc.

I also like the idea of the fact I am getting rid of 3 joins in the system.
 
A motorsport company, I will post full details once it arrives, I cannot remember their name. Looks like it will be tomorrow or Monday now it arrives, hopefully the master and slave too so I can build it all up on the bench and photograph.

The fittings and pipe are all stainless.

I think once it all comes together (I accept that first time it might not all work spot on but I will get there) it will be a really nice solution. It was going to cost me about £15 for a new slave jump pipe, then about £10 for a branded non-bluebox clutch flexi, this worked out about £3 more and has so many advantages I can see.

I am thinking that it would make it possible to undo the slave and just pull it up into the engine bay for maintenance or what not. I also think it will make bleeding easier as I could actually fill from the slave in an elevated position back to the master, refit the piston and then lower it down into the engine bay and fit etc.

I also like the idea of the fact I am getting rid of 3 joins in the system.

Yes I agree with what you are saying, that’s part of the curiosity for me, as it’s something I have often thought about. The brake lines too, from the joins on the front all the way to the calliper, and on the rear from the T piece to the wheel cylinders.

As for bleeding the new SS system. I would bleed it like I normally do, wesco oiler with brake fluid and a piece of pipe, push it over the slave bleed screw, pump the Wesco until the master cylinder reservoir is full, tighten the nipple up, then give it a few pumps the conventional way.
 
This is what I now have:

20210222_123845.jpg


It is not all fitted yet because I spray painted the clutch pedal tower, slave is in, pipe is connected to slave, routed up the bulkhead and ready for the master to go in. Old rigid pipe removed and all looks pretty neat.

Once I get it all hooked up and bled I will post a few more images. Really happy with the setup thus far though.
 
The pipe came form this chap:

https://www.brtmotorsport.co.uk/pro...0-tdi-clutch-hose?_pos=2&_sid=8dcb57bfd&_ss=r

The exact spec of my clutch line is a 3/8 banjo for the master end and a 7/16UNF union with a male flare on the pipe, the flare is SAE 45 however, I actually think the slave is JIC 37 - I will let you know if this is a problem when I pressurise it! I know it is a mismatch and I know it is not right, but I think given the nature of the seating face and the relatively low clutch pressure I am certain it will hold.

I spent a long time in the workshop working it all out and finding an adaptor online but after some tests of a 45° flare into a 37° flare I decided the flare would probably seal - I might not use it on a 3000PSI hydraulic line, but for a clutch I decided to go for it. If it leaks I will order a JIC to SAE adaptor.
 
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