1275 Clutch Slave Cylinder to BE Clutch Line

[lbcfan]

I installed my engine this weekend. Aside from dropping the engine onto the steering rack once it went well, but with one exception.

In replacing my smoothcase with a ribcase I ordered a slave cylinder for a 1275. Now installed, the cylinder seems to have a female thread just slightly bigger than the male end on my original clutch line.

I did not want to retrofit a flexible hose and I have trouble determining the sizes on these tapered threads. The male is about .396" OD, and the female is about .389" ID, and the threads won't engage. Can anyone give me the proper sizes and/or point me to a source for an adapter, female to male, that would make up the difference? There is no room for a simple bushing.

I will try to upload a photo in a couple of days. No-one around here can properly admire the beauty of the installation... I have to say that the green engine looks great against the cherry red compartment.

Michael

 

[Gerard]

Michael,

The larger fitting into the slave is a 7/16-24 (or should be). I have an original here and the thread O.D. on the flex hose .430. If you are at around .396, either you have measured wrong or it is an odd size since 3/8" would be .375, Check again otherwise, it would likely be 3/8"-24. I think some of the repro stuff is not the same as original sizes.

 

[Billm]

It is just as easy to just put the Bugeye slave back in and just use it!
BillM

 

[lbcfan]

Thanks Gerard. It was difficult to measure accurately under the car. Is the 7/16" connection on the hose a tapered thread or a straight thread with a copper washer? I can't tell from the catalog.

As suggested, it might be easier to go back to my old slave cylinder.

 

[Gerard]

Straight... used w/copper crush washer.

 

[longbridgehealey]

Yep, I just finished swapping the 948 for a 1275 in our Bugeye, along with the ribbed case. I just used the Bugeye slave and it's working out just fine! Good luck to you.

Larry

 

[nomad]

If you change your master cylinder to 3/4 for front disc brake change you may want to change the clutch slave to the 1275 one. I made that switch and cut off an old 1275 hose fitting and brazed a tubing fitting to it for the 948 line to screw into.

Kurt.

 

[Gerard]

Kurt,

Unless you want to go to the trouble go plumbing dual circuit brakes. there's really no reason to go to the expense and hassle of modifying the footwell to accept the later pedal box. As mentioned in another thread here, this also requires relocating the wiper motor.

About 6 years ago, I worked out making 3/4" bore tandem (original Bugeye style) combination master cylinders. They can be set of with both bores to 3/4" (which I think is the way to go), but can be a combination of 7'8" and 3/4".

There have been about 75 of these converted MC's installed to date and feedback has been 100% satisfaction.

See: https://gerardsgarage.com/Garage/Tech/DbrakeUg.htm

 

[nomad]

I agree, Gerard, and I have checked out your offering's and like what you have.

I was lucky enough to get ahold of a MK3 AH 3/4 bore dual master that was in good rebuildable condition and that is what I fitted to my BE when I went to front disc's. I believe the 1275's were supposed to be run by a 3/4 master so I fitted the 1275 slave. Am I right on that??? Been awhile. Every thing works fine though.

Kurt.

 

[lbcfan]

Thanks for the reassurance. I removed the new 1275 slave cylinder today and went back to the 948 unit. Kept the 3" rod. Good to know it will do the job.

Of course I had gotten cute and extended the bleed nipple with an additional pipe, so I had 3 difficult to reach connections instead of the usual 2.

Michael

 

[Gerard]

the 3/4" master was used with both 7/8" and later, 1" slave cylinders. I'm not sure at what point the 1" slave was introduced, but does coincide approximately with the introduction of the 1275, if not at it's outset

 

[longbridgehealey]

I forgot to mention the 3 " rod - we kept that, too. Good luck!

Larry

 

[Gerard]

I mention this in the interest of preventing the proliferation of misinformation. The correct push rod length for a 1275 is 2-11/16", measured from the centerline of the hole to the end. I don't know if 3" is an "abbreviation" for the correct length, but someone will certainly misunderstand this and make one the incorrect length. It does make a difference. 948 and 1098 is 2-3/8"

 

[lbcfan]

Gerard-

The catalogs call it 3", but you are correct as usual. The 3" seems to be the approximate overall length- not measured to the center of the hole.

Regards,

Michael

 

[Gerard]

What catalogs are those?