Clutch Woes - Need some technical assistance

[jjscott]

I have a 1275 in a bugeye. The master is the original 7/8 on both bores. It has a diaphragm spring clutch installed and worked by a 7/8 bore slave. All the parts are new, including bushings, pins, forks, etc. The car is not yet running. I found the pedal effort to work the clutch was too high to be comfortable; I doubt my wife could drive it.

I just got a 1275 slave with 1" bore and attempted to install it. Surprise, the fittings are different and the metal pipe bugeye fitting with the balloon end is too small. Looking in the Moss catalog it seems the 1275 slave mates to a flex hose. I assume the hose seals to the slave with a copper washer, correct? It does look like the slave will accept a compression fitting of the correct size though.

What do I need to attach my metal bugeye pipe to the 1275 slave? If I buy the hose will the bugeye fitting attach to the other end? Please don't tell me I have to unscrew the bugeye line from the master. The master connections are impossible to get at with the master installed.

In a perfect world there would be some kind of an adapter that matches the bugeye compression fitting to the slave body. I'm going crazy with this thing. I need something to go right.

Jim

 

[nomad]

Jim, I used an old 1275 hose and cut the slave end off. I then brazed a fitting for the british bubble flair on to it. I'm sure there are other ways that may be simpler. The 1 inch slave will help the pedal pressure but I believe that the 1275 master was 3/4 so it may still be a bit stiff.

Kurt.

 

[Gerard]

The 7/8" clutch line parts, including the hard line, are different sizes and not interchangeable.The later clutch master cylinders had a fitting on them to accommodate the larger line and fittings.It did seal with a copper washer, so you could possibly used one of those if you could fine one. It was designed to come straight off the back of the MC, so in the case of the tandem MC, it would stick straight up (more or less), and I 'm not sure if the machined surface around the port would have enough clearance. The other option is to make up a braided/teflon hose with the appropriate fitting sizes on each end. You can find the hoses and fittings through either Summit or Pegasus. You can buy them made up in custom lengths or buy the pieces and assemble yourself.

The other option is to convert your MC to 3/4" (both bores), which you should have anyway if you have disc brakes. I have done dozens of these conversions and everyone always likes the improvement in clutch performance too. These are still available through me.

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

 

[jjscott]

In my case the drums are retained, so I need the 7/8 bore on the master side. With the 1275 clutch, the 3/4 bore clutch master is correct. My clutch master is 7/8. That's what I have to work with.

After a lot of internet searching an an hour at the NAPA store I haven't yet found the "correct" adapter. To accept the bugeye hard line and screw to the 1275 slave the adapter should have a 3/8-24 female bubble fitting on the line end and 7/16-20 male bubble fitting on the slave end. The AN -4 fittings have a 7/16-20 thread and will screw into the slave.

anplumbing.com has an adapter that might work. It is 989541 on https://www.anplumbing.com/Adapters/Brake+Adapters-90.html

It has a female 3/8-24 bubble on one end and male 7/16-20 AN on the other. The question is whether the threaded AN end is long enough to bottom out in the slave and seal. If not, the question is whether there is enough flat surface on the AN end to use a crush washer instead of relying on the tapered end to seal.

I plan to call ANPlumbing Monday and talk with them. I'll post what I find. Thanks to Kurt and Gerard for the replies.

Jim

 

[Trevor Jessie]

Isn't the original bugeye line 3/16"? Since you are wanting to reduce pedal effort, I think it would be prudent to also switch to 1/4" line.

 

[jjscott]

The adapter from AN Plumbing works.

The nose of the -4 AN end needs to be filed shorter and a crush washer used on the slave connection. This is what I was advised by the AN tech guy. The bugeye hard line screws right in to the other end of the adapter. The installation went without a hitch. I did a preliminary bleed and found the pedal effort to be noticeably reduced. I'll re-bleed in a couple of days to be sure all the air is out and check for leaks.

No doubt the correct 3/4 master would be a preferred solution, but my 7/8 master seems as though it will work OK with the 1" slave.

Jim