Rear Brake Cylinder Weirdness

[John Moore]

I'm converting my Bugeye to disc brakes. I had my MC re-sleeved to 3/4" and in the rear I got 1275 rear brake plates. I'm in the process of putting together the rear plates and ran into a problem when I tried to fit the brake cylinder. I bought the aftermarket cylinder from Moss (180-386) but when I try to install it on my backing plate, I noticed the locating pin is on the wrong side?! weird! Take a look at the photos and imagine me turning over the cylinder and putting it on the plate. Did I get the wrong part? Has anybody else run into this? Should I just drill another hole for the locating pin? Strange.

 

[spritenut]

Typical from them. I have seen this before with their parts.
Just drill a new locating hole in the back plate.
Haven't you heard their policy "file to fit" :wink:

 

[Trevor Jessie]

Wait a minute Frank, I thought the locating pins were purposely put in different locations for different bore sizes.

I was thinking that the rubber bumper cars had a larger bore than the pre-67 models.

 

[John Moore]

Is it possible I have backing plates from a 1500? If so, does it matter? What is important is that I have the correct cylinders to match my MC and front Disc brakes.

 

[Trevor Jessie]

Correct John. You want the wheel cylinder to match the MC and front calipers.

 

[John Moore]

So I guess, I should just measure the bore of the cylinder, if its 3/4", drill a new locating hole and make it work, right?

 

[PeterC]

John, the cylinder in your hand is the 1275 cylinder. That makes the backing plate for a 1500.

The bore of a 1275 cylinder is 3/4.
For a 1500 is .6875 (11/16) (1/16 smaller)

Same master cylinder. Same calipers, Same shoes. Same drums. What were they thinking?


Peter C.

 

[John Moore]

Thanks Peter,

Makes me feel better! And I have NO IDEA what they were thinking!

 

[bugimike]

BMC has a "better idea"!!