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 Posted: Mar 14, 2020 08:04AM
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GB
Locating pins and backplates are matched according to age and application - if your backplates are original and the locating pins are in the wrong place then you've got the wrong size cylinders...

My microfiches are suggesting you should be using a GWC1129 rather than an 1102.

 Posted: Mar 14, 2020 07:13AM
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CA
Yes, I did drill the hole in the backing plate. I ended up welding the hole shut and re-drilling it in the right location. In hindsight it probably would’ve been easier to relocate the pin on the wheel cylinder but I didn’t think of that.
I was thinking the pin was required to keep the wheel cylinder from rotating but I guess once the brake shoes are in place they hold the cylinder somewhat. But I still don’t think I’d install one without the pin. 
The car has drums with twin leading shoes on the front. The master cylinder has been replaced with the later stepped bore one. It’s back together now so I guess we’ll have to see if the rear brakes are too much with 3/4” bore cylinders.
I was looking at pictures online and it appears that GWC1101, 1126, 1129 and C1065 have the locating pin on the opposite side compared to the GWC1102 and 1131.
Anyways, thanks for all the replies.

 Posted: Mar 14, 2020 05:34AM
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US
Consider that you may change from drum to disc and a different dia cyl is required to balance braking. It is possible to
pull the small split pin drill cyl and move the pin. Yes there are some backing plates with a raised area either side of cyl
base. Over the years I have taken apart rear brakes with no pin at all some with a hose clamp holding the cyl in place. I
have set up rear brakes with out the hand brake linkage welding up the access. Brakes should be take seriously. Steve (CTR)

 Posted: Mar 13, 2020 03:07PM
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US
I just ground the pin off. The old backplates have locating indents on either side which serve sam purpose as pin.

 Posted: Mar 13, 2020 02:12PM
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Or just remove the pin.  Its there to ensure you fit the correct cylinder to the correct car.  A plan no longer valid....

Cheers, Ian

 Posted: Mar 13, 2020 09:48AM
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US
I thought he did drill the back plate just a little off. Oh yeah he could remove the pin clamp the cyl to the back plate and drill the cyl for the pin in the correct location through the org back plate hole. Steve (CTR) There is always more then one way to skin a cat.

 Posted: Mar 13, 2020 08:59AM
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Or drill the back plate.
I never knew there was a difference in wheel cylinder locating pins.

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Mar 13, 2020 08:10AM
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US
If you think about it the bleed valve will locate the cyl. use a small rat tail file to move the hole where you need it. Don't make the hole bigger
just elongated. Steve (CTR)

 Posted: Mar 12, 2020 09:44PM
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CA
11/16" bore if drum braked.  If discs up front go smaller, at least to 5/8" bore on a sedan...or you will be swapping ends in the wet.

 Posted: Mar 8, 2020 07:10AM
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CA
I need to fess up here. That was my thought as well but unfortunately I didn't drill the new hole in the right spot. I foolishly assumed it was exactly opposite the original hole but it's not! But the new hole is close enough that I can't easily drill a second hole. So at this point I figured it would be simpler to get a proper fitting wheel cylinder.

You can see in the picture that the pin is on the opposite side but also closer to the edge on the GWC1102.

 Posted: Mar 7, 2020 11:10PM
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Cant you just drill a new locating hole in the backing plate?

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Mar 7, 2020 03:54PM
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CA
Which rear brake cylinders will work on a 1980 Canadian Mini? I have a set of GWC1102 and the locating pin is on the opposite side.