40 replies to this topic

[GT Jimmy]

Looks like there's no limiter at all,I'd be surprised if they didn't lock up. The set up on mine is pretty much standard for a 1980 GT I think bar the yellow tag cylinder. Mine was never fitted with a servo

[CDY]

Interesting.
Do you remember what Master Cylinder was on your ‘80 1275gt and if it had an inbuilt PDWA or a separate PDWA on the bulkhead (which is no longer available)?

[Chris1275gt]

This is an older post on 1275 brakes that sorted my 1275gt brake issues with Moke spider looking through his factory microfiche
https://www.theminif...1275-gt-brakes/

Edited by Chris1275gt, 31 January 2021 - 10:25 PM.

[GT Jimmy]

The one I took off prior to the resto was a black tag master cylinder. I probably still have it in the loft with the other bulkhead valve I took off. I replaced them with new parts when it came back from paint

I'll get some photos tomorrow if they are still there

I'm a firm believer if it ain't broke don't fix it, so if your system works I'd leave it. Mine hadn't ran for a few years before I bought it so replaced the whole lot, including calipers and rear brake back plates and drums etc

[CDY]

That is good info but did you ever find out who was right, Moke or Minispares?

 

my 1275gt is a 1980 and I am fairly sure fits in to the bracket of:

 

From Car 21570A to ?????  Single Circuit, 8.4" Discs (no servo), 1/2" Rear Wheel Cylinders, No Regulating Valve

I would still love to know what is the correct Master Cylinder as it must have a connection for the brake warning switch.

 

Any ideas?

[GT Jimmy]

Have a look at mini spares GMC167 master cylinder, the switch for the brake test according to the description isn't available so is blanked off. that would be what was originally fitted. I'm sure it had a black tag

 

GMC227 is the one i fitted with the yellow tag, the brake test switch can be hooked up to it, not that anyone ever uses it lol

 

Found the old limiter valve from the front bulkhead in the loft, no sign of the cylinder

 

 

My car was only 10 years old when taken off the road so I believe it was original

[Itsaminithing]

All the reference material i can find says GT Jimmy is correct about everything for a 1980 GT.

Tandem brake system, no servo, originally used a black tag master cylinder (NLA so usually replaced with a GMC227 yellow tag), & a FAM7821 brake limiter valve fitted.

I wouldn't want to run a single circuit without any form of brake bias, but each to their own.

 

These sites might be useful to you....

https://classicregis...81-mini-1275-gt

https://www.minicoop...75-gt-register/

 

[Spider]

I remember someone else asked a similar question about a year or so back.

 

The late GT's had the GMC167 Master Cylinder, no valve of any type anywhere and 1/2" Wheel Cylinders on the back.

Going to the Yellow Tag master may introduce some issues though as it has a stepped bore and so develops different pressures between the 2 circuits.

[Itsaminithing]

Mark Huthert :Anatomy Of The Mini gives the following information....

 

GMC167 used on GT with diagonal split 1977/78 (with no regulator valve).

GMC173 (later became GMC198) used on tandem systems 1978-1980.

GMC192/GMC195 (Black Tag) tandem system 1980-85.

 

 

 

 

 

[GT Jimmy]

I remember someone else asked a similar question about a year or so back.
 
The late GT's had the GMC167 Master Cylinder, no valve of any type anywhere and 1/2" Wheel Cylinders on the back.

Going to the Yellow Tag master may introduce some issues though as it has a stepped bore and so develops different pressures between the 2 circuits.

I've had no issues after fitting the yellow tag, it passed the mot brake test

[Spider]

Sorry for my post above guys, I didn't see this thread had a second page !

That info had already been covered.

 

Have a look at mini spares GMC167 master cylinder, the switch for the brake test according to the description isn't available so is blanked off. that would be what was originally fitted. I'm sure it had a black tag

 

Yes, the original switches for the GMC167 Cylinders are NLA - not that they ever worked from new.

I blank that hole off with a 3/8" UNF Bolt and fit the Cap from the Yellow Tag Cylinder.

[CDY]

Hi all and thanks for the information.

 

As my car is an April 1980 build, if I am correct from all the posts, it would have had a single system with no valves anywhere, 1/2” wheel cylinders on the back and a GMC167 master. The switch would have fitted in line but that is NLA so is often capped off.

 

Excuse my ignorance but could someone explain what ‘Black Tag’ and ‘Yellow Tag’ refers to?

[GT Jimmy]

Some master cylinders came with a black or yellow tag just for identification purposes I think because they look very similar, I could be wrong. If you look at the picture I posted of my set up you can see the yellow tag, which means it's a GMC228.

The GMC167 I took off had a black tag

[Spider]

As my car is an April 1980 build

 

I have had a look at my Fiche and also compared that to the list on the Mini Spares website, with the 'catalogue' listing;-

 

http://www.minispare...ers.aspx?1~9~77

 

If you scroll down to item 10, yours for the UK Market would have been Front / Rear Split, with a GMC173 Master Cylinder and a FAM7821 Pressure Limiting Valve on the Bulkhead. That's also what I have in the Fiche. As the GMC173 is NLA, Mini Spares suggest the Yellow Tag Master (GMC227) as a replacement, which should be fine, however, if you are looking to do a restoration with all parts correct, a GMC167 is the same as the GMC173, except that the GMC167 has Metric Threads.

 

[CDY]

Thanks Spider, that’s really helpful. Thanks also to everyone else who has contributed to this question. It has been interesting.