40 replies to this topic

[CDY]

Hi. I have a 1275gt registered in July 1980, getting on to be the end of production of these clubman style 1275gt.

 

The car was refurbished prior to my purchase but I think the restorer used the wrong brake system.

 

At the moment it has a single brake line system with no pressure regulation valve on the rear subframe.

It has a brake test switch that I am sure is not connected as their is nothing to connect it too!!

 

what is the correct brake master cylinder and brake system for this car?

 

can anyone help?

[richmondclassicsnorthwales]

Have  a look at this - hopefully explains a bit better

 

http://www.minispare...px|Back to shop

 

As long as the brakes have met all the MOT requirements, then don't worry too much. If you do want to upgrade, then that is entirely up to you.

 

Both valves - be it the bulkhead PDWA or the rear pressure valve are - well - can of worms - but - if you feel safe enough - don't fix it if it isn't broke !

 

If you do want to upgrade - use a rear adjustable bias valve and do without the PDWA valve which would have fitted on the bulkhead, and servo it.

 

Just an idea for the pot - and the first idea- see what other members would do

[GT Jimmy]

My 80 GT never had a valve on the rear sub frame, I didn't re use the black tag cylinder but replaced it with the yellow tag master cylinder in the previous post. Had to do some simple wiring, full instructions were supplied

[CDY]

Thanks One Carb Or Two

I have looked at the mini spares master cylinder and did wonder about this. 
 

My concern was the rear brakes locking up without a rear pressure valve. Is this a problem do you think?

 

The other thing is that if I leave it as it is, the brake test switch is redundant. is that normal and okay?

 

Thanks.

[CDY]

Thanks One Carb Or Two

I have looked at the mini spares master cylinder and did wonder about this. 
 

My concern was the rear brakes locking up without a rear pressure valve. Is this a problem do you think?

 

The other thing is that if I leave it as it is, the brake test switch is redundant. is that normal and okay?

 

Thanks.

[GT Jimmy]

Do you have a valve on the front cross member?

[CDY]

Hi GT Jimmy. I can’t see any valves at all only “T” connectors, one on the front bulkhead below the master cylinder and one on the rear subframe front crossmember.

The system appears to be a simple single line system with a traditional master cylinder, nothing else.

[GT Jimmy]

Do you have a valve on the front cross member?

The test switch works as you snip the old black plug off that connected to the old black tag cylinder, join the wires together with a spade connector, attach it to the cap, then another wire goes from the other cap connector to an earth. Even I managed it lol

[CDY]

Unfortunately there are no terminals on the master cylinder as it is the original type for a single system.

[GT Jimmy]

Here's what I've got

 

[cal844]

My 1980 estate has the FAMwtf valve with no limiter at the rear, Black tag Master cylinder, 7.5 Cooper S disc coversion.

A 1980 car should have the FAMwtf valve on the bulkhead and no rear line valve. Can you please post some pictures of your current set up?

Ideally we would need the following ::

One of the Master cylinder and pipe work leading from it.

Any pressure reducer (FAMwtf valve, or Tee piece) at the bulkhead

The rear Tee piece at the end of the front to rear pipe

A size from a wheel cylinder.

These will let us know what you have and what changes to recommend.

Unfortunately I can't be more help.


Cal

[Chris1275gt]

I have a 1975 1275gt. Single line the gmc 172 master cylinder 8.4 discs at the front and 1/2 rear cylinders no other valves. It stops no problems with no rear wheel locks and passes mot. As far as I can tell that's how it's always been. It's just old school the harder you press the pedal the quicker it stops. The only slight problem I have is the rare occasions I drive her indoors polo and usualy do a couple of emergency stops before I'm off the drive.

[cal844]

I have a 1975 1275gt. Single line the gmc 172 master cylinder 8.4 discs at the front and 1/2 rear cylinders no other valves. It stops no problems with no rear wheel locks and passes mot. As far as I can tell that's how it's always been. It's just old school the harder you press the pedal the quicker it stops. The only slight problem I have is the rare occasions I drive her indoors polo and usualy do a couple of emergency stops before I'm off the drive.

I do the emergency stop thing all the time in my (9N3, 07 reg) polo, its frustrating 😁

[CDY]

Hi Cal.

Thanks . I attach three photos of the Master cylinder and T piece on the bulkhead, one of the T piece on the rhs of the engine bay ( which merely branches to the offside front wheel) and the last one is what I think is just a T piece on the rear subframe.

 

Unfortunately I don’t have the rear wheel cylinder size as I haven’t long had the car very long although it should be standard for a 12” rear wheel for a 1275gt. Front are the 8.4 discs.

 

any help or advise, whilst trying to keep it as original as possible, is very welcome.

 

thanks and hope the pics help.

Julian  F0E5FFC0-6F7F-4A27-8E0B-CAF00FFB3E87.jpeg   153.17K   11 downloads  B70A8B57-8106-430A-A00C-14B7209A5F8C.jpeg   118.66K   7 downloads

 

Attached Files

•  B93D9835-1739-4CF9-A613-A6F92FDE6B45.jpeg   162.91K   1 downloads

[Chris1275gt]

That is exactly the same as my 75. You'll know if it's not 1/2 cylinders on the rear as it will lock up and have a slightly longer pedal travel. I think the original brakes on my 80 1275gt was a split diagonal system with no servo but a limiter valve on the rear, so someone has swapped it back to single line.