14 replies to this topic

[mini-mad-mark]

Hi All,

Anybody tried/will it work:

 

8.4 discs but using the old style single line master cylinder and rear brake limiter valve on the subframe?

will be easier for my project

 

I have got all the other stuff if necessary (yellow tag M/C and the infamous FAM7821)

 

At this point I could go for an 8.4 to 7.5 conversion if the 8.4 wont work with the single line set up but I am using 12inch wheels so can go either way.

 

Its for my project not a race car so I don't need anything exotic just something that works

 

Thanks in advance

[Spider]

Yes, it will work. The 1275 GT's were like this from 74 until you guys went to Tandem Brakes.

 

You'll need to use the right size rear wheel cylinders, most like 5/8"

[mini-mad-mark]

Cheers - not sure I'd ever seen anyone use this combination 

[nicklouse]

often used and standard as mentioned above,

[richmondclassicsnorthwales]

I have used this with no limiter valve, work great ! ( and no - there was no rear wheel lock up either) as Moke says - use re-vised rear cylinders

[Homersimpson]

Do you also need the master cylinder with the larger reservoir?

[richmondclassicsnorthwales]

I have used the tin type and the yellow tag master with no limiter valve, with the yellow tag,   you don't have to hold more fluid for the brakes to work.  It is as long as you have fluid.

 

Depends how you want to plumb the system in too

[Homersimpson]

I have used the tin type and the yellow tag master with no limiter valve, with the yellow tag,   you don't have to hold more fluid for the brakes to work.  It is as long as you have fluid.
 
Depends how you want to plumb the system in too

I thought the Cooper s single line master cylinder was larger because the disc brakes needed more fluid in reserve as the pads wore down?

If this isn't the case why was the S master cylinder larger in terms of its fluid reservoir?

[richmondclassicsnorthwales]

Some had servos so had more plumbing, more fluid needed in lines, made sense to fit bigger masters on these lines than to fiddle and fart about

 

You could have a bucket full of fluid, but when the system has fluid in it you don;t need that bucket of fluid

[absx2]

Its always nice to have a little extra fluid but I would guess the S cylinder was that size due to the rally cars needing the extra fluid as they could wear the brake pads out in a single rally stage so for homologation reasons the production cars would need the same specification.

I have used the small baked bean can cylinder loads of time on 8.4" discs but I like the little extension tubes so I can see the fluid level.

[Spider]

In some markets, like ours, the Reservoir legally needs to hold enough fluid to go from full pads & linings to only 20% left (from memory) without topping up.

 

I don't think this type of ruling applies in the UK otherwise, the Yellow Tag Masters wouldn't comply - they don't here for this reason.

[Chris1275gt]

Hi
I have a 1975 1275gt and have just refurbished the single line brake system to it's original 74/76 set up with 8.4 discs gmc1720e large tin type master cylinder , gwc1129 17.5mm rear wheel cylinders and it Didn't have the rear limiter and no servo. I have also fitted new disks drums and brake pads all round it's still all bedding in and at 1st felt a bit hairy as I'm used to modern car feather light stopping power. Once you get a little used to it, it's back to old style the harder you press the quicker it stops! It has just passed it's mot so no problems with it just got to get used to it. I would add that i think it does make you a better driver as you have to think a bit more approaching junctions and roundabouts as modern car drivers I've noticed stop at a junction in the last 5 metres by just resting your foot on the pedal, me included.

[whistler]

Yes, it will work. The 1275 GT's were like this from 74 until you guys went to Tandem Brakes.

 

You'll need to use the right size rear wheel cylinders, most like 5/8"

Is that instead of a pressure limiter?

[carbon]

 

Yes, it will work. The 1275 GT's were like this from 74 until you guys went to Tandem Brakes.

 

You'll need to use the right size rear wheel cylinders, most like 5/8"

Is that instead of a pressure limiter?

 

I would strongly advise using a pressure limiting valve on the rear brake circuit. With 7.5 inch discs the 5/8 inch bore (16mm) work well but you may need to still tweak the pressure limiting valve to prevent rear wheels locking up under hard braking in wet.

 

With 8.5 inch disks these should stop better, and may need to use rear cylinders smaller than 5/8 inch bore or an adjustable pressure limiting valve to get the correct balance.

 

And if the brake set-up is not factory standard then this is one of the areas where you must notify your insurer of any alterations from standard to avoid the risk of cover being voided in case of any accident (even if it was not your fault).

[Spider]

 

 

Yes, it will work. The 1275 GT's were like this from 74 until you guys went to Tandem Brakes.

 

You'll need to use the right size rear wheel cylinders, most like 5/8"

Is that instead of a pressure limiter?

 

I would strongly advise using a pressure limiting valve on the rear brake circuit. With 7.5 inch discs the 5/8 inch bore (16mm) work well but you may need to still tweak the pressure limiting valve to prevent rear wheels locking up under hard braking in wet.

 

With 8.5 inch disks these should stop better, and may need to use rear cylinders smaller than 5/8 inch bore or an adjustable pressure limiting valve to get the correct balance.

 

And if the brake set-up is not factory standard then this is one of the areas where you must notify your insurer of any alterations from standard to avoid the risk of cover being voided in case of any accident (even if it was not your fault).

 

 

I have read and take on board that some guys have run this set up without a limiter valve and without issue.

 

In line with Carbon, I have to say, I would run one of one type or another, if for no other reason than 'insurance' that the rear wheels won't lock.

 

As far as I am aware, all Minis made - except the Diagonal Split Tandem set ups - had a limiter valve of one type or another. I could be wrong on this and happy to be corrected.

 

The Diagonal Split Tandem arrangement didn't have them as there 2 separate rear circuits, so this would involve a special limiter valve that could shut off both circuits while keeping them hydraulically isolated from each other, otherwise, if 2 separate valves were fitted, one wheel would almost certainly shut off before the other and the difference could be vast. In this set up, the means of 'limiting' was done by fitting very small wheel cylinders (1/2" if I recall).