29 replies to this topic

[mvahora]

Just trying to figure out what brake setup i have and which wheel cylinders i need to purchase as replacements.

 

Ive got the black tag tandem master brake cylinder in a front rear split.

 

The rear line is going into a pressure regulator which is mounted on the rear subframe. its hard to tell which one it is but either the 21A2031 or 21A1774. I've read online and on calverst that these are useless and can be removed to a simple T adapter?

 

Is it best to open the rear drums to check which cylinders I need to use or can someone tell me based on the MC i have?

 

Also are there any wheel cylinders on my front discs that would need replacing?

 

 

 

 

[Spider]

Have you got discs or drums on the front ?

[mvahora]

Have you got discs or drums on the front ?

 

Got the 7.5 discs on the front.

[stuart bowes]

disc brakes don't have cylinders, they have calipers which the brake line feeds into

 

if seized up the caliper as a whole can be replaced, or in some cases rebuilt depending on their condition and whether or not it's economically worth doing

Edited by stuart bowes, 18 July 2023 - 11:06 AM.

[Ethel]

The only setup without any valve was the diagonal split. It used 1/2" wheel cylinders.

 

In a sense it's not the brakes, it's the rear grip, which is down to rear end weight, suspension, tyres etc. 

 

...but, if it's the same/related line pressure at the front brakes it'll affect how much they bight, causing torque reaction weight transfer.

[Spider]

Ive got the black tag tandem master brake cylinder in a front rear split.

 

The rear line is going into a pressure regulator which is mounted on the rear subframe. its hard to tell which one it is but either the 21A2031 or 21A1774.

 

 

That regulator is unusual for this set up, but will work just fine.
 

 

 

Have you got discs or drums on the front ?

 

Got the 7.5 discs on the front.

 

 

They'd almost certainly be 5/8" Rear Cylinders.
 

[mvahora]

Ive got the black tag tandem master brake cylinder in a front rear split.

The rear line is going into a pressure regulator which is mounted on the rear subframe. its hard to tell which one it is but either the 21A2031 or 21A1774.

That regulator is unusual for this set up, but will work just fine.

Have you got discs or drums on the front ?

Got the 7.5 discs on the front.

They'd almost certainly be 5/8" Rear Cylinders.

Alright so managed to get some spare time so i opened up the left rear drum and as expected the cylinders are leaking. Ive attached a picture of it. it has 8 r-52 stamped on it if that helps.

Just want to be sure i replace them with the correct ones/parts.

My mini had the entire break setup changed years ago so year and model of my mini doesnt really help. Engines been changed etc.

Ive attached pic of the discs on the front and the drums ive got on the rear. Running 13/7 wheels with the spacer drums as per pic.

How hard is it to open the rear wheel cylinder and check the bore size?

On a side note would there be any benefit changing to yellow tag master cylinder? And what dictates the size/bore of rear wheel cylinder i choose to use? Is it based on engine power spec or what?

Thanks a ton

Edited by mvahora, 20 July 2023 - 07:52 AM.

[Spider]

I don't think it's a big job to slip a boot off a rear cylinder and measure it. You could put a line lock tool on the flex hose and remove the cylinder, especially since you are replacing it anyway.

You might get a slightly better pedal feel with a Yellow Tag over a Black, but otherwise, there's no advantage at all.

[mvahora]

pics

Edited by mvahora, 04 November 2024 - 11:56 AM.

[mvahora]

rear drums

Edited by mvahora, 04 November 2024 - 11:56 AM.

[mvahora]

I don't think it's a big job to slip a boot off a rear cylinder and measure it. You could put a line lock tool on the flex hose and remove the cylinder, especially since you are replacing it anyway.

You might get a slightly better pedal feel with a Yellow Tag over a Black, but otherwise, there's no advantage at all.

 

measured them today. they're a 19mm bore.  minispares website mentions that the 19mm is used mainly with the 21A2031 brake regulator.

 

So to recap I've got the black tag master cylinder, rear cooper spacer drums, front 7.5 discs, 19mm (3/4) rear wheel cylinders and most likely the 21A2031 brake regulator.

 

Is this a correct setup for a 1310 fast road mini with 13*7 wheels? 

Edited by mvahora, 21 July 2023 - 09:02 AM.

[Spider]

I would expect with 3/4" Rear Wheel Cylinders and discs on the front, the rear wheels would lock up. That's something best avoided.

It doesn't sound right to me.

 

It sounds very much like a previous owner has assembled all this from a drum braked car. The Rear Wheel Cylinders are in my view, the wrong size and the regulator valve isn't, to the best of my experience, the original regulator used with Tandem Brakes.

[mvahora]

I would expect with 3/4" Rear Wheel Cylinders and discs on the front, the rear wheels would lock up. That's something best avoided.

It doesn't sound right to me.

 

It sounds very much like a previous owner has assembled all this from a drum braked car. The Rear Wheel Cylinders are in my view, the wrong size and the regulator valve isn't, to the best of my experience, the original regulator used with Tandem Brakes.

 

Crazy what you end up finding. Good thing I decided to check.

 

So what do you think is best in order to get them right?

 

Was looking at the minispares brake id chart but obviously there is nothing there that suites  a black tandem mc running 7.5 discs  with a regulator.

 

The only closest match I see on that chart is the black tandem mc used on 1275GT Diagonal split with 8.4" discs and that used 1/2" rear wheel cylinders with no regulator.

 

for the life of me I cant figure out why people don't do things properly the first time. Its not really that hard is it.

Edited by mvahora, 21 July 2023 - 11:37 AM.

[stuart bowes]

I'd say on the contrary it's actually very easy to get something wrong, that's the problem isn't it

 

maybe the person who did it didn't even realise there were different sizes and what difference that would make ?

 

I haven't a clue either I would have to do the same as you are, ask someone else with experience

[GraemeC]

I think you'll find you have 8.4" discs