8 replies to this topic

[JonnyAlpha]

Hi;

 

Just been watching this video on Drum to Disc conversion , in the comments the author mentions that you need to fit a Rear Brake Proportioning Valve to adjust the pressure being applied to the rear drum brakes to avoid lock up?

Any advice on whether this is the case?

They are not sold with the kits.

 

TVM 

[smudger068]

Hi Jonny.

When I fitted my minisport 4-pots I had to fit one to mine as it would happily lock up the rears. I fitted mine just after the master cylinder. It is an adjustable one. Some put them inside the cab. (Even though it will pass an MOT with it in the cab, it is technically illegal! make of it what you wish).

Thanks Lee.

Just looked this is the one I have fitted.

https://www.demon-tw...wE&gclsrc=aw.ds

Edited by smudger068, 30 May 2019 - 07:55 AM.

[Gaz66]

Years ago I made my own from a rear compensator valve, the one thats mounted on the rear subframe on single circuit systems.

Drill and tap the end and screw in a bolt/wing bolt to adjust the pressure allowed to the back . I dash mounted mine so it could be adjusted on the move.

[Ethel]

The same valves were used with drums or discs, so I don't think it's absolutely necessary. It might offer an advantage if you drive really hard with the car empty.You could alternatively swap the wheel cylinders to a smaller bore: also reduces pedal travel.

 

I reckon drums are more likely to lock the rear, only it's less noticeable as the front is likely locked up too.

[nicklouse]

All depends on what you have to start with. Never changed anything on mine when I changed As there was no difference.

Not watched the video but I ask you this is it the same spec car as yours? If not treat it as all it is. Someone working on their car.

[nicklouse]

Ok to elaborate on this. Single circuit brakes disc or drum used the same regulator for the rear (there were some variations depending on place of build and sales area) and its job was to stop the pressure going over a set pressure so that the rear brakes did not lock up in test conditions. What the brakes are on the front has zero bearing on this.

Please also consider that this was on a “standard” car with standard ride height and suspension. Which is why people find that they need add some means of reducing the pressure to the rear when they start playing with the car changing it from standard.

Lowering it results in the rear of the car lifting sooner as there is less suspension travel.

Lightening the car reduces the contact pressure on the ground.

Changing the spring rate changes the way the cars weight transfer works.

But if you are playing with the above you should have already been thinking about how the brakes are working.

My advice, if a single line braking set up is leave it as is then if you find you need less mod the valve as per the info in Vizards How to modify your Mini or buy one for MiniSpares.

[Itsaminithing]

Have you come across this site?.... https://www.calverst...technical-info/

I found it useful when i changed my braking system & it let me dial in exactly the rear brake pressure i wanted.

If you do decide to put in a regulator then check what the connector threads are  -a lot of them available on the internet have a 1/8th NPT thread so you'll want to buy NPT/Metric adapters to make life easier.

Edited by Itsaminithing, 03 June 2019 - 08:42 AM.

[Gaz66]

A bit off topic but when I installed my modified valve I  also installed a hydraulic handbrake kit.

On testing the handbrake down the road the car stood on end nearly as the front wheels locked!

So, always pipe up your hydraulic handbrake correctly which is backwards to how you would think you would do it.

[nicklouse]

and also place it between the regulator and brakes.