No rear brakes (at all)
Turbo Mini Forums

Had the mini on a brake tester today, the fronts are great and bounced straight off, but the rears didnt register anything, not even one iota....?

(handbrake worked fine btw)

It annoys me a little as recently i renewed everything on the rear subframe (pipes, flexis, shoes, cylinders) so i know the components are tip top

Could it be the bias thing on the bulkhead, I know they fail alot, but what happens when they do?

Symptoms like what I have?

Cheers

Joe

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

i would say its the bias valve, i have had 2 fail, both leaked brake fluid from the far left hand side of the unit when they did. both times lost all rear braking as you describe :) and there not cheap new either :(

Yes i moved to the darkside

Instagram @jdm_brett

They are one of the worst things on a mini

Fit a master cylinder with a single output (bean can style), the use a t piece to send one line to the front and one to the rear via a limiting valve to the back

ah, sounds like the culprit then

i have a spare fortunately, ill stick it on tomorrow and hope for the best, its a servo car with 2 outputs on the master, if just ditch this valve thing and run the feeds direct, will i still need a limiter on the rear?

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

You could just guess what the fault is, but changing parts unnecassarily can work out a bit expensive too!

It could well be the Master Cylinder is defective ie seals by-passing etc.

It could be the PDWA is defective.

The front to rear brake pipe could be crushed/defective.

Have the brakes examined/rectified by someone who knows what they're doing.

The car could be lethal to other road users. . . .

thanks laurence, i might just leave it as it is tbh, never liked rear brakes anyway

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Cheers Tom!

Suggesting he gets the brakes fixed properly (after I suggested a few possible causes of the problem) is far more than you have done.

It's easy to sit there & snipe at people, but not so easy to try & help out, but you probably don't know how to fix cars professionally anyway. . . .

laurence, thise might help you become an even bigger tit:

http://cgi.ebay.co.uk/Dual-Breast-Enlarger...=item414ea3ea91

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Having worked at a Mini centre in my time I'd say that Nic and Brett are spot on, and the bias valve is the place to start.

However Laurence, have you actually any experience of Minis? As all you seem to do is spout the troubleshooting section of the Haynes manual, or spread misinformation, as can be seen in a number of your posts when other members have needed to set the record straight.

As for your comments in my direction, I actually prefer the term repair as opposed to "fix", but each to their own.

PS- It is far easier for me to sit here and click the "Ban" button, so carry on with the personal insults if you wish.

Yes joe, if you chuck away the proportion valve then you will need some form of bias vale in the rear line.

The TT has this setup but without the servo, I'm considering doing it on the sprint.

I have some eggs handy too if you need teaching how to suck them.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Not sure if your's is servo or not, but if it is:

http://www.theminiforum.co.uk/classifieds/...ct/11222/cat/17

Now now children lets play nice, im with nic on this one, fit a bias valve and bean can type resevoir. Jobs a good un!

Edited by MikeRace on 21st Apr, 2010.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

That means you will be running a single system though. Although fine for performance of the brakes it is not so good in a fault situation. If you do what we have done on the TT you can do this with either a servo or non servo system and it just needs a bias valve fitting.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

I've found that if a Mini sits for several years, then both rear slaves can seize.

I would first check that you are not getting brake fluid pressure at the slaves before checking the PDWA.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

That's a good point Paul, I was also going to say the same as Ben, keep the split system.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Is the "bias valve" you are talking about, the part on the left side of the pic?

Is there a possibility to test the functional efficiency of this part?
Regards, Andreas

http://www.minifreunde.at

ya Andreas,
The part on the left hand side under the engine steady is the brake proportioning Valve, to test this valve crroectly you need two high presure brake guages. With these you can conect them to both outlet, IIRC you sould see a 60/40 pressure difference if this valve is working correct, In my experence they never work well. Best system is to use the later type master cylinder like you have in the picture but insted of this valve in the bulk head use the older type valve on the rear of the subframe they tend to work very well. You can even mod them to make them adjustable,
regards,
Paul.

Sorted :)

Swapped over the pdwa badness and they are fine now, spat it out on the first dab

Was a surprisingly easy job to, managed to do it without even grazing a knuckle!

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

On Saturday i drove a slalom with my mini. (The bloody bonnet did not wanted to stay closed):



After the training run's the mini lost ALL rear brake. The pedal went depper to the ground, but at a certain point it had good pressure. (Handbrake works fine.) It's a front/back splitted brake system. So i assume, that the rear brake circuit is completly failing.

My questions:

1.) Is it the PDWA, or could it be the master cylinder?

2.) Referring to this post:

Edited by akirch on 15th Jun, 2010.

http://www.minifreunde.at

mine didnt leak, but the pedal was fine too

if the pedal went down to the floor, then it sounds like there is pressure loss in the system somewhere, i.e. a leak or a hose expanding/balooning

could one of your rear cylinders be weaping behind the drum out of sight?

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

I'll tread carefully with this one as PDWAs confuse me slightly and there is a difference between PDWAs and bias valves. Mine stuck rather than "failed", if there is a pressure drop to one circuit (say rear in this case) then the PDWA can seal it off to maintain pressure in the front circuit. Mine being 30+ years old sealed it alright and the shuttle in the valve stuck even when the rear circuit was back to normal. No leaks, pedel feels fine just no rear brakes!

Edited by Jay#2 on 15th Jun, 2010.