35 replies to this topic

[mattyb]

Re shelled mini 25

Having a real problem bleeding brakes - new master cylinder - mini 25s should have front/rear split but cannot get firm pedal despite pressure and two man bleeding /non return bleed pipe- HOWEVER IF I CLAMP BOTH FRONT FLEXIBLE HOSES THE PEDAL FEELS ROCK SOLID !!

the "T" piece on the rear sub frame looks like the attached pic - is this correct ?? cars does has the front mounted pressure differantial warning actuator


(ive sorted other bits on the car which have been wrong (ie pre verto slave cylinder on verto clutch car !!) so wondering if this is another "mix n match" wrong fitting !)

any ideas anyone ??

cheers

Matt

Attached Files

•  rear_reg_valve.jpg   1.22MB   53 downloads

[Big_Adam]

Errm, you have ADJUSTED the front drums right? As you'll get plenty of squish if not.

[mattyb]

Errm, you have ADJUSTED the front drums right? As you'll get plenty of squish if not.

its discs on the front and appear to be new - though I will check the rears - has any one got any ideas on if there should be a combination of brand yellow tag master cylinder, a PDWA (which i think is the later type (FAM7821) which has a brake pressure regulator and what appears to be a brake regulator fitted to the rear sub frame

[Kam]

Thats a regulator valve sitting on the rear subframe, minispares CLICKY

Front/rear split as you say should have this sitting there instead, minispares CLICKY

Have you got this sitting on the bulkhead just to confuse things, minispares CLICKY

I think you already said you have the above so a pick n mix is looking likely.....

[mattyb]

Thats a regulator valve sitting on the rear subframe, minispares CLICKY

Front/rear split as you say should have this sitting there instead, minispares CLICKY

Have you got this sitting on the bulkhead just to confuse things, minispares CLICKY

I think you already said you have the above so a pick n mix is looking likely.....

many thanks Kam - I'll try adjusting the rear drums and see if that improves the brake pedal feel, but suspect that something will have to be replaced - would you go for removing the pressure regulator mounted on the rear sub frame and replace it with the "t"piece 3h2424 ? I do have the fram 7821 mounted on the bulkhead - (the 3h2424 is the cheapest option !!

cheers Kam

Attached Files

•  frnt_pdwa.jpg   1.17MB   115 downloads

[Kam]

If you remove it and replace with the T piece then at least you got a normal setup. Front/rear split as you know would have that limiter valve on the front bulkhead followed by a T piece on the rear subframe, but if someone has decided along the way to fit a brake regulator valve on the rear (whether they knew what they were doing or not) I'm not sure how that works alongside the limiter valve up front? Maybe they thought it was a brake bias valve or something they were fitting?

It may be the cheapest option but still a ball ache to change as the pipe length may be longer now once the T piece is in, that rear pipe comming from the front will be awkward

Other than that you gotta go back to basics, adjusting drums (as above) on the rear, checking wheel cylinders, and making sure fluid is comming out at all corners when your bleeding

[mattyb]

If you remove it and replace with the T piece then at least you got a normal setup. Front/rear split as you know would have that limiter valve on the front bulkhead followed by a T piece on the rear subframe, but if someone has decided along the way to fit a brake regulator valve on the rear (whether they knew what they were doing or not) I'm not sure how that works alongside the limiter valve up front? Maybe they thought it was a brake bias valve or something they were fitting?

It may be the cheapest option but still a ball ache to change as the pipe length may be longer now once the T piece is in, that rear pipe comming from the front will be awkward

Other than that you gotta go back to basics, adjusting drums (as above) on the rear, checking wheel cylinders, and making sure fluid is comming out at all corners when your bleeding

checked and adjusted the rears (off side lever was stiff and not releasing, so at least the hand brake now works perfectly !) - made no difference to pedal feel - bought the "t" piece from Moss in Bristol today and reckon it shouldn't be too difficult to fit, so will try that

fingers crossed this sorts it because I'm not keen on paying for a new PDWA !

[bmcecosse]

The pressure limiting valve on the rear subby is EXCELLENT - keep it! But get rid of the ghastly pressure regulating valve at the front. Are the calipers on the front discs on the correct sides - with the bleed nipples uppermost ? If not you will never get them bled........

[Artstu]

The bulkhead mounted device is not a pressure regulator, it is a valve that should only come into play if you have a leak, the valve is then supposed to close off the leaking circuit and leave you with braking on the other circuit.

The pressure difference is taken care of by the size differences in the master cylinder, so in theory you don't need the valve on the back that someone must have added at a later date.

My bulkhead valve was stuck to one side, causing almost no braking to the rear brakes, I binned it and the brakes are the best I've had, no pressure reducer on the rear either. But I don't have the supposed benefit of the bulkhead safety valve now, not that it seemed to do much when I did have a leak.

[Carlzilla]

If youve clamped both front flexi hoses to the calipers, and its fine. then it sounds like youve got air in the calipers at the front. make sure if youve had them off that the bleed nipples go at the top. Ive made that mistake before

[mattyb]

If youve clamped both front flexi hoses to the calipers, and its fine. then it sounds like youve got air in the calipers at the front. make sure if youve had them off that the bleed nipples go at the top. Ive made that mistake before

I reckon the calipers are on up side down ! pic of the off side (drivers side) think the nipples pointing down !

Attached Files

•  front_brake.jpg   1.1MB   36 downloads

[ado15]

Indeed they are! Assuming they are both pointing down, you need to swap them side to side and you should be able to bleed out the air.

You shouldn't need the regulator on the rear frame. This was only used on the single line brake systems prior to 1977. A plain tee would have been standard on your car.

Edited by ado15, 01 November 2010 - 03:25 PM.

[Big_Adam]

Seconding the upside down callipers.

[mattyb]

Seconding the upside down callipers.

Hopefully this is where the problem is ! as I mentioned above, I bought my mini as partially rebuilt project - the chap I bought from mentioned the the previous owner to him couldn't get it running and had wrongly fitted the distributer !!, and the slave cyclinder was a pre verto one, so I should have guessed that there would be other random bits !
At least i've now fully checked the braking system - I've fitted the t peice on the rear and allthough the brake bias valves are rubbish i'll leave it on, swop the calipers and see how things go !

many thanks to all !!!

Matt

Attached Files

•  100_0733.jpg   1.27MB   25 downloads

[Artstu]

I see your problem now! you've not got a master cylinder