7 replies to this topic

[29guitarman]

hi, just noticed my limiter valve is leaking,
I'm wondering if it is possible to service it and put new seals on it, or if i even need one, just that the one i have seen on minispares is £87! a lot more than i can afford!
I am running drums all round and would like to convert to disks on front at some time and would it make a difference to just do all that?

[Cooperman]

You must have a brake limiter valve. If you don't the rear wheels will lock under braking and you'll spin the car.
It's probably not worth trying to recondition it and as it's a safety-critical component it's best to replace it with a new one just to be absolutely safe.

[tiger99]

Yes, overhauling hydraulic components is only for those with sufficient experience to be sure of doing it correctly. Knowing when a part is scrap, and when it only needs new seals, is a large part of it. I am never happy with inexperienced people overhauling master or wheel cylinders, as it is really vital to spot any scoring, wear or corrosion in the bore and scrap it, rather than shoving in a set of new seals. How do you know how much wear is acceptable?

Garages NEVER overhaul hydraulic components nowadays, as they were often getting it wrong, and nowadays there is legal liability, probably not covered by their insurance. That is why repair kits are now so hard to find, indeed impossible for many vehicles.

In this case an even bigger problem is getting the new seals.

As Cooperman says, it is a safety critical part. If you can't afford to replace safety critical parts when necessary, you should not be running a car.

[bmcecosse]

Is this the ghastly PRV (Pressure Regulating Valve) taper nose valve - on the bulkhead just under the master cylinder? Or the 'real' Pressure Limiting Valve on the rear subby? I threw away my PRV - and fitted instead a subby type valve - except I fitted it up front where I could easily get at it to adjust the spring pressure till i got it 'just right'... Trouble is finding a subby valve these days - but I found it very much better.

[Cooperman]

That's right. But if doing that mod and fitting the early limiter do please remember that the PRV has METRIC threads whereas the old-type vale is 3/8" UNF threads, so you have to change the front to rear brake pipe.

[klivins]

had to sort mine out to pass MOT in time, while new one arrives to post office, so opened up a non servicable item. The problems were rear brakes too weak. The o ring had become hard as redwood. Changed that and now my temporary fix is lasting for second month. Still, want to change this valve to old style regulating valve. Where to get one?

[29guitarman]

cheers guys, yeah its the bulk head one, is it worth it to change to the one on the subby? since i posted this, the car has been sat for a day, and the breaks, well, are none existant haha!
where can i get one of these valves? i cant see any on minisport, but there is one on minispares, £70 mind, any cheaper ones? i will fork out if nessesary

[bmcecosse]

The old valve is much better in my view - some brave folks modify it to make it adjustable which would be handy. And yes -it has the unf threads, not the metric threads. I used to pick them up nos at autojumbles - but not seen any for a good few years now. Crazy system that mixes safety critical threads on brakes in a car. Mind you - nothing new for BMC, the Morris Minor has some unf and some bsf threads throughout which causes much grief to inexperienced owners......