V 4 rear brake cylinder bleed nipple size and thread?

[wonky door]

Hi all, does anyone know what size the bleed nipples and what thread they are likely to be please? I know this may not be a precise science. Thread more important than size I think.

[BIRDIEMANGO]

NO I DON'T BUT THEY ARE THE SAME CYLINDERS AS A MINI,FROM MEMORY THE LOCATING PIN IS OFFSET,FROM LEFT TO RIGHT.

[melle]

The rear bleed nipples are 1/8" UNF (I just bought two sets of these), the front bleed nipples and all hose connections are 3/8" UNF. Mini (or other British Leyland cars for that matter) rear cylinders are indeed usable; Birdie is right, for some you need to drill a new hole for the pin. Beware, they all look more or less the same on the outside, but they come with different piston sizes (95 uses a larger diameter than 96 as well). I once bought a set and got two different ones. Cost me eight trips to the MOT station and a full brake system overhaul before I figured the new pistons caused the imbalance between the left and right rear brakes...

[wonky door]

Thanks chaps . At the moment we are some way short of the mot but I’ll have to remember to check the cylinders if there is an imbalance. In the meantime it’s mini bleed nipples and master cylinder seals.

[greg124]

95 uses a larger diameter than 96 as well...

I thought I'd better check this out, Melle, as I've bought a set of replacement rear cylinders for my 95 that are described as being for '95/96'
So I've measured the bore of the old cylinders that came off the 95 and 96, and both are 11/16" and share the part number 99023C. It's likely that one or both are not original after 40-odd years.
Do you know the specified difference in bore size?

[melle]

Just checked the parts book (chapter 5, section 5:3), they're apparently only different up to chassis number 95.074.986. 99023C is not a Saab part number, perhaps Lockheed? Also not sure if it's the number for the casting, or the whole assembly. The ones I had looked identical from the outside, only the bores/ pistons were different and you had to take them apart to notice it. Not sure of the diameters, it's been at least a decade since I measured them, but from what I remember the ones on my old 95 were 3/4". Not sure if I ever measured the ones on my 96.

[BIRDIEMANGO]

I ALWAYS THOUGHT THAT 95 ESTATE WHEEL CYLINDERS WERE A BIGGER BORE? THE REAR AXLE WAS CERTAINLY DEEMED A SPEC' UP FOR A 96 RALLY CAR.

MAYBE IT WAS JUST THE REAR MINI WHEEL CYLINDERS THAT WERE AVAILABLE DIFFERENT BORES?

TOO LONG AGO,TOO MANY CARS WORKED ON,SINCE THEN.

[Fliptop]

Jools is correct, up to 1970 anyway. Early 95s were a 3/4" bore, 96s and post 1970 95s were 5/8".

I doubt there are many 95s around (if any) that still have 3/4" wheel cylinders, but you never know.

I've used Mini Cooper cylinders many times when they were easier to source, and just drilled the backing plate for the locking pin which is in the mirror position of the Saab item. But I think you can get the correct type pretty easily nowadays - I've seen them advertised often enough.

[melle]

Good to see my memory served me well regarding the 95 wheel cylinder bore. Wonder why they changed the diameter at some point? Was this when the Lockheed brake master cylinder was replaced with ATE?

Beware of cheap Mini wheel cylinders, on some the seals will give in within a year. Good ones are cheap enough anyway.

[wonky door]

Good to see my memory served me well regarding the 95 wheel cylinder bore. Wonder why they changed the diameter at some point? Was this when the Lockheed brake master cylinder was replaced with ATE?

Beware of cheap Mini wheel cylinders, on some the seals will give in within a year. Good ones are cheap enough anyway.

Cylinders appear to be ok,the bleed nipples are poor though. We hope .

[Fliptop]

Good to see my memory served me well regarding the 95 wheel cylinder bore. Wonder why they changed the diameter at some point? Was this when the Lockheed brake master cylinder was replaced with ATE?

Beware of cheap Mini wheel cylinders, on some the seals will give in within a year. Good ones are cheap enough anyway.

I thought that but looking at the workshop manual tonight, the wheel cylinders changed for MY70 and the ATE master came in for MY71 so its not the same. I suspect it was just cheaper to use a common cylinder than to have two on the factory floor...two that look identical to the techs building the cars.

Yeah, cheap ones to be avoided, but you can get AP and Lockheed for the Mini cheap enough. There is also an 11/16" one for the Mini, so halfway between the two...just to make any buying decisions even more complicated

[BIRDIEMANGO]

THOUGHT SO REMEMBER NOW,THAT FITTING THE 95 REAR WHEEL CYLINDERS,ALLOWED YOU TO DO STUFF LIKE THIS IN THE 96,ON TARMAC? KEEP THE SPECTATORS HAPPY....
THIS WAS AROUND 1995,AT ANGELESEY, TY-CROES,LONG BEFORE IT WAS MADE INTO A CIRCUIT.

[melle]

My 95 was MY74 and it had 3/4" rear wheel cylinders, probably not original from what I read in the parts book and in this thread.

[greg124]

Thanks Melle, Jools & Al. That's put my mind at rest and will go ahead and fit the new cylinders, which also have the anti-rotation pin on the correct side

[1st4saabs]

Are you sure the rear bleed nipples are 1/8” UNF?
I thought they were 1/4” UNF like mini ones?