problem with dual brake master cylinder

[tarynus]

Hi guys,
Just had a misadventure with a new dual brake master cylinder I got from ebay. I ordered this last year and only had a proper look at it now fitting it back on...
First it is about 1cm shorter than the original and the holes where the pipes fit in are not in the same position. So i though I'd just slightly bend the pipes and fit them in.
But the problem came next, I fitted one pipe nicely, but then the second one would not go in. So i try a bit harder and just end up messing up the thread on the brake pipe end.
It is only then I realise that the 2 holes on this master cylinder have 2 different threads!??

Apparently the one with the problem has a 3/8 UNF thread, which I believe is not the common size, right?

So I'm looking for the cheapest solution to solve this, I thought I could get flaring tool and re-do the end of my pipe fitting 3/8 unf nut on the end, would that work? or will the pipe be too thick? Or is there a better solution?

Thanks

[Carledo]

There is a unique dual circuit master for LHD cars. The English market one has 2 different size metric unions, one is the standard metric male (the one nearest the servo) and the front one is an oversize one the same as is fitted to the rear brake cylinders on some Peugeots. The LHD master has the front union at a different angle to the UK one and both are standard metric male.
I have a LHD one which I bought NOS at last years Stoneleigh show and fitted to the Carledo. Unfortunately it failed very quickly and though I resealed it and it seems OK, in the name of ultimate safety I bought one of Aluns stainless sleeved ones. So if you want my LHD one, I am prepared to sell it fairly cheap, or I can ship it to Alun for reconditioning and he can then send it on to you, though as you can imagine, this will add considerably to the cost. However it's probably the only way you'll get one since the LHD ones are even rarer than hens teeth!

Steve

[tarynus]

Hi carledo,
So the one i bought is rhd one then... Is it not possible just to adapt it by changing the union which is the most away from the servo? Now that i have messed up the thread i ll have to do something about the pipe anyway

[sprint95m]

Apparently the one with the problem has a 3/8 UNF thread, which I believe is not the common size, right?

3/8"UNF is a common size, certainly for British cars up to the late 1970s.
If you PM me your address I will send you a union.....




Ian.

[sprint95m]

On its way to you Thomas....






Ian.

[tarynus]

That was quick, thanks a lot Ian
Has anyone done this modification before (unlikely i guess) or is there any reason it could go wrong?
Also do you know what kind of tool is required, is it a double or bubble flaring tool, any you would recommend? I have never done that kind of job before...

[Edin Dundee]

I've tried to do metal brake pipes before with a Laser tool - not the cheapest but certainly not even a mid-range tool. Complete waste of time.
It might be easier and cheaper to replace the entire piece of pipe with copper, the cheap flaring tools will cope with that.

It might be even cheaper still to get a company or local garage to make a new piece of pipe - take the old one off and hand it in.

[Carledo]

I would guess if you bought it from british ebay, it will almost certainly be a RHD one - anyone with a LHD one over here would certainly advertise it as such! But like I said they are very rare, I bought the only one i've ever seen!
I am slighly confused by the presence of UNF unions though. The "normal" dual circuit master (GMC224 IIRC) has metric unions in 2 differing sizes, this is the one that is most easy to obtain. There is however an "early" dual circuit master which my partslist from 1975 gives as part number 519978 (though I think the number has been superceded) perhaps this is the one you have, I don't know if this early one has UNF pipe fittings, it's possible. No doubt someone will come on and tell us! What is NOT possible is to have a cylinder with mixed metric and imperial unions, there ain't no such animal!
As Edin says, the easy way is to get the pipe made up by your local garage in copper, every garage in England has the equipment to do this, (even me) I can't believe France is any different - just check the union Ian has sent you in the master cylinder before you go dashing of to get it made!

Steve

[tarynus]

This is odd, as on the union which is closest to the servo fits ok, so i guess its metric, but the one which is further away from the servo is smaller and i tried fitting a 3/8 bolt in and it seemed to go in... I'll post a picture of it maybe you can tell which MC it actually is.

[Carledo]

Thats what confused me, The LHD cylinder I have and the late RHD one both have all metric unions, however the late RHD one has the bigger union at the front, the LHD one has both unions the same size.
I look forward to the photos, perhaps that will resolve it!

Steve

[tarynus]

Here are the pics: the new one( at the front) has two different unions but unlike yours it is the front union which is smaller and which is no doubt 3/8 UNF. Got it on ebay from a seller called sukjac, if it rings a bell...

MC1.jpg (113.06 KiB) Viewed 2269 times

MC2.jpg (114.69 KiB) Viewed 2269 times

mc3.jpg (129.33 KiB) Viewed 2269 times

What do you think?

[Carledo]

The new one is most definitely the early series RHD Sprint one, the one I have the part number 519978 for. It is recognisable by the two screws holding the rear end of the reservoir on! I would recheck both the union holes with the UNF union that Ian is sending you, its more than likely that both are UNF in the cylinder. Its also quite likely that a bodge has been done on the car in the past to fit a non standard cylinder, seeing as they are rare as rocking horse poo in England, supplies in Europe are probably non-existant, so someone in the past has "got round it"
The old one, I don't recognise though it may be one from a Volvo 340 which is known to fit a Dolly.

Steve

Just looked at the pix more closely and the rear hole does seem slightly larger. I find it hard to believe that there are mixed threads on it, but the evidence is there! The rear hole is definitely not big enough for what would be the front union on a later cylinder, a normal metric or UNF union would fall straight into that with a couple of mm to spare!

[tarynus]

Thanks steve, I'll wait till I get Ian's union then and see what I can do from there

[Jon Tilson]

Some years ago I bought a NOS dual master off ebay which turned out to be an lhd one.
Its been in a box in the garage ever since.

I'll dig it out and see if its still useable.

Jonners

[tarynus]

I have messed up one of the union thread so i ll have to cut the pipe and refit one, i might aswell fit a union which fits the lhd one but thanks anyway jonners