Clutch Hydraulic Line

I am trying to replace a failed clutch slave cylinder on my 1970 MGB. My problem is the connection between the flexible hose which comes from the slave cylinder and the steel tubing which leads to the master cylinder. This connection is at a bracket fixed to engine compartment. There is a small nut on the steel tubing side of the bracket and a larger nut on the hose side. The whole connection is fairly rusty/dirty and so I can't tell which of these nuts is supposed to turn. I think the nut on the steel tubing side may actually be fixed (won't move). Does anyone know which nut should turn? Also, the nut on the steel tubing side seems to be an odd size; I have a full complement of metric wrenches but none them fit exactly. Do I need a special wrench for clutch hydraulic lines?

Thanks very much for your time - I have been frustrated by this problem for a while now and would appreciate any help I can get. :)

Michael Lytton
Oregon, USA
1970 Pale Primrose MGB

Regarding the nut size on the steel tubing - I had to take an 11mm wrench and use a file to make it a little larger. I'm not sure what the nut size is (maybe some kind of "32nd"), but I marked my new tool for future use!

Soak the whole assembly with PB Blaster - several times, and overnight if you have time. I can't remember if the top nut slides or not, but I held it in place and turned the hose with a big wrench. It took a LOT of force. If you loosen the nut that holds the hose in place (part 22 in the Moss catalog), its easier to get the big wrench on the hose. I had enough play in my steel tubing that I was able to pull the nut on the steel tubing below the bracket, so both wrenches were on the bottom side, and easier to work with.

Many people cut the hose off so they can get a deep socket on the hose fitting, and then hold the steel tubing nut with a wrench. Whatever you do, you're going to want to change the hose out, anyway - they are prone to failure (especially after 30 years), and can be bad even when they look good.

Its a LOT easier with the engine out, I hear, but thats a LOT of trouble for a slave cylinder!

Let us know how it comes out.

John

Use standard wrenches. The car did not come with metric bolts from the factory. Undo the hose from the slave cylinder, then you can turn the whole hose when removing it from the steel line.

KimMG,

I was never able to find a standard wrench that fit the particular nut we're talking about. Do you know what size it is?

I have also found that some inch wrenches will not fit some MG fuel and hydraulic line fittings. I normally use a line wrench on pipe fittings and I noted the problem when my 7/16" Craftsman line wrench wouldn't fit some of the clutch and brake fittings. I did some checking with a dial caliper and found my 7/16" wrenches aren't all the same size. They are all Craftsman. They vary about .002" to .003". My long Craftsman professional 7/16" fits the clutch line fittings the others will not. I never have any trouble with any of these wrenches on 7/16" nuts or bolts in the MG or other places. The brake pressure failure switch used on 68 and later chrome bumper cars is another problem area with standard wrenches. The front fittings are a tight or impossible fit for the 7/16" the rear fittings are a sloppy fit for the 7/16". I don't have any Whitworth wrenches but that may be what is required for proper fit. It could be some 32nd. inch sizes but they are almost impossible to find in bigger than ignition wrench sizes. I have never found an inch size wrench to fit the rear brake bleeder screw, a small metric wrench as I recall 7mm is a better fit. BTW, my 11mm open end wrenches are about .002" bigger than the 7/16" wrenches, the long professional 7/16" wrench is the exception.

Maybe the cheap made in China wrenches will work better on the fittings, I don't have any to try.

I guess this is picky but most MGB's built for the USA market after 1967 do use a few metric bolts. Most smog pumps have a Lucas plate but in the fine print it reads, made by Hitachi. The pump is assembled with metric bolts and the UK mounting adapters on the pump use inch size bolts.

Clifton

I really appreciate all this info; you folks are very helpful! :)

I will not get to work on my B until this weekend, but I will post my progress.

~ Michael

I finally got time to work on the B, and successfully removed the flexible hose. The way I did it was I purchased a set of deep sockets and a small tight-fitting adjustable wrench. I cut the flexible hose as close as I could to the fitting. I put the adjustable wrench on the 7/16 nut on the steel line side of the connection, and a 13/16 deep socket on the flexible hose side. This worked fine, so now I'm finally putting the new hose and slave cylinder on.

Thanks for everyone's help!

~ Michael

Make sure the bleed nipple is in the right hole. For shipping purposes the bleed nipple will usually be in the wrong hole on a new slave cylinder.