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MG Midget and Sprite Technical - AN hardware

I need some help with hooking up a slave cylinder for the clutch using AN fittings. I know AN are 37-degree fittings and that a standard automotive flaring tool cannot be used to make the flare.

1. I am hooking up to a CNC brand slave cylinder that is already installed on a Datsun trans. Engine is installed. Cannot remove the fitting in the slave cylinder without moving or possibly removing the engine. I want to avoid that.

2. Installed in the slave cylinder is what I think to be an -4AN male fitting. A braided hose came with the cylinder which will hook up easily but I want the engine bay to look more original from the top side. I want to install a 3/16" hard line from the master cylinder.

3. I purchased a -3AN 90-degree swivel elbow to fit the hydraulic line, but it does not fit on the existing slave cylinder fitting.

Any ideas on the best way to solve this problem?

I have found a -3AN to -4AN reducer. It is anodized aluminum. The fitting in the slave cylinder is brass, the -3AN swivel fitting is zinc plated steel, as are the fittings on the hard line. Is it a problem to use a brass/aluminum/steel assembly?

As always; thanks for the info.


Paul Noeth

Im not sure i graasp what your asking...

But on the question of combining metals..some will advise agiant it... but i have connected the old steel brake tubing with the stainless steel AN fittings with no issue.... i also this past weekend combined stainless AN fittings with some aircraft aluminum fittings for the oil pressure line

No problems so far....

Go for it and see what happens... worst case if you survive the firey crash you will have a great story to tell


So your wanting to hook up a steel brake tubing hard line off of 2) AN fittings ?


Id give a AN supplier a ring for a chat ....but yes its do able... expensive if there in no actual fitting to do that.

If there is no fitting avialable.... then you would need a length of the stainless braid hose (6 inches ?) that can attach to the AN fitting on the slave then another AN fitting on the end of that whixh would have a high pressure compression fitting that would hook into the hard brake tubing that will go to the master.... remember the master fitting is a wierd, size so dont throw it away... you will need to use it with the hard. line

This is how i went from my master with a AN fitting and stainless braid to to the cars hard brake line....

I can post some pics tomarrow if you want




I am asking what is the best way to hook up a 3AN fitting to a larger, what I assume to be a 4AN fitting. I found the aluminum reducer and that seems to be a good solution, but maybe not. Ater the fact I always hear you shouldn't have done this or that. Thought I would ask before hand.

Correction on the fitting coming from the slave cylinder, it is steel. It looked like brass but after checking again it must be yellow chromated zinc. That makes the assembly, steel/aluminum/steel. I didn't know if that was advisable. Not worried about a firey crash, but worried about doing something stupid. Ya never know what you don't know.

Paul Noeth


If I can reduce to an 3AN fitting then I am golden. If aluminum/steel is no problem then I am good with the reducer I found.

But how do you determine what size the fitting actually is? The specs I've found say the 3AN is for 3/16" line but I don't know the size or thread of the nut. The 3AN is a little small for the fitting coming out of the slave cylinder, so I am assuming it is a 4AN sized for 1/4" line.

I don't know of a local supplier of AN hardware so it is a little expensive to just order stuff to see if it fits.

Paul Noeth

I would not worry about mixing materials. So long as the flare/seats/threads match. However, I would not run a hard line to the slave with out some coils to absorb the vibrations.
Trevor Jessie

You want to be able to join AN fittings to a conventional hardline? If so you put a nut coupling on the line, then a sleeve coupling, then you flare the line. The flare retains the sleeve coupling, the AN fitting seats on the sleeve coupling and the nut coupling screws onto the AN male/male adaptor (or male/whatever adaptor).

The male/male adaptor can be -3/-4

One day there might be a book with this stuff (there have been MG magazines with this stuff in) in but for now here's a photo of what I said above.

Daniel Thirteen-Twelve

OE Clutch pipe is not 3/16", try 1/4".
As for not using the braided line in the quest for "originality" after changing the Gbx, seems brain dead and asking for trouble to me. There is probably some good reason why everybody including the factory decided that vibration isolation is worth the trouble and expense of hoses and fittings and brackets.

FR Millmore

If you want to save some money and weight is not an issue then you might try using JIC fittings rather than AN. They are the same design and flare but JIC fittings are usually steel or brass and will do just fine in place of the stainless steel or aluminum AN fittings.
Paul, if you can't find the fittings David shows then you can always go from a standard tube flare to a pipe thread and then from the pipe thread to AN or JIC. That's basically what I had to do when installing my residual pressure valves.

B Young

Paul, why can't you remove the slave to work on it without moving/removing the engine? If it is because you can't get to the socket headed bolts, you can make a tool that will work. Just get the proper size Allen wrench/hex key and cut off the end of the short arm just a little longer than the amount you need to get fully into the head of the bolt. That will allow you room to maneuver the wrench around the frame.
Jack Orkin

Who is David? Is he the same person as Dennis and Dan and Danny?

try for AN fittings

Daniel Thirteen-Twelve

Thanks everyone for all of the input.

Trevor, I do have a coil (1) in the vertical part of the line. It is barely visible in the photo, but you have to know what you are looking for to see it. I used one coil because that was how many were in the original line, but you bring up a good point. The original ran to the right side of the gear box and was longer than the new one, giving it more flexibility, no doubt.

Jack, the problem is with the cap screw you cannot see. If I used a shorten hex key I may be able to engage the socket but I could not turn the key more than a few degrees. If I could turn it 60 degrees and move key to the next flat I doubt that there is enough clearance for the bolt to come out of the hole. Anyway the cap screws were properly torqued when they went in and I would rather not mess with it if possible.

I could not find the fittng I need at Aircraft Spruce, but they did list the thread size and the fitting from the slave is -4 AN. I found the reducer I need at Jeggs. Apparently the steel/aluminum/steel connection will not be a big deal so I am going with the reducer off the slave fitting and turning the corner with the -3 AN swivel. At that point the line will come straight down and connect with a -3 AN sleeve and nut. That will be pretty clean.

FR, my '66 has a 3/16" clutch pipe from the factory, same size as the brake line.

Brain dead? What's brain dead is pretending that one of these cars can be brought up to modern day standards. That's brain dead. What I am doing is making the car as best it can be without destroying its character. I would call that a lofty endeavor. Others would call it a hobby (or maybe insanity). I have no aspirations to built a concours show car any more than I aspire to built a modern-day automobile. But I will, and have, gone to lengths to make this car look, as much as possible, like it just left the factory; while at the same time improving its driveability and reliability. Hence the five-speed, radial tires, etc.

If you want to laugh, here is how brain dead I can be. The starter solenoid is a predominate feature under the hood. I've installed a planetary gear starter (I don't pretend to maintain originality) which has it's own internal solenoid. Rather than leave the solenoid mounting bracket empty in the center of the engine bay I mounted the old-style solenoid where it can be seen and added a copper buss bar across the terminals. Hooked up, everything looks fairly original but the old-style solenoid is just decoration, it does not operate. Along the same lines, I am cutting off the lower part of the Datsun shift lever and welding it to the upper part of the MG lever, leaving on the shift knob with the 4-speed pattern. What shows in the cockpit will look like original MG. How's that for brain dead? To each his own.


Paul Noeth

Well ... as i hate to do anyrhing the simple easy way...but there is this idea instead of pulling the engine why to just loosen it and jack it up in place to get to the slave for its removal... maybe 3 to 5 inches is alll that needed. It wont be easy, but doable and easy faster then engine removal

I'll get my coat
S G Macfarlane

On my car while I've replaced rubber flex line with s/s braided hose I've also kept the rigid lines. I'd guess a s/s braided line weighs in more than a rigid line and is likely to cost more. But, to my eyes very long s/s braided lines look untidy and shout 'DOESN'T KNOW HOW TO FIT HOSE TO RIGID'.

A while back I converted the clutch line to the smaller bore pipe not finding a single good argument to stay with the thicker pipe and I think the debate can be found in the archives.

Daniel Thirteen-Twelve

This thread was discussed on 04/05/2011

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