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MG Midget and Sprite Technical - Clutch plumbing - some Datsun content

I'm just replacing my tandem master cylinder (hereafter referred to as 'mc') and I'd like to improve on the current clutch plumbing from the Rivergate kit (I have a Datsun 'box).

The standard arrangement is a flexible hose all the way from the mc to the slave. The flexible hose fits to the mc with an adapter and seals using an aluminium washer between the adapter and the mc housing. Yhis is, of course, less than ideal and the mc housing was never designed to create a seal here.

The flexible hose is also a pain to route. I'm therefore thinking of doing it all with a rigid pipe with the correct flare fitting at the mc end and a loop to absorb engine movement (i.e. as original) or rigid most of the way then a short run of flex to slave.

I'd appreciate your thoughts on the above but I also have some specific questions. Can anyone let me know of the size of the fittings required for:

i) The tandem master cylinder
ii) The Rivergate billet slave cylinder.

Many thanks in advance.
Jeremy Cogman

I have no experience on dual cyl or rivergate slave cyl. With the std slave cylinder, the flex hose helped for bleeding off the car, as the slave is moved to the opposite side of the bell housing, with the bleeding point at bottom, not top. If rivergate supplies the kit and washer then it's got to be a sound idea?
Btw if re-using a washer, be sure to aneal it
d cusworth

Jeremy. I have installed a copper pipe set up as you are considering. I installed it a few years ago and its still performing O.K.
The Sprite MC is 3/8 UNF. I cant assist re the Rivergate slave as, from memory, I fitted a Std Sprite one.
Alan Anstead

A hard line from the mc to the slave is a good idea as the hard lines never bulge under pressure.
I have a Datsun box with the Morris Service kit, but it can't be that different than R'gate. My first issue with my flexible hose was to keep it as far away from the exhaust as possible. I have this image of boiling hydraulic fluid. It would be easier to route away from heat with a hard line.
I don't know what slave you have, but for sure its a commonly available threaded inlet size.
Phil Burke

Although I still have the flexible hose to the slave, it's not ideal as I once had a part of my previous hose occasionally (as it turned out)rubbing against the chasis. Over a number of years it rubbed through the outer braiding, causing it to prick a small hole in the rubber hose underneath.
The result was hydraulic fluid sparying over a hot manifold (the slave is under that side of the car) causing smke, smells and a loss of clutch. I now have it routed slightly differently and well insulated from anutying which migh rub.
frogeye Gary

Thanks for your input folks, Gary, I hope you can have my old hose if I can get this figured out.

Alan is, of course, right on the mc being 3/8 this being a standard SAE 45 degree flare. The billet slave has a 1/8 tapered pipe thread in it's body into which there is an adapter threaded. This adapter (to which the flexi hose attaches) is JIC -4. This is a 7/16 thread but with a 37 degree flare. Using standard 45 degree flare fittings on this is, of course, a no no.

So I either need to find:

- A JIC -4 to SAE adapter (any size in the latter really 3/8 or 7/16 ideally), perhaps even a short flexi hose.

- Something with a 45 degree flare (male or female) that will screw in to the pipe thread in the slave cylinder.

- Worse case scenario, a generic clutch slave with the correct cross section / throw that will offer me an SAE fitting.

Does anyone know what we call the 45 degree SAE fittings (SAE really being an American term) in the UK.

Jeremy Cogman


I am sure that on one of the three Datsun conversions that I did for other people I fitted a stock 1275 slave.

Unfortunately circumstances do not permit me to look at the car nor speak with its owner.

Could you have an adaptor made, to the specs you want, if you cannot find one suitable.

I have a small firm nearby at Bexley, Kent called Engineering Solutions. They have done some work for me in the past.

Google Engineering Solutions Bexley for their site.

Alan Anstead

Thanks Alan, details duly noted for future use (I had the devils own job finding someone local to do a modification on the gear linkage of my Alfa 33).

I have however found the adapter I need, pricey postage from the States but the seller was very helpful and I've not found similar anywhere else.

This will screw into the Rivergate billet slave (checked with Will) and take a standard 45 degree flare.

Now all I need to do is practice my flaring as I've never done it before.

Thanks as ever for your input folks.

Jeremy Cogman

This thread was discussed between 12/08/2012 and 16/08/2012

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