Leaky axle

[Sam Monoogian]

Since I removed the Ford axle from my car it's emptied half of its oil onto the garage floor. Its leaking from the joint between the diff housing and the main axle body. A sealant has been used rather than a gasket - Is this normal? What should I replace it with and where can I get it?

[John E]

I would prefer to use a gasket with a small amount of sealant. A gasket should be available from your local Ford dealer or you could try one of the Se7en specialists such as James Whiting or the Se7en Workshop The oil is either 80 or 90EP and its available from Halfords.

 

[R2D2]

I have an early Lotus Cortina with an alloy diff casing which always used to leak oil from this joint and a couple of years ago a pal of mine gave me an old Ford service bulletin which recommended throwing away the gasket and using a silicone sealer. It has never leaked oil since and I have adopted the practice ever since.

[deanteam]

Sam, we have Ford axles and one is not reinforced, this one has a tendancy to work its 'nuts' loose so that it leaks. I check regularly the nuts even though they are nylock. We have used seal plus silicone but have heard the same advise as Chris.

 

Chris, you mention the alloy diff casing. I have been considering one for the seven however, I have heard that these are not always stiff enough. This might only apply to the 'new' casings which can be supplied from people like Burton and T.Tompson, have you any comments? Would you think that the weight reduction would be worth it? Any comments please.

 

[R2D2]

I think that the new castings made by Flowtech and Tony Thompson are manufactured from LM25 and are heat treated to a much higher strength than the early units that Lotus supplied in the Cortinas.

 

The higher strength will not affect the stiffness as the Young's Modulus of the alloy will be almost identical but the bolts can be fastened to a slightly higher torque.

 

The main problem with the early Lotus Cortina diff was, I believe due to the A frame causing twisting of the axle casing, the use of a paper gasket, the differential expansion of the alloy casing and the size of bolts holding the diff casing into the axle.

 

The Mk1 Cortina axle had relatively small bolts on the diff/axle flange and the same Ford Service Bulletin that recommended removal of the gasket also gave a procedure for replacing the studs that locate the diff with a larger diameter. (In fact they recommended the same size as the Mk 1 Mexico uses as standard.)

 

I carried out both mods and didn't experience any further problems.

 

I know quite a few people using the new alloy diffs in Elan racers without problems and they certainly seem capable of surviving 160-170bhp twin cams without too much problem.

 

We should be aware that the Elan obviously doesn't use an A frame and the main diff case is an alloy casting.

 

On the Lotus Cortina I used to rally we had also replaced the A frame and used leaf springs and a panhard rod for reasons of ground clearance and wheel movement but I imagine that this mod. also gave the diff/axle case joint an easier time.

 

The weight saving must me about 4kg and it is all unsprung so it should be a benefit.

 

I realise that a new alloy diff is expensive but I think I would risk one if it were my car.

 

Hope this helps.