The 'E' Type Forum

Advice please.

I've come to look at the diff and surprised at the amount of iron filing centred around the drain plug.

To those who are far more experienced in stripping these than me, what could you typically expect from a 60 year old differential.

The crown drive looks good although I've not checked wear pattern yet.

I've attached a photo of a magnet I used to pull it out. Probably 3 times this amount in total.

Advice would be most appreciated.


Many thanks


Al

Though your photo is unfortunately out of focus, it still appears to me that the amount of metal present on the magnet is alarmingly high. To me this suggests a full disassembly to determine which components, exactly, are the source of all this material. I would think it would be fairly apparent once everything is clean.

Time to send it to Alan Slawson? Details to be found on here. Especially if it’s a US 3.54 and you want someone to change it to 3.07

Geoff

Many thanks for the responce. I was aiming to do a full strip down. As you say steve, the amount of debris is so great the problem should be fairly obvious.

I've done input/output bearings on this style diff for my cobra. It will be interesting to split the actual diff this time.

Alun

Al, if you plan to do the work yourself then I’d still advise chatting to Alan Slawson. The bearings are difficult to find and having been doing this work over many years he is the best source for getting the bits. He does seem to be happy to help the self-builder.

Geoff

Geoff Wrote:

The bearings are difficult to find

Hello Geoff,
Alun's car is an S1, therefore, it will probably be a Type 1 diff, and therefore, using opposing, tapered roller bearing on the output shafts. All of the bearings for that model diff are readily available from any reasonable bearing supply.

Regards,
Bill

Thanks Bill. I know Alan has a good source of these which is why I forwarded my recommendation to chat with him. But if they are readily available then that’s good news. Thank you.

Geoff

Hello Geoff,
The Type 3 differential used a double row, angular contact ball bearing race, with split, two piece inner race. When assembled and held together by hand, there is a slight gap between the inner faces of the inner race halves. When pushed together via the securing nut, the two halves are pressed together until the inner faces are in interment contact, and at that point, the bearings are in correct pre-load.

Unfortunately, these bearings made by Hoffman, haven't been available for many years, and I would be surprised if Alan has any. The alternative offered by SNGB and others is a very poor replacement. It's a double row, angular contact bearing of the same ID/OD, with a solid, one piece inner race, and therefore, no scope for pre-load. They are 2mm narrower than the original, which requires a 2mm spacer ring for both the inner and outer bearing race. The spacer for inner race is located concentric by its bore being a close running fit on the axle, but SNGB supply a spacer for the outer race that has the same OD as the bearing, which is wrong.

There is no amount of available bore for this spacer to be located concentric with the bearing, and as the spigot bore outboard of the bore for the bearing, where the outer bearing spacer is located, is larger than the OD of the bearing and spacer, once the nose of the bearing retainer plate, come brake caliper bracket, starts to enter its spigot bore, sight and control of the spacer is lost, where it can then fall to the bottom of the spigot bore, unless the spacer is held concentric with the bearing with grease, or glued in place with bearing retainer. A more sensible solution would be to make the OD of the outer race spacer a slight running fit in the spigot bore. However, even with this spacer being located concentric with the bearing, there is still no pre-load of the bearing.

Later differentials, starting with Series 3, perhaps Series 2 XJ6 cars, and other models circa that time, the output shaft bearings system reverted back to that used with the Type 1 and 2 Salisbury differentials, that being opposing taper roller bearings. The angular contact bearing, with the built in pre-load would have been introduced for expedience sake in assembly; you simply torque the securing nut to press the halved of the inner race together with no further adjustment. The opposing taper bearings isn't an inferior system, in fact, it would be arguably better when sharing axial and radial load.

Given the poor alternative to the correct Hoffman bearing, if the output shaft bearings have to be replaced, it would be better to convert the differential to use the Taper Roller Bearings. The taper roller bearing and shaft assembly is entirely interchangeable with the angular contact bearing system without modification to the differential housing. New parts are not available, therefore, you have to find the parts from the later model differential. New parts not being available is not entirely correct, for I manufacture the bearing housing/brake caliper bracket as a new part, and supply the output shaft on an exchange basis. There is a "metal on" condition of the angular contact bearing output shaft, that allows for it to be re machined to the specifications of the taper roller output shaft.

Regards,

Bill