Removing Diff & replacing seals...how easy?

[Steve Campbell]

Hi all

I have some weeping from the diff RH seal (car is a 2008 Duratec, not sure of specific Diff). How easy is it to remove the diff (I did it once about 12 or 13 years ago on a 1.6ss but seem to remember I followed a step by step guide from somewhere !). My mechanical skills are average but I’m always willing to give stuff a go….I also now have an 18 year old to assist or feed me the / tea & biscuits :-).

What about replacing the seals once the diff is out (probably do all 3 once it’s out). Anything special needed ?

If anyone can point me to an idiots guide (I can’t find what I used last time) it would be much appreciated.

Thanks
Steve

[upsidedownmark]

Diff removal is technically simple, but an absolute pig of a job. Seals, I don't know..

[BertBert]

upsidedownmark said:

Diff removal is technically simple, but an absolute pig of a job. Seals, I don't know..

And getting it back in is even worse!

[Steve Campbell]

Well, got it up on the stantions to take a look and the brake lines are solid through to the calliper (not braided) and I also have an anti roll bar which looks like it complicates things.

Advice welcome …. I’m diving in tomorrow night 😁

[BertBert]

I don't think it's at all complicated. Just a lot to take off and the diff is a big heavy thing to get out and in.

[agatebox]

Never done it but what appears the “interesting” part is refitting the diff, trying to align the bolts but ensuring that you have the correct spacer washer/shims combination on each side (that are used to position the diff correctly in the chassis), make sure to make a note of these when dropping the diff.
Removing the boot floor helps access and gives an additional option of supporting/steadying the diff rather than just trying to balance/align it on a jack.
Hope it goes well :-)

[lowndes]

I’ve built a couple of Duratec cars recently, 360 and 420R. (2020 and 2021 vintage). Your car may be different. That said, the attached diagrams from the build manual may help with the overall picture.

As others have said, fitting the diff can be pretty brutal. I imagine you will have to dismantle most of the rear suspension to get at it. Like the diff, the A frame also needs centring with shims and washers which is a fiddly frustrating business. Once I had the correct spacings I held the washers together with cellotape to hold them in place.

You may need to grind a point onto the long top diff bolt to get it through. I used transmission jack to hold the diff, others have supported it on straps on an engine crane by first removing the boot floor.

Goodluck

[AndrewGP]

I did this recently on my 2012 Duratec car after my LSD shat itself and needed replacing. Some good advice above, it can take a long time to do and it’s quite fiddly getting the diff in and out. To help, I borrowed a plywood jig a mate had made up.

I don’t have the measurements to hand but hopefully the picture helps if you want to do something similar. It made the job so much easier, as the diff was supported on the trolley jack much better which made alignment of the bolts quick and painless, especially as the diff itself is bloody heavy!

[DCL]

I suspect the car in question uses the Ford Sierra diff. That is significantly different, but plenty of Caterham manuals online for the date in question. Although the driveshaft seals are easy to change, and the pinion is possible too, personally I would remove the diff and do a full overhaul, or send it to someone like Road and Race transmissions. The reason being is that leaky seals usually indicate worn bearings, or badly set preload, and best to fix it for the longer term.

Edited by DCL on Friday 19th August 13:42

[Steve Campbell]

Thanks folks. Have decided not to remove diff as it’s only the drive shaft seals that are weeping (and only RH side very minor but will replace both sides. It was in with PT Sportscars recently and they didn’t indicate any underlying problems…..probably should have paid them to sort rather than think I’d give it a go :-)). It is 14 years old but has been flawless in this arena since I bought it 12 years ago.

We have the drive shaft out, but how the hell do you get the seal out ? Do you need a special tool ? It seems pretty firmly ‘in’ and we’ve tried with no luck to shift it…..tips appreciated !

Edited by Steve Campbell on Friday 19th August 18:27

[Steve Campbell]

Well, I borrowed a seal puller and the first one came out no problem. The 2nd however, is stuck fast. The puller is actually pulling through the metal rim ! Now stuck and not sure what to do. Might have to take the diff out and take it to a garage

[DCL]

If you mark the castellations (Sierra diff) so it can be returned to the same place, you can remove the bearing race. That will make it easier to remove the seal. But a special tool is best use, either purchased (ebay) or fabricated. They can be very tight, and they have their own 'o' ring seal that needs care not to be damaged.