Differential removal, Ah! lots of shims!!

[CTrickle]

Morning all,

We (My dad and I) have removed our engine, gearbox and diff as we are replacing the noisy straight cut gearbox for a standard one and an LSD in place of the stupid fun crushing standard one.

The engine and gear box are easy as pie to remove, the diff is harder in my opinion but it is possible to remove it without removing the DeDion tube. Anyway, onto my question, as I removed the diff rather allot of shims fell from the four possible locations! I assume there are shims to stop the diff from 'jiggling' about or is there a bigger reason, e.g does it have to be completely straight? It can only be around 5ish mm slack.

Thanks for any help.

Ed.

[Shaun_E]

The shims allow you to adjust the position of the diff to get it perfectly central in the car. This is from the assembly manual:

10 The lower mounting is attached to the
chassis using bolts (2) through the metallistic
bushes with washer (4) between the bolt head
and the bush. Washers (16) are then placed
between the bushes and the differential to obtain
correct position of the differential. The
differential has to be located centrally in the
chassis. Fig 4 refers.
x x
3 1 2
1 Lower mounting bolts
2 Upper mounting bolt
3 Nyloc
Fig 4 Position of the differential in the chassis
NOTES
(1) Some tubes not shown for clarity.
(2) Washers not shown for clarity.
(3) Measurements 'X' must be identical
± 2mm.
11 The position of the differential should be
measured from the machined surface of the 2
unused lower mounting bosses, on the side of
the differential casing, to the inner edge of the
outer chassis tubes. This measurement 'X'
should be identical ± 2mm.
12 Use further washers (16) between the
metallistic bushes and the differential. Care
must be taken not to force too many washers
between the chassis and the differential since
the small amount of movement allowed by the
rubber bushes will be eliminated thus causing
excessive noise and vibration to be transmitted
into the car. All free play must be taken up and
washers (12) are supplied to aid this.
13 Remove the upper mounting bolt (1) and
refit with washer (9) under the bolt head.
Centalise the differential using washers (16) and
(12), as required, between the metallastic
bushes and the differential. Use a further
washer (9) and nyloc nut (6) on the end of the
bolt. Tighten the upper mounting bolt and lower
mounting bolts to 40 lbft (55 Nm). Check that
the differential is central ± 2mm. Adjust if
necessary.

[Aeroscreens]

Pretty sure when I upgraded to a LSD I managed to get the diff in and out without removing the DD. Although it did result in a few scraped knuckles. BTW that's with a '93 chassis and diff

[CTrickle]

Ahh yes, I have the knuckles of a clumsy man in a razor manufacturing factory!!

Thank you very munch for that information. It will be put to good use.

I can't wait to try the car with the new diff.

[downsman]

It seems strange that a previous owner chose to use a straight cut box with an open diff

[mickrick]

Oooh! Donuts....

[CTrickle]

downsman said:

It seems strange that a previous owner chose to use a straight cut box with an open diff

That's exactly what I think. One of it's previous owners invested in changing the original ford engine (Pinto or crossflo) for a stage 2 tuned Dunnel 1800 Zetec and that I suspect is when the straight cut box arrived. Weird there was no uprated diff and there is no reason for a straight cut box as it would have had 175bhp.

We buy it and it turns out the stage two head has been lifted and replaces with a standard one. Doh!

[BertBert]

Perhaps both had failures (head and previous diff) and were replaced by cheapskate parts?

[CTrickle]

BertBert said:

Perhaps both had failures (head and previous diff) and were replaced by cheapskate parts?

Indeed this could be an option, that could have been a bad day for the previous owner!!

[mickrick]

Once the diff has been centered, you could take the washers out, measure the thickness of them combined on each side, and have a single spacer turned up to replace them.

Edited because I can't spell thic!

Edited by mickrick on Thursday 22 November 18:44

[Incorrigible]

Hang the diff from the long bolt first, with no washers. That makes it much easier to shim up the bottom 2 bolts before then removing and shimming the long bolt.

Also I think it's best to measure the gap between the pinion flange and the chassis to get it central