HELP !! Diff fitting !! or not...

[Andy_B]

Morning all...been out in the garage trying to fit my diff...eventually got it up into rough position ...drivers side aligned perfectly and bolted up...passanger side is out by about 12mm on the large side..ie diff is 12mm wider ...now i cant ease the holes on the chassis as the diff is smak on center where it is with a nice equal gap both sides...so do i cut the chassis mount off and re fabricate...or can i loose some beef from the top of the diff ...bottom bit is ok as it needs 12mm worth of spacers to pack it out ....hope this makes sense...am just calming my temper down a bit !!

[loony]

Looks like you have 7,5" Scorpio/Granada diff... not Sierra 7".

Top mount of 7,5" diff is.... about 12mm (half inch) wider and left upper mount need to be modified.

[james3004]

I had the same problem, found it easier just to buy a 7 inch diff, you can't cut a lump off the diff as I tried it and the wall isn't thick enough.

[Andy_B]

kinda worried about chopping into the diff is there going to be enough meat around about it ??

[tex]

have you checked the diff ratios? i had a scorpio diff the big one and the ratios are not that good.. too long if i remember right [you can tell by taking the cover off its painted on the crown wheel edge]

[Andy_B]

After a quick google and removing the tag from the diff its a 3.91:1 ratio...please tell me this will be ok....???

[loony]

You have to modify chassis/diff mount plate - not diff itself.
I don't think that chopping diff is a good idea ;)

3.91 it's quite short ratio... it depends what you expect, but top speed will suffer...

I think standard Sierra diff is 3,62:1 ratio and is more suitable for lightweight roadster.

[Eternal]

I did this the other day on a 7.5" was not too much trouble.

Last post on this page http://www.haynes.co.uk/forums/showthread.php?t=4468&page=13
and first post on this one http://www.haynes.co.uk/forums/showthread.php?t=4468&page=14

If you get a 2nd bracket and weld it to the edge of the bracket so its flush then cut out the top of the original bracket. All you then need is a longer bolt m12x60 and a 28mm spacer.

[Andy_B]

Thanks Guys...Eternal especially...i even commentet on your work and it didnt click....i have some steel plate left over so will hack out another bit for the mount...thanks again

[Eternal]

I have some spare 25mm round ally bar if you want i can drill and make you a spacer. Just let me know how wide you want it and your address and i will make and send it off.

[Andy_B]

Thanks very much for the offer Eternal but i have (or my work) has a good supply of steel and some lathes etc etc

[Eternal]

Sure thing. Offer open if required.

[Andy_B]

Thanks again ...just been out and chopped the diff bracket and re welded on the other side...managed a pretty nifty bit of grinding and welding if i dont say so myself...will post a pic of the Eternal mount ! when its done....

[snapper]

There was an earlier comment on the diff ratio saying that the 3.9 is not good and the 3.6 is better, it is a personal preference but if you have an MT75 box the 3.6 has the edge, a type 9, I prefer the 3.9.
The problem is either a first gear that is to low/short or a 5th gear that is to high/long.
Either 3.6 or 3.9 are good for 7 type cars with 4 cylinder car engines, 3.3 and 3.14 better for big torquey V engines and revy bike engines IMHO