Diff backlash?

[Spitfire2500]

Just noticed that there seems to be quite a bit of backlash in the Spit diff -- not sure if I should do something about it or not

Reckon there's roughly about three-quarters of an inch of rotational slack in the prop. Excessive?

Only noticed cause I was fiddling about underneath the car. There's no other outward sign there's anything wrong -- diff isn't clunking, rumbling or whining.

Don't want to wait if it's likely to crash and burn any time now (there'a a Quaife LSD in there which I really, really don't want to wreck), on the other hand if it'll last for ages yet I'd rather wait for a short while cause I've spent rather a lot over the last two months on the Spit and Saloon as it is  :o

It's a 3.63 BTW.

[Smallfry]

Ideally want about 3 to 4 mm backlash at the rim of the input flange. Any less is way too tight which will cause overloading and overheating of the gear teeth and bearings, which is NOT good.

More than this and you have either got very poor workmanship or some serious problem. Are you sure the input flange splines are not worn or the nut loose.......... most likely, and probably because some "expert" re used the collapsable spacer............whatever, DON'T run it like this, or you WILL be needing a new one.

Who put the Quaife diff in .......eh ? eh ?

[Spitfire2500]

[quote by=Smallfry link=Blah.pl?b=spit,m=1178659370,s=1 date=1178662966]whatever, DON'T run it like this, or you WILL be needing a new one.[/quote]

Fair enough -- I got exactly the same advice from Chic Doig at almost exactly the same time you posted your reply so I'll drop the diff out over the weekend.

Quote:

Who put the Quaife diff in

To be honest I don't know. Chic Doig supplied the diff (with the Quaife in it at my request) when the Spit was being rebuilt/converted. I do know they didn't put it together themselves -- they sub'd it out to one of the specialists. It was one of first bits I got when the rebuild started in 2000.

Been on the road since mid-2002 and has done about 12k miles -- there is a fair bit of power going through it but still expected it to last a bit longer that it has.

Cheers,

[Smallfry]

I reckon you should be able to run 180 to 200 hp through a properly built unit using the right oil............. even more with a Quaife diff in it.

I think your problem will to do with shimming, preloads, or nuts not being done up properly ! When you get it back make sure you can turn the input flange easily using only one finger and thumb. If you can't, don't accept it. And don't accept any crap about it settling in either....................It won't ! What it will be, is knackered again.