UK Auto - Diff Ratio

[AussieEtype]

I have been told that all UK spec autos were fitted with 3.07 diffs but some other sources say 3.31- can someone confirm what was fitted to autos as standard from the factory.

Thanks

Garry

[Bob.]

Hi Garry

The Autocar for 1 April 1971 states "automatic transmission cars will use the latest Borg-Warner 12J unit and will have higher final drive ratios; 3.07 at home, 3.31 for America."
Manuals at 'home', having 3.31 at launch, 3.54 for America. 3.07 was offered as an option from April 72 then became standard from Mar 73 (3.31 for America) according to Skilleter, pub 1979 or Dec 71-Jan 72 and Dec 72 according to Clausager pub 2011 - take your pick).

No changes that I can see are recorded for 'home' market autos although some else may know differently - Peter?

Hope this helps
Bob

[AussieEtype]

Thanks Bob - so 3.07 it is then.

Cheers

Garry

[PeterCrespin]

According to the factory launch brochures, US 2+2 sixes and V12 manuals debuted with 3.31 and the UK six cyl auto was a 2.88 (Motor Magazine). I'm pretty sure the US V12 auto was also 2.88 - in fact the V12 XJS and XJ were 2.88 as well. I haven't looked at every source, however, so there's a slight caveat on US autos..

[angelw]

Hello Peter,
On launch,
1. Manual trans for U.S.A and Canada was 3.54:1
2. Manual trans for all other countries was 3.31:1
3. Automatic trans for U.S.A and Canada was 3.31:1
4. Automatic trans for all other countries was 3.07:1

Later cars to the U.S.A and Canada of all types were 3.31:1

I'm unsure what was fitted to later cars to other countries.

Regards,

Bill

[PeterCrespin]

I only gave info for LWB cars as those were the only autos and the question was about autos.

I went by factory brochures on Jag-lovers and in one case (2+2 6cyl auto?) a Motor road test, again as scanned on J-L. Ergo, not my numbers but the factory's. As foryour first catrgory Bill, I know eventually all SWB were 3.54 in N-America but don't think they started that way at launch?

Pete

[angelw]

Hello Pete,
As this section of the Forum is related to S3 cars, SWB doesn't come into it, nor does 6 cylinders, except for four S3s with 6 cylinder engines that were built before that form being dropped. Accordingly, my information is related to S3 V12 cars only, which I believe is the Series Garry is inquiring about.

First picture below is General Data for Late S3s USA specification cars. Second picture is General Data for very early S3s showing World Wide final drive specification.

Regards,

Bill

[PeterCrespin]

Righto, apologies. I'm like Pavlov's dog - when someone says 'launch' I automatically (geddit?) think of Geneva and our favourite tester speeding lantern-jawed across Europe to his date with destiny.

Maybe it was Lorenz's duck...

Pete