New diff, changed characteristics?

[gordy.r]

So, I bought an AO2B diff for my 1994 Jspec TT auto about 8 months ago.

 

I had it fitted last week, and I had my old AO2A open diff removed.

 

Previously with the old open diff, when the car was in Manu mode and doing 60mph, I would select 2nd gear and the revs would sit at 4k rpm. Just a nice sweet spot for both turbos to be on spool and give a good pull in acceleration.

 

So I tried this the other day when driving home after having the new diff fitted, Manu mode, 2nd gear at 60mph and the revs shot up to 5k rpm.

 

Strange I thought. So I slowed down and matched my revs to 4k rpm and the speed now showing was 50mph.

So....the question is....

 

Have I been sold maybe an AO1B instead of an AO2B or is it an AO2B but I need to change my speed sensor what with changing the diff from an open to a lsd?

 

Any help much appreciated.

 

Thanks.

[Scooter]

In advanced search put in 'spreadsheet' as the search word and 'homer' in the members bit and you'll get a few links with a great spreadsheet attached where you can input your car type tyre size etc, then you can select different diff ratios and match the graph lines to your in car rev data which should help you id the diffs

[David P]

Jack up rear on one side, select N, mark prop-shaft position, rotate wheel 360 degrees and count the number of prop rotations.

 

3.8 = A02B.

 

4.1 = A01B.

[gordy.r]

Thanks for the advice guys, I'll give David P's advice a shot and see how I get on