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[husky12]

i need a diff for my 2.5 v6 and i have a 2.5 TD diff sitting here i was told by some one that it would be a little bit higher geared because diesel's don't rev as high but i always though they were lower ration than the normal 2.5 v6 diffs? any thoughts?

[Kevin Wood]

It will be quite a bit higher geared. It won't be very nice to drive, IMHO.

Have a look here. Guessing a TD will have a 3.45 diff.

http://www.omegaowners.com/forum/index.php?topic=90497.0

[husky12]

gud man helped loads

[ajsphead]

I have a diesel diff in my manual 2.5. It did feel a bit sluggish but not as bad as you might think. Indeed, for pottering around in, the difference is negligable. Fitted an M Tech opel tuning chip and the performance is near enough restored bearing in mind I don't expect miracles after 146K miles but I now get improved fuel consumption, more relaxed cruising - indicated 70 mph is indicated 2650 revs and great extension to the gearing so just as the V6 is taking off above 4K so the speed begins to take off too. it'll just clear 70 in second and is nudging 3 figures in 3rd (at Castle Combe circuit). With the chip, I'd definitely do it again.

[zirk]

I have a diesel diff in my manual 2.5. It did feel a bit sluggish but not as bad as you might think. Indeed, for pottering around in, the difference is negligable. Fitted an M Tech opel tuning chip and the performance is near enough restored bearing in mind I don't expect miracles after 146K miles but I now get improved fuel consumption, more relaxed cruising - indicated 70 mph is indicated 2650 revs and great extension to the gearing so just as the V6 is taking off above 4K so the speed begins to take off too. it'll just clear 70 in second and is nudging 3 figures in 3rd (at Castle Combe circuit). With the chip, I'd definitely do it again.

Was about to post, you might just get away with it with a Manual, but you beet me to it, Auto wise I would have to agree with Kevin, wouldn't expect it to be a good set up IMO.

Economy wise again with a Manual, some improvement with the expected given loss in performance, as for a 2.5 Auto and a 3.45 Diff, cant see it working myself, as standard the Auto Box will only lock up at around 55 / 60 mph, so with a Diesel Diff fitted that figure would be higher given the torque and speed, the economy could be worse until 60 / 65 is reached, and on a Motorway Cruise I would imagine the Auto Box changing up and down like a Yo Yo on the slightest incline.

The 2650 RPM at 70 doesn't seem right to me though with a Diesel Diff fitted or the 2.5 Box has a different gearing to a 3.0/3.2 or the speedo is reading high? I know from experience a 3.0 Manual with 3.7 Diff reeds around 2600 rpm at 70 and at 3000 rpm with a 3.9 Diff, that is with a calibrated speedo though, so might explain it but would expect a 3.45 Diff on a Manual to be in the region of 2350 rpm at 70.?

[Kevin Wood]

Yes, auto box is higher geared than the manual to start with and, as said, lockup will be so high that fuel economy will suffer. The auto is a bit high geared in standard form IMHO.

Not such an issue in a manual because first gear is silly low anyway, and you'll just delay the upshifts to compensate.

[husky12]

put a normal 2.5 v6 diff in and when in limiter in second it does 75, the 2.5 td diff only done 65 second gear limiter. (car is a drift car) and also y does it keep breaking half shafts. ive broke 2 on the track in the last 2 days???. tyres and wheel sizes are all same. it never broke any other shafts on any other omegas i had