Hi folks, on my never ending quest to actually learn something (or just sound like an idiot); As the title suggests, I have recently had a complete diff change.

I drive a VYSSII wagon with a Harrop HTV1900, the suspension has been upgraded (Koni adjustable all round and Whiteline Sway bars front and rear, with the Diff cradle bush and few others being changed as well). My old Diff had 3.73 gears in it and the new Diff (complete Diff swap, not just gears) has 3.45 gears in it.

Previously I had not experienced any axle tramp when 'accidentally' turning the tyres (it's easy to do with the blower.....); I have noticed since getting the new Diff that (especially in the wet) when the wheels are turning (by accident of course - seriously), the car sounds like there is a jack hammer going off (it seems MUCH louder on the driver side than passenger.. but this just may be b/c that is where I am sitting...) and I have to back RIGHT off really quickly (the noise is SOOOOO loud that it scared the crap out of me when it happened, as I just wasn't expecting it ... my daughter was in the car the other day and taking off a little quickly the tyres turned and the noise freaked her right out - it's REALLY loud). With the old DIff I NEVER experienced axle tramp even with the blower (it was as smmmmmoooooooth as a babies bum even when the wheels were spinning,wet or dry, not that I do it intentionally, HONESTLY!!).

Added to the above I have also noticed considerably more 'drone' and vibration through the car and the engine seems to labour a bit on acceleration (say cruising at 80 and put the foot down slowly to accelerate smoothly to 100 it moves due to the blower but the engine seems to labour... there seems to be a completely different sound and vibration out the back than there was prior to the Diff replacement?)

Does anyone have an explanation for this (tweaking was made to the EFI live setup to cater for the gear ratio change)? I love the new Diff and ratio (as the old was seriously noisy) but the axle tramp issue is seriously p1ssing me off and the drone in the exhaust and extra vibration in the car is getting to me as well (it just seems so much different and the only ting that was changed was the Diff and gear ratio).

I am reluctant to hassle the tuner/mechanic at this stage, as he has been great in the past and I have had to go back and hassle him more times than I would have liked over the previous Diff and I just don't want to sound like a complete whinger and piss him off until I know that this issue is actually normal?

If it is normal, and the issue is just due to the new ratio (tyres not turning as quickly with the new ratio???) then I might have to seriously consider going back to the 3.73 gears as the axle tram is just TOOOOO much (and with the blower the tyres tend to turn way more than you intend).

Any advice?

Thanks in advance,