gearbox & diff
 

ive got a classic and my gearbox has gone yet again i have one lined up, but unsure. the diff ratio on mine is 4.111 and the new one is a 3.900 so will i have to change diffs? its also of an 02 bugeye would i need propshaft or any thing else for this matter your advise may bring me my joy back cheers:notworthy

Hi mate sorry I cant help but what I do know is that that diff will need to match the box so you will have to use the 3.9, im nopt sure if you will need to change anything else but im sure one of the experts on here will help you out!

does any experts on here no any information will go down kindly

I'm interested to hear replies on this one as I've just bought a TY754VN2AA gearbox from an MY02 bugeye which I'm fitting onto my MY00 classic which originally had a TY754VN1AA box on it. I'm posting the figures here as it should be the same boxes that 'qckev' is on about.

Ratios are as follows:

VN1AA VN2AA
1st 3.166 3.166
2nd 1.882 1.882
3rd 1.296 1.296
4th 0.972 0.972
5th 0.738 0.738
Rev 3.416 3.333
T.R. 1.000 1.100
F.D. 4.111 3.900

So would this mean that the rear diff would have to match the front diff (F.D.) i.e. 3.900:1 or do you have to multiply this by the transfer ratio (T.R.) to get 1.100 x 3.900 = 4.290:1?

Im not sure about this, I was under the impression the classics all had the same front diff, as long as the rear diff matches the box then i would have thought it woulkd be ok. I think what you need is the prop and some other bits as well. Of course I could be wrong and shall wait to be corrected!

Well I'm going to have to find out the answers to all these questions myself this week as my gearbox has completely jammed in third gear now and I can only select 3rd or neutral which isn't much good for stop/start traffic, hill starts or reversing off the drive! :(
I'll let you know how it goes (probably badly!)

Finshed the gearbox change, everything went ok!
I phoned up David at API to check if I needed a rear diff or not and he said that the new box (VN2AA) is a drop in replacement for the old one (VN1AA). Ignore the figures I quoted in my post below, they must be wrong, the table was a bit confusing.

So the prop fits, the driveshafts fit - tho I did have problems getting the gudgeon pins through the driveshafts/front diff output shafs and in the end got some slightly narrower dia pins from work which fitted fine - clutch is fine - was a pain to get aligned tho.

The only difference I spotted is that the bugeye box has an extra wire connected to it (which was removed) had no earth wire connection that goes to the back of the bulkhead under the i/c (which I swapped over) and the dipstick is different, blue plastic band on the bugeye red on the classic so the new boxes need less oil than the classics?

Drove it around the block (about a mile in total) and jacked up the rear diff but there was no movement from the wheel so I don't think I'm getting any diff wind up, felt fine, must be ok!

I did notice the change was slightly more notchy but thats probably going from a box that has done 110k to one that has only done 35k.