Removed box once again and have found obvious damage to the differential oil seal. Good news I suppose. It triggered a memory that may have been the cause of the damage. When I was dressing the gearbox with stuff before putting it back in last time I remember tapping the short half-shaft into the box for no other reason than somewhere to put it and why not as it has to go in at some time. Only problem is I tapped it into the wrong side of the differential housing. I realised as I brought the box nearer to the car to fit it and tapped it out again to put it into the other side. I have since learnt that the seals on each side are different, with the O/S one I damaged being a smaller diameter. As this was literally the last time I could see the seal because it went straight onto the engine, this is why it happened to what I thought was a checked good seal.
So fate dealt a curious hand last night. I spotted a VERY low mileage Grande Punto 1.3 MultiJet gearbox on eBay that I offered £140 for, which was accepted. Went and got it from Preston, complete with gearlever mechanism with housing and double bowden cables still attached. Giving serious thought to using the cables now as they are just better in every way I can think of including weight!
The reason I got yet another gearbox is because although it is handy that FIAT keep using old box designs for me to use in old cars, they do trend towards lower and lower final drives due to the larger and larger standard wheel sizes on cars these days. This means the Uno Turbo ratios now look really long and a tuned Uno could always do with longer ratios. Part of the solution is to use larger wheel diameters and the other is to get the right box. The Abarth 500 is pretty good, but rare as hell to buy and probably least likely to be in good nick. The diesel boxes are a great alternative with even higher 4ths and 5ths and can be found for a fraction of the cost an "Abarth" box will fetch. The reason we can't just use the fab UT box is boxes of this age are not compatible with the FIRE bellhousing due to shaft diameters. I could get an older box from other non-current model cars, but how often do you come across a 1500 mile gearbox from a 10 year old car?
Below is one of my comparison sheets I've made up based on part numbers with known tooth counts as opposed to the often wrong manuals and other hearsay.
And here are the gear/speed projections using a simple Excel calculator...
Standard Mk2 Uno Turbo including wheels/tyres:
195/50r15s with Uno Turbo box (my previous engine setup):
195/50r15s with GP T-Jet box (was about to use):
195/50r15s with GP 1.3 MultiJet Diesel box (the proposed setup)
So, if you are still reading this, the conclusion is I will have a little lower ratios in all but 5th over the UT box, but it is the best I can do I think. Certainly better than the T-jet box (which was free) and I'm now sort-of glad it had to come out again!
One day, I hope another person will do this conversion and be happy to read all this info. Or maybe it is me in the future when I forget why I used the parts I did!
