Technical Gearbox

[Fastone]

Hey,

My uncle and me are thinking about preparing an Uno Turbo for slalom. We were wondering if it is possible to fit a different gearbox from a slower Uno (or other Fiat) to a Turbo without making any changes?

Thanks

Stijn

 

[thepottleflump]

Can't answer your question although there are definately some options I don't know if you'll achieve the desired result. I'm sure AlexGS will know!

I also hope you're fitting some suspension upgrades for slalom. Always thought the UT suspension is weak as standard and not well matched to the engine. Too much power despite rumours Fiat kept the engine detuned! I've this feeling it wouldn't take much to over cook it into a bend and wham bye bye Uno.

I've also been driving my UT for the last couple of weeks while waiting to service my Alfa (didn't want to go over the service interval for warranty reasons) and jumping back into the Alfa it feels like a little gokart, solid, direct and confident in comparison. Surprising since it's a much bigger car. Guess that's progress and it is 14 years younger

 

[alexGS]

Hi Stijn, welcome to the forum

You would have some difficulty fitting other Uno gearboxes to the Turbo because the driveshafts are different. Specifically the Turbo has inner CV joints rather than the 'Tripode' universals that live in the differentials of the lesser Uno models.

Ignoring the driveshaft difference, the closest is the Mk1 Uno 70 about 1988, which came with a similar gearbox to the original Mk1 Turbo - a single gearchange rod going into a 'bellows' at the bottom of the gearbox. Most other Uno 60s and 70s have a different style of gearbox with a gearchange linkage that has a vertical bar at the back of the gearbox and a rectangular 'tin' cover on top (this gearbox is similar to the one used in Uno 45 models). Fitting this to the Turbo would be a waste of time as it's probably not strong enough.

The later Mk1 Turbos (like mine), seemingly quite a number of them in 1988, came with a Tipo-style gearbox having two balljointed rods on top and the gearchange linkage inside the car rather than underneath. I believe this later style of gearbox is much stronger and you should be able to find a working replacement out of a Tipo. However, there are more driveshaft differences - the 1372cc Tipo comes with Tripode joints (again), not sure about the 1580cc models. I expect that internal components of the gearbox could be exchanged.

Sorry this possibly isn't the news you were wanting, but bear in mind that you may be able to use FIAT Strada parts to repair an early Uno Turbo gearbox?

As for suspension, I've put some effort into lowering and stiffening the suspension of my Uno Turbo. You cannot cut the springs, due to their conical shape, so you have to fit replacements. Quite easy to do, particularly when the original shock absorbers are likely to be due for replacement by now. I feel that the next biggest weakness is the driver... !

Cheers,
-Alex

 

[Fastone]

Hey guys (and girls),

thanks for the information so far. The suspension would definately be upgraded. I don't think many cars could really do well with standard suspension in any form of motorsport.

On the gearbox issue, just to clarify, if we would use a mk1 Uno 70 gearbox, is it a straight swap, or do other parts need to be changed?
Would it be possible to use a different type gearbox of a different Uno if other parts are swapped as well?

Thanks

Stijn

 

[Chas Uno]

Actually, I think there is no reason why you couldn't use a 70 gearbox seeing as it uses the same engine block as the turbo. Not sure about the driveshafts though, but you could use the 70 driveshafts instead. Only problem being that you would lose the split driveshaft on the drivers side that is meant to combat torque steer. But as Alex has pointed out, your problems is going to be whether the geabox is strong enough to cope with the extra torque of the turbo.

Your other option would be to use the gearbox final drive from a lesser Uno in your turbo box. Not sure if they will fit, or if they will be compatible or strong enough?

For information, the final drive ratios work out as follows:

Mk1 45 and 45S (OHV engine) - 4.071 : 1
Mk1 55 and 70 - 3.733 : 1
Mk1 45 999cc FIRE - 3.733 : 1
Mk1 Turbo - 3.588 : 1

If you can find an old ohv 45 gearbox, this will give you the lowest ratio diff of 4.071 : 1. Failing that, a 45 FIRE or 55/60/70 gearbox will give you 3.733 : 1.

Whether the final drive units will fit the turbo box I have no idea...

Alternatively, fit smaller wheels or lower profile tyres as these will also lower the ratios in the process.

 

[alexGS]

On the gearbox issue, just to clarify, if we would use a mk1 Uno 70 gearbox, is it a straight swap, or do other parts need to be changed?

No, not a straight swap, other parts would need to be changed (the driveshafts, as Chas says, and possibly the gear lever and linkage) - and it would be a downgrade because the Uno Turbo gearbox is stronger and the gearlever action is better. You didn't say what gearbox you have already, or what is wrong with it?

Would it be possible to use a different type gearbox of a different Uno if other parts are swapped as well?

Same problem with the driveshafts, and the gearbox off a 903cc engine would not fit the clutch on the Turbo.

My comments about earlier models (Strada, X1/9, 128) were basically concerned with internal components being exchangeable with the early Mk1 Uno Turbo 'box. If you have a later Mk1 box (with the top-linkage for the gearlever, no rods running under the car) then you need a Tipo box for spare parts.

Hope this makes things clearer!
-Alex

 

[Fastone]

Hello,

It has been a bit busy here for the past couple of weeks, exams and all those other interesting things when you are still studying.

In any case, thanks for the information. It has made things quite a lot clearer. To (finally) answer your question about the gearbox, Alex, we don't have one yet, we don't even have a car yet. We are just trying to gather information on what the possibilities are for us to do slalom with a Fiat. That is basically the only thing we have decided so far, that it has to be a fast Fiat.

I know this it the Uno part of the forum, but am I correct in assuming that the Punto Turbo has exactly the same engine/gearbox as the Uno Turbo?

Thanks

Stijn

 

[Chas Uno]

I know this it the Uno part of the forum, but am I correct in assuming that the Punto Turbo has exactly the same engine/gearbox as the Uno Turbo?

Thanks

Stijn

Basically, yes, but the same as a mk2 Uno Turbo NOT a mk1. I think the basic engine block is the same, but again not sure of things like ECU's or fueling, though I suspect they must be very similar. Not 100% sure on the gearbox though, but I think the last of the Unos did use a Punto style gearbox?

 

[Fastone]

Is the difference between an Uno Turbo mk1 and mk2 big? I figured the difference was more cosmetic rather than technical like it is the case for the current models.

Thanks for all the information so far

Stijn

 

[SteveNZ]

You are wasting your time fitting a non turbo box to an Uno turbo. This quita af effort. The turbo box has many advantages. most Uno NA race cars here have turbo box conversions.

Mk2 box has higher ratios. Punto box is quite different

 

[unoracer]

As per the last post, I race a normally aspirated 1500cc uno mk2, and use the mk2 'tipo design' uno turbo gearbox, which has had a cwp fitted from another tipo box, which brings final drive from the standard 3.353 to 3.733. I am still looking at changing this again for next season, to take it to around 4.0, providing the mk2 uno 1.7d cwp fits! I also use 13" alloys and slicks to keep gearing down, but am also having to consider 15" alloys & slicks to give me a better tyre 'footprint' and hopefully better cornering speed!! (All at the expense of gearing going upwards again of course with taller rolling road radius! When you start developing race cars, there are so many factors to consider like keeping cars weight down! 15" wheels then mean more weight than 13" wheels/tyres