Uno Turbo close ratio gearbox build for hillclimb

Non-engine, eg: aerodynamics, gearboxes, brakes, suspension
Slim
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Uno Turbo close ratio gearbox build for hillclimb

Post by Slim » Sun Feb 02, 2014 12:14 pm

Hello everyone,

I race my Uno on the hill and I'm in the middle of building myself a close ratio gearbox made from various Fiat/Lancia boxes.

I have the following parts/ratios to use. I will note options where I have them.

Final drive Opt 1: Uno turbo 17/57 (3.352) Opt 2: Coupe 2.0 16v 15/56 (3.562)

1st and 2nd Opt 1: Uno turbo - 1st 3.909 and 2nd 2.267 Opt 2: Coupe 2.0 16v - 1st 3.545 and 2nd 2.267

3rd gear: Alfa 156 BTCC 21/34 (1.62:1)

4th gear: Alfa 156 BTCC 25/31 (1.24:1)

5th gear: Alfa 156 BTCC 28/28 (1:1)

I will be using a 14' wheel with a 185/55/14 tyre, total diameter is 21.81''.

In the table below I have input, final drive Opt 1 and 1st and 2nd gear Opt 2.
Fiat Uno Turbo close ratio gear box bulid.xls
(30.5 KiB) Downloaded 92 times
I think this the the setup I will finally use but am open to suggestions?

Liam
Last edited by Slim on Wed Feb 05, 2014 11:25 am, edited 1 time in total.
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Guy Croft
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Guy Croft » Sun Feb 02, 2014 1:52 pm

Good effort - but those drops hardly represent close ratio.

Close ratio is c 800rpm drop 2-3 3-4 etc with very tall 1st gear..

Put in some ratios from a Quaife box and you will see what I mean..

G
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Slim
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Slim » Sun Feb 02, 2014 9:55 pm

Hello Guy, Maybe I should have called it ''closer'' ratio gearbox build.

I have been thinking and in reality I will not be going all the way to 6000 RPM in 1st, 2nd or 3rd.

Attached is what I think is a more realistic change pattern.

Liam
Fiat Uno Turbo close ratio gear box bulid.xls
(30.5 KiB) Downloaded 79 times
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Guy Croft
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Guy Croft » Mon Feb 03, 2014 1:24 pm

Ok - How about overlaying the standard ratios on that graph?

G
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Slim
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Slim » Mon Feb 03, 2014 9:26 pm

Not sure I can manage the overlay.

Here is the same spread sheet with the standard 1372 Uno turbo ratios.
Fiat Uno Turbo standard gear ratios.xlsx
(16.36 KiB) Downloaded 59 times
Here are the drops changing gear at 5000 RPM in each gear.

My build:
1st to 2nd - 1,750 rpm
2nd to 3rd - 1,375 rpm
3rd to 4th - 1,125 rpm
4th to 5th - 1,000 rpm

Standard ratios:
1st to 2nd - 2,125 rpm
2nd to 3rd - 1,750 rpm
3rd to 4th - 1,750 rpm
4th to 5th - 900 rpm

So, seem's strange that the standard ratio has less of a drop between 4th and 5th?!

Liam
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MattD
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by MattD » Wed Feb 05, 2014 12:40 pm

Slow day & had 5 mins to spend. Below is the merged data from both the "OE" and "CR" graphs.
Fiat Uno Turbo OE vs CR gearbox build.xls
Merged Gear Ratio data
(56 KiB) Downloaded 83 times
Personally, I'd be using the OE gearbox as a 4 speed, spending less time dipping the clutch & between gears, and looking at where I was on the hill.

Rgds
Matt
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Slim
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Slim » Wed Feb 05, 2014 6:08 pm

Matt, thanks for merging the data into one graph.

Having gears closer together will make it easier to keep in the boost out of and between bends. I have also suffered with the large gap between 2nd and 1st when changing down in tight hairpin (road speed too high to be able to select 1st). The Coupe 1st and 2nd are closer and will help this. I can always change it if it doesn't suite my style of driving.

Personally, I enjoy changing gear and tend to keep my eyes on the road when doing so.

Thanks

Liam
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Guy Croft
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Guy Croft » Thu Feb 06, 2014 11:46 am

Thanks very much Matt!

Kind of you to merge that data, just did not have time myself,

sincerely,

G
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fingers99
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by fingers99 » Thu Feb 06, 2014 12:57 pm

The 500 Abarth (but, of the T Jet engined cars, only the 500 Abarth), used the same gearbox.

There was, for one year only, a race series: Trofeo Abarth 500 GB.

Might be worthwhile seeing if there were any close ratio gearbox parts made.
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Slim
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Slim » Thu Feb 06, 2014 7:18 pm

Fingers99, which 500 used the same C510 box?

Liam
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Slim
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Slim » Thu Feb 06, 2014 9:50 pm

Fingers99, I believe the box fitted to the Trofeo Abarth 500 GB cars was a Cambio M32 box?

Liam
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fingers99
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by fingers99 » Fri Feb 07, 2014 3:23 pm

Slim wrote:Fingers99, I believe the box fitted to the Trofeo Abarth 500 GB cars was a Cambio M32 box?

Liam
Pretty sure it wasn't. The Bravo and Punto used either the M32 (which I think is a GM box) or a Mitsubishi box. Both are 6 Speed, both -- I think -- are equal length driveshaft boxes with a centre shaft (there has to be a name for that pattern, but I just say "just like the MR2 Turbo" box).

The 500 series generally use a variant of the same box as used in all the FIRE engined cars (conventional, cup type, unequal length driveshaft) while the 500 Abarth needs to be able to handle more torque (but has less space) so goes cups style, 5 speed, old Alfa box.

Our Polish friends are cheerfully putting the T Jets into Seicentos, but it seems the 6 speed boxes are just too big. This is a shame as there are lots more of them about!

HoSDo on Fiat Forum did a fair bit of the research as he destroyed the standard Fiat box on a Rotrex charged Mk1 Punto.
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Slim
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Slim » Fri Feb 07, 2014 7:21 pm

What sort of power was the Rotrex Punto?

Liam
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Slim
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by Slim » Fri Feb 07, 2014 7:44 pm

Fingers99, see attachment, on page 36 it lists the gearbox as being M32...
Spare Parts List - 500 ABARTH ASSETTO CORSE.pdf
(2.63 MiB) Downloaded 79 times
Also found this.

http://www.abarthcars.co.uk/site/UK-EN/ ... -corse.pdf

Liam
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fingers99
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Re: Uno Turbo close ratio gearbox build for hillclimb

Post by fingers99 » Fri Feb 07, 2014 9:33 pm

yes, that looks definitive: 2 driveshafts with the same part number. Must be just the 500 Abarth and SS that had the 5 speed, so they're unlikely to offer anything special.

Still, it may mean that there's enough room for the Bravo T Jet and box in a Cento. (After all, Toyota squeezed both kinds of boxes in the MR2 Mk2 -- the n/a one is a tiny little thing.)

It was a 1.4 16v in the Rotrex Punto. I know they were shooting for something like 150+ bhp and something like 170Nm before the box went. Might be worthwhile PMing HoSDo on FF. (After all, he's in Italy -- providing the Carabinieri have not impounded him for running the wrong air filter or something.) The thread can be found there with a search for Punto Mk1 1368 Fire Rotrex Supercharged!.
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