Uno turbo/delta hf turbo gear ratios....

[Infectus-Guy]

I am going to be preping my 1.6 Delta HF turbo i.e. for a spot of hillclimbing next year and i'm trying to find out if there's a lower ratio gearbox that i can fit. I'm going to have to be all about the torque and low ratios if i want to be competative, so i'm going to remove the T3 turbo that i've fitted and go fo a smaller T2 from a coupe 20v turbo, which should be a bit bigger than the original T2 that the delta came with from the factory. Thats the easy bit though!
I wonder if anyone knows the gear ratios for the Lancia hf turbo compared to the uno turbo. I've got the ratios for the uno-

1st : 1 3,909
2nd : 1 2,267
3rd : 1 1,469
4th : 1 1,043
5th : 1 0,875
Reverse : 1 3,909
Final drive 3,353

I can't seem to find the ratios for the hf turbo box though. Would it be the same for the older carb'd hf turbo? Is the uno box weaker?
Thanks for any ideas,
Guy

[WhizzMan]

What base gear box is on the 1.6 IE? Is it the Fiat C503? Or is it a smaller one? The smaller one, also used on the Uno Turbo is the C510.

Gear ratios for the C503 can be "borrowed" from Alfa V6 FWD cars with 5 gears, as well as several Fiat/Lancia models. Final gears (fwd only?) can also be taken from those. The six speed is the C530. I'm not certain how much internals are interchangeable, but I know that Alfa people have successfully transplanted whole gear boxes to former 5 speed FWD cars. The Alfa Q2 differential fits in both these boxes. The early 145 JTD also has a 5 speed gear box, later JTDs have the 6 speed box. Older "TD" engines tend to come with the lighter box, so watch out.

The C510 is used in a lot of other Fiat group cars. Notably almost all Alfa 16V twin spark cars. Those are plenty and you shouldn't have much trouble finding a few for near scrap prices if all you want is some gears out of them. As said above, older TD Alfa's have the C510 box as well. No JTD ones do, so check if it's a common rail or a VM mechanical pump based engine if in doubt.

[TomLouwrier]

hi Guy,

I think you'll find that practically all boxes for street applications have more or less the same steps between their gear ratios. That certainly goes for the Fiat/Lancia/Alfa group but other brands are not very different either.
It may be that a certain family of transmissions runs its specific combination of box and final drive ratios, but the overall result of the total gear train will actually be pretty much the same.
Not illogical if you realize that most cars have similar engine speed ranges and similar wheel sizes.
Main difference will be between the smallest and largest engine, and some between petrol vs diesel.

You may of course fit a very short differential giving you a 1st that is too short to use, so you have 2nd - 5th available: effectively a 4-box and still not really 'close'.
A six speed box on a very short diff may thus end up as a "5-speeds usable, pretty close".
Of course the proper thing to have is a true 'close ratio' box with tall 1st, normal top and the rest crammed in between. Hard to get and not cheap.

In all cases you use the final drive to set up top speed versus acceleration, depending on your engine, the track and the sort of racing you'll be doing.
And of course you can do some adjustments by choosing the right tire size.

regards
Tom

[Infectus-Guy]

Of course the proper thing to have is a true 'close ratio' box with tall 1st, normal top and the rest crammed in between. Hard to get and not cheap.

Yes of course, so simple but i'd not really got my head round that until you said this. Long 1st and the rest bunched up, and as you say VERY expensive.
Guy

[James Bowen]

Hi,

The below attached may help. It is a list of Lancia / Fiat group cars, and their respective standard gear ratios. There is not much difference between them, as you will see....

Gear ratios for Fiats.pdf

Standard Gearbox ratio's for 'older Fiat Lancia group cars.

(68.13 KiB) Downloaded 1215 times

Hope this helps,
thank you James

[GMK]

Hi,

The following ratios are taken from the Lancia Delta workshop manual, March 1988:
1600 HF Turbo ie
1st: 3.583
2nd: 2.235
3rd: 1.524
4th: 1.154
5th: 0.903
Reverse: 3.667

I'll scan the page soon to show the complete set of ratios for the Delta - 1100, 1300, 1600GTie, 1600GTie France, HF Turbo, Turbo DS.
Let me know if you need anything else form the manual.

Hope this helps
Gus

[Infectus-Guy]

Brilliant, thanks for your help guys. Looks like i might look into the interchangeability of the stronger Fiat coupe and Alfa gearboxes, it would mean converting to hydraulic but thats not the end of the world.
Guy