Final drive ratio for 4 speed x1/9

Post by **Guy Croft** » June 28th, 2006, 1:13 pm

true, even Ferrari owners are starting to ask me 'how much?'... get the odd (?) phone call for head work.
I wonder if it's still true that when you phone Riva and ask 'how much?' they say if you have to ask you can't afford it. I wish I'd never sold mine.
GC

[off topic!!]

Charlie · Post by **Charlie** » June 28th, 2006, 1:44 pm

I totally agree about buying quality parts when it comes to cars that are used in anger on the race track. There is also quite a market for your average classic car enthuasist who wants to carry out some mods to his steed. Generally these people own a few classic cars which are only used at the weekends during the summer and put into hibernation for the winter months. Because of the infrequent use and the number of cars they may own , they probably get it hard to justify spending money on race spec parts for these cars. It depends on what you want from your car. For me the driving experience is the main criteria when it comes to owning a classic car. A car is meant to be driven , not mothballed and the x1/9 is a stylish car which handles well and is very involving to drive. I have no intention of doing track day work but generally put 5000 miles a year on the clock.

Post by **Guy Croft** » June 28th, 2006, 2:17 pm

Very true Charlie.

Do you have any closeup shots of the engine and supercharger conversion that you'd like to share, I am very interested indeed in supercharging.

GC

Kev Rooney · Post by **Kev Rooney** » June 28th, 2006, 11:23 pm

I learnt my lessons a long time ago re value for money. If you want it to last then build it with the RIGHT bits from the start,it actually saves money in the long term.

My cars are all 'bitsas' but they are however planned from the outset and the bits needed to make it work as a whole sourced and bought. Sure I look for a 'keen' price but I DO understand why certain things are 'dear' .

It's taken me 20 years to decorate my house, driving is SO much more fun !!

Regretably this doesn't answer the original question though, apologies.

Julian · Post by **Julian** » June 29th, 2006, 8:20 am

Getting back to the original question - I did some digging through some archives last night and found my little chart of immediately compatible gear sets (caveat - I haven't tested all combinations to make sure they actually fit).

The final drive ratios that I am aware of are as follows:
3.562 - Mk1 Uno Turbo w/ antiskid
3.588 - Mk1 Uno Turbo w/o antiskid, Strada II 105TC 1983 on, Strada II 1.5
3.590 - Strada I (upto 1985)
3.765 - Strada II 1.3, Strada II 105TC upto 1983
4.077 - X1/9 (1.3 and 1.5)

From the original question I would guess that it is the Strada II 1.3/105TC box that is of interest to you. The 105TC is virtually impossible to locate but you might just have a bit more luck tracking down the 1.3.

The original file is in excel format and includes formula for calculating speed in gear according to gear ratio, revs and road wheel diameter. It is attached for anyone interested. If anyone knows of other valid sources of ratios I would like to know as it has a significant impact on the "cheap" options available for my road cars :)

Charlie · Post by **Charlie** » June 29th, 2006, 8:26 am

Hi Guy,
I have taken some close up shots of the engine bay last night showing how drive was obtained from the crank and I have some pictures of the supercharger , bypass valve, and inlet manifold combination before it was fitted. Unfortunately I forgot to bring the camera lead to upload these pictures , but they will be uploaded to the readers car section tommorow.
It,s great to find somebody who has an interest in supercharging. Most engine upgrades on the x1/9 use the Uno turbo engine. Although I have carried out the supercharger conversion to a 1300 ,it would also be a very good up grade on the 1500. The supercharger I used is from a BMW mini cooper S. It,s a lovely fit in the confined engine bay and because of the 60 degree twist in the rotors, it generates axial flow and the outlet is a V shaped port which can be mated easily to the original down draught
manifold. It also puts the carb in a nice cool part of the engine bay compared with the origional set up which makes the car prone to hot starting problems.

lidox19 · Post by **lidox19** » June 29th, 2006, 4:13 pm

Hi Charlie,
If you are interested there in a Delta 1600 GT engine and box on an internet auction site at the moment.I'm sure someone will correct me if I'm wrong, but I think the Delta 1600 GT has the same engine and gearbox as the 105 Strada. I hope it's the same as I bought a GT box to swap the final drive in to my x1/9 5 speed.

thank you
Andy

http://cgi.an internet auction site.co.uk/Lancia-DELTA-1600 ... dZViewItem

Acki · Post by **Acki** » June 29th, 2006, 7:11 pm

Julian wrote:Getting back to the original question - I did some digging through some archives last night and found my little chart of immediately compatible gear sets (caveat - I haven't tested all combinations to make sure they actually fit).

The final drive ratios that I am aware of are as follows:
3.562 - Mk1 Uno Turbo w/ antiskid
3.588 - Mk1 Uno Turbo w/o antiskid, Strada II 105TC 1983 on, Strada II 1.5
3.590 - Strada I (upto 1985)
3.765 - Strada II 1.3, Strada II 105TC upto 1983
4.077 - X1/9 (1.3 and 1.5)

These are with differential ratio. These are ratios from engine to the rim.
I will look for you in my uno sheets.

@Guy: Sorry but it doesn't sounds like he want's to drive races with his car so I thought ... :oops:

Post by **Guy Croft** » June 29th, 2006, 7:46 pm

No - Do not worry about your post! Anyway we'll just work the technical charm on Charlie till he races!!

Right Charlie?!

So long as it is relevant to the discussion and presented as a manner as interesting as possible - write posts without fear of being 'off topic' or in the wrong place.

We are ALL merely humans trying to learn about things and each other and sharing a common bond.

GC

Julian · Post by **Julian** » June 29th, 2006, 9:50 pm

Sorry Acki - i suspect this is a difference in language use. As far as most people I know are concerned the diff ratio *is* the final drive ratio - one and the same thing.

The spreadsheet does work out the combined drive ratio as part of the calculation if you need to extract it.

Charlie · Post by **Charlie** » June 30th, 2006, 7:51 am

Hi, everyone,
Thanks for all your help on aquiring the gear set that I required.
All is in hand now as I have ordered them from Juniper racing.
They can supply OE parts or straight cut upgraded parts. They have confirmed that the OE parts are good for 120bhp for a track car. :) :) :)
Charlie

Acki · Post by **Acki** » June 30th, 2006, 8:01 am

Julian wrote:The spreadsheet does work out the combined drive ratio as part of the calculation if you need to extract it.

But the X1/9 1.5 Mpi gearbox is maybe the same like the Uno 1.5 Mpi gearbox?! When you install the 5th gear pair in the Uno Turbo gearbox you have a longer 5th gear.

I think the gear ratio is that what you have to know and the dif ratio with both you can realise a shorter or longer gearbox, what you like.

I must learn more englisch I think... :oops:

Julian · Post by **Julian** » June 30th, 2006, 9:03 am

The early SOHC (non-FIRE) Uno gearbox is indeed much the same as that in an X1/9. In theory the gears are fully interchangeable but it is not the entire story.

To give an example the Uno Turbo gearbox uses needle roller bearings instead of solid bushes for mounting the gear rings to the shafts. Not quite as durable in terms of absolute maximum loading but preferable for efficiency purposes.

It is possible to cherry-pick the ratios for your gearbox using the list I have as a guide but there is no indication as to the quality of construction or the exact fitting.

When re-building my race gearbox to use the Uno Turbo driveshaft layout instead of the standard X1/9 layout I had all sorts of problems. The gear shafts turned out to be a different diameter making it necessary to have any replacement components machined to fit. I couldn't use the needle bearings (as mentioned above) due to the way the gear rings were mounted. It turns out the gearbox I had was far from standard though, initial enquiries suggested it might be a Colotti gearset but when I sent the damaged parts off to Italy they proved to be otherwise. Thankfully Colotti were more than willing to cut new gears to match for the same price as their own gears.

What I have done since is experiment a little with different gear pairs for 5th gear and the diff ratio. The Uno Turbo diff proved very good but in conjunction with the matching 5th gear it left too big a hole in the ratios and the engine just bogged down unless I revved right to the red line in 4th. The original 5th gear gave much better performance even if it did chop a good 10mph from the top speed. Not just a matter of how fast you could go in 5th but I could actually accelerate at a meaningful rate. If the engine bogged down I might as well just stay in 4th...

There is of course much more to that story than just the gearing as I had all sorts of engine problems as well at the time so it is perhaps rather unfair to be making any meaningful comparisons. Ultimately what I needed was a 2 mile straight to repeatedly try different ratios over. Sadly the speed with which the gear ratios can be changed is a long way from ideal. You would only get to try 3 or maybe 4 combinations in a day making it a very expensive proposal if hiring out proper testing facilities.

Post by **Guy Croft** » June 30th, 2006, 11:35 am

that's a very, very good post Julian.

GC

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Final drive ratio for 4 speed x1/9

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