205/Mi16 Diff ratios

neil

neil

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Fellow Frogger
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Parry has just prompted me on a small point that I may have forgotten? :confused:

Is there a difference between the diff ratio of a S1 205gti and a S1 Mi16?

If so what are they?

Thanks

Neil
cheers!

<small>[ 21 October 2003, 01:46 PM: Message edited by: neil 416 ]</small>
 
Close Parry. 3.94 and 4.43. More importantly, the gear ratios also differ, which means the overall gearing is almost identical.

eg 5th gear
0.866 x 3.94 = 3.41
0.76 x 4.43 = 3.36
 
OK Peter

Whats going to happen when I put my S1 205gti diff in the Mi16 gearbox?

and

Will it fit without no problem?

Neil
 
Use the Mi16 1st gear and diff, with the other 205 gears. This gives the closest set of ratios, with the lowest diff. Hang on tight. You won't believe the acceleration. Top speed is approx. 200km/h @ 7000RPM.

The best combination:

1st 2.923 (from Mi16)
2nd 1.850 (the same in every gearbox)
3rd 1.360 (from 205)
4th 1.069 (from 205)
5th 0.865 (from 205)

diff 4.430

It's a bit low for highway cruising, but you didn't build the car for that. Right?

<small>[ 21 October 2003, 09:13 PM: Message edited by: PeterT ]</small>
 
Are the gears easy to interchange and would you recommend doing the swap with 1st gears on a gti '90 model. Would it matter whether it was modded or not? ( i just find 1st is a pain in the ass too high) Also if a 2nd synchro needs replacing can one be taken from a Mi16 gearbox /405/some type of cit
 
If it's a 90kW GTi, with a BE3 gearbox, you've already got the best set of gearbox ratios, with the high 1st gear. Unfortunately, the diff is too long at 3.62:1. You need to swap it for a 3.94:1 diff from a 75kW GTi. Swapping gears between BE1 and BE3 can be tricky, but I think the diff. is relatively straight forward. Ask Adrian Wuillemin.
 
Ok Peter

So whats going to happen when I put the 205 diff with the Mi16?

I'm not looking at changing the gears around and will be keeping the mi16 box intact but with the 205 diff.

I'm assuming that the acceleration will be better but rev to high on the highway?

Neil
 
Sorry, but you can't do that. The diff. pinion gear is cast on the end of the output shaft, which supports 3rd,4th and 5th gears. To change the diff. ratio you need to completely dissamble the gearbox. There is a good cross sectional drawing in the Haynes manual.

revs at 100km/h will be approx. 4000, 12.5% higher.
 
Bugger I think just about covers it from my end. cry :mad: cry

Peter are the internals of the diff the same in an Mi16 and S1 205 diff ie the sun gears etc.

I'm assuming the diff-pinion gear is the main gear of the diff? and this is what is ultimately different? :confused:

Neil
 
Perhaps you can put the 205 donk bank into the car to use the LSD. mallet

That gota suck though. What are your plans then?
 
The output shaft/pinion and the crown wheel are a matched set, and thus determine the diff. ratio. If you've got two BE1 boxes, the internals are identical. Many of the internals are identical on a BE3 too, but some differ. Best to ask Adrian for specific differences.

Have you thought about the overall ratios? If you can live with low 1st gear, I'd put the LSD into the 205 gearbox. The rest of the ratios will be a lot closer than the Mi16 ratios. There's really nothing special about an Mi16 gearbox, other than the low diff.
 
Parry

Good news I pulled the LSD out of the 8V diff and will be able to fit it to the Mi16 diff on Saturday. :D dance

So on Sunday I will give it a good bash up my local mountain to test the lsd.

Neil cheers!
 
Sorry Peter I meant the 90 model 75kW with BE3 gearbox and high ratio first. Can this be easily swapped with others? Is the 75kW too underpowered to deal with anything lower?
 
Two-oh,
if you've got the 75kW engine, you've most likely got the low 3.25:1 1st gear, along with the 3.94:1 diff. You wouldn't want any lower diff in a road car. It's worth changing 1st gear if you had to pull the box apart for any reason, otherwise I'd leave it as is. I'd go looking for more power instead.
 
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