Gearbox choice for Beta VX

[jazzygeoff]

Hey guys,

Please excuse my ignorance :-) I'm in IT not mechanics. My engine has now been stripped and the car has gone off for a bit of panelbeating before the new VX engine goes in next week.

Now I'm not sure if this is possible but I have been told by a few people that it is, basically I was thinking about using my standard 1600 box on the new 2L VX engine. This will save me a lot of money and I have been told that the shorter gear ratios will actually increase my 0-100 time. This car will be a road car and I'm more focused on acceleration than top spead.

So any advice will be great.

Thanks Geoff.

[Guy Croft]

Geoff, hi

you might well find that the only difference is the 1600 (normally apsirated) gearbox just has a lower final drive; if that is correct (and I am sorry I don't have any Lancia gearbox ratio data) then the acceleration when fitted to the Vx unit compared with the OE gearbox for that car will be 1) much quicker but 2) the speed in each gear may be reduced (unless you rev the engine higher, which may not really be possible - or worth it) and 3) the achieveable top speed will be lower too.

(2 & 3 because in standard trim the Vx which is 136 bhp @ 5500 rev/min, 152 lbf ft @ 3000, really struggles much over 6000rpm)

I hope that is some help. Andrew Cliffe at Omicron (a member here) might know more, here is his email:

Andrew@omicron.uk.com

(If you write to him please tell him I posted this. I'm sure he has plenty to do)


GC

[jazzygeoff]

Hey Guy,

Thanks for the advise, this is what Andrew replied with. So I think I may be keeping the 1600 box with the low final drive.



Hi Geoff

Most Betas used the same set of gear ratios but changed the final drive
to suit the likely characteristics of the car. The feeble engined
versions needed a low final drive (numerically high) in order to
maximise performance, whereas on the more powerful ones this was lowered
as it gave a more relaxed cruising speed.

Gearbox__1600________ 2000VX

1 _______ 3.500_______3.500
2 _______ 2.235_______2.235
3 _______1.522_______ 1.522
4_______ 1.152_______ 1.152
5_______ 0.925_______ 0.925

Final ____ 4.071_______3.263

I've just been doing this on my own Montecarlo which is a little more
complicated, but the gearing is effectivley the same. I'll dig out the
piece of paper I did some sums on and I'll reply with some maths. I'll
assume a 7000rpm rev limit. My car is going to be track orientated as
well, so I went for a 4.462 final drive rather than the 3.714 they came
with.

__________________________________________________________________________

Hi Geoff

According to my figures, and assuming 6500rpm and 175/70/14" tyres, the
theoretical maximum speed in each gear would be as follows. Real world
would be less as calculations do not take into account aerodynamic
losses and so on.

gear-------1600--------------2L VX
final drive-4.071 - 3.263

1st -------32mph----------- 40mph
2nd -------50mph----------- 63mph
3rd -------74mph---------- 92mph
4th --------98mph---------- 122mph
5th --------121mph---------152mph

Calculating acceleration is somewhat harder as there are a lot more
factors to consider, but there are various simulators that attempt to
simulate a cars acceleration (eg Car Test or Car Test 2000) There
will be in increase in acceleration, and it will certainly seem faster.

I would suggest sticking with the 1600 box to start with, and if
required source a VX box at a later date. We have a VX box available
if you want.

Best Regards

Andrew

[Guy Croft]

Thanks for the acknowledgement Geoff!


Thanks very much Andrew at Omicron (respected family firm of Lancia specialists) for the very helpful and carefully considered reply.

GC

[jazzygeoff]

yes,

A big thanks to both you and Andrew on this. It has saved me quite a bit of money and, I'm going to stick to the standard 1600 box.

When it's all up and running I'll post some times and speeds per gear and see how the 0-100 time has improved.

Geoff

[pewe484]

Hi, Geoff. I stand to be corrected but the 2.0ltr VX gearboxes I believe were uprated to cope with the extra power.
I sold mine recently as the car had come to the end of its useful life due to tin-worm but the motor engineer (and fellow Lancia Owner's club member) who bought it reckoned they used up-rated bearing etc.
I see there is one on offer and would suggest that if it's in good nick you think about buying it.
There were only something like 300 VXs (coupes and HPEs) imported into the UK so a genuine VX gearbox is about as rare as rocking horse poo.
Best of luck with the project, Pewe.

[tmvolumex]

One thing to be aware of when attempting to swap the final drive between Lancia transaxles is that the pinion gear shaft carries the transmission gears and there were 2 different styles used in the transaxles. Some of the shafts use needle bearings and some use a grooved plain bearing (bushings). The two styles are not interchangeable. IE in order to change the final drive you have to use the final drive ring and pinion of the desired ratio and the gear set that goes along with it.
tmvolumex