[DMCForum] DeLorean Differentials (was: Re: Racing)

["therealdmcvegas" <dmcvegas@xxxxxxx>]

Even if the first genereation S1 & S2 Esprits didn't use the same
transaxle as the DeLorean, the point is their differential ratios that
were used. The PRV is a fantasic engine, but is the scape goat that
keeps getting blamed when smaller cars keep beating ours off the line.
It's our gear & wheel ratios that are killing us.

The multiple-piece input shaft is certainly a problem with trickles
over to the 5th gear. The whole thing will begin to flex, because the
input shaft begins to twist, because it's so damn weak! Hence 5th gear
failure. Esprit World is probably THE best source for transaxle
information on the Renault box shared by the Esprit & DeLorean. Not to
mention it written in English, which I can understand. They have a
wonderful write-up on the Derrick Bell modification for the input
shaft. Even a video of the man himself explaning it.
http://www.lotusespritworld.co.uk/EModifications/Gearbox.html

Myself, I'm not too keen on having first gear suddenly going into a
straight-cut. Even if the material was made allot stronger to stand
the pressure, I can only imagine just how noise 1st gear must now be.
Daryl Tinnerstet knew a guy here stateside up in Washington who was
able to fabricate a new single-piece input shaft, just like Derrick
Bell made. Except that he was retaining both the stock gears, as well
as the shaft diameter, so you wouldn't need to modify the trans casing.

Here are the specs for the box overall:
http://www.lotusespritworld.co.uk/ETechnical/Gearbox.html

And here is the history of how Lotus tested, and adapted the box for
their use. As well as what differences there are between a
"Lotus-Spec" trans, and a regular one.
http://www.lotusespritworld.co.uk/ETechnical/Gearbox_Testing.html

GTO Engineering takes it a step farther, with their 6-speed
conversion. They fabricate all new internals. I wouldn't mind having
one, but the only place to get it in the US wants $8,000! So I guess
I'll be happy with 5 forward gears for right now.

-Robert



--- In DMCForum@xxxxxxxxxxxxxxx, Martin Gutkowski <martin@xxxx> wrote:
> I'm not the Lotus expert here but I know the S1 and S2 used a Citroen 
> box, not a UN1, and all the Esprits with Renault UN1's had a 3.44:1, 
> same as us - but my information is secondhand, though from reliable
sources
> 
> I've spoken at some length to a Renault/PRV and gearbox specialist who 
> confirmed that of the several hundred esprit boxes he has rebuilt, all 
> are 3.4:1
> The principle difference between the UN1 and the 369 is simply that it 
> has an extra linkage for the crossgate whereas the 369 just uses the 
> main crank. The UN1 is designed for two cables rather than rod and 
> cable, like ours.
> 
> I've heard conflicting stories as to whether Lotus strengthend the 
> internals on their gearboxes. Certainly on the late turbos and the V8's 
> they quite easily twist driveshafts, and a LSD is a good investment if 
> you drive them hard. They hit the same problem as us with the input 
> shaft coupler, and have an additional problem with 5th which is taller
> 
> I'm not arguing with you that it's a bad idea to lower the final
drive - 
> I'm doing that with mine. Although the alpines have the same final 
> drive, their wheels are smaller.
> 
> Martin
> 
> therealdmcvegas wrote:
> 
> > --- In DMCForum@xxxxxxxxxxxxxxx, Martin Gutkowski <martin@xxxx> wrote:
> > > Actually the Esprit and all the Alpines have the same as ours -
3.44:1
> > > But the esprit has a taller 5th which they break
> > >
> > > Martin
> >
> > The Alpine may have a 3.44:1 differential, but the Esprit certainly
> > does not! Going thru this list, I've not seen a single Esprit which
> > has had anything less than a 3.88:1
> >
> > http://www.lotusespritworld.co.uk/models.html
> >
> > In fact, on certain 4-cylinder, N/A engines, Lotus was kicking
> > differentials up to 4.38:1!
> >
> > http://tinyurl.com/8wsy9
> >
> > Going thru that list too, Lotus labeled the Renault transaxles as UN-1
> > types, followed by the number suffix as the individual model # of the
> > UN-1 platform. I also have an Eagle Premier "Service Highlights" book
> > that calls the transaxle a UN-1, with the number being the model
> > suffix. It even shows a diagram of how to read the transmission tags.
> >
> > -Robert
> >
> >
> >
> >
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