lotus esprit un1 version

tony · 03-28-08, 02:23 AM

Hello,

I searched the forum for the un 1 upgrades, looks like not other choicess exept the gto racing kit

also I think I read about fellow Lambo member machined his own primary shaft,

Is there other options out there more resonable for us with weak us dollar

or any new tricks that someone did lately to beefup their box

thanx in advance
tony

Paul Thompson 'Hooligan' · 03-28-08, 03:57 AM

Hi Tony -

Welcome to the Forum - I think it's been covered before but there was a beefier one piece main shaft conversion, (not the 6-speed conversion) that was also being sold by Chris Cole (formerly Mach 1 Transmissions) and also I think by Andy at Tornado Cars. Might be worth trying them for more details.

Also - Ron used to have an Esprit, he might also know of some suitable upgrade routes.

Thomas Rouw · 03-28-08, 07:29 AM

The upgrade kit with the better input shaft is from here they also supply them to tornade iirc.

grtz Thomas

tony · 03-28-08, 03:15 PM

I heard Derek Bell is not offering the upgrade anymore,
his desighn will be available through halloway performance
in few months

also I think tornado is ofering gto racing product
so that leavs only gto racing

how can I get a hold of Chriss Cole any more info on his upgrade?

thanx for the replys guys
tony

BruceLambo · 03-28-08, 04:21 PM

Hi Tony. I have a Lotus Esprit but I dont have the upgrade kit in it.
You're right about the price of the upgrade kit. It is very pricey.
I have upgraded one of my UN1 boxes for use with a 406 V8.
What I did was to check out what was done with the ugrade conversion and then armed with pictures and facts, trotted off to my local gear cutting/machining company.
They had done similar things before for other boxes so this was no different.
I wound up getting the same thing made for less than half the cost of the advertised upgrade. Also a few other small mods done at the same time - and you can get the clutch spline cut to what ever you want as well. But there is nothing wrong with the Ford one, as Ive gone to that!

tony · 03-28-08, 04:31 PM

great Bruce,
did u keep the stock ratio on the 1st gear?
not sure on v8 but at 8k rpm range I need to give it a break
to pop in second if not it grinds

I would love do go that round since I am on a tight budgett
I would realy apritiate any help I can get from you

also where should I look for good price on quaife atb

BruceLambo · 03-31-08, 04:01 AM

Hi Tony. Yes I kept the stock 1st gear but had the option of going lower, but with a 3.44 diff I needed to still be able to drive around town! Second gear can also be changed if you needed, but its not too bad as it is. Probably just close 1st to around 3.0 or so.
Anything can be made you know. The 5th gear isnt too bad at .89. Some have the .76 ratio and that theoretically would put you in the bloody fast category, but my take on it is that you need more power to push the .76. Also the .76 is placing more stress on the shaft and gears as they are on the overhang (and of course overdriving). One change Im doing is making the 5th gear 22% wider to around 22mm from 18. It has been known to strip, but some of this I would also attribute to heat issues, so run a cooler.

As for the quaife diff, I believe the only place you will get one is GTO engineering.
I have put the 4-spider diff unit out of a 369 box into my UN1-13. A small spacer/alingment plate was made and I rebushed the crownwheel output shaft bearing surfaces to take the 2mm smaller shafts. Works fine.

tony · 04-01-08, 08:40 PM

Hi Bruce,

I have the UN1-26 so called lotus high torque gearbox with different .82-5th and 3.89-final ratio,

something like 1st/2nd – 2.77 X 1.93. I think would be perfect,
bring it close ratio keep it on a power band

the engine I am trying to go with is 20B rotary mazda, so I will need longer primary shaft with gm t56 style spline, so I can use havy duty twin plate clutch and flywheel I have laying around from a rotary to t56 project

so far I emailed and called lots of places with no luck,
only albins gear got back to me they said they can do custom ratios,
so I emailed them back if they can do custon primary shaft,
hope to hear positive from them

so when u did urs how did u aproach the machine shop did u give them
any drowings or have the shaft with u and ask tham to make modified copy

posted and emailed everywere no luck
u r my only hope now

thanx again
tony
thanx again

tony · 04-01-08, 08:48 PM

here is some info on the lotus box

Esprit 'Renault' Gearbox

if anyone interested

BruceLambo · 04-01-08, 10:58 PM

Hi Tony. Yes the high torque box has the different material for the CnP and a few other small things. But it still has the dreaded undercuts on 5th and the reduced spline sleeve coupler on the input shaft.
My shaft is a lot longer than the wellknown upgrade one as Ive used a chev bellhousing and put my adapter plate between the box and the rear of the bellhousing so the shaft needed to be about 2" more.
I took the original shaft, and a few ideas on paper to a good machining company that deals in shaft and gear design/manufacture. I showed the foreman some photos of a 1-peice shaft, we tossed around a few ideas, done a few measurements and he said "no problem!"
To make the new gears, they simply machined off the gears and shrunk and welded on a new billet, then cut the new gear teeth into the billet and hardened it accordingly. This saved a lot of remanufacturing of the gear. They do this as part of their business and have none ever fail.
The first gear is straight cut because of restrictions in size of the cutting head up to the reverse gear teeth. No biggie.
Ive attached a pikky of my gearbox so far. The diff unit is a 4-spider from a 369 box and the round plate above it is the spacer for it.

Eric Johnson · 04-02-08, 07:20 AM

Tony,

Thanks for the Renault info.Very informative.

tony · 04-02-08, 06:12 PM

ur welcome Eric,

Bruce,

looks like I am in good luck with albins gears,
they can build 1 pc shaft heat treated out of en36 steel,
they gaved me a decent price,

I am hoping to fit everything with quaife atb under us$4k

thanx again
tony

BruceLambo · 04-03-08, 02:03 AM

Tony, yep same stuff I had mine made out of en36.
Oh just one thing though, to make the shaft diameter bigger at the bearings, have the centre of the bearing bored out, say 1mm to give you a 2mm larger shaft size. There are no oversize bearings available, so hence boring the centre out. There are a few other parts like washers, sleeves etc that need to be bored to suit but again, no biggie.

tony · 04-04-08, 02:51 AM

Bruce,
not sure I understand the problem with 1st gear,
is there a way to get it helical cut, would hate to
have that loud reverse driving sound, it will probably be
even louder with 1st gear being thicker, but I can live
with that if I have to.

also albins they can do it but it will take them 14-16 weeks,
so will try to search for some more local places next couple
weeks before I put my order with them.

tony · 04-04-08, 02:57 AM

Is there good email for GTO engineering,
their web site is down, or a phone #

thanx

BruceLambo · 04-04-08, 10:02 PM

Remember that reverse gear usually uses 3 gears to do the job. The first gear is using just 2. The straight cut is due to the size of the gear cutter. A helical cut one would hit the reverse gear teeth if it was used. The factory used some other sort of cutter, I believe to be very expensive and hence not stocked by too many gearcutting companies.

Try these options:
G.T.O. ENGINEERING
Scarletts Farm
Scarletts Lane
Hare Hatch Nr Twyford
Berkshire
RG10 9XE

Tel: +44 (0)118 9401101
Fax: +44 (0)118 940 1372
Email: gtoracing2001@hotmail.com