WHAT TRANSMISSION COULD REPLACE UN1 ? - LotusTalk - The Lotus Cars Community
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post #1 of 109 (permalink) Old 02-16-2012, 06:16 PM Thread Starter
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WHAT TRANSMISSION COULD REPLACE UN1 ?

I would like to collect your thoughts on replacing UN1 with more durable and modern transaxle able to handle up to 400 lb-ft.
I'd like to start discussion by presenting an idea of using 6 speed Cayman S transmission.
I'm curious if anyone has installed one like this in his/her Esprit, yet?

California Motorsports Porsche 987 987c Boxster Cayman transmission section

http://www.californiamotorsports.net...701%202005.pdf

178.33 MPH at 7000rpm, cable shift. They're modern technology; shift lightly and more quickly than the UN-1 and you could use/adapt a Porsche Boxster shifter.Getrag rates them conservatively at 380nm which is about 280 ft-lbs of torque. For road use, not drag racing, one might get away with 400 ft-lbs.
Also available in Audi Avant version http://www.advancedautomotion.com/pr...products_id=29

TRANSMISSION SPECIFICATION

· Type: G87/01

· Original equipment for: Boxster 987 05-08; Cayman 987 07-08

· Description: H Pattern 5 speed manual transaxle with triple cone synchromesh (1st/2nd only) and synchronized reverse

· Limited Slip Differential: Not offered as optional equipment by manufacturer

· Speedometer: None

· Trans controls: Shift cables

· Clutch: Hydraulically assisted push clutch, single plate

· 1st gear 3.50

· 2nd gear 2.118

· 3rd gear 1.429

· 4th gear 1.091

· 5th gear 0.838

· Final drive 3.556
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Last edited by MRDANGERUS; 02-16-2012 at 07:44 PM.
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post #2 of 109 (permalink) Old 02-16-2012, 07:31 PM
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This one is an automatic...
Quote:
Originally Posted by MRDANGERUS View Post
If you want a porsche transmission, then maybe look at these guys...
SPECIALIZED SERVICES FOR PORSCHE TRANSAXLES-GBOX Transmission
They will help engineer a Porsche G50 in a kit car, or probably an Esprit as well.

Travis
Vulcan Grey Esprit 89 SE

My Lotus Project Photo Collection
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post #3 of 109 (permalink) Old 02-16-2012, 07:37 PM
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I have a friend who plans to put one of these behind some LS variant. He says it's a pretty common swap for mild V8s. I think there might be an issue with the starter placement though.
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post #4 of 109 (permalink) Old 02-16-2012, 10:00 PM Thread Starter
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post #5 of 109 (permalink) Old 02-17-2012, 12:24 AM
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G50's are bulletproof and ideal for high torque applications, but have to be turned upside down and fitted as they are orientated the wrong way round in the Porkers. GT40's and Ultimas use them ok as their chassis has better space/positioning, and they swear by them for the racing applications. The Esprit however is a tougher proposition and I only know of one that managed it at some very high angle for the CV joints. It was done in the UK for a track car, but the parts were sold on, and I think a guy in the States ended up with them

The other Getrag units, like those used in the Boxter/Cayman and later Boxter S/Cayman S, are not rated as highly but are a far easier fit for the Esprit. Their Audi variants have been popular with GT40 replica builders for a long time as they are far cheaper to obtain, and a few Esprits have also fitted variants of them (such as Andy Hills' Audi 4.2ltr V8 project) and I am in the process of trialing one myself with the tuned LS3. The one Advanced Automotion promotes is the old 01E FWD version, reputedly stronger than the newer ones like the 01X/0A2 due to its cast iron bearing carrier.

Last edited by B33 ENN; 02-17-2012 at 03:29 AM.
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post #6 of 109 (permalink) Old 02-17-2012, 09:35 AM
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Not sure about fitting in the Esprit but as others have stated I know that Factory Five GTM car uses one to bolt up to a LS motor. Here is what they use off their website.
Other Components/Parts

Porsche Transaxle Parts from 1990-1998 2-wheel drive 911 models

Porsche G50 or G50 variant transmission including clutch disk, pressure plate, throw-out bearing, inner CV joints and starter
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post #7 of 109 (permalink) Old 02-17-2012, 09:37 AM
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If someone could get that 911 trans to work, I don't think there would be an Esprit that could put out enough torque or horsepower to even worry about handling the swap with ease......power wise.
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post #8 of 109 (permalink) Old 02-17-2012, 08:19 PM
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I'm in the process of fitting an Audi 01E to my LS3 powered 914. I sourced mine from Advanced Automotion. Because of HP for my application I used a custom 1-2 gearset and went with full WPC treatment. I also went with a Wavetrac diff which I can't wait to try. I think this trans would be a good candidate for an Esprit. If used behind a 4 cyl you could probably just use one without any mods.
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post #9 of 109 (permalink) Old 02-17-2012, 10:11 PM Thread Starter
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post #10 of 109 (permalink) Old 02-18-2012, 01:47 AM
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Quote:
Originally Posted by MRDANGERUS View Post
That looks pretty nice. Only $2600!
I'm wondering if it'd clear Esprit trunk floor and the rr brace.
That one is too long as it is the 4WD version. You want the FWD that looks like this:



It is short enough to fit the body length with an adaptor plate, but will require a custom cross brace as it is higher than the Renault UN1-2x series. (If you intend to use it with a Lotus engine, it may require a revised engine height/position to align the input/output shafts, therefore new mounts.)

As far as I know the 01E only came in these ratio sets:

1 - 3.50
2 - 1.89
3 - 1.23
4 - 0.86
5 - 0.67
6 - 0.56 (/0.60)

F - 3.85

or

1 - 3.75
2 - 2.14
3 - 1.51
4 - 1.17
5 - 0.97
6 - 0.82

F - 3.85


You would need to check if the power/torque characteristics of the engine you intend to use will work well with the longer or shorter set (although AA might offer some customised ratios.)

Last edited by B33 ENN; 02-18-2012 at 01:53 AM.
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post #11 of 109 (permalink) Old 02-18-2012, 03:40 AM
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Some measurement here:
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post #12 of 109 (permalink) Old 02-18-2012, 08:59 PM Thread Starter
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Here is a cable shift for 01E
Audi Shifter - Lambo Lounge

And here are the gear ratios for Audi 013, 016 and 093 serial numbers
http://www.lambolounge.com/Chassis/T...-915/index.asp

Which one did you choose?

Last edited by MRDANGERUS; 02-19-2012 at 09:28 AM.
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post #13 of 109 (permalink) Old 02-19-2012, 09:47 AM
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Fitted an 01X as it was available, but considered an 0A2 also.
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post #14 of 109 (permalink) Old 02-19-2012, 04:25 PM
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I admire you fella's techno. savvy.

Was on the Porsche Rennlist site for almost 9 years.
I hate to say it but it seems Lotus owners are more sophisticated and more 'keen' than the 928 owners.
I do NOT mean to over-state!
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post #15 of 109 (permalink) Old 02-19-2012, 10:04 PM Thread Starter
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0A3 Trans = B6 S4, is rated 450Nm, but is hard to get. Quattro is too long for Esprit. Is the 2 WD tranny shorter than C35 or UN1?

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post #16 of 109 (permalink) Old 02-20-2012, 02:33 AM
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Torque ratings for quattro transmissions (like the 0A3) are quoted as a shared figure across both outputs, and converting to FWD would reduce it considerably. I don't have dimensions to hand but I believe the FWD units are slightly longer than the C35/UN1(inc. bell housing).
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post #17 of 109 (permalink) Old 02-20-2012, 04:41 AM
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...no matter, you have to do a lot of fabrications - bellhousing fitment, clutch parts, half shaft, linkage and many many more. So, I will start with this one
TXL 300 - 600nm torque approx 530in/lb
...at the end, It's not cost effective.
why not find strong internal parts for UN1 and go from there?
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post #18 of 109 (permalink) Old 02-20-2012, 11:27 AM
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I stuck with the Renault unit through many of my adventures with uprated Lotus engines, and never broke one. I still have a couple of them lying around somewhere. It's actually a very strong box given its original application. It was raced, and is still used in many uprated Esprits, as well as GT40 replicas etc.

However, engine power has marched on significantly, but I believe the old Derek Bell re-engineering of the UN1 internals is still available through GTO Engineering.

If added to the cryo-tempering and REM isotropic super finishing procedures becoming more available lately, I think it could easily handle any uprated Lotus Esprit engine - except perhaps the most extreme ones.
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post #19 of 109 (permalink) Old 02-20-2012, 12:52 PM
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I agree....that's what I did - GTO Engineering - I'm not going extreme.
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post #20 of 109 (permalink) Old 02-26-2012, 07:13 AM
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[/QUOTE]If added to the cryo-tempering and REM isotropic super finishing procedures becoming more available lately, I think it could easily handle any uprated Lotus Esprit engine - except perhaps the most extreme ones.[/QUOTE]

Cryogenic treatment vastly improves your load and longevity of metal parts. I see a lot of people rebuilding their motors and wonder why they dont have the liners, pistons, valves i.e. all internal parts treated.

There is a caveat! You must have someone really good do the treatment and VERY few in the WORLD use good cryo coolers and know how to heat treat after very well!

Shameless Plug:
We treat a lot of racing teams internals: Top fuels drag cars see six times the life from valve springs alone after cryo treatment.
I have attached an article for some interesting reading.

If you need any info I can help:
Bentzion (at) metal-wear (dot) com
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File Type: pdf Cryo Article in Performace Engine Mag.pdf (360.1 KB, 671 views)

Last edited by Gatso7; 02-26-2012 at 11:42 AM. Reason: grammaticle error
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