Isuzu Gearbox

[graham]

I am keen on doing a 5 speed isuzu gearbox conversion as my +2 didnt have gearbox with it . Have read earlier post on topic but cant seem to find any results for adapter plates and mounting alterations. Maybe someone has drawings.

[garyeanderson]

Hi Graham

A google searches on lotuselan.net reveals quite a few hits on the Isuzu box.

"isuzu 5 speed" site:www.lotuselan.net/forums

http://www.google.com/search?hl=en&q=%2 ... f&oq=&aqi=

"isuzu gearbox" site:www.lotuselan.net/forums

http://www.google.com/search?hl=en&q=%2 ... f&oq=&aqi=

The Isuzu ratios suck except for possibly the Isuzu impulse GT but if thats all you can find in New Zealand than go for it. John Connin was warm on this box at one time but I think that he has moved on to other idea's. As for a gearbox for your plus2 I would find a Ford 4 speed box on ebay, if you can't find one locally and get it running. Unless someone gives you a Isuzu box and drops it off at your garage I'd do the Ford thing. 67 to 70 Cortina GT models have the 2.97 1st gear with the shifter at the rear of the tailshaft and the early 63 to 66 cortina's have the right tailshaft shift rails and shifter location but awful ratios. A little surgery and you have a Lotus box. If you need to reduce the revs on the highway, try the 3.54 ring and pinion from the RS2000 Escort. This gives 19 mph/1000 rpm. When that doesn't fit you needs than try the 5 speed swap. Just 2 cents that you didn't ask for.

[msd1107]

More answers for which you did not ask:

elan-f15/quantum-mechanics-john-esposito-speed-offering-for-elans-t19015.html is a drop in T9 5-speed.

http://www.conversioncomp.co.nz/about.php has advertised Elan kits. Colin recomments the T50 transmission and he claims to be able to offer other gear ratios. However, it is not clear this is a drop in conversion.

David
1968 36/7988

[AussieJohn]

Don Mace has done quite a number of these conversions, I dont know if he is on this forum, he moved from Sydney a few years ago, if you cant get any more info then email me.

[Lincoln62]

The Gemini rally guys like the diesel Gemini box, not sure why, might be worth investigating.

Here are some ratios from the Gemini forum.
Gemini
3.790
2.175
1.417
1.000
0.855
R 3.826
F 3.9

Gemini Twincam
3.174
1.963
1.364
1.000
0.855
R 3.402
F 3.909

Piazza Turbo
3.431
1.963
1.364
1.000
0.775
No reverse or final.

tc/d 5sp -
1st 3.507:1
2nd 2.175:1
3rd 1.418:1
4th 1.000:1
5th 0.856:1
rev 3.759:1

te 5 sp -
1st 3.467:1
2nd 1.989:1
3rd 1.356:1
4th 1.000:1
5th 0.855:1
rev 3.438:1

diesel 5 speed
1st 3.48:1
2nd 1.99:1
3rd 1.36:1
4th 1.00:1
5th 0.86:1

Peter
66S2

[garyeanderson]

Jewels posted this link on her cortina mk1 site.
http://www.cortina-mk1classifieds.com/f ... php?t=1210
Not to much about Isuzu boxes but the folks at Dellowauto.com.au offer a pretty nice pdf that give spline counts (input and output), shift locations on various boxes, input length, pilot bush diameter, various bellhousings, etc. 35 pages, 611kb so its easy to download. All good info for the mix and match people around.

http://www.dellowauto.com.au/catalogue/ ... motive.pdf

I still have the feeling if you want to swap a 5 or 6 speed box into an Elan or Plus2 you would be better off to take the engine along with the box. Any of the newer 4 cylinder alloy powerplants with box would make these vintage Lotus cars a match on the highway for the modern cruisers of today.

Gary

[gordont]

Graham and Aussie John

Don Mace retired up the coast a few years back (with his Elan) but I still do see him occassionaly (and no he is not on the forum).

I will drop him a line and see what he has to say but I do know of a few Elans around with this conversion done by him.

cheers

[graham]

Thanks for the replies sounds like a hot topic -have had contact with one owner doing tha swap in NZ, matched ford bell housing with izuzu photo looked good. car was originally a 5 speed and I thought it would be good to replace with 5 speed. I do have a 2s130 4 speed box. As speed limit in NZ is 100kph not a lot of cruising at 70mph+.

[msd1107]

graham,

If for you the gearstick is meant to be used 4 times to get to cruising speed, the below discussion can be safely ignored.

All the Isuzu gearboxes are sedan gearbox ratios. As such, they are more or less unsuitable for the relatively lightweight pedigreed +2, with 1st gear being too low, larger than desirable gaps between the ratios, and 5th not high enough.

There was quite a discussion about this on a recent 6-speed thread, and a thread on the Esposito 5-speed. There have been many other threads on 5-speeds in the past.

elan-f15/speed-gearbox-for-the-elan-t18541.html
elan-f15/quantum-mechanics-john-esposito-speed-offering-for-elans-t19015.html
These threads have a link to a downloadable spreadsheet so you can evaluate all the Isuzu gearbox ratio variants.

After all the above, the Esposito 5-speed with the BGH 2.75 1st and .82 5th probably is the best you can do for your +2. It bolts straight up so there are no conversion hassles. The big impediment is the cost, especially if you can do much of the Isuzu adaptation yourself. But this is a decision between you and your credit card.

Good luck on your +2. Let us know what you do and your evaluation of the results.

David
1968 36/7988