Lotus Elan

T9 gearbox conversion

PostPost by: alaric » Wed Jan 18, 2006 8:41 pm

Hi all.

You probably recall my long agony chain re the fitting of my Voigts box over christmas. Since that chain I've had visits and emails from other interested elan owners that want to do the same conversion.

The outstanding concerns appear to centre on how well this box performs in practice i.e. what's the gearchange like? Is it as good as the 4 speed ford box? Does the modification to the tail section affect the quality of the change? Are the gear ratios ok?

I can't answer these questions at the moment, as I am still awaiting the return the Elan's body. I am very happy with the box - it's certainly nice and shiny on the bench, appears to have been built well, and the clutch actuator set up is very neat.

Some feedback from people that have the t9 fitted would be appreciated.

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PostPost by: worzel » Thu Jan 19, 2006 9:36 am

Hi Sean

Can only speak from experience so no claim to this being a definitive reply-

I converted my car 7 years ago- cannot fault the conversion (mine was done by the person who designed the original conversion back in 1982). I supplied the box, he carried out the alteration and I fitted it etc.

In terms of change quality the 4 speed is probably slightly better- but only just- the curious thing is that changing "slowly" at lowish revs is actually not as good as "fast" ones at higher revs (the opposite of what I'd expect).

I know the intermediate gearing is slightly different from the 4 speed but I can't honestly say I've really noticed it. The main difference in my own car is that 1st on the T9 is lower than the 4 speed and third a bit higher. I run a sprint with 3.54 diff and tyres of 1836mm rolling circumference so that gives 22.7mph in top per 1000rpm.

3rd now gives about 95 at peak revs so quite useful. Don't expect a magical transformation in refinement or noise- there isn't any but 70 is now an easy 3100revs.

Incidentally, you can obtain an even higher 5th ratio if your conversion uses a box from a 2.8 engined car. 5th on these is 0.82 but by swapping the complete 5th gear cluster from a box sourced from a 1.6/2.0 sierra or similar and ditching the one in place you can obtain a 5th ratio of 0.75.

I'm doing this later this year to give me 25mph/1000 revs because I've found that it pulls strongly in top anyway and I sometimes think I'm still in the old box's 4th!.

Good luck with the conversion- well worth it.

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PostPost by: John Larkin » Thu Jan 19, 2006 4:09 pm

I had an Alan Voigts box installed in September 2005. The gearchange is notchy in the 1st/2nd gear plane, but faultless for 3rd, 4th and 5th. The car is quieter at speed. The clutch action is really easy. It seems to be a quality package.

There were a few problems installing it: front splined shaft on propshaft would not go into the gearbox, and machining was required; Voigt's differential spacer had to be omitted because it pushed the engine and gearbox too far forward (a dimensional issue with my twenty year old Spyder chassis?); raised bump on underside of gearbox fouled the exhaust and had to machined off. I was unhappy with the clutch pipe being bracketed from the exhaust (I was afraid of boiling the fluid) so I had this modified. Cost was ?4500 all in.

Overall I'd recommend the conversion.
John Larkin
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PostPost by: Foxie » Thu Jan 19, 2006 7:52 pm

The cost of an Alan Voigts T9 conversion is about the same as a newly reconditioned Lotus 5 speed. The difference is the Lotus 5 speed is marginal reliability and a rubbery and uncertain gearchange, especially between 4 and 5. I bought a used Lotus 5 speed 3 years ago. It was fine when I put it in, but the bearings failed within 3,000 miles. (And I didn't abuse it !)

The Lotus 5 speed uses special bearings , now obsolete(stepped dia outer races) which have not been produced for years and are now rare. The T9 was Ford's bread and butter for years and is very reliable, strong, and would be no problem with rebuilds.

I fitted the T9 in my Spyder chassised +2 two years/ 9,000 miles ago. It's been to Florence and back, over the Alps, and to Denmark and Sweden last year.
I'm very pleased with it.

The 2.9 1st gear in the 4 speed gearbox was not very practical, the 3.65 in the conversion is much more useful, especially on alpine hairpins !

The layout of the gearchange is much better, reverse is on top left, 4/5 on the right. Nice concise action.

The concentric clutch release used is much lighter than the original.

The clutch bleed is much more accessible, to the rear of no. 4 exhaust pipe. In my constant search for perfection, I drilled some holes in the mounting bracket to reduce the heat path and increase cooling, but I don't think there would be any danger of boiling the clutch fluid even without this.

Of late I am having to use a longer clutch pedal stroke to engage 1st/reverse, will check it out soon.

I had to do some metal removal in the Spyder chassis (the central web) and trim some excess metal off the gearbox casing. I supplied Alan Voigts with drawings and details, I think he has incorporated this in the installation directions. There is a big lump of aluminium underneath the casting which interfered with the exhaust, I sawed /ground this off. Maybe AV has rectified this in subsequent kits. The gearlever mounting turret is secured with 3 bolts, a big improvement on the Lotus 4 or 5 speed types.

As mine was the prototype T9/Spyder chassis installation, I fabricated the gear box mounting plate myself. I made drawings of this for Alan Voigts.

The fitting instructions were a little short on clutch piping & speedo cable arrangements, but we managed to figure it out.

I found it necessry to remove the selector detent spring plug in order to remove the engine and gearbox as a complete unit, as it jams under the firewall. A cut-down ratchet ring spanner and some gyaecological experience comes in handy.

Very interesting to hear about the 0.75 overdrive option, I'm sure this could be ordered with the kit if required.

In short, I am completely happy with this conversion, it's great, I would never be able to live with the old 4 speed.

Sean Murray
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