Lotus Elan

5-Speed Candidate Conversion Chart

PostPost by: tower of strength » Wed Apr 16, 2008 7:15 pm

with regard to the overdrive unit, on a TR6 and I believe some Healeys the od operates on 2nd to 4th, giving 7 gears! Now I believe these cars are dramatically heavier and have far more torque than our cars so i doubt durability would be an issue(bear in mind 300BHP jags had OD fitted too). As for fitting, you would need to have 2 propshafts made up to fit the over drive unit into the drive line, the speedo drive would come off the over drive unit, so a longer cable would be needed the oil supply would be internal within the unit, when fitted to a gearbox tailhousing the overdrive often shares the gear oil with the box but has its own drain/filler, the pump is within the overdrive unit.. To install it, you would have to either "create" a removable access panel in the chassis, about a foot long or play "automotive gynaecologist " through either end of the chassis, engine or diff removed.

to operate it, a simple switch would do the job, later herald/vitesse steering columns have the switch on the column, the foot switch already mentioned, the triumph/MG jobbie on the gearKnob or a discrete switch on the dash.

Assuming the unit would fit inside the chassis, I rekon this could be a relatively easy/stealthy conversion with very few draw backs. Also as these units were very popular on other marques in period, then surely a "period" modification wouldn't offend the purists too much!?

Mark
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PostPost by: msd1107 » Wed Apr 16, 2008 7:38 pm

Gary,

Very clever idea.

I originally thought the OD ratio of .733 was going to be too wide.

However, with the Elan wide ratio & OD ratios of 2.97, 2.01, 1.40, 1.00, and .733, this produces a FoM of 90.8.

OD 3rd is not too useful, giving 1.026.

The car probably would want a differential ratio of 3.9 or 4.11 since the OD is so tall.

David
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PostPost by: steveww » Fri Apr 18, 2008 9:30 am

An other thought :roll:

If off the shelf 5 speed boxes are compromised because of ratio sets thus requiring new gears to be machined. Why not have a 5 speed gear set made for the 2000E casing?

It has been done for the MINI http://www.kad-uk.com/gearbox.htm so it may be possible for the 2000E?

Who knows some gear shops?
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PostPost by: robcall » Fri Apr 18, 2008 11:08 am

steveww wrote:An other thought :roll:

If off the shelf 5 speed boxes are compromised because of ratio sets thus requiring new gears to be machined. Why not have a 5 speed gear set made for the 2000E casing?

It has been done for the MINI http://www.kad-uk.com/gearbox.htm so it may be possible for the 2000E?

Who knows some gear shops?


SNAP!
http://www.lotuselan.net/forums/viewtop ... 3143#83143
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PostPost by: CBUEB1771 » Fri Apr 18, 2008 12:49 pm

I was surfing Quaife's site yesterday and noticed a new offering, a replacement for the Sierra T-9. See http://www.quaife.co.uk/Gearboxes. I wonder if Quaife could be persuaded to do a forward gear change version? The current offerings are expensive (3500 and 3100 GBP for dog and synchro versions, respectively) and the ratios are really intended for competition (2.536, 1.718, 1.281, 1.000 and 0.883 for the synchro version).
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PostPost by: CBUEB1771 » Fri Apr 18, 2008 12:56 pm

I tried to post a couple of different URLs from Quaife to go directly to the T-9 replacement box but every one of them just sends you to their home page. From the home page click on "online shop" then "cars" and finally "gearboxes".
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PostPost by: johnc » Mon Apr 21, 2008 5:50 pm

It has been said that the Lotus Elan close-ratio has excellent gear spacing, and the idea has been floated that it in combination with a custom cut 3.2 ring and pinion would provide an attractive solution for our desire of increased cruising speed.

Anyway, attached is a quick analysis to determine (1) the equivalent close-ratio transmission gear set using standard ring and pinion ratios, and (2) determine which candidate 5-speed transmissions have 2nd through 5th gear sets which are a close match.

Interestingly, the early Isuzu MSG 5-speed in combination with a 3.7 ring an pinion is a close match. And the standard T9 or latter Isuzu MSG 5-speed in combination with a 3.9 ring and pinion are a close match.

Both the early and late MSG 5-speeds where used in the Isuzu Pup (small pickup).
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