View single post by StevenD57
 Posted: 03-03-2013 02:45 am
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Joined: 04-10-2009
Location: Hubbard, Ohio USA
Posts: 103
Yesterday after almost two years of on-again off-again design work, preparation, and fabrication I got to drive one of my Jensen-Healeys with a five speed transmission where the fifth gear is an overdrive ratio that lowers the engine speed while cruising on the highway. This is something I have been dreaming about for around five to ten years when I used to drive another one of my four-speed equipped Jensen-Healeys around on the freeways around Atlanta and was frustrated by what I felt was a very poor gearing design that artificially limited the comfortable highway cruising speed of the car.

So after all of this work and waiting, how was it? Well the initial experience is tempered by the lack of a gearshift knob that has the correct thread to match the Toyota W58 gearshift lever and a certain amount of harshness due to the transmission mount cross member still needing some work to correct some clearance problems around the back end of the Toyota transmission case. Plus I finished up the initial install only hours before having to prepare for an extended business trip so I only got to drive the car across town to visit Art DeKneef in Mesa AZ (southwest suburb of Phoenix) and then back to North Scottsdale so I did not get a whole lot of seat time as of yet and I am still a little new to the experience. So far I can see the 800 - 900 drop in RPM when cruising at 70MPH but I have not been able to enjoy any extended higher speed cruising in the 80 - 85 MPH ranges.

Technical details:
  • Toyota W58 transmission out of a late 1980's Toyota Supra
  • Lotus Excel bellhousing that Dan Eiland helped me obtain back in 2011
  • Altered the Lotus bellhousing to switch from hydraulic to stock JH cable operated clutch mechanism
  • Toyota Clutch kit (larger diameter clutch than stock JH one)
  • Re-drilled flywheel to use  dowel and bolt pattern to match the Toyota pressure plate
  • New driveshaft with Toyota slip yoke and longer length to account for the shorter overall transmission length but with correct flange to bolt up to input flange on the original JH four speed rear axle
Long term plan:
This first car is just the initial prototype of what I hope to be many more 5spd installations. I have two or three other cars I would like to convert to 5spd transmission setups. Plus I know there may be other JH owners who would also like to do the same conversion without spending huge amounts of money and time to source all of the required bits. Since the Lotus Excel bellhousing is such a hard piece to find here in the US (and possibly Europe), my current design efforts have been concentrated on altering the existing four speed bellhousings that are so relatively plentiful to accept either the Toyota W58 transmission or the Ford T9 transmission. I already have two 4spd bellhousings in the fabrication stages, one for each transmission, using fixtures that will enable the production of duplicates once the initial trial installations have been certified to work properly. I expect to enter into series production soon since I already have pre-orders from two folks who have already supplied me with their spare four speed bellhousings. Once I have the final designs of the altered bellhousing available they will be supplied on an exchange basis where the buyer will have to supply a stock four speed bellhousing
Steve DuChene

Last edited on 03-03-2013 05:53 am by StevenD57