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Living the dream: JH W58 5spd  Rating:  Rating
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 Posted: 03-03-2013 02:45 am
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StevenD57
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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

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 Posted: 03-03-2013 02:12 pm
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Sander
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 Posted: 03-03-2013 02:39 pm
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StevenD57
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 Posted: 03-03-2013 02:42 pm
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Jensen Healey
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Wow! Great work Steven!
I'll have to look in the boneyard for a bellhousing.
I installed a rear end from a 5 speed car into my '73 to alter the cruising rpm's. The 4 speed gearing is a little funky with this setup but the power upgrades I've done have improved the torque so it drives fine.
Sander, these cars are not museum pieces, they are meant to be driven, modified, rebuilt, raced, and ultimately, scrapped.
Whoever has the most fun wins!
Kurt

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 Posted: 03-03-2013 02:57 pm
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StevenD57
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Here is some information on the gearing of the various transmissions (Thanks to Tim Engel for the figures):

..................... 1st ...... 2nd .... 3rd ..... 4th ..... 5th
Toyota W58......3.285.... 1.894... 1.275.. 1.00 ... 0.783

Getrag 245 ...... 3.37 ... 2.16 ... 1.58 ... 1.24 ... 1.00

Ford T9 ........... 3.36 ... 1.81 ... 1.26 ... 1.00 ...0.80

JH 4-spd ......... 3.12 .... 1.99 .... 1.30 .... 1.00

Last edited on 03-03-2013 03:14 pm by StevenD57

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 Posted: 03-03-2013 09:02 pm
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subwoofer
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Jensen Healey wrote:
Sander, these cars are not museum pieces, they are meant to be driven, modified, rebuilt, raced, and ultimately, scrapped.
Whoever has the most fun wins!
Kurt


Seconded!

There are some people who thrive on having the car as it looked in the showroom the day it rolled into the shop and consider a car an investment - a lot of the classic car mags seem biased to this view.

Then there is the other crowd, the ones that simply can't sit still and have to improve any problem areas as they are discovered. The purpose of a car is to drive, not sit in an air conditioned glass box. A driven car will eventually wind up with improvised solutions, improvements and more or less well thought out replacements for worn out bits when the old ones can't be repaired anymore.

As long as both crowds exist, the car can be seen both on the street and in museums.

Steve: If you do a T9 conversion kit, send me an email. The old 4-speed isn't in better shape than it has to be in...

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Joachim

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 Posted: 03-03-2013 11:36 pm
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StevenD57
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The first T9 bellhousing is at the machine shop waiting for some available CNC mill time. Once we have the T9 transmission flange bolt pattern on there then the design work on the location of the clutch fork pivot can be finalized. After that comes the first trial install. I have three T9 transmissions to choose from so I am all ready to go with the last part.

Last edited on 03-04-2013 06:00 am by StevenD57

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 Posted: 03-04-2013 12:08 pm
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jcdean
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Definately interested in the T9 converstion.  Thanks for taking the time and interest in doing  this.

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 Posted: 03-06-2013 09:55 pm
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roverman
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T5 vs T9 ? I plan to use an R154, in a future build,(big hp). Cheers, roverman.

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 Posted: 03-06-2013 11:13 pm
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StevenD57
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Unless you are planning on a big turbo I don't think you will be developing enough torque to exceed the capacity of the W58. Toyota spec'ed the R154 in the twin-turbo Supra cars. The NA 3.0L Supra's were just fine with the W58 torque capacities. The torque capacities I have seen for the two gearboxes is:

 W58: 300-350ftLb

R154: 450-550ftLb

BTW, Torque is what breaks gearboxes, not horsepower.

Last edited on 03-06-2013 11:13 pm by StevenD57

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 Posted: 09-08-2014 06:07 am
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Randallclary@icloud.com
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So what ever happened to the T9 conversion? I am right in the middle or restoring my Mk 1 #13046 and going with a 2.2 L stroker crank, 10.5:1 compression pistons and ported head and want to reduce highway RPMs to a reasonable noise level. This looks like a great solution if it works.

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 Posted: 09-08-2014 06:16 pm
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subwoofer
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There have been bell housings for Vauxhall slant-4 to Rocket/T9 boxes on eBay, but none currently. AFAIK one of those should work, the 907 shares bolt pattern with the Vauxhall, right?

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 Posted: 09-10-2014 07:58 pm
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roverman
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So is the T9 mounting pattern, comparable to Ford/GM T5? If so, why not a T5? Plentiful and cheap, a good combination. roverman.

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 Posted: 09-10-2014 08:08 pm
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subwoofer
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T5s are rare in this part of the world, T9 and Rocket gearboxes are still plentiful. I don't think the T5 has the same bolt pattern, being a Borg-Warner box rather than a Ford (Europe) box.

--
Joachim

Last edited on 09-10-2014 08:09 pm by subwoofer

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 Posted: 09-11-2014 04:02 pm
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Art DeKneef
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This is from Steve the last time I talked with him earlier this year.

He has moved to Colorado and does not have the bell housing with him there. The equipment was moved to a different place for modifications and I don't know the status of what happened after that.

I would guess the project is on indefinite hold until Steve gets the time to work on them again.

Art

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 Posted: 12-21-2014 04:54 am
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StevenD57
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I am in Ohio now but I have not been able to locate a good CNC capable machine shop yet that seems interested in doing these small job lot type of things.

The last machine shop I had in Phoenix had time control issues (they would promise to have something ready in a week or two and then still not have anything done three or four weeks later). When I finally confronted the owner about this after having the project drag on for WAY too long he threw the project back in my face and refused to share any of the intellectual property I had developed.

I have two semi-finished bellhousings. One for the W58 and another for the T9. The T9 conversion bellhousing is somewhat simpler than the W58 due to the simple bolt pattern for the T9.

Last edited on 12-21-2014 05:03 am by StevenD57

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 Posted: 12-28-2014 10:52 pm
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DeDub
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I'm getting ready for a W58 swap in my track JH; my Getrag 5 speed has to be shifted with a soft hand to keep from grinding and probably only has a few more races in it. If a W58 bell housing becomes available, I'd like to know.

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 Posted: 01-04-2015 03:03 pm
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jdenglish
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Not exactly front page news but the 5-speed Getrag gear box rear end is not well suited for the W58. It's set up for a 1:1 final ratio. The W58 is a true overdrive in 5th. It took me one drive around the block to start looking for a 4-speed rear end.

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 Posted: 01-04-2015 03:44 pm
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NigelK
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There seems to be some degree of consensus on both sides of the pond that the W58 gearbox does not work well with the taller 3.44 diff fitted to JH5s and GTs.

This is directly relevant to me at the moment, as my GT engine is being upgraded from factory standard to 907/912HC hybrid next month, and the workshop is trying to persuade me to ditch the Getrag 235/5 and upgrade to the W58 at the same time.

I am not keen on this for a number of reasons - i) I like the quirkiness of the dogleg 235/5 and its close ratios, ii) I don't want to have to incur even more expense by changing to a 3.73 diff to make the W58 work properly, and iii) I am concerned about the amount of modification required to make the W58 fit (my mantra is that all upgrades must be fairly easily reversible to factory spec).

On the other hand, the 1:1 5th gear in the 235/5, even with the taller 3.44 diff, is a real pain on the motorway, as 70mph = a rather noisy 3500rpm.

From a technical perspective, fitting a standalone overdrive unit would be the perfect solution, giving me a true overdrive top gear for the motorway while keeping the 235/5 close ratios for the winding stuff. But there simply isn't enough room in the transmission tunnel for an overdrive unit. I've thought about fitting the ZF S5-18 gearbox from the Lotus Sunbeam which has a dogleg shift pattern and can have a proper overdrive 5th gear, but it's very expensive in the UK and I think substantial modifications to the transmission tunnel would be needed to make the shift mechanism fit. I am sure fitting more soundproofing to the car would help reduce noise at cruising speed, but this would be dealing with the symptoms, rather than the cause.

More recently, I've been thinking about fitting the Getrag 265 and bell housing from the Lotus Eclat S2.2, which while rare is obtainable in the UK. While this is not a dogleg gearbox, it does have fairly close ratios 1st - 2.96, 2nd - 1.93, 3rd - 1.39, 4th - 1.00, 5th - 0.81 (NB these are different from the 1st and 2nd gear ratios for the 265 box in its BMW and Jaguar incarnations).

While these ratios are still fairly tall, they were considered to work pretty well in the Eclat S2.2 even with the optional taller 3.73 diff. My GT post engine upgrade should have more torque and bhp than the Eclat (which had the 912LC engine fitted). Plus I'm still on 185/70/13 tyres i.e. smaller than the 205/60/14s fitted to the Eclat. Relative to the W58 box, the gear change revs drops for the Eclat 265 are also fairly consistent and closer to the peak bhp (6500rpm) to peak torque (5000rpm) difference for the 912HC engine.

So I am hoping that the Eclat 265 gearbox could work well with the 907/912HC hybrid engine and 3.44 diff. I would also hope installing this box would be fairly easily reversible (if I wanted to go back to "matching numbers", or if my calculations are wrong and the 265 gearbox proves too tall in practice).

Any thoughts / comments would be greatly appreciated.

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 Posted: 01-04-2015 04:20 pm
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jdenglish
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My W58 conversion was the "close ratio" version and was completed in 2010.
It is an absolute pleasure to drive. The shift gate is tight and the individual gear ratios seem perfectly matched. (With the 4-speed rear end). Almost as if it was a CVT.

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