Jensen-Healey Transmission & Clutch

Healey Journal

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After buying the car I found that a little time spent cruising the highways and byways lead me to appreciate what a screaming little engine the Jensen-Healey had- it could rev up very nicely, but the aggravation was that it really needed to because of the car's gearing. Traveling for any extended time at motorway speeds was off-putting. I considered moving to the Jensen-Healey 5 speed as used in later cars, but its gearing was no better so that problem wasn't remedied.

The other common fix was to swap in a Toyota 5 speed transmission. This is a very popular swap with Big Healeys too, and also for BMC "A" engined cars like the Morris Minor, MG Midget/AH Sprite; and just coincidentally, also my "A" engined Olympic.

This swap is greatly facilitated by Lotus's use of that transmission in its later cars too. All I had to do was to find one and it should just bolt right together. In theory. So I soon acquired a Lotus Eclat/Toyota W58 transmission with bellhousing (hydraulic); and a clutch “kit” (Pressure plate, drive plate & throw-out bearing) and it was installed too when the engine is done.

One minor problem arose because the spigot (pilot) bearing wasn't right. No matter what I ordered from Lotus nothing at all seemed to fit. So my engine builder machined one of the too-large Lotus ones to fit the input shaft.

A steel flywheel from a turbo Esprit (much lighter weight~13 lbs). This needed drilling for the pressure plate and that was soon done, though the fit was tight. The rational for using a lighter flywheel is that it allows the engine to respond much more quickly- accelerating faster. The downside is that there less momentum in the flywheel to help smooth the engine's running. The clutch disk, pressure plate and throwout bearing from a Toyota were used, but a lack of clearance required shims between the pressure plate and flywheel to gain enough clearance for the clutch to work properly.

The Lotus transmission used the usual hydraulic master/slave cylinder arrangement for the clutch but the Jensen-Healey transmission used a cable. Either I'd have to use the bellhousing and make the cable fit or I'd have to leave the hydraulics alone and convert the clutch pedal to push a master cylinder rather than pull a cable. I'd seen a couple of conversions where the cable pulled a lever that activated the master cylinder but these all seemed a little crude. When speaking with Martin Shirley from the Jensen club I discovered he'd contrived a jointed pedal within the pedal box that would allow the master cylinder to be mounted to the pedal box as if it were meant to go there.

He modified my pedal box and it looks very good. This allowed me to use a Lotus master cylinder along with a lotus slave cylinder so everything should be compatible and work. Should be....

While I was doing all this it also seemed a good time to have the brakes seen to... there weren't any problems, but since the whole pedal box was apart it was a good time to have the brake booster rebuilt and to replace the master cylinder with a new one. This would give an entirely new brake system  with the exception of the hard brake lines and the rear drums- new rear slave cylinders and brake linings; new calipers, pads and disks, and new sreel braided flexible lines front and rear, with a new master cylinder and rebuilt booster.

The other transmission also needs to be adapted to the Jensen-Healey's bodywork. The gear shift lever on the standard transmission is located XXX inches further back than is the one from the Lotus. The shifter tower then needs to be swapped out for one that is longer, or fabricate a longer one to fit. Martin Shirley also makes a kit that moves the shifter back to the proper position. This was readily fitted and then installed.

Tower cut for the extended knuckle.

The final modification needed was to shorten the driveshaft and to modify it to use the Lotus front yoke to fit the transmission's rear shaft.