When British sports cars ruled the world most were available with Laycock overdrive. Except Morgans.
Compare a Plus Four and an OD Triumph TR3. The Morgan wins on roadholding but loses out to the TR’s lighter shift and flick-switch ratio changes. And the Morgan is stuck with 4000 rpm freeway driving. Improving a car’s performance, enhancing its character, is always the aim of manufacturer and enthusiast alike. For any 4 speed Morgan the options include: -1) Overdrive -2) “taller” rear axle -3) 5 speed conversion.
Early +8s need only fit the Rover SD1/late TR8 (LT77) or newer R380 5 speed. For Ford Kent engined 4/4s the obvious fix, a Ford Sierra bolt-in gearbox. An ’82-’87 Type 9 5 speed, 175 mm first motion shaft, bolted bellhousing (changing to alloy saves 18 lbs.) Tuned cars benefit from the Sierra 4X4 close ratio unit. Additionally, source a European style sliding yoke driveshaft, use a hydraulic center release bearing, shorten the shift lever, fabricate transmission mount, reposition handbrake, modify Merkur speedo cable and reshape the cover.
Turning to the Plus Four, it has long attracted amateur development engineers with a number of approaches. Adding a Jaguar Overdrive to the Moss box is covered completely in Fred’s book, but the parts are no longer cheap. There is additional weight of 40 + lbs. and an extra 9 inches of transmission cover to fabricate. This tends to invade seating areas on both sides. Such considerations dissuaded the factory long ago.
Another seemingly obvious approach is to bolt a TR overdrive gearbox direct to the engine. However, frightening frame butchery is a common feature of those conversions known to the writer, leads one to be concerned about frame design integrity, does it negatively change the handling of the car, what the car was originally intended to do? And, moving so much weight forward, would again be another cause for concern regarding handling.
Then there is the “taller” rear axle: something of a trade off. The benefit, less frantic flat road running. The penalty, less flexibility, requiring more downshifting to maintain performance. Past procedure was an MGB axle with MGC 3.307 gears and some cobbling together, but a fully engineered conversion is now available.
A five speed conversion would be the perfect solution for Morgans except there are none! Fortunately TR s are well served in this area and one of the best engineered units is produced by Herman Van den Akker. Herman, Supersport #5954 owner Paul Marchant, and the writer worked together to produce a Morgan application. But first you have to have the gearbox for the conversion.
The gearbox is a Toyota Celica ’82-’85 W58. It has an alloy case, which saves about 50 lbs. over a Mossbox, so the more forward location does not hamper handling. Three gearsets were used, all very similar so choice is irrelevant, but avoid the early 90’s wide ratio truck gearbox. There are 3 different shift lever positions. The most common emerges between the back four top cover bolts on the Mog housing. This is the one you are seeking at the wrecking yard. Go ahead and get two while they are cheap and plentiful. You will also need:
- machined alloy bellhousing (HVDA)
- hydraulic center release bearing and hoses
- splined output flange
- clutch disc
- pilot bushing
- speedo cable
- new output shaft seal
- ¾ inch integral reservoir clutch master cylinder
- clutch m/c spacer/mounting block
- TR6 diaphragm clutch cover
- Toyota transmission mount
- Lengthened driveshaft
- Weld-in firewall crossmember closing piece
- Bolt-in box section crossmember stiffener
- Tubular engine bay corner brace kit
- ¼ inch alloy engine mount spacers (2)
- bolt-in transmission mount H frame
- handbrake ratchet/outer cable bracket
- outer cable whitworth locknut
- adjustable clutch stop
- remote control shift lever kit (optional)
- fiberglass transmission cover (optional)
The Toyota gearbox should need no more than rear oil seal. Replace bellhousing with new, install bushings, redrill flywheel, fit TR6 clutch, install center release bearing, check a couple of critical clearances and bolt up. The optional fiberglass cover should be trimmed in two places to increase pedal space.
The Morgan frame firewall crossmember requires removal of a 1 inch crescent below the gearbox. Continue to bolt up box section stiffener, weld in closing piece, fit tubular corner braces, and bolt in gearbox H frame with mount attached.
The pedal cross shaft assembly needs modifying to that of a hydraulic 4/4. Dismantle, drill out swaged tube from clutch pedal and actuating lever, weld together, pin to a new short shaft, and reassemble brake pedal and mounting blocks. Drill crossmember and install in car, 1-11/2 inches left of original brake position (left hand drive) will provide the correct spacing for most feet. Fit up the master cylinders, clutch stop, trim firewll flanges slightly to clear starter motor bulge on bellhousing. Re-fit engine/gearbox combinationation with ¼ inch spacers under the engine mounts. Connect up hydraulics, install extended driveshaft, mount handbrake bracket on the right, NOT left, side of the H frame. Fit the speedo cable. The Toyota gearbox connected to a Morgan speedo using 165X15 or 195/65X 15 tires will give a more accurate reading than the original. Finally, heat and bend the gas pedal to clear the cover.
If you decide to keep the original cover, cut down the center from the shift hole forwards, spread to the same width as the rear and weld in new sheetmetal, new cutouts, a little more panelbeating and it will fit. Remove the Toyota rubber mounted shift lever extension, heat and bend the remaining lever back slightly, fit the Morgan knob. It will fall exactly to hand as before!
The new shifter works on a different, much improved plane, enabling flick of the wrist gearchanges instead of elbow in the passenger ribs shifting. In this writers humble opinion, a Toyota gearbox conversion will transform your Morgan! Do it yourself or the call the writer….1-831-917-6999 (San Francisco Bay Area)
Best Wishes, Michael Anthony…….submitted by Gordon Craig.