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SUPRA 5 SPEED MANUAL GEARBOX COMVERSION
for VOLVO 200/700 series B21/B23/B230 engine

by Anthony Hyde, Canberra, AUSTRALIA. Anthony.Hyde@anu.edu.au


INTRODUCTION

The alloy cased Toyota Supra 5 speed conversion is manufactured by ‘Dellow Automotive’ in Sydney, Australia. Dellow has over 20 years experience in conversions, and offers Volvo owners kit #S-V to suit the popular tilted red engined B21/B23/B230 Turbo or normally aspirated version. The kit offers converters a flying head start with the number one requirement a bellhousing, plus a speedo cable, clutch disc & related parts. Note the kit does not include a modified crossmember, g/box to trans mount, or modified tailshaft, this is up to you. For 140 series owners with an upright B18/B20, a Toyota Celica 5 speed steel case kit is available. As can be seen in the pictures, the box is of very neat design, which by comparison makes the M46 seem pretty industrial.

Rear: Volvo M46 with Overdrive
Front: Alloy cased Supra W55 with Dellow bellhousing

The camera lens has distorted the length comparison.
Overall length is within 10 mm. Shifter position is within 5 mm.

The 240/760/740 Volvo turbos use the M46, an in-house 4 speed design coupled to a UK designed Laycock overdrive for 5th reportably good for near 225 hp. This two-section transmission is fine until the complicated O’Drive wears, causes trouble, and is very expensive to replace, or repair perfectly. Owners face high cost again when it's time to replace the gearbox and this is where I drew the line. I wanted 5 real gears based on a strong design at a reasonable price.

Volvo manufactured a 5 speed M47 v.I&II, but for performance driving with a turbo engine it’s just not strong enough, one problem area being the low friction synchros. Strong 5 speed options to suit a 4 cylinder are Supra, Getrag or Volvo M90. The Supra is readily available with suitable ratios and can handle 300+hp, the Getrag M50/51 or 262/265 found in BMW’s are expensive (bellhousing from SAM in Sweden), and the M90 only a dream outside Europe.

M46 + Overdrive

Supra W55

Supra W59

Supra W58 (US/Can)

1st - 3.71:1 or 4.03:1

1st - 3.57:1

1st - 3.95:1

1st - 3.28:1

2nd - 2.16:1

2nd - 2.06:1

2nd - 2.14:1

2nd - 1.89:1

3rd - 1.37:1

3rd - 1.38:1

3rd - 1.27:1

3rd - 1.27:1

4th - 1.00:1

4th - 1.00:1

4th - 1.00:1

4th - 1.00:1

5th - 0.79:1

5th - 0.85:1

5th - 0.85:1

5th - 0.78:1



SUPRA
Pros:
choice of gearboxes (hence ratios) depending on availability, perfect gear stick position, light weight, kit includes speedo cable, based on a strong design

Cons: Lot of effort required to modify crossmember & g/box to transmission mount

ROAD TEST: W55
Supra shift quality is good and direct, but does not push into gear as easily as a good M46. Gear ratio spread is very progressive through the range, better than the M46, with less time taken for third gear to rev out! Shifter throw is 5 mm less at either end of say 1st to 2nd so 10 mm less gearshift travel in total. As expected, a few top gear resonances compared to the M46’s isolated Laycock overdrive system. The Supra W55 5th gear reduction of 0.85:1 is not as low as the Volvo overdrive's 0.79 which is an advantage in flowing traffic as your not continually catching up with the car in front. The 0.85:1 reduction also offers improved hill climbing and top gear acceleration.

Interested in the conversion detail, please read on.


FITMENT

Ultimately the Supra W55 was my choice for fitment into a sporty 244 with a 94 B230FT turbo engine, replacing a M46+OD. For Australian buyers, Dellow can supply a 2nd hand serviced box as well, which they purchase in large numbers from Japan. A Supra tailshaft yoke is extra. Dimensions for the Supra are very similar to the M46/OD with overall length being only 10 mm shorter. The box fits inside the 240 chassis tunnel with ease, with the shifter position in the tunnel hole being perfect, much joy there. Specify the 20 1/2" shifter position. The gearstick has a well executed dog leg angle for an ideal position. The alloy cased Supra weighs 33 kg + 5 kg for bellhousing etc, and is lighter than an equivalent cast-iron cased M46+OD by 7 kg (15.4 lb), representing a weight saving of 18.5%. This difference would not be as great with the later 1985-on alloy case M46+OD ’Type P’ on turbo models. There are no markings on the gearbox so it’s difficult to establish you have the right model other than referring to the details on the receipt.

Overall the Dellow kit is a good product, especially the bellhousing, all well thought-out and made. From a precision perspective, the important 'locating dowel fits’ were spot-on for the bellhousing to engine and opposite bellhousing to gearbox. It pays to trial fit every mating component you can in advance, so allow time for this. I found plenty of hand filing was required to fit the Volvo rubber shift-fork-boot and also the hydraulic clutch slave cylinder, memo to Dellow. The yellow foam Volvo sound insulator saddle can be used again and fits neatly around the g/box & tunnel. For markets that use a clutch cable, the setup can be adapted. A custom 9" clutch plate is part of the kit, of good quality and made by Australian manufacturer PBR. If you transmit a lot of torque perhaps Dellow can supply a heavy-duty version. Note: 84-on turbo models use a 9" clutch with a stepped flywheel, with earlier turbo and normally aspirated models 8.5".


I chose to use the genuine Volvo shift-fork in preference to the unit supplied, which required hand filing of only 0.75 mm off each two legs to fit the carrier. The supplied ball pivot was reduced in diameter to suit the shift-fork. The supplied carrier & thrust bearing are of heavy-duty design and should be long lasting compared to the less durable Volvo unit. The flywheel centre bearing is replaced by an oil impregnated sintered-bronze bush, or spigot, pressed into a steel shell which is specially made to suit the conversion. The speedo cable is well made but too long for a 240. I have detailed to Dellow a few refinements to enhance the conversion.

Crossmember and Gearbox mount
The most challenging task was modifying the Volvo transmission crossmember and fabricating a gearbox mount to fit. There are tight space limitations because the end of the g/box is near the crossmember and every piece requiring fabrication has an angle on it.

It should be noted the Volvo engine & gearbox sit in a cradle with three mounts inclined to one other, with the rear transmission mount inclined close to 32 deg from the vertical. By comparison, the standard Supra mount is a straight up and down affair which in my opinion does not suit the inclined Volvo setup. This is the reason for the extra work.


As usual, half the battle is working out what you want and then making thin alloy sheet mock-ups to get sizes and angles right. First step was to build a trick angled bracket from the g/box to the topside of a Volvo transmission mount (heavy duty B30). Next the crossmember adaptation that now attaches to the rearward factory chassis holes (like auto model) being better for weight distribution.

Tailshaft
The front section of the Volvo two-piece shaft requires adapting, and its worth noting the following: - Volvo tailshafts come in two diameters 1 3/4"& 2", - depending on model have different front lengths, - Supra uses a sliding spline affair vs the Volvo's fixed 4 bolt flanges. Two new yokes are required to fit the front section. 1) Supra splined gearbox yoke, and 2) matching weld-yoke, combined with a matching universal joint.

Dellow sell a Supra yoke with Ø25.4 mm (1") uni sizing, which is in between Volvo sizes of Ø23.8 mm (15/16") or 27 mm (1 1/16"). My original M46 front shaft was too short in length so I converted to a longer and larger 2' dia shaft off an auto 240 series. In Australia, the Hardy Spicer #17R-26-330 weld-yoke has a 1" uni and suits a 2" tube. From metal disc to centre of weld-yoke I chose length 416 mm. Adapting tailshafts has its problems even with perfect phasing. Old shafts can give mixed results for various reasons, so find the newest you can. Balancing is mandatory. A one-piece shaft is an alternative but the diff angle could require modification upward.

Conclusion
After a few months testing of the conversion, I’m happy with the result. The fitment has taken a lot of effort and free hobby time, and when it works properly the pain is quickly forgotten. With conversions there is usually something to sort out at the end, in this case the tailshaft. The gearstick position makes shifting into all 5 gears a pleasure.

- Anthony Hyde

For conversion information contact:
Dellow Automotive &emdash; 37 Daisy St, Revesby, Sydney AUSTRALIA
Mail to: PO Box 43, Revesby North, NSW 2212 Australia
Ph +61-2-9774 4419, Fax +61-2-9774 3873

 

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