T50 No More - W58 Gearbox Conversion Pt.2

I can't sleep so i figured i might as well write the second part of my W58 gearbox conversion. In case you missed it, the first part is about fabricating the T50 bellhousing to W58 box adapter. By the way, i can't really be sure if mine's really W58.. it could be W57 which only differs on the shorter 5th gear. I thought it were only W58s that had steel sandwich plate like mine, but some googling got me to doubt that. Anyway, it shouldn't really matter.. I won't be using the 5th much and they both handle crazy torques.

Before i did the swap, i was prepared for a bit of customizing in getting the correct clutch disc. You see, W58 and T50 have different input shaft diameter and spline count. T50 is 24.1mm with 21 splines while W58 is approximately 28.6mm with the same spline count. A 4A-GZE clutch disc fits perfectly to W58. Now, since my clutch disc is 200mm or 8 inch (which i found out only later after i took off my T50 and actually strange since i should have the 212mm or 8.5 inch clutch with my smallport 4A-GE), i will have to find a clutch disc of the same diameter but with the bigger W58 shaft input diameter.

How about the GX71 Cressida's clutch disc which came with the W58 box i bought? This is good news for smallport users: Cressida's 1G-E clutch is exactly 8.5 inch and should fit smallport's flywheel just fine. So, how about my 200mm disc? Armed with the knowledge that G and W boxes have many similarities (for example, they interchange bellhousing) and that G boxes are found under our beloved KF chassis Toyota Kijangs, i went to see if these local commercial vehicles have the disc i needed. And you know what? I got lucky!

That above is 200mm clutch disc that fits my W58 box and flywheel! It's stock clutch for 4K equipped KF40 Kijang. So, i guess i'm safe from having to customize every time i replace the clutch set later in the future. Also found on the pic above are bush sets for my W58 shifter stick, front and rear gearbox seal and a new clutch release bearing. All of them interchange with G boxes as well. Part number for the clutch disc is 31250-YD010 just in case you need it. Ignore the cable lugs you see.. They're to recondition my starter wire.

Bolting the gearbox to the engine was quick which means the adapter must be doing it's job. The gearbox was fitted to the engine and pulled out again to confirm whether the input shaft really mates with the pilot bearing. Once it's confirmed, the box was again fitted to the engine, the bellhousing to engine bolts were fastened and the gearbox end was lifted using a jack and we arrive to this minor problem.

Nothing to worry about.. An angle grinder was used to cut a bit off the tunnel to clear the shifter. Apparently i wasn't so lucky in getting the W58 with the wrong shifter position. There are four known shifter position for W5x gearbox based on the distance from the front and mine's the obviously the furthest which is why i had to cut a bit of the tunnel to clear.

Depending on the tilt you're after with the gearbox tail, you could use the W58 crossmember, drilled to fit the existing mounting holes and add some rings as spacers or you could use a pair of angle iron like Assassin1000. I use the earlier method.

In my case, this way gets the engine to tilt at near stock angle.

One thing that surprised me on the swap was that i had to shorten my driveshaft by 20mm. I was on the impression that this wasn't necessary based on my initial research on the net but apparently i was wrong. In total, now my driveshaft is approximately 40mm shorter than stock Charmant as converting from S to T-series diff demanded the same requirement as well.

Luckily, W58 driveshaft yoke fits my stock U-joint just fine.. so less headache there.

Finally, what to do with this ugly gap from the trans tunnel?

LOL, the solution was again the ever-useful chopping board.. Yet another use for this lovely kitchen inhabitant.

A bunch of measurements, drilling and cutting later.. Here's the final result, all done.

It took two days to complete the swap work with the biggest time waster being going back and forth the machine shop to finalize the pilot bearing spacer and to shorten the driveshaft but other than that, the work was pretty easy.

Stay tuned for Part 3 where i will explain the basic differences between T50 and W5x gearbox and my driving impression with the new box.