Car Mechanics (UK)
More haste, less speed
Back in the 1970s I had a Vanden Plas Princess 3.0 with an automatic gearbox that developed a leak at the front end. I didn’t have the special tool to align the torque converter to the transmission, but I reasoned that, because the torque converter stayed with the engine during separation and the transmission wasn’t going to turn during the seal replacement, it should go back together without the need for a realignment tool. Balancing the very heavy transmission on a screw trolley jack on a garage floor was far from ideal and, try as I might, I couldn’t get the transmission to mate with the torque converter.
So I decided to convert the car to a manual gearbox with overdrive. I got all the necessary parts from my local scrapyard and all went well, except that the last inch or so was tight when mating the bellhousing to the engine, requiring a bit of force. Wanting to finish the job, I pressed ahead when I really should have stopped to consider what wasn’t right.
Once on the road, I started to get a squealing when changing gear and soon couldn’t engage 1st gear with the engine running. I realised what I’d done wrong: in the crankshaft on the automatic, there is a steel bush to locate the torque converter and there is never any relative motion between the two. On a manual gearbox, this steel bush is replaced by a bronze bearing that locates the gearbox input shaft, but crucially allows the shaft to freely rotate within the rear of the crankshaft during gearchanges.
By not replacing the steel bush, I had friction-welded the gearbox input shaft to the steel bush at the rear of the crankshaft. I had to smash the bellhousing with a club hammer to get to the clutch bolts to disassemble the mess. That was followed by a sheepish return visit to the scrapyard to admit my error and get a second gearbox, followed by a trip to a bearing suppliers to get a phosphor bronze bush.
The lesson? When something doesn’t quite seem right, stop and work out why!