why is the w58 weak

[Chris Wilson]

Ive been searching for days now to see if anybody has actually explained in detail why the w58 is so weak.Has anybody come across a right up or could explain why.

 

 

Gearboxes are rated by how much torque (twisting moment) they can handle, at a certain RPM. Put gearbox A behind a low torque engine and it will live for years, put gearbox A behind an engine with double the torque and it won't live long, if at all. Torque rating is governed by many things, but the main ones are gear width, shaft diameter, bearing diameter and case strength. High torque capable gears are wider, making a gearbox longer and heavier. You can use trick materials, exotic heat treatments and X-Ray inspection, and have a smaller, lighter gearbox lifed in hours, like F1. You can say sod the size and weight, give me a bullet proof `box that'll last a million miles, and you get a modern HGV gearbox. The W58 is constrained by the shaft spacing, meaning the gears can't be bigger diameter, the shaft diameter (changing that is a total re-engineer of the `box), and casing rigidity, again, a major re-engineer. Weakness in synchro capacity can be worked around by getting rid of them and going to a none synchro, dog engagement internals, and you can maybe also get wider gears in as dogs are shorter, longitudinally, than a synchro pack. There may be a dog internal kit available from some of the transmission specialists, but it'll be terrible in a road car, and far dearer than fitting a six speed used Getrag. 60's and 70's US manual gearboxes were often quite tough, but VERY crude. Muncie did some capable of handling huge torque, but they were only 4 speed, which, when mentioned in the pub, is nowadays akin to saying you have leprosy

 

So it's nothing blatantly wrong with the W58, Toyota chose a cheap to produce, off their shelf box, that they ran near the upper limits of its design torque, it just doesn't like people nailing higher torque engines in front of it, especially with multi plate or high clamp force clutches that put shock loads into it. Even less will any `box near its torque limit like drag race starts, that's a sure way to kill it. Hope that helps.

[Josh42]

Chris, do you offer gearbox refurbishment?

[mellonman]

Short answer because it was designed for a n/a , why waste money on a stronger one when it works just fine

[Chris Wilson]

Chris, do you offer gearbox refurbishment?

 

 

I do, it's mainly race transaxles I do, but I will do road car boxes so long as if they are not specced for the job I am not expected to give any sort of warranty whatsoever

[Josh42]

That's good for me Chris.

Ill email you what I'm after.

Cheers