Thread: Replacing a Gearbox

You sound like me a few weeks ago. I am just about to put my gearbox back in after swapping out the main shaft from my donor car. Check out my thread in the S2a section, complete with some photo's.

I also could have simply swapped the gearboxes but decided to pull the original gearbox apart to see exactly what had failed. This revealed the broken main shaft. After pulling out the donor gearbox I decided I didn't want to risk installing that without checking it out internally first. Then, when I drained the oil and water came out with it, I confirmed my view.

So bit by bit I came to the decision that the best thing to do was just use the complete main shaft sub-assembly from the donor and keep everything else original. All has gone relatively well, the gearboxes are simple to work with and there's no big mysteries in there.

If you know the condition of the donor box is good, then maybe for you simply doing a swap is best and then dismantle the broken box as time permits and maybe repair that as a spare or sale item.

Good luck with it.
Cheers
John B

Thanks John,

I do know the history of this box, it was professionally rebuilt a few years ago and has hardly been driven since. Everything feels very solid (when taking it for a test in the vehicle it's in now) and smooth. So at this stage I'll probably do a straight swap and pull mine down when I have more time.

Seems like you're in one heck of a better position than I was then.
The bell housing on mine was only attached loosely with a few of the bolts. Several nuts were missing entirely, several were loose or finger tight at best and very few actually tightened up. I believe this contributed to or caused the failure of my main-shaft. If you are happy with the installation as it was I can understand the temptation to simply unbolt one gearbox and bolt on another.

On the other hand, the alignment only needs to be a tiny amount out and it could be a factor in future life expectancy of your new gearbox. If, and it's quite an if, the process to measure and correct the alignment of the adapter plate is simple then it seems to me it would be worth doing. There is a fair amount of "hassle" to change the gearbox, although it's all easy work and I don't think there are any "traps" for you in it.

I should be able to tell you how difficult the alignment check is after I've done it because I really need to do it. If you lived closer than the other side of Australia I'd invite you around to participate in my learning experience. The question is whether you can wait as long as it'll take me to run through it and then report back to you. It's likely to be a couple of weekends away.

Cheers
John B