Main shaft issue

[66an]

Hello
I have my syncro gearbox under restoration. Between the main shaft and the constant pinion shaft there is a needle bearing. This bearing have made a lot of wear on the main shaft.
I was thinking of grind the surface on the main shaft down and after that press a sleeve on it in order to create a new surface for the needles.
Anyone here who have experience of the problem or any thoughts about it? Or a tip where I can source a used one in good condition, or a new one?

[abowie]

Take it to your local engineering shop and get their advice. There are a number of potential techniques that could fix this but whatever you do you need to ensure that the surface is appropriately hardened, or it will just wear again.

[johnney]

Hi Mats,
Denis Welch Motorsports can sell you a new main shaft, see link below.

https://www.bighealey.co.uk/jaguar/jaguar-gearbox

[66an]

Thank you for the response!
Yes I realize that the surface for the needles must be hardened. One possibility is to use a needle bearing inner ring, it will have the correct hardness. I have found a suitable ring with 1" outer diameter and 13/16" inner. Means that I have to grind the main shaft down from 1"to 13/16".
The question then is if this can be a strength problem? I have noticed that "bighealey" drill a smaller oil hole(the centre hole I presume) in the shaft just to increase strength. And the outer diameter affects the strength much more than the diameter of the inner hole.
So maybe its wiser to buy a new one?

[angelw]

Mats wrote:

The question then is if this can be a strength problem? I have noticed that "bighealey" drill a smaller oil hole(the centre hole I presume) in the shaft just to increase strength. And the outer diameter affects the strength much more than the diameter of the inner hole.

Hello Mats,
Saying a pipe of equal diameter is stronger than a solid bar is false. Accordingly, drilling a hole the length of an existing rod is not going to make it stronger.

With regards to reclaiming your existing Main Shaft, Hard Chrome would be a viable solution. Hard Chroming doesn't require a large reduction of the original diameter of the bearing journal and any company involved with this type of work would be cognizant of hydrogen embrittlement and the steps required to counteract it.

Regards,

Bill

[66an]

Bill, sorry if it was unclear written. It is an oil hole in the centre of the original main shaft. In Dennis Welch main shaft the centre hole is smaller than in the original one.

Thanks for the tip about hard chrome. I will check it out with a suitable workshop.

[66an]

Often it's of interest to read how problems in a thread are solved...
Finally I bought a new main shaft from Dennis Welsch Motorsport.
My gearbox is now restored and ready!
Thank you!