3 replies to this topic

[MaximMini]

Hi Everyone,

 

I'm currently in the process of rebuilding my engines and gearboxes (see my signature for the project blog) and came by this situation yesterday.

 

I measured the diff output shafts, diff cage bushes and crown wheel bushes to see if I have to get new bushes fitted.

 

The measurements read:

- diff output shafts: 26.13 .. 26.15 mm (1.029 .. 1.030")

- crown wheel bushes: 26.22 .. 26.24 mm (1.032 .. 1.033")

- diff cage bushes: 26.30 .. 26.32 mm (1.035 .. 1.036")

 

This means a maximum clearance of 0.19 mm (0.007") which looks ok for me. Which is a bit strange is the fact that, while the measurements on all crown wheel bushes are within a very small range as are the measurements of the diff cage bushes, they are actually different.

 

Have you come by this situation and what is your opinion on the clearances?

 

 

Cheers from the Pied Pipers Town

 

[ACDodd]

They are knackered. Fit new bushes and have them bored on a lathe concentric to the main roller journals to a clearance of +0.001".

Ac

Edited by ACDodd, 02 December 2019 - 10:43 PM.

[MaximMini]

Hi Ac,

 

Thank you very much for your reply. I actually used a gearbox rebuild series you once did as a reference but then had a clearance of 0.01" and not 0.001" in mind. Might be down to the fact that I haven't been raised in the imperial system .

 

Since we are talking about a clearance which is in the same region as the tolerance between the smallest and the biggest outer diameter of my output shafts. Do I need to get the bushes machined indiviually for each shaft or is there any way to get the shafts grind or polished to the same diameter?

 

My goal is to assembly two gearboxes and have one complete set of parts on the shelf in case of any failures (or a third project).

 

Thank you very much fro your input

Christian

[ACDodd]

I machine the bushes to a matched pair with the shaft that runs with them.

Ac