LT230T rebuild question

[harbspan]

Am rebuilding my LT230T tranny case on a 96 Discovery 300tdi manual and see in the overhaul manual that LRT 41-107 set up tool is reqd to take a measurement to calculate the correct spacer to use to set the preload on the intermediate shaft, as crush spacers are no longer to be used. This tool is basically a flat plate with a dummy shaft mounted vertically to set the gear up on with the bearings in place. This would be easy to make however I need to know the exact height of the dummy shaft for the calculation formula to work does anyone know this height.... or another way to work out the preload??

[vougese39]

Am rebuilding my LT230T tranny case on a 96 Discovery 300tdi manual and see in the overhaul manual that LRT 41-107 set up tool is reqd to take a measurement to calculate the correct spacer to use to set the preload on the intermediate shaft, as crush spacers are no longer to be used. This tool is basically a flat plate with a dummy shaft mounted vertically to set the gear up on with the bearings in place. This would be easy to make however I need to know the exact height of the dummy shaft for the calculation formula to work does anyone know this height.... or another way to work out the preload??

well as the crush spacer crushs it preloads the bearing which inturn increase the kg preload required so if you are fitting a solid tube you will not be able to preload the box properly unless the spacer is designed to give the optimum preload?

what i used to do is rap some string around the intermeadiate shaft then tighten the stake nut then pull the string and the gears with a spring balance to obaint the kg pull which= the resistance required to preload the bearings

[mickeyw]

I was fortunate enough to have watched and discussed a demo of LT230 building on Ashcrofts stand when I was at Billing last weekend.

The crush tube is certainly still used. They always use a new tube when new bearings are fitted. The wall thickness of the tube is considerable, but it can sometimes need to be crushed by as much as a couple of mm! I am told you will struggle to crush the tube sufficiently with an ordinary socket wrench.

For this they use an air impact gun and keep giving the nut a bit more of a buzz until the correct crush and preload is achieved. This is something that is determined by an experienced hand. Essentially you need to remove any end to end float in the shaft, but still be able to turn it by hand. The shaft should have only marginal 'run on' when you let go of it. I was surprised how tight the shaft is on new bearings.

I have seen the string and spring balance method in the LR workshop manuals, this may be a more reliable way to check the preload if you are not experienced at gearbox building.

[JimAttrill]

Yes, unfortunately we do it on the feel method. It's always hard to explain how to do it, but once you have seen it done and felt the play or lack of it, you can do it yourself. As above, "The shaft should have only marginal 'run on' when you let go of it".

[harbspan]

Thanks guys for the advice, especially the tip on the 'feel' of the run on. My RAVE manual stresses not to use the crush tubes anymore, that they must be replaced with a fixed length tube. The length determined according to the measurements calculated with the LRT 41-107. Can only figure that the crush tubes must gradually give under load over time and thus lose preload and then wear on the shaft, as has happened in my case.