Thread: Gearbox evaluation

Originally Posted by Ricrose

I am finally getting back to my Landie after months of being way too busy with my day job.
The engine is now running (no leaks) and yesterday I mounted the gearbox on the engine stand and gave it an initial clean.
I could not test it when I got it.
My question to those with experience is - can you evaluate the condition of the box without tearing it down? I have tried searching the forum and web and haven’t come up with anything.

I understand that it is out and easier to do than at any other stage - but it may not be necessary.
Thanks in advance.

hard question to answer if you dont know the history of the box if you need help dont be afraid to ask jim 30 s1 gearboxs on standby complete or parts

It is impossible to fully evaluate the condition without stripping it, but there are some things you can check. For a start, drain the oil from both main box and see what (other than oil) comes out - any bits of metal, or water, suggest theat stripping it may well be a good idea. The box should turn easily and smoothly in any gear by hand, and changes should be easy and smooth.

Even if these tests are all OK, while you have it on the stand I would remove the gearbox top and look for damaged gears (look especially at first and reverse idler) or synchromesh assemblies. Also turn it over and remove the bottom plate of the transfer case for a similar inspection. And while you have it on the stand, replace both output seals, replacing or sleeving the output flanges as necessary. This means removing the handbrake drum, so check the handbrake while you are at it.

Thanks for the replies - when I drained the oil it was really good - hence the question. I think I’ll follow your suggestion JDNSW - everything else’s on the Landie has been really good but dirty.

yes but you need a good torque wrench, a set of feeler gauges, an electric motor with a shaft the same size as the input shaft and some hose and a welder..... (and a steel bench)

drain and check the oils. which youve done

first of take the selector lid off the box, then you can inspect the syncros. as well as the general condition of the teeth of some of the gear, remove the detents and springs.

next using the torque wrench to turn the input shaft select all the gears and watch the reading on the wrench it should stay very stable at a given value for each gear with 4th gear having the lowest reading getting marginally higher for 1st second third and reverse. Conduct this test for each gear with the Tcase in high low and neutral. Now add a drag load to the outside of the handbrake drum and repeat. there should be no change in the relevent mangnitude of the deviations from nominal for each gear or relative to the other gears. If there is check the handbrake drum is clean and working properly.

put the box back together and leave out the detents and springs for now.

With that done.. bench the box and weld it down, hook up the electric motor to the input shaft with a rubber hose as a flex coupling and with oil in the box work it through each of the gears and use the handbrake to generate a dummy load. Watch the gearshift for movement as you load an unload the handbrake while starting and stopping the motor.

drop the oil again check its condition. if its all good put the detents and springs back.

Thanks for the replies - when I drained the oil it was really good - hence the question. I think I’ll follow your suggestion JDNSW - everything else’s on the Landie has been really good but dirty.

I really like the torque wrench suggestion - I’ll see how far I go, probably not as far as welding the box to the bench - but I can follow it and think it’s a solid test.

Originally Posted by Ricrose

I really like the torque wrench suggestion - I’ll see how far I go, probably not as far as welding the box to the bench - but I can follow it and think it’s a solid test.

you only need to weld up a mount to get the motor and the box to stay in alignment. chunks of wood tactically screwed and bolted to the box will keep it square and then something to keep the electric motor in true and to provide some torque reaction control is all thats needed.. I may or may not have done this with ratchet straps, a couple of railway sleepers and housebricks before today.....

If you happen to have a friend who can hold a bar..........................


make sure you take video.

Sounds like fun - I’ll see if I can hunt down an electric motor. I should have one somewhere! Thanks.
If I get there I’ll definitely video.