Gearbox whine

dag019 · Apr 21, 2017

I had an ashcoft reconditioned gearbox last summer and have had no problems with it until now.
The reason it was replaced last summer was the lay shaft bearings had failed and it was whining in every gear accept 4th. This time however it is only making a noise (bearing whine) in 4th and 5th. In both high and low box. Does anybody have any ideas what it could be or how to diagnose any further.
If it is the gear box it is still under its 12 month warranty so will remove it and take it back if that is at fault. But I only have a couple of months left on the warranty to work out the problem.

lightning · Apr 21, 2017

Have you contacted Ashcroft to see what they think?

jamesmartin · Apr 21, 2017

dag019 said:
I had an ashcoft reconditioned gearbox last summer and have had no problems with it until now.
The reason it was replaced last summer was the lay shaft bearings had failed and it was whining in every gear accept 4th. This time however it is only making a noise (bearing whine) in 4th and 5th. In both high and low box. Does anybody have any ideas what it could be or how to diagnose any further.
If it is the gear box it is still under its 12 month warranty so will remove it and take it back if that is at fault. But I only have a couple of months left on the warranty to work out the problem.

could be a few things ,its ashcrofts problem

dag019 · Apr 21, 2017

jamesmartin said:
could be a few things ,its ashcrofts problem

I haven't contacted them yet I wanted to make sure it definitly sounds like a gearbox problem rather than transferbox or axles. Don't really want to get them involved for them to tell me the gearbox is fine and it is something else.

jamesmartin · Apr 21, 2017

dag019 said:
I haven't contacted them yet I wanted to make sure it definitly sounds like a gearbox problem rather than transferbox or axles. Don't really want to get them involved for them to tell me the gearbox is fine and it is something else.

it could be, you can run with each prop removed in turn in diff lock to help rule in or out an axle and prop and either t/box output bearing, but its difficult distinguishing between the 2 boxes with only that to go on,have you checked the oil in both boxes and its condition ie contaminated

dag019 · Apr 21, 2017

I haven't checked the oil recently. But about 6 weeks ago last time I checked the oil was the correct level and good condition. I will check it again tomorrow. If it is worth running without the props they are easy enough to take off to test the axles. I just don't really want to have to drop the gearbox again!

Rougharse Racing · Apr 23, 2017

If you put the transfer box in neutral you can run the main gear box up and down the gears to check for noises. It won't be under load but may help pin down the issue.
As you probably know, 4th gear is straight in and out, so if 4th has knackered bearings I would expect it to be noisy in all the gears. (could be wrong)

dag019 · Apr 23, 2017

jamesmartin said:
you can run with each prop removed in turn in diff lock to help rule in or out an axle and prop and either t/box output bearing

I did not get chance to do this today but will try and have a go one eveing this week to get some more information. How does that rule out an axle as surely everything will still be turning? If it is one of the diffs or output bearing on the tbox would it not be dependant on speed and therfore should be differant in high and low range or am missing something?

jamesmartin said:
have you checked the oil in both boxes and its condition ie contaminated

I have checked all the fluids today and they are all at the corect level and look clean and nearly new (should be as less than 12 month old). The front diff oil was the only one that did not look new so I will change that tomorrow.

Rougharse Racing said:
If you put the transfer box in neutral you can run the main gear box up and down the gears to check for noises

There is no noise with the transfer box in neutral but the noise is only there when driving when the drive train is under load either accelerating or engine braking.

Are there any other tests that I should try to diagnose the problem?

jamesmartin · Apr 23, 2017

dag019 said:
I did not get chance to do this today but will try and have a go one eveing this week to get some more information. How does that rule out an axle as surely everything will still be turning? If it is one of the diffs or output bearing on the tbox would it not be dependant on speed and therfore should be differant in high and low range or am missing something?

I have checked all the fluids today and they are all at the corect level and look clean and nearly new (should be as less than 12 month old). The front diff oil was the only one that did not look new so I will change that tomorrow.

There is no noise with the transfer box in neutral but the noise is only there when driving when the drive train is under load either accelerating or engine braking.

Are there any other tests that I should try to diagnose the problem?

nothings a 100 % certain but axle is not under load so if there is a fault there it should be noticably different

dag019 · May 8, 2017

jamesmartin said:
nothings a 100 % certain but axle is not under load so if there is a fault there it should be noticably different

Having now replaced the front diff oil that made no difference.

I have also run it without the front prop (I ran out of time to do the same with the rear but will try in the week). This made things slightly quieter but the bearing whine was still present. With both props fitted it is now noticeable in third, and may be present in first and second but is difficult to tell due to engine noise. It is most noticeable under load in fourth gear.

dag019 · Jun 15, 2017

I had a bit of time last night and took the trandferbox sump off to inspect the intermidiate gear as advised by ashcroft (who were adamanet it cannot be their gearbox). There is a little bit of side to side movement, how much lateral play would be expected/is acceptable on the intermidiate gears?

Gearbox whine

dag019

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lightning

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jamesmartin

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dag019

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jamesmartin

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dag019

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