Gear box whine

[Paulcovy]

hi all
My 4 speed Manual box whines when driving and stationary but goes away (quiet) when you apply the clutch ,
Any suggestions ?

I have replaced all the main bearings except the needle rollers and the really expensive one at the back
Thanks

 

[harveyp6]

If you've replaced the first motion bearing and it's still noisy then it can only be either the laygear bearings, (the most likely cause), or the bearing that supports the front of the mainshaft in the back of the first motion shaft or the bearings that the gears on the mainshaft run on, but tbh I don't think that you'd be able to hear those even if they were worn.
Make sure that all the grommets around the gearlever and in the tunnel are correctly fitted. They are noisy because of their all ally construction, and that massive bellhousing on the front.

 

[Paulcovy]

Thanks Harvey for you reply
It’s so noisey that I think I need to change up when I’m only at 2000rpm , it’s the first time I’ve driven it for 2 years due to the engine rebuild and tons of other work I’ve done , il look into what you’ve said , but the minute the clutch goes down it’s silent

 

[harveyp6]

At a standstill the only bearings moving are the ones I mentioned, and from the way you describe the noise, new or not, my money is on the first motion shaft bearing. Laygear bearings won't be that noisy, neither will any of the others.
I had one like yours, really noisy when I went to the bloke's house to test it, then when we got back from the test drive I removed the box and dismantled it on his driveway in front of him to prove I was right. That bellhousing acts like an amplifier.

 

[Paulcovy]

Nice that’s great , il look into that thanks again Harvey you’ve been a great help as always

 

[Paulcovy]

This is a spare set of shafts I have which bearing are you referring to I’ve replaced the front input shaft bearing and the two taper rollers on the lower shaft .... can to much pre load in the lower shaft taper rollers cause this noise , thanks

 

[harveyp6]

You have to remember that the layshaft taper bearings are fully immersed in the oil, and they don't have that big bellhousing to amplify any noise, so regardless of the preload, whether too much or too little I just can't see those making the kind of noise that you're getting.

Either way, it sounds like (did you see what I did there....) the box is going to have to come out and be dismantled again to see what's going on. If it's really that noisy then the cause should be easy to find when it's in pieces.

One thought, did you fit the shim in front of the first motion shaft bearing, or if you had a bearing that was covered one side, which way around did you fit it?

 

[Paulcovy]

Yes I’m sure I did fit the shim , and the bearing was not covered. Thanks again

 

[Paulcovy]

Have removed and stripped the box again today , haven’t found any wear in of the bearings , however there seemed to be some play in the front input shaft bearing , I also found that when measuring to oil it was around half a litre down than the book states, the noise wasn’t there on first start this morning but retuned within a minute or so , also seemed to be loudest when hot. I shall replace the layshaft bearings and first motion shaft bearing again and see if this sorts it.Also the book says to use a spring balance to set the preload for the layshaft bearings , is there any other way of doing this ?

Anything that sounds dodgy? Would the oil level being half a litre cause the fault ?
Thanks

 

[harveyp6]

Also the book says to use a spring balance to set the preload for the layshaft bearings , is there any other way of doing this ?

There's not really any other way to do it. You need to wrap enough cord around the shaft to get a long even pull, which will give a more accurate reading on the spring balance. The problem you have is not having a large selection of the shims needed to alter the preload.

Would the oil level being half a litre cause the fault ?

They only hold 1.75L so you're over 25% down on what you should have.

 

[Paulcovy]

Do you think that could be the cause? The oil level?

I’m going to replace all the bearings again and rebuild it again I’m just afraid of having the same problem as I couldn’t see a obvious fault with the box once I’d stripped it down

 

[harveyp6]

If the noise is really bad I can't see it just being low oil level causing it. Most of those boxes leak so I bet there are loads running around needing a litre top up and they're not all whining like yours.

If you still have the problem when it goes back in this time you could try posting a video.

 

[Paulcovy]

Ok I will do that , is there any bearing manufacturer I should stay away from I think the ones I bought were skf which I’ve never had an issue with before.Also the old bearing has a groove cut into the outer race which the replacement never had ?How much play in the input shaft is too much would you say?
Many thanks again for your help

 

[harveyp6]

If they are genuine SKF bearings I'd expect them to be of a high quality. A groove cut into the outer race isn't normal, so fitting one without the groove returns it to how it should be.
It's difficult to say how much play is too much when I have no idea how much play you have. I'd say not a lot, but that won't mean much to you.

If you still have it in pieces and want to post some pics of the parts I can have alook to see if I can see anything.

 

[Paulcovy]

This is the groove I mentioned

 

[Paulcovy]

This is the one I’ve fitted which is suspect noisy

 

[Paulcovy]

Also have replaced these previously as well

 

[harveyp6]

That was on the bearing that came out? That outer surface is an interference fit in the bellhousing so i can't see the groove making any difference.

I presume you changed all the bearings you did because the box was noisy, but having done that the noise is worse than it was before?

 

[Paulcovy]

There doesn’t seem to be any markings on the races either

 

[Paulcovy]

No it was an auto and I’ve made it Manual I’ve got the box and a few others and stripped them all and did the bearings as I had no idea of the history of the boxes , the engine ect was also rebuilt , then all had gone back together for its first drive in 2 years , then the gear box started whining.