Transmission whines when decelerating. Is this normal?

Cheburashka · Post by **Cheburashka** » Tue Nov 13, 2012 12:09 am

Someone asked this question a month ago and got no answer. I have the exact same issue. When I'm slowing down there's a whining sound from the gearbox. I'd like to know if that's just what you get with straight-cut gears, or if it's a sign that something is wearing out.

Thanks

jensey · Post by **jensey** » Tue Nov 13, 2012 2:04 am

When I'm slowing down there's a whining sound from the gearbox

In every gear or just in fourth gear ?

If in every gear, check your trans bearings
If just in fourth gear, check your gears, shifrfork and your bearings.

The reason I don't give an answer on these questions is that it leads to another question.

"can I fix these with the engine in the frame ?
"Do I have to split the cases ?"etc, etc,etc.

Most people are afraid to get into the engine, and want to stay away from it, so they ask questions to get the problem out of the gear box into something simple or want to hear " it won't heart the engine".

Jensen

mike in idaho · Post by **mike in idaho** » Tue Nov 13, 2012 11:28 am

The 250/305s have a spring-loaded tensioner mounted on the bottom run of the primary chain. The top run of the chain goes temporarilly slack on the over-run (compression) because the bottom gets pulled tight. Doesent hurt anything (that's just how it works), it does sometimes add another little sound to what's going on there.

bonjour · Post by **bonjour** » Tue Nov 13, 2012 2:24 pm

I also have the noise, but only when driving (but mainly decellerating) in 3rd gear.

It's not loud or something, but I personally tend to hear every single noise out of any engine.

I don't think it will do any harm, because like you say, gear tooth's are straight.

Old Kreidler's (mopeds) also have the same sound, around where I live people really like Kreidler moped's, and the whining sound out of my 305 sounds similar to a Kreidler, only less loud. But the idea of the sound is the same, and it really comes from the gears.

I think it's due to the flat teeth of the gearbox like you said, from the Kreidlers we know that that is the cause of the 'typical' sound.

I would say the gears are a little worn, but that doesn't matter at all if you drive it like you suppose to do. Just normal and relax, but with some rpm's...

jensey · Post by **jensey** » Tue Nov 13, 2012 2:50 pm

QED, you got the answers you wanted.

It's normal, you don't have to worry, it's good, it doesn't harm etc. etc.

Jensen

Cheburashka · Post by **Cheburashka** » Tue Nov 13, 2012 4:36 pm

I'm certainly not looking for a prescription for rose-colored glasses. I tend to be the kind of person who will disassemble first and ask questions later, and I'm paranoid about noises. My MG Midget whined in first and reverse. After much troubleshooting, I found that it whined in those gears because all MG Midgets whine in those gears. When I was told that the sound in my top end on the CA77 was probably something serious, I disassembled the top end and replaced the pistons. I'm not afraid of a little mechanical work. I'm afraid of unnecessary mechanical work due to faulty diagnoses of noises, as when I spent three hours trying to figure out why there was a clicking sound when I rotated the crank on my CA77 when it was out of the frame and later found that the kickstarter shaft had dropped down a notch and was causing the click.

In this case, it sounds as though the whine is not normal. I'll keep an eye on it and try to figure out under what circumstances it makes the noise so I can diagnose it more accurately.