Dreaded gearbox noise = eventual certain breakdown/damage?

[zam]

Hi guys,

I've read up most of the threads on the well known gearbox problems. However, there doesn't seem to be much talk of breakdown/damage over time if the noise/bearings issue is not repaired.

Unfortunately my knowledge of motor mechanics is several levels below zero 

So my question is, if left unresolved, what is the future outcome of the gearbox noise problem?

[culzean]

Noise will keep getting worse in lower 3 gears over many thousands of miles, until not enough volume on radio to cover it

Don't remember seeing any reports of actual gearbox failures on this forum,  and I don't believe the bearing housing or gears gets damaged,  so always possible to fit new bearing.  Noise is caused when end thrust applied to gearbox layshaft (intermediate shaft) bearing from helical cut gears,  I looked at old bearing from my wifes Jazz after it had been replaced and to be honest the bearing spun very freely and hardly discernible noise, certainly no visible damage.   Lower 3 gears always take a hammering on any vehicle because they are used to accelerate car from standstill and get used more on shorter journeys,  so normally first to give problems.

[philiph]

I have the same probleem with me Jazz. I didn’t really notice it until the dealer made me aware. Im doing mostly highway so i cant be bothered with the noise. Is it safe to drive further?
If its get so loud the radio cant cover it anymore i dont mind to get it repaired. 

[culzean]

I have the same probleem with me Jazz. I didn’t really notice it until the dealer made me aware. Im doing mostly highway so i cant be bothered with the noise. Is it safe to drive further?
If its get so loud the radio cant cover it anymore i dont mind to get it repaired. 

It is just one bearing that was not up to standard and the race gets a bit pitted, it will not fail but will just get noisier.  The modern helical cut gears ( much quieter than straight cut, listen to rally, and British touring car races and you can hear their straight cut gears whining, but straight cut gears can transmit much more power for a given tooth size ) develop a thrust along the axis of shaft and the bearing on end of gear shaft needs to absorb this force as it rotates,   The thrust is lower gears while accelerating is at its biggest which is why the noise starts in first gear and then progresses to higher gears later on...

[Jocko]

I ran mine until the noise got too bad then had it repaired.

[philiph]

Thanks for the information

Jocko, hope you’re well. How many miles did your Jazz run before you got it repaired?

[Jocko]

Thanks, I am feeling much better.
I was first aware of my gearbox grumbling at 150,000 km, I had it repaired at 162,000 km and it has now done 178,000 km.

[degzi]

Mines been making a noise in 1st and 2nd since about 100k I'm now on 118k miles. Sound has got a little more noise and it's noticeable in 3rd a bit now.
I don't really notice mine unless I accelerate hard.

[Jocko]

That's how mine started. The lower gears seem to put a heavier load on the bearing and as the bearing gets worse it affects higher gears. The company that repaired mine do about one Jazz every week. They go not remove the gearbox from the car to do it. Total cost was £324 for all bearings, seals, oil and labour. It came with 12 months unlimited mileage warranty (expires next Saturday), and I left car one day and picked it up the next.

[bus_ter]

I don't have this (yet!). My Jazz is at about 85K. I have a couple questions about this issue..

Do you think the gearbox Oil has an affect on when this occurs. Would regular changes, using Molyslip etc help?

Do all Mk1 Jazz's eventually succumb to this issue? Or is it just a batch (non identifiable?) that have the lower grade bearings?