Gearbox noise

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robmurray
Posts: 88
Joined: Sun Sep 21, 2014 11:01 am
Dino: Fiat Dino 2.0 Coupe
Location: Marlow, UK

Gearbox noise

Post by robmurray »

I have just had my gearbox rebuilt by a very reputable company. It had all new synchros and all new bearings plus, of course, gasket kit and oil. The gears were fine and re-used.
All works perfectly now but there is a significant amount of whine form the gearbox - it is much louder. Any theories on what this might be? The people who rebuilt it have provided a warranty but they think it is just a normal noise.
Any advice appreciated.
Thanks
Rob
Dinoswede
Posts: 109
Joined: Sat Apr 05, 2014 4:22 pm
Dino: Fiat Dino 2.0 Spider

Re: Gearbox noise

Post by Dinoswede »

By coincidence, I have spent the last Winter overhauling two different 2 Litre gearboxes!
Re your "new" transmission noise, I can think of a few possible causes:

1. If the noise is heard regardless of which gear you are using, it may be the first gear set
between the constant mesh shaft and the lay shaft, that is slightly re-positioned, compaired
with before dismantling.
It could happen, e.g. if using bearings with slightly different dimensions than original,
re-positioning the gears in relation to each other.
2. Unfortenately, it happens new bearings are defect from factory, which in most cases are
hard to find out before installation...
3. Which type of oil are you using? A thick mineral SAE 90 EP oil sometimes makes a gearbox
less noisy than a modern, fully synthetic gear oil.

Dinoswede
robmurray
Posts: 88
Joined: Sun Sep 21, 2014 11:01 am
Dino: Fiat Dino 2.0 Coupe
Location: Marlow, UK

Re: Gearbox noise

Post by robmurray »

There are two noises - one which varies with engine revs and a whine when you accelerate through the gears.
Do you think I should worry?
Thanks
Rob
Dinoswede
Posts: 109
Joined: Sat Apr 05, 2014 4:22 pm
Dino: Fiat Dino 2.0 Spider

Re: Gearbox noise

Post by Dinoswede »

Rob, my experience is, most old gearboxes are making some kind of gear noise - but of course, there is a
certain limit, over which it is not acceptable. I have understood it as it is much more noise than before
the rebuild, which of course is very irritating!
Questions below are only a try eliminating different possible sources for the noise - not trying to offend
you in any way!
1. Are all rubber boots and centre consol parts re-installed after the rebuild? These are important for
stopping noise from engine/gearbox assembly getting into the car.
2. When you hear a noise following the engine revs, are you hearing that noise when revving the engine
in neutral and the clutch pedal pressed down? If so, that sound probably is from the clutch release bearing.
3. Re the whining when driving in different gears - is it increasing when applying more engine power? Is it
a change when braking with engine in a low gear - which means "loading the other side of the gears"?

Having not test-driven your gearbox, it is impossible to say if "you should be worried" or not.
Try finding another gearbox expert and get a "second opinion"!

Dinoswede
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