Gearbox rebuilt, still some noise?

[Beatman]

So got the gearbox rebuilt. Fair bit done to it, repairs to 1st and 2nd forks, dog teeth on outer hubs repaired and a bearing and seal kit installed.

Also installed brand new genuine clutch kit but for some stupid reason when I release the clutch there is noise.

Now we are guessing that the clutch release bearing is still in gentle contact with the pressure plate fingers perhaps? Gearbox operation is fine otherwise.

Could a failing master or slave cylinder contribute to this? What about the clutch release bearing spring? when I was was inspecting the setup it didn't appear as if it had any effect in returning the bearing, more just to keep the bearing clipped to the fork. If so what is supposed to return the bearing after depressing the clutch. Surely there must be some mechanisim to keep the bearing off the pressure plate fingers when not depressed?

Very interested to hear what people know, thanks.

[Steve_M]

There is no mechanism to hold the release bearing away from the pressure plate fingers, it stays in contact ready to disengage the clutch.

Any release bearing noise is normally heard when the cluch is depressed as this is when the release bearing is loaded.

Bearing noise heard when the clutch is released and the vehicle is stationary is normally associated with main shaft bearings, this noise would also be heard when driving in gear.

If the bearing noise is only during driving and from the gearbox it would normally be either countershaft bearings or diff bearings.

Common bearing noise on many Honda models is the front (closest to clutch) main shaft bearing, both jazz and civic suffer from this, often blamed on the small bearing size.

[Beatman]

The noise is heard once the clutch is released whilst stationary in neutral. If it is also noisy while moving I can't hear over the din of the engine.

Are genuine gearbox internals still available? I wonder if they forgot to change all the bearings or couldn't source them all aftermarket. I'm sure they didn't even attempt to go genuine as they told me parts wouldn't be available from Honda when I asked.

Well I hope the release bearing has some tension on it if it's going to be up against the pressure plate otherwise you might expect some wear or noise?

[Steve_M]

Both mainshaft bearings are still available to order, thou no stock in Europe so would have to come from Japan.

[Beatman]

While I was snooping around the web I'm sure I read that another model Honda that shares the E07 motor uses the same auto box as the D series civics, would that not mean that manual D series boxes would fit too? I know the ratios are off but there might be a way around that yes?

I've been investigating engine swaps also and there are really no options better then whats in there already. All the new Honda motors need to be mounted the other way round which does't feng shui with the fuel tank and the engine bay is asymetrical to accommodate it. Plus the E07 is slanted giving correct weight distribution. Your never going to maintain that with a different motor.

[Steve_M]

Your probably thinking of a Honda Life, info from wikapedia.

It used the Honda E07A engine, 660 cc SOHC 3-cylinder, 4 valves per cylinder, with Honda's PGM-FI as standard equipment. Transmission is 5 speed manual transmissions, or a 3-speed automatic transmission.

A D series Civic never had a 3 speed Auto and knowing the size of a Beat gearbox, there is no comparison to a civic one.

[Moriniman]

Most release bearing wear occurs when the bearing is spun from zero to high rpm, so continual light contact can be an advantage and is standard practice on race cars. They're not graphite blocks any more!

Many automotive bearings (and seals) are just standard off the shelf items and can be obtained much more cheaply from a bearing stockist (I mostly use simplybearings.co.uk). Sometimes the bearing has a non standard part number, but comparing dimensions will find you a suitable bearing.

If a gearbox was noisy before rebuild, it will often still be noisy afterwards as new bearings will put worn components into new alignment.

[Beatman]

I'm thinking perhaps they did the bearings but the input shaft itself may be worn? Does that sound possible? You can hear a slight noise with the engine engaged to the box even in neutral. How many things could cause noise when the input shaft is the only thing connected?

[Steve_M]

The only shaft that is turning when the car is in neutral, clutch engaged and car stationary is the main shaft.

So 2 mainshaft bearings (1 at clutch end and 1 outer)

Each syncro has a needle bearing in it to allow the gears to run free. (never really a problem as there is little load on these)

Its normally the clutch end mainshaft bearing that causes all the noises, it runs at engine speed and get very little lubrication as it only splash fed, it also often gets overlooked as it stays in the gearbox front case when all the shafts are removed and can be a pain to knock out.

You may be able to isolate where the noise is coking from using a listening stick e.g long screwdriver and listen to the end casing and the bell housing and see where the noise is worse.

It could be the gearbox was not shimmed properly and is very tight, but as you say gear operation is OK, I would think its no too tight.

[Steve_M]

No. 23 is front mainshaft bearing.

[Beatman]

Thanks for the help guys. I will start by trying to hear which end of the box it's coming from and take it from there.