Interference fit bearing sleeve

I note that you say that the bush should not rotate on the shaft, but as both the shaft and the housing appear to be hardened it would be possible to just have a fully floating bush with no interference fits involved. Provision would need to be made to feed oil from the outside to the inside of the bush.

Not knowing the details of the design I do not know if such a bush would be fully retained axially. Also it depends on the actual finish in the bore where the apparent indentations are.

If I remember correctly, EP oils have sulphur content which has an adverse on copper based bearings, this may make such bushes short lived, but this may be acceptable to you.

Neil

Might be worth contacting HCP in Mansfield - they mainly do motorbike forks, but I'm sure they will advise. No connection, just a happy customer.

Links to https://www.hardchromeplating.co.uk/

Rob

..and I've had good product and service from A M Philpott in Luton..

A M Philpott Hard Chrome Plating

Neil I love it. The power of lateral thinking. The bronze can be located axially as there are snap rings both ends of the inner sleeve. Sidesteps the problem of interference fits both ways.

You are also right about the issues that modern gear oils containing sulphur create in use with bronze bushings. This gear oil is known as GL5. GL4 doesn't contain sulphur derivatives and is OK in these gearboxes which have bronze synchro hubs, also for back axles with bronze crown wheels. If I've understood things correctly.

Thanks as ever

Ep90 gear oil? Do be careful that it doesn't contain extreme pressure additives that eat yellow metals.

I wasn’t aware that there was any form of oil pump in those Fairey overdrives. Are they not just splash lubricated? I had two fitted to my Series lll - one always ran very hot and its replacement was a far better unit (ran cool and drive selection was far smoother).

Hopefully my comments re GL4 and GL5 oils cover this.

As to the "pump" concept, the main output gear is drilled radially with small holes in the lands at the bottom of the teeth. Hence oil brought up from the sump riding the gear teeth is squished under pressure through these holes as the teeth mesh, providing lubrication to the bearing inside.

Edit :

Bear in mind that oil for the final drive gear is from the sump of the transfer box.  In theory this oil is  kept separate from that in the bottom of the overdrive so hopefully the cooling of the inside bearing is better.  

Edited By Simon Williams 3 on 13/07/2023 20:53:24

I second that solution

Ian P

I have just had a thought. You can get over sized rollers to replace the original rollers in the bearings. You could get the bore re-ground to clean up then order oversized rollers to fit.

https://www.rgpballs.com/en/products/precision-cylindrical-rolls-rollers-and-needle-rollers/?gad=1&gclid=CjwKCAjw5MOlBhBTEiwAAJ8e1sIUYsMtsSAadQ46WskNmzYYmh5x2FaBsLBy3U9PSSIGsn4BkDtz6BoCGZ4QAvD_BwE

David

Removed

Edited By duncan webster on 14/07/2023 17:18:50

Is there any reason why the bush cannot be retained in the external housing, with the shaft rotating inside it? It would only need a light press fit, or Loctite. The oil holes could be drilled through after fitting.

Or isn't that complicated enough for you guys?

A floating bush has been suggested earlier but I think it is difficult to predict how this would behave. As the assembly heats up the bush will expand, and tend to bind in the housing. To ensure that it floats properly it would have to be quite a loose fit, in which case it may not work well as a bearing.

Just a thought if not already rejected create your bronze bearing sleeve in 2 stages:-

1. Press fit design OD from Limits and Fits leaving bore sllghtly undersize.

2. Once fitted to Housing Precision Bore/Ream to give Transition fit with shaft.

In the original set-up the needle roller cage is retained onto the coupling that fits inside the above gear by two C-Clips. These retain and locate the needle roller bearing on the coupling. Pressing a bush into the above gear means it would not be possible to fit the leading retaining C-Clip, or the parts cannot be assembled.

This type of needle bearing assembly allows for some degree of self alignment, endwise within the housing bore. It may need several trials to get any pressed-in bearing, in the correct endwise position.

A few words of caution.

If this bush should seize at speed then not only is the gearbox and transfer box going to suffer, but it could also lead to an accident. It may also mean invalidating the insurance on the vehicle, as fitting this bush would be modifying it.

Regards

Gray,

If they can do it over the pond ..... link