It sound as though I need the shims at the bottom right, to cure the backlash issue. If Quaife don't want to supply them, I am fairly sure they could be sourced elsewhere.
When searching for a possible explanation for our screaming bevel boxes I wanted to see how BMW makes their bevel boxes on their motorbikes (which don’t scream) In a German motorcycle magazine I found a picture of a rear wheel drive of the BMW 1200 GS. And as you can see on the pictures they looks similar except the support of the pinion wheel !!
The picture on the BMW unit shows that the pinion shaft is supported on both sides. But ………. (so far as I can see) in the Qauife bevel box there is NO support on the end of the pinion shaft !! For the pinion shaft it has only one bearing in the main housing and probably one more bearing in the screwed on removable bearing housing which get attached to main housing. (so far as I can see on the picture) So both bearings of the incoming shaft are on the same side.
When driving, the pinion wheel is trying all the time to push itself out of the crown wheel due to the force on it. Because there is only support on one side of the incoming shaft, it will create (depending on the load) a huge force on this bearings. The bearing near the crown wheel will get a force away from the crown wheel. The force on the bearing in the removable housing will be to the opposite direction ! Due to this force, the shaft try to move the removable bearing housing (which is bolted on the main housing) to one side. And because it’s just bolted on there will be always some movement possible.
When shimming the whole unit for optimum play between the teeth there is no force on this removable bearing housing. When driving and applying force on this removable bearing housing it will be forced in one direction. But that direction will create more play between the teeth of the pinion and the crown wheel Which also results in the fact that optimum shimming will be impossible, because when shimming this force on this removable housing is not there. So far as I know the amount of noise is very critical to the amount of play between the teeth. So everyone can understand that if we get more play we’re getting noise. Explains also why the noise is gone when taking your feet of the throttle because the force is gone which pushed the pinion wheel out of the crown wheel so don’t create the biggest play possible anymore.
This also could explain the leaking which some boxes have on the incoming seal because the shaft will be pushed all the time to one direction/side in the seal (also because of the length leverage bearing and seal) The difference in noise level when hot can also be created by more play between the wheels due to the expansion of the housing.
Is my simple view correct ? I don’t know but it looks to me a explanation for the noise. What can we do about it ? The best way would be a better layout (like BMW) but that means there need to be complete new bevelbox developed. Perhaps a better fixation for the removable bearing housing to the main housing will also do the job so the two housings will more act as one piece.
Who can we blame for this ? Quiafe ? They say: We made it how MMC told us to make it. Can we blame MMC ? They say: It’s constructed by Quiafe and they are the specialist in this field. We only can hope that a company ( Garage 56 ?? ) develops a better constructed piece of machinery (like the upgrade of the compensator to the Centa unit)
Note in the picture from the garage56 facebook entry two bearings are missing, sent off for analysis. I'm sure that the pinion shaft is supported in the same way as BMW and Guzzi bevel box's, typically with a pair of taper roller bearings, it wouldn't make sense for it not to be.
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone
Regarding the question over re-conditioned bevel boxes, these have been available since June last year. All of the re-conditioned boxes are returned to Quaiffe for stripping and repair as necessary, some units only the casing is salvaged everything else is replaced, others to a lesser degree. New ones are also available from stock. I can't understand why anyone would need to wait more than 10 working days for delivery of a new unit. Both have separate part numbers and are priced accordingly.
Regarding the question over re-conditioned bevel boxes, these have been available since June last year. All of the re-conditioned boxes are returned to Quaiffe for stripping and repair as necessary, some units only the casing is salvaged everything else is replaced, others to a lesser degree. New ones are also available from stock. I can't understand why anyone would need to wait more than 10 working days for delivery of a new unit. Both have separate part numbers and are priced accordingly.
Mark Evans
Hi Mark,
Thanks for your note, first time I've heard there's a choice of new or reconditioned.
For many of us the issue is that there is no guarantee that a replacement box will be quiet. I had mine replaced last Nov for a leaking seal and the new box after 1,800 miles is much noisier than the original.
Regarding the question over re-conditioned bevel boxes, these have been available since June last year. All of the re-conditioned boxes are returned to Quaiffe for stripping and repair as necessary, some units only the casing is salvaged everything else is replaced, others to a lesser degree. New ones are also available from stock. I can't understand why anyone would need to wait more than 10 working days for delivery of a new unit. Both have separate part numbers and are priced accordingly.
Mark Evans
Dear Mr. Evans,
Thank for your reply which give us the hope that there is light at the end of the tunnel.
So far as I know no one on this forum knew about re-conditioned bevel boxes.
Some weeks ago I wrote an email to Quaife directly to ask them about this possibility and they told me to go back to MMC without mentioning that a refurbishment of their boxes would be possible. They answered me that my email to them had been forwarded to MMC and I could expect an answer from MMC (from which I never got a reply).
Many of us are willing to pay extra money for a bevel box that don't scream as the ones we have now but ......... do we get any guaranty that this will be also the case ? (see the post from Chris99 two days ago)
Can you inform us what the best way is to get this repair done and how much this repair will cost us ? Can you also inform us if it will be possible to swap our old bevel box for a refurbished one ? Or do we need to buy a new one in case of a swap ?
Once more thanks for your help and your support to get this nasty problem with the M3W's solved.
It would also be interesting to know what is the cause of the noisy bevel boxes and what is done differently during the re-conditioning process.
I know absolutely nothing about this subject.... but if the gear teeth were very slightly skewed (i.e. not facing each other dead square) could that cause increased noise?
If the bevel gears were straight cut you would expect them to be noisy. They are however, spiral bevels, which by their nature are supposed to reduce noise and vibration.
I cannot believe that Quaife were "treading new ground" when the bevel boxes were designed and produced for MMC. I would assume that the spec MMC supplied to Quaife was with regard to overall shape and dimensions including mounting details, reduction ratio and power/torque capabilities, but full details of the internals, I am pretty sure would have been left to Quaife to sort out.
