Puma Stripped to the Bone to check Rotor Bearing

[knoxie]

Hello

Somebody asked me if I had any photos of the Puma rotor stripped to the bone! so here they are, they were taken a few years ago, the new Puma uses a Key on the Rotor to key the rotor and the rotor bearing (seen on here with the grooves in it) to stop them both slipping, this one was stripped because the power 48V 35A had started to make the rotor slip on the bearing.

One thing that has been noticed, on the Pumas even the newer ones that the main bearing is fairly fragile, you can see on this picture the grease that appears to have spun up out of the bearing due to use and rotor speed, on high RPM pumas people running them at 60V and up you may find over time this bearing will be a problem, I havent looked in to it but it may be possible to change this bearing for something more robust? as I have seen these Seize now on 2 x pumas that were being used at high RPMS.

If you removed the phase wires and the top collet it may be possible to remove the circlip seen in the pictures and remove the bearing replacing it for another more robust unit, You can of course split the rotor from the gear however this is not for the faint hearted it took ages getting the rotor back on to this motor properly.

I had these piccies on an old hard drive thought some of you may be interested, If anybody does manage to swap out this bearing I would love to hear about it, it will almost certainly fail at some point or start to dry out, a way to check this is disconnect the battery from your controller and move the bike backwards, any significant resistance is indicative that the bearing is dry and or failing.

Good luck

Knoxie

 

[Jozzer]

Nice one Knoxie.

More feedback on the 2 motors here, bearings had failed due to extreme jumping (Gary is hereby named the E-bikeKiller), but that wasn't what locked them. Locking was due to overeager hammering when reassembling and pinching the circlip into the rotor bearing.
Outer bearing had failed on Clives, and the slipping was actually the outer gear ring Again though, I think this was caused by the jumping not the speed in this case (not least because both bikes were used offroad and not at very high speeds, and both had less than 10 hours of use on them)

Beware of trick riders wanting to "test" your e-bikes! :lol:

Andy's motor had a cracked shroud (the funnel shaped part twith several screws around the axle at wired end) too, maybe the bearings fault again, or perhaps Bob with the hammer!

PS, not that it made any difference to thier strenght, but the newest model with "team hybrid" stamped on it had a metal shrouded bearing rather than the plastic one you show there. Perhaps they are better sealed? Time will tell! I think next batch will be different agaiN!

Steve

 

[knoxie]

Hi Steve

Ok cool! yes I think the Jumping was the problem, these should have been fine if it wasnt for that, the inner bearing on the shaft is that slightly 1 way? it seems that there is more resistance in 1 direction?

How repairable do you think they are? its a hell of a job to remove the motor, maybe easier to remove the phase wires and slide the collar off the stator and get to them at that end?

I would be interested to know what the factory are doing now, Clives bike hadnt been jumped though although it had taken a lot of abuse superfast starts and the like.

Let me know how you get on with them and if you manage to repair them.

Cheers

Knoxie

 

[disadvantage]

Many thanks for the pictures, Knoxie. You always provide quality content to this forum.

I'd like to remove (and put back in) the axle from the rotor in my Puma motor. Once the axle is out, I want to chuck it into a lathe and drill a hole clear through it. This way, I can run heavy phase power wires out one side of the axle, and the hall sensor wires out the other.

I managed to get my motor striped down to a rotor + axle assembly, but got stuck on how to remove the axle.

Is the axle just a press-fit into the rotor?

Can I press it out, drill my hole, then press it back in?

What sort of tool or jig did you use to remove and replace the axle?

I remember you suggested replacing a bearing with a higher quality one. Do you recommend any other modifications while I have everything apart?

 

[knoxie]

Hello

Thanks for the compliments! yes its a press fit, on the new ones there are also keyed, If I were to do it again I would not press the rotor off though, you shouldn't need to do it unless you want to key it, I welded mine across the top of the bearing where it meets the rotor, it hasn't moved since.

If you are just changing the phase windings you only need to remove the collar, also I wouldn't remove much metal on the axle, there really is no need to change the phase wires unless they are damaged, just making them as short as you can from the axle is usually enough, all mine are std and have never been a problem.

There are plenty of threads on here about people changing the wires if you need to check them out, Geoff57 made a nice job of his using multi stranded wire.

Good luck with it and posts pictures of what you do, again I wouldn't remove the rotor unless you really want to and you like a challenge! getting it fitting square back on the bearing is a trick and half, we did it on a lathe with a dial gauge, then welded it vowing never to take it off again!

Cheers

Paul

 

[Jozzer]

Clive's bike had been jumped by Gaz (The Destroyer).
I look froward to seeing what the next batch of motors will bring, I know they will be different. I'll look into replacement bearings if I get time, and potential upgrades too.

Steve

 

[solarbbq2003]

any hints on how to remove the outer ring gear? some sort of puller?