MP3 Bearings+battery issue

[Bwizz]

After going through an unintended .water ford the other day next time out the hub bearings are howling.
I notice the larger bearing is available on e bay China shop  for £16 .inc postage
Aound £45 in UK . Anybody got any thoughts?

Another qwirk of the bike is that after the throttle led lights stopped giving any progressive indication of battery charge.
I now find the first clue thet the battery is getting flat is there seems to be a harsh vibration about 3 miles before It goes completly . This usual?

[Bikemad]

Hi Brian, have you tried squirting some WD40 or 3 in 1 oil into the bearing to see if it will ease the noise?

If you can't get away with lubricating the bearing and it does need to be replaced, I think the £16.80 eBay bearing will be suitable, as long as you don't mind waiting for it to arrive.

I strongly recommend you choose the 6917RS rubber seal option instead of the 6917ZZ metal shielded option (6917-2RS is not an option) to reduce the likelihood of water getting in again:



The 6917RS bearing on eBay may only have one rubber seal instead of two, but a 6917-2RS should definitely have seals on both sides.
It might just be that it is named differently, but if it does come with  only one seal, make sure it is fitted with the seal on the outside. 

It might be prudent to replace the smaller bearing on the other end of the axle at the same time (also with the rubber seal version 6302-2RS) as it was also subjected to the same unintentional dunking.

Alan
 

[Bwizz]

Hi Alan . yet again thanks. I had found your enclosed information on the site! In the interim I found a local bearing supplier that will do the two for £40. I'm going with that being impatient!
Any thoughts on the other issue. is vebration when battery going flat normal?
Brian Cornwall

[Bikemad]

Is vibration when battery going flat normal?

Usually if the battery gets too low the battery's BMS will simply cut the power completely, but it shouldn't affect the smoothness of the motor while it is still supplying power.

I did notice while testing the MP4 with a poor battery pack that the controller automatically reduced the power to prevent the voltage falling below the minimum voltage setting. This feature of the MP4 controller was very useful as it only caused the power to drop noticeably under heavy load instead of the motor suddenly cutting out.

Is this the same infrequent vibration that used to happen at any state of charge with the old battery?
If so, did the new battery make any difference to it at all?

I have never experienced any motor vibrations related to low batteries on any of my motors, but I only have two batteries equipped with BMS protection (one 24V battery and one 48V battery) and I usually allow either of them to get too low.
I mainly use "non-BMS" LiPo packs which are simply equipped with an audible low voltage warning alarm, but I don't like to run them low enough to activate the alarm.

Alan
 

[Bwizz]

Hi Alan. I have a new battery ready to fit but as the old one is still covering around 20 miles with pedal assist. and otherwise up to now reliable. I wanted to get maximum use from the old one. This vibration seems to be a new quirk and is quite consistent just before the battery dies. Not been reading about the latest updates so I did not know about the battery alarms. Seems to be issues with the latest mp's ?

[Bikemad]

Not been reading about the latest updates so I did not know about the battery alarms.

Brian, the alarm function is only for my homemade LiPo packs, the GM packs don't need one as they have their own BMS to protect the battery.
The three types of battery monitors that I use are commonly used throughout the R/C modelling community for monitoring LiPo and LiFePO4 battery packs:







I thought I would just clarify this to avoid any further confusion. 

Alan
 

[Bwizz]

Collected the new bearings this morning. I have seen the hub strip down step by step on the site . Is there anything to be aware of whilst replacing the bearings? I'm surprised how big the left hand bearing is!

[Bikemad]

Brian, I suggest you tackle one side at a time by removing the respective side cover, as this will allow the other side to keep the stator assembly nicely centred and hopefully prevent it from touching against the magnets.

If you mark the side cover in relation to the valve with a piece of sticky tape etc., it will allow you to refit the cover in exactly the same position that it was removed from to prevent any possibility of throwing the rim slightly out of true.

If the bearing does not come out of the cover very easily, I would try warming the cover up using a hairdryer or even placing the cover in the oven at 80~100 degrees C. (Hopefully the paint can withstand this temperature.)
As the cover expands with the heat it should allow the bearing to be removed more easily, but don't forget to wear some suitable gloves to protect your hands from the hot cover.

The left hand bearing has to be that big to allow it to fit over the controller housing. 

Please let us know how easy the bearing replacement process really is.

Alan
 

[Bwizz]

Thanks Alan. a few pointers there that weren't  obvious. !
Just got to collect a new tyre and rear mech and then i'll get on with it

[Dirk]

MY MPII (external controller) Rear Bearing is dragging badly after exposure to rain, after only 20 Miles use. So I am trying to regrease it, and get it working again. In Baja far from any new parts source. Guess I have to open the pie plate to get in there and clean it all up. Seems a little too easy for water to get in there and so quickly wreck an otherwize fairly new motor, even though, yes, it is an older version. Sure hope the MP 5 series is better sealed and not as vulernable to sudden death of the bearing after just one rainy exposure!  Suggestions anyone??

[GM Canada]

Hi Dirk,

I did a quick search of the forum and saw a suggestion of spraying wd40 in there as a temporary quick fix. I have bearings if you need them but I also realize you are on vacation so that doesn't help your immediate needs. Maybe someone else can suggest?

Gary

[Bwizz]

Hi Alan as requested summary of bearing replacement. To say the least pig of a job. The ease of the dismantle hub video is a joke.!
Following video I started on the left controller side first. after removing all retaining bolts. I tried to follow the video trying to pull of the casing with gentle persuasion from mallet on cotroller  housing and thin screwdrivers around case . I would say it is almost impossible to do it this way without damaging the mating surfaces of the aluminium  casing. Finally after working around with biiger screw drivers ,tyre levers and wedges. the casing came of leaving the bearing stuck on the controller housing. I was then able to knock of the right hand casing with a dift through the centre of the motor. with the right hand casing removed .I was able to get at the left hand large bearing . this was still well stuck .but with more persuasion came away. After cleaning up the damaged left hand casing with a file. I applied some silicone around the respective joints and re assembled.
If I was to do this again . This is the way I would do it.
I would pull the joining pins out of the main battery lead . Then everything would pass through cetral hole in the left hand casing,
with out touching the controller wiring. I would make some sort of tol to fit on the threads of freewheel centre on the right hand casing. Pull of the right hand casing first with the tool. This would give me acces to the bearing of the left hand casing and be able to remove the bearing with a drift directly on the bearing.
Otherwise I suppose I could have tried, heating the left hand casing. and hoping the aluminium casing would come of the "outer race " of the bearing.  Not as per the video where the inner race comes of the controller housing. "don't think you would have a hope in hell of this happening. with a motor that has seen some use.
In summary not a job I would want to do again in a hurry. The noisy large bearing had rubber seals on both sides!
Moral of this story avoid deep water with electric bikes!