Thought it might be tidier to start a new thread for this. There's some slight duplication so please bear with me.
If you haven't seen the other thread, the crank in my Trek Powerfly (2017) has seized and won't turn. There is approx. 1.5-2mm of play at the edges of the pedals. The motor is a Bosch Performance Line CX Gen 2. I've owned the bike for four years and the motor has never been serviced in that time and probably not since it left the factory.
I don't ride often but when I do it's usually the sandy loam soil of the Surrey Hills or BPW. The bike doesn't have a hard life but it gets thrown into the back of the car once the ride is over, it then gets cleaned when I get home - same day if daylight permits, otherwise it could be a couple of days before the brushes come out. Hardly surprising that my crank has seized.
_IMG_20240414_160320_087 (Medium) (Small).jpg (166.63 KiB) Viewed 1837 times
_IMG_20240414_160313_382 (Medium) (Small).jpg (148.14 KiB) Viewed 1837 times
_IMG_20240414_153917_279 (Medium) (Small).jpg (145.8 KiB) Viewed 1837 times
Got the cover off to find that the bearings circled yellow are seized. Knocking out the large bearing shouldn't be too hard but removing the gear and smaller bearing is likely to more difficult.
_IMG_20240421_163607_869 (1) (Medium) (Small).jpg (108.77 KiB) Viewed 1833 times
The blue circled bearing keeps the gear on the crank. From the videos I've seen, this gear should have come off with the cover in the photo above. The crank and gear turn by hand but it's clear the bearings are goosed. Getting it off could be tricky given the circuit boards...
_IMG_20240421_163612_513 (1) (Medium) (Small).jpg (112.97 KiB) Viewed 1833 times
As I understand it, the actual gear driven by the motor is located beneath the circuit boards circled purple. Haven't been able to check that yet.
_IMG_20240421_163612_513 (2) (Medium) (Small).jpg (109.55 KiB) Viewed 1833 times
This is the idle gear circled yellow in the photo above. Took a good blast with a Mapgas torch and a few squirts of PlusGas but it came off and amazingly the bearing still turns but is very graunchy.
IMG-20240506-WA0002 (Small).jpg (56.64 KiB) Viewed 1833 times
This is the outboard drive side bearing. This is the first bearing on the drive side to cop all the crap you ride through. Turns but the noise and feel make you wince.
IMG-20240506-WA0003 (Small).jpg (73.59 KiB) Viewed 1833 times
The gears don't look too bad, no rust on them but another problem encountered - I should be able to pull the two gears apart, it's "just" resistance fit but nada. To be dealt with later.
IMG_20240504_174022_329 (Medium) (Small).jpg (106.46 KiB) Viewed 1831 times
Crank has some surface rust but isn't as bad as I'd feared.
IMG_20240504_174328_706 (Medium) (Small).jpg (140.81 KiB) Viewed 1831 times
If the bearings are particularly bad, the gears on the crank can damage the PCB - looks like I've been lucky:
IMG_20240505_132129_885 (1) (Medium) (Small).jpg (75 KiB) Viewed 1831 times
No idea what these gears do. They are spinning very freely but there is a tiny bit of play so I'll be stripping this soon enough.
IMG_20240505_201830_685 (Medium) (Small).jpg (125.76 KiB) Viewed 1824 times
Same for this one which runs off the gear from the electric motor (circled purple and hiding beneath a PCB). Speaking of which, the bearings in this motor gear feel spot on - spinning quietly and freely.
IMG_20240504_174357_869 (Medium) (Small).jpg (148.97 KiB) Viewed 1824 times
_IMG_20240421_163612_513 (2) (Medium) (Small).jpg (109.55 KiB) Viewed 1824 times
To remove the crank completely there are a few circlips to remove, then you need to remove the torque sensor which is easy enough. There is a cover on the non-drive side which once removed with a small slot screwdriver exposes a six-point star nut. A close fitting six point socket deals with this.
IMG_20240505_194208_024 (Medium) (Small).jpg (122.12 KiB) Viewed 1824 times
IMG_20240505_194234_053 (Medium) (Small).jpg (115.1 KiB) Viewed 1824 times
Once the nut has been removed you can extract the torque sensor, unclip it and set it aside.
IMG_20240505_194051_757_1 (Medium) (Small).jpg (85.09 KiB) Viewed 1824 times
Once the torque sensor is removed you then need to remove the six screws holding the PCB in place and gently push it/lift it from its resting place so that the final crank gear has clearance. Easier to manipulate the PCB by pushing the connector plugs fom the non-drive side into the motor (towards the drive side):
_IMG_20240414_160316_114_1 (Medium) (Small).jpg (86.63 KiB) Viewed 1824 times
The PCB doesn't need to be moved far:
IMG_20240505_202824_772 (Medium) (Small).jpg (139.71 KiB) Viewed 1824 times
IMG_20240506_125307_976~2 (Medium) (Small).jpg (95.16 KiB) Viewed 1823 times
The gears are supposedly held together by a resistance fit but there's no budging them. Tried using a bearing puller to no avail. Moved on to a heat gun but that wasn't getting the steel warm enough.
Eventually at @maccecht's suggestion, managed to separate them by using a 22mm socket as a drift - I was slightly reticent because I didn't want to damage the plastic largely gear but that was unfounded.
IMG_20240511_185026_733 (Medium) (Small).jpg (108.76 KiB) Viewed 1823 times
IMG_20240511_185430_051 (Medium) (Small).jpg (102.16 KiB) Viewed 1823 times
Once separated we set about trying to remove the bearings with a drift with only partial success:
IMG_20240511_184819_380 (Medium) (Small).jpg (130.87 KiB) Viewed 1822 times
IMG_20240511_184809_908 (Medium) (Small).jpg (129.43 KiB) Viewed 1822 times
The outer race for the needle bearings is still in-situ and despite there being a minimal lip to get a drift on, it's not budging, using the drift is justs deforming the race. Next step is get a weld on it and hopefully the heat difference will unseat it.
IMG_20240511_185034_640 (Medium) (Small).jpg (111.46 KiB) Viewed 1822 times
That's it so far. I should really get the bearing kit ordered. : I should also point out that there are a couple of very helpful videos on Youtube, one from Ebike Motor Centre and another from The Yorkshire bike Mechanic. I'll post links separately.
Q? Given the faff taking the thing apart, what would you routinely have to do to stop the thing self-destructing like this? It looks like you'd have to strip it down clean/grease it etc pretty regularly. (Or send it to someone to do it). Doesn't look like washing the bike each time would actually help much. I may be being hypercritical but that's a bit )
Q? What are the odds on getting it back to condition at a reasonable cost? I don't expect they price the parts very competitively. (I'd have been pricing up a new/refurbed one soon after the cover came off ).
Doubt is not a pleasant condition.
But certainty is an absurd one.
Voltaire
Way back in time when I was mtbing on bikes with serviceable bottom brackets I’d fit o-rings on the outside of the bb axle against the bearing cup as an extra barrier against muck getting in.
Count Steer wrote: ↑Sun May 12, 2024 7:29 am
Excellent thread!
Q? Given the faff taking the thing apart, what would you routinely have to do to stop the thing self-destructing like this? It looks like you'd have to strip it down clean/grease it etc pretty regularly. (Or send it to someone to do it). Doesn't look like washing the bike each time would actually help much. I may be being hypercritical but that's a bit )
Q? What are the odds on getting it back to condition at a reasonable cost? I don't expect they price the parts very competitively. (I'd have been pricing up a new/refurbed one soon after the cover came off ).
I think as a bare minimum, checking and replacing the two outboard bearings which are the first thing to go - if they are in good condition turning freely and quietly then the inner bearings should be fine. If the outboard bearings are in any way noisy or rough then further checking inside required. Replacing those outboard bearings can be done with the motor in the frame though it's a lot easier with it on the bench. You definitely don't want to use any kind of jet wash, even a bike specific one, on these bearings - gentle degreaser and brushes. How often you need to do that depends on where you ride and how frequently. I'd assume I'm at the wrong end of the bike caring spectrum btw.
If everything goes to plan, my costs excluding my time will be £137 for a full bearing kit, £20 for a cheap gear puller and possibly another £15 for the grease that Bosch pack the motor out with (need to find it online but I assume it's similar to marine grease). I am considering buying a cheap hydraulic bearing press for £70-£100 as it will see more use with doing head stock bearings and wheel bearings. The only issue with that is the space it takes up but even I take the plunge I'm up at £280 to get the motor running. I did have a quick Ebay at secondhand motors and they were starting at £300. I seem to recall one of the Youtube videos mentioning the job would be £300-£350. If I used my bike weekly then I'd have paid for the shop to do it but I can justify the downtime and am keen to learn. I also have a very understanding missus who doesn't object to me doing this on the coffee table so am not stuck out in the garage and @maccecht on hand to help too.
Gregor wrote: ↑Sun May 12, 2024 8:02 am
Those seals aren’t much cop by the look of it.
Way back in time when I was mtbing on bikes with serviceable bottom brackets I’d fit o-rings on the outside of the bb axle against the bearing cup as an extra barrier against muck getting in.
At the very least I think marine grease on the outside would help slow down the water ingress so I'll be trying that if this goes to plan.
You can buy DIY service kits for the Bosch units. Just in case you weren't aware (i'm sure you are) they're not cheap but i guess they'll have all the bits needed. https://www.ebikemotorcentre.com/produc ... epair-kit/
Nordboy wrote: ↑Sun May 12, 2024 11:46 am
You can buy DIY service kits for the Bosch units. Just in case you weren't aware (i'm sure you are) they're not cheap but i guess they'll have all the bits needed. https://www.ebikemotorcentre.com/produc ... epair-kit/
Thanks Nordboy. To be honest, I wasn't aware that Bosch did DIY service kits so thank you for the link. I've got this in my watch list which is a similar price but appears to have different bearings: https://www.ebay.co.uk/itm/145388814704 ... p_homepage
I can see me going for the Bosch Service Kit + on this occasion. Still cheaper than a secondhand motor.
Nordboy wrote: ↑Sun May 12, 2024 11:46 am
You can buy DIY service kits for the Bosch units. Just in case you weren't aware (i'm sure you are) they're not cheap but i guess they'll have all the bits needed. https://www.ebikemotorcentre.com/produc ... epair-kit/
Thanks Nordboy. To be honest, I wasn't aware that Bosch did DIY service kits so thank you for the link. I've got this in my watch list which is a similar price but appears to have different bearings: https://www.ebay.co.uk/itm/145388814704 ... p_homepage
I can see me going for the Bosch Service Kit + on this occasion. Still cheaper than a secondhand motor.
They are good kits and nice to see Bosch supplying them tbh, rather than making people pay for it to be done.
There's youtube videos showing how and where all the bits go as well. Makes even people like me think they could have a go without totally cocking it up
)
condition at a reasonable cost? I don't expect they price the parts very competitively. (I'd have been pricing up a new/refurbed one soon after the cover came off 
).
