Gen 4 Rebuild by with pics

[Doomanic]

In Nov 21 I relegated my Rail to second bike status after I bought a Kenevo SL.

In March 22 I decided to try and sell it as I needed the space in the garage. Unfortunately, when I took it out to clean it up for pics I realised that the motor wasn't working; it powered up and walk mode worked but pedalling did nothing. As it was out of warranty I got in touch with @Bearing Man and arranged a strip down and repair estimate.

This was the response;

Water/dirt has got in through the left hand crankshaft bearing which is what typically happens with the Gen4 motor we have found. The crankshaft assembly was semi -seized together as was the left hand crankshaft bearing. Please find attached estimate to repair, if you are happy to proceed just let us know and we will get your motor repaired as soon as possible.

And the quote for repair;

And here's the pics he sent me...

The repair was completed in quick order and the motor has performed flawlessly ever since. I think the cost of repair was fair for the amount of work involved and the turnaround was very fast.

My apologies to @Bearing Man for not posting this sooner, but procrastination is my middle name....

 

[Dax]

That is nasty! Good job @Bearing Man

 

[Tony4wd]

Price seems very reasonable.
Is that dirt that's in the motor or a combination of rust/grease?

 

[Bearing Man]

Price seems very reasonable.
Is that dirt that's in the motor or a combination of rust/grease?

It was dirt! This is not uncommon with the Gen 4 once the crankshaft bushes wear badly.

 

[Tony4wd]

It was dirt! This is not uncommon with the Gen 4 once the crankshaft bushes wear badly.

Can owners tell whether the crankshaft bushes are significantly worn by feeling for movement in the crankshaft? Will the shaft move up/down by a millimeter or two?

 

[RustyMTB]

Great job & a fair price imo. Probably won't ask him to be my wedding photographer though.

 

[Bones]

Interesting about the bushes as mine has a mm or so of play in the crank arms. The shop recons that's acceptable?.
It has done just over 4k hard miles

 

[Ark]

Interesting about the bushes as mine has a mm or so of play in the crank arms. The shop recons that's acceptable?.
It has done just over 4k hard miles

probably time for a service if you wanna see 8k

 

[Ark]

Interesting about the bushes as mine has a mm or so of play in the crank arms. The shop recons that's acceptable?.
It has done just over 4k hard miles

I was just googling if anywhere near me does it for mine when the time comes.

cycletech list it on their website as a service
and they have people all over the country that will collect your bike or do the work at your house.
makes me wonder if they can do a bearing change without sending the motor off anywhere then, maybe even Infront of you whilst you watch and take photos for us

In the middle halfway down this page

Mobile Service Center | BOSCH e-Bike Specialists

Mobile bike repair Shop That Comes To You. Every BOSCH e-bike needs a mechanic once in a while, to make sure that your bike runs smoothly. On-site Service & Repairs.

www.cycletechuk.co.uk

Find one near you Locations | Find a cycle technician within striking distance and ask them

 

[Bones]

Personally I will do it myself. I have an assortment of hammers

 

[Bearing Man]

Because these are bushes and not bearings, you will feel a slight bit if play, even on a new Gen 4 motor. This is usually around 2mm by the time it gets to the very end of the pedal arm.

The picture below shows how the dirt gets into the motor and you can see the plastic bushes shown on our cutaway.

 

[Stevewild31]

If the shop said water ingress from the left hand crank is 'typical' - What can we do to prevent it?

 

[Doomanic]

Move to Utah?

 

[arTNC]

Move to Utah?

LOL!...yes...or west Texas. I know you folks in the UK and other often wet environments would lose a ton of good riding time if you refrained from riding in the wet, so I totally understand. I just won't hardly ride my dirt motor or my MTB/emtb in water or mud anymore. Decades of racing my state's dirt motor enduro circuit involved rain or shine commitment. I just don't have to do that anymore, and the number of dry vs. wet days is favored strongly by the dry days in my home area and yes...southern Utah which I visit somewhat frequently. I'm sure there is still dust/dirt ingress to some degree but at least not accelerated by water. Very interesting thread about this issue and the service that fixed it. Thanks.

 

[Ark]

If the shop said water ingress from the left hand crank is 'typical' - What can we do to prevent it?

Refresh the grease every 6 months or so

Bosch Gen4 Seal Service & Grease up

I made a quick vid on how to save your motor. Hear me speak! In HD!

www.emtbforums.com

Some people have also made comments saying from the factory its possible to have barely any grease behind the seal.