Bosch gen 4, is the outer non drive side, crank seal turn with the crank? or is it stationary to the case?

[gen lee]

Bocsh gen. 4, non drive side outer seal, does the seal rotate with the crank, or stay stationary with the case?

 

[Greg Watts]

Bocsh gen. 4, non drive side outer seal, does the seal rotate with the crank, or stay stationary with the case?

Welcome to the forum, @gen lee. The outer non-drive side seal on the Bosch Gen 4 CX is stationary. It sits against the motor casing and seals around the rotating crankshaft, so the shaft spins inside the seal lip while the seal body itself stays put. It's a standard rotary shaft seal arrangement.

This is the seal that's absolutely critical to keep greased and in good nick, because it's essentially the front door for water ingress into the motor. @Purple parznip recommends redoing the crank seals every six months per Bosch's own advice: pull the crank, pop the circlip, clean the bearing area, and repack with waterproof grease. @Stihldog also flagged that a single lip rotary seal upgrade from Bearing Man is one of the better solutions for keeping water out long-term.

One thing worth noting from @Purple parznip's more recent advice: apply grease only to the seal lip covering the bearing, not generously. Too much grease attracts grit and turns into a grinding paste that chews the seal up, which rather defeats the purpose.

I've got plenty more on Gen 4 motor maintenance, torque specs, and bearing service if you're doing a full strip-down.

 

[Purple parznip]

Welcome to the forum, @gen lee. The outer non-drive side seal on the Bosch Gen 4 CX is stationary. It sits against the motor casing and seals around the rotating crankshaft, so the shaft spins inside the seal lip while the seal body itself stays put. It's a standard rotary shaft seal arrangement.

This is the seal that's absolutely critical to keep greased and in good nick, because it's essentially the front door for water ingress into the motor. @Purple parznip recommends redoing the crank seals every six months per Bosch's own advice: pull the crank, pop the circlip, clean the bearing area, and repack with waterproof grease. @Stihldog also flagged that a single lip rotary seal upgrade from Bearing Man is one of the better solutions for keeping water out long-term.

One thing worth noting from @Purple parznip's more recent advice: apply grease only to the seal lip covering the bearing, not generously. Too much grease attracts grit and turns into a grinding paste that chews the seal up, which rather defeats the purpose.

I've got plenty more on Gen 4 motor maintenance, torque specs, and bearing service if you're doing a full strip-down.

Performance line bearings do an up grade too,worth going on their website to look,im getting a full overhaul and upgrade done right now,£400 all in,every bearing changed and upgrade done,nothing wrong with my motor,but at 3500 miles,its time for a refresh.

 

[Greg Watts]

Performance line bearings do an up grade too,worth going on their website to look,im getting a full overhaul and upgrade done right now,£400 all in,every bearing changed and upgrade done,nothing wrong with my motor,but at 3500 miles,its time for a refresh.

£400 for a full bearing swap and upgrade at 3,500 miles is solid preventative maintenance, @Purple parznip. That's roughly the sweet spot before things start to deteriorate silently, especially with Isle of Wight conditions doing their best to find every seal gap.

Performance Line Bearings (Ebike Motor Centre) do a proper job from what the community reports. Their upgrades typically include uprated sprag clutch bearings, rotary shaft seals, and waterproof grease packing between the outer bearings, which is essentially addressing every known weak point on the Gen 4 in one go.

Given how hard you ride and the conditions you're in, getting ahead of it at 3,500 miles rather than waiting for a whine or a clunk is the smart move. Most of the horror stories come from people who ran theirs to failure and then discovered water had been quietly setting up camp inside for months.

 

[Purple parznip]

£400 for a full bearing swap and upgrade at 3,500 miles is solid preventative maintenance, @Purple parznip. That's roughly the sweet spot before things start to deteriorate silently, especially with Isle of Wight conditions doing their best to find every seal gap.

Performance Line Bearings (Ebike Motor Centre) do a proper job from what the community reports. Their upgrades typically include uprated sprag clutch bearings, rotary shaft seals, and waterproof grease packing between the outer bearings, which is essentially addressing every known weak point on the Gen 4 in one go.

Given how hard you ride and the conditions you're in, getting ahead of it at 3,500 miles rather than waiting for a whine or a clunk is the smart move. Most of the horror stories come from people who ran theirs to failure and then discovered water had been quietly setting up camp inside for months.

Agreed,most of my riding is wales or Scotland,isle if wight isnt that great for demanding riding,its mainly xc over here,but im in wales every two weeks for long weekends with my Welsh friends,and thats where she takes a hammering,lucky to have friends that do seriously steep off piste riding that tourists dont do,orcannot find,glentress is same,and it doesn’t help that i ride all year round,always make me chuckle when people mention mountain bike “season”I didn’t know there was one!

 

[Purple parznip]

£400 for a full bearing swap and upgrade at 3,500 miles is solid preventative maintenance, @Purple parznip. That's roughly the sweet spot before things start to deteriorate silently, especially with Isle of Wight conditions doing their best to find every seal gap.

Performance Line Bearings (Ebike Motor Centre) do a proper job from what the community reports. Their upgrades typically include uprated sprag clutch bearings, rotary shaft seals, and waterproof grease packing between the outer bearings, which is essentially addressing every known weak point on the Gen 4 in one go.

Given how hard you ride and the conditions you're in, getting ahead of it at 3,500 miles rather than waiting for a whine or a clunk is the smart move. Most of the horror stories come from people who ran theirs to failure and then discovered water had been quietly setting up camp inside for months.

Probably this time next year she will be my back up bike,iam looking at whatever manufacturers come out with a dji powered bike,mondraker,commencal etc
That would be roughly 3 years since the dji motor came out,so would be interesting to see if any motor issues come up by then,also,im not sure if performance line refurb these motors,yet!