Ah, yes! That’s what I need to do. A simple modification on one of the tips.
Thanks
Thanks
Broken bolts on Bosch CX motor
- Thread starter Jona
- Start date
fasterjason
Member
I have three seal kits coming in from QBP tomorrow, and I plan to install on two motors from 2020, and one from 2021.
I also need to order one for the Gen 3 motor for a friend. Anyone changed the seals on that motor?
I also need to order one for the Gen 3 motor for a friend. Anyone changed the seals on that motor?
No, only on both sides of a Gen4 Bosch CX. It does seem like it could be a yearly or 2-year service, depending on the type of riding.
Bosch Gen 3 does not have seals, only a plastic cover on the drive side was fitted to the later ones. Pic below
If you are riding off road in wet or muddy conditions, I would strongly recommend removing the "seals" cleaning and re-greasing every 2 to 3 months. Remember, these are not seals they are just shields and they rely on the grease to do most of the sealing, which is why it's worth looking after.
Well, I’m probably guilty of extending this service for too long. With the right tools and parts/grease this is a fairly easy task for the average garage mechanic like myself. I can certainly understand the need for the Bosch tacky grease at regular service intervals, but the Bosch seal ring (metal/rubber) may not wear out as fast as the grease disperse’s (IMO). There’s enough additional grease in each kit for 3-4 servicing’s.
I’m surrounded by Bosch gen4 motors (10-12) that likely need this service. I personally ride in all weather conditions, submerged several times, and rinse off the dirt when needed.
The cir-clip on the drive side gives me some problems though. I don’t want to deform or scratch the crankshaft threads each time I remove this cir-clip. I hope to modify my old cir-clip pliers to easily fit this particular drive side clip.
The pictures and suggestions that you and others have provided will also be helpful. I’ve ordered two more kits and in the meantime, since it’s raining cats and dogs, I will try to modify a new tool so I can easily add this service.
Side note; I visited the LBS (Trek) again yesterday
and made them aware of a rebuild service available from Cyclo Chrome in Quebec, Canada. I think our LBS simply replaces the entire motor ($$$) rather than fix it.
Well…that was easy.
I modified my old cir-clip pliers that are typically used for most cir-clips. I simply grounded down the rounded tips to create square tips. No further modification was required.
The tip of the tool now fitted perfectly into the channel and between the pointy ends of this special cir-clip. I then expanded the cir-clip and easily removed it without touching the crank threads. There is enough friction, and or stiction, that the tool grabs the cir-clip easily for removal or installation.
I modified my old cir-clip pliers that are typically used for most cir-clips. I simply grounded down the rounded tips to create square tips. No further modification was required.
The tip of the tool now fitted perfectly into the channel and between the pointy ends of this special cir-clip. I then expanded the cir-clip and easily removed it without touching the crank threads. There is enough friction, and or stiction, that the tool grabs the cir-clip easily for removal or installation.
Good job, and 10 x cheaper than our Snap-On onesWell…that was easy.
I modified my old cir-clip pliers that are typically used for most cir-clips. I simply grounded down the rounded tips to create square tips. No further modification was required.
View attachment 127178
View attachment 127179
The tip of the tool now fitted perfectly into the channel and between the pointy ends of this special cir-clip. I then expanded the cir-clip and easily removed it without touching the crank threads. There is enough friction, and or stiction, that the tool grabs the cir-clip easily for removal or installation.
Can't help but mention, I was always taught that aluminium embodied into a grinding wheel is extremely dangerous because it expands faster than the wheel and can also overheat the wheel causing it to shatter! Maybe worth getting a dressing tool 
Good eye, and thanks. This grinder is rarely used but the/some aluminum has embedded into the coarse grinding wheel. I will definitely “dress” that before next use.Good job, and 10 x cheaper than our Snap-On ones
This new and specific tool was cheap, and easy to make, has only one purpose…but wow!.… It’s handy for this purpose.
Side note; I’m more of a “wood” guy.
Anyone recognize this thing that I made?
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ralfturfsmurf
Member
Gosch gen 4 in Trek rail 7 2023
2 broken bolts on one side. Motor replaced under warranty.
2 broken bolts on one side. Motor replaced under warranty.
TS25 (Torx security 25 with 5 point not six point). Can be replaced with standard T25 or better still TP25's However, the standard ones are quite high tensile machine screws.
No idea what would be strong enough or not, we only use the original screws. but looking at them they are:
Flange headed TS25 5 point machine screw M5X0.8X16 Black nitride finish.
If you use a standard type machine screw, find something with a large head to grip the ally mounting bracket and spread the load as well as possible. Don't use washers, use a medium strength Loctite.
Flange headed TS25 5 point machine screw M5X0.8X16 Black nitride finish.
If you use a standard type machine screw, find something with a large head to grip the ally mounting bracket and spread the load as well as possible. Don't use washers, use a medium strength Loctite.
Krakaride
Active member
Yep. I have, and I let a Bosch service centre "try" and fix it. They did a very poor job too. After 100kms of non abusive riding, two bracket bolts came loose as well as the frame bolts. None were tightened to spec or any Locktite was used. I drove 10.5 hours, 880kms for a ride holiday and within the 1st 5kms of riding, the motor came loose. I had to remove the motor and retighten every thing with the inclusion of Locktite. Pretty disappointed with the mounting design and reliability on Bosch's part. And equally with my local Bosch dealership/service centre. Can't fault the motors performance and reliability to date though. Almost 10,000kms on it now. The Gen5 through bolt mounting system looks so much more robust.
It sure does. A number of Bosch gen4 motors around me (friends &family) , including myself, have had the bracket bolts loosen. A couple of motors had the bracket bolts sheared off. Removing a broken bolt from the magnesium motor casing is almost impossible.
Fortunately I’ve only replaced two drive side motor casings. With the right tools, that can usually be done in the bike cave. The non-drive side casing is a different animal.
Wilbur
Active member
Don’t wait until you have a failure! A bit of preventative maintenance goes a long way.
I pull the motor once a year to do the crank bearing seal service, and check the bracket screws then. Any that require tightening get removed and ret-torqued with fresh blue Loctite. Hardly ever a squeak from the mounts. If you start getting creaks it time to pull the motor and check them.
I pull the motor once a year to do the crank bearing seal service, and check the bracket screws then. Any that require tightening get removed and ret-torqued with fresh blue Loctite. Hardly ever a squeak from the mounts. If you start getting creaks it time to pull the motor and check them.
My procedure exactly
. Besides the new bearing seal kit, install a new castle nut with the latest torque recommended (35nm). Keep a spare …just in case.
