Check the security Torx bolts on your downtube! 2018 models.

[Telkwa]

I'm torn between adding to the "Known Issues" or starting a new thread. The "Known Issues" thread is kinda cluttered with replies etc.

This is only going to apply to a year or two of Trek models. I have a 2018 Powerfly 5. The battery drops into a large pocket in the frame, where it's secured by two assemblies. The upper one locks the battery in place. The lower piece is partially plastic. It has the electric contacts. Both of these assemblies have aluminum baseplates.

Each plastic assembly is held in place with two security Torx bolts. "Security" means they've got those dimples in the middle so a standard Torx bit can't be used. The heads of the bolts are on the underside of the downtube, exposed to everything your front tire sprays up. Pull the battery out and you can see the nylock nuts that the Torx bolts screw into. Well, you can see three of them anyway. The lowest nut is hidden from sight, way down by the motor.

A couple of days ago I noticed that the two lower Torx bolts were loose. I could reach into the opening and move the plastic assembly back and forth.
The bikes are under warranty but the shop is a two hour drive. I called them. A mechanic said any security Torx bit will work.

Our local Home Depot had DeWalt DWA1TS-7V security Torx bit set. The T-25 bit is the one you'll need. The Torx bolts go thru the frame, then thru an aluminum baseplate. The aluminum baseplate is cast with slots that retain nylock nuts that the Torx bolts screw into.

Clean out the Torx head with compressed air, a tiny pick, a finish nail held with pliers, whatever you can find to thoroughly clean the grit from the heads. You want the Torx bit to insert fully into the bolt. Then gently tighten the Torx bolts. It would be better to re-tighten in the future than crack the plastic pieces inside the frame, so less is better.

If the lowest Torx bolt is loose you'll have to drop the skid plate, also T-25 but not security so any T-25 will do the trick.

I'm going to cover the four Torx bolt heads with little squares of duct tape to protect them from grit thrown up by the front tire. I might smear some grease into the head, wipe off the excess, then apply the tape. The grease will prevent corrosion, and it'll squish out of the way if I need to tighten the bolt again.

 

[Marci jo]

That’s weird. You should not have to duct tape together a new bike.

 

[Telkwa]

Now all I need is some bailing wire...

 

[tegnamo]

If you have a torque wrench, consider applying 6Nm to each screw. Also, the nuts they thread into are metal with nylon locker built-in (lock nut...). But...threadlocker could still be an option. Just be cautious if you remove the screws entirely because the nuts that they thread into can wander out of place...

 

[Telkwa]

tegnamo, where did you get the 6 Nm? I asked the bike shop mechanic for a torque and he said he didn't know. As you mention, the nuts inside the frame pocket are nylock. I failed to mention that in the OP.

I don't know about other Treks that used this design, such as the Super Commuter, but on the Powerfly 5 you definitely don't want to attempt removing the lowest of the four security Torx bolts without understanding what you're getting into. The nylock nut is hidden from sight, below the plastic assembly and above the motor. If you started loosening the lowest Torx bolt the nylock nut would come up out of the plastic slot that it sets in. Then it would start to spin. You'd probably be able to reverse course and get it tight again, but complete removal of the Torx bolt would entail dropping the motor so you could get at the nylock nut. This wouldn't be the end of the world if you knew what you were getting into and had the right tools.

 

[tegnamo]

There is indeed a torque for that fastener. 6Nm is not the spec but is a safe torque to use. But if you're greasing the bolt head you could consider 5Nm. I heard it from some shop at some point. They seemed pretty certain on it.

 

[Telkwa]

I didn't explain my comment about grease very well. If I do apply some grease, it will be to fill the Torx head itself to prevent corrosion and to keep dirt out of the Torx head. If I fill the top of the Torx bolt with grease, I'll cover the head of the bolt with a piece of duct tape to keep the grease in place.

My thoughts about grease have nothing to do with the threads. I just want to protect the bolt head.

My comment earlier about Never-Seez concerned the four standard Torx bolts that secure the skidplate. I put Never-Seez on the threads because Never-Seez is an excellent protection against corrosion and I know there will never be a problem removing the skidplate bolts.

BTW, off the subject a bit but while removing the skidplate bolts I was surprised to see that the two rear bolts go thru a plastic shroud before threading into the frame. I didn't realize until then that there are two plastic covers that completely hide the Bosch motor from view.