TQ HPR50 motor whining on Fuel EXe?

[davida]

Hey everyone, my tq hpr50 on my fuel exe is whining.

@Greg

 

[Greg Watts]

The HPR50 whine is a known character trait rather than a warranty emergency, but it's worth knowing the details.

The most common cause is the sprag clutch not fully engaging when assist is very low (under about 10W), which produces a grinding or whining sound. @Rob Rides EMTB confirmed TQ's own explanation: at minimal torque the clutch doesn't seat properly, and it's essentially harmless. Performance and durability aren't affected.

That said, there's a firmware fix available. @Hitorogoshi found that a TQ flash tool at your LBS can reduce the grinding noise instances, so worth asking your dealer to run the update if they haven't already.

If it's more of a rattle at higher cadence (around 90rpm rather than at low assist), that's a slightly different beast and TQ's recommendation has been a motor swap under warranty. @DBSwiss had both the original and replacement motors develop the same noise, which is either reassuring or deeply unsatisfying depending on your outlook.

What's the noise like — low assist whine, or more of a rattle when you're spinning faster?

 

[davida]

The HPR50 whine is a known character trait rather than a warranty emergency, but it's worth knowing the details.

The most common cause is the sprag clutch not fully engaging when assist is very low (under about 10W), which produces a grinding or whining sound. @Rob Rides EMTB confirmed TQ's own explanation: at minimal torque the clutch doesn't seat properly, and it's essentially harmless. Performance and durability aren't affected.

That said, there's a firmware fix available. @Hitorogoshi found that a TQ flash tool at your LBS can reduce the grinding noise instances, so worth asking your dealer to run the update if they haven't already.

If it's more of a rattle at higher cadence (around 90rpm rather than at low assist), that's a slightly different beast and TQ's recommendation has been a motor swap under warranty. @DBSwiss had both the original and replacement motors develop the same noise, which is either reassuring or deeply unsatisfying depending on your outlook.

What's the noise like — low assist whine, or more of a rattle when you're spinning faster?

its a whine that comes and goes. It doesn't rattle at all.

 

[Greg Watts]

its a whine that comes and goes. It doesn't rattle at all.

Sounds like the classic sprag clutch behaviour then. A coming-and-going whine without any rattle is pretty much textbook low-assist engagement noise on the HPR50. As @DBSwiss found with both his original and replacement motors doing exactly the same thing, it's essentially baked into the design rather than a sign something's about to give way.

Worth asking your Trek dealer to check for any pending firmware updates regardless, as that's the easiest thing to try first. If the whine is getting louder over time or starts appearing at higher assist levels, that's when you'd want to push for a warranty inspection. But a noise that comes and goes at low effort? Probably just the sprag doing its thing.