Hub motor makes a clunk when braking

[A Monell]

I have a 800 watt rear 36volt yescom motor (2s2p 5000mah 6 cell Turnigy packs) with a Lyen 9 4110 fet controller and I noticed when braking with regen (on the mildest setting) I get a clunk noise. This only happens the first time I brake after having power on.
The axle is tight and the fit on the 2 -1/8" stainless torque plates seems snug. I have even tried marking the parts to see if there is movement, and there seems to be none.
Is there anything internally I should be worried is getting loose? Or any good way to check for miniscule axle rotation?
Thanks, Alex

 

[Nobuo]

Check that the axles are correctly and tight attached and also the rim spokes. You should upload a close pic

 

[sn0wchyld]

I have a 800 watt rear 36volt yescom motor (2s2p 5000mah 6 cell Turnigy packs) with a Lyen 9 4110 fet controller and I noticed when braking with regen (on the mildest setting) I get a clunk noise. This only happens the first time I brake after having power on.
The axle is tight and the fit on the 2 -1/8" stainless torque plates seems snug. I have even tried marking the parts to see if there is movement, and there seems to be none.
Is there anything internally I should be worried is getting loose? Or any good way to check for miniscule axle rotation?
Thanks, Alex

pretty sure your torque arms are loose or have play in them.

 

[dogman dan]

I agree, not enough movement to see it, even with the marks. But it's happening enough to make the noise.

 

[A Monell]

Thanks, I was mainly worried there was something that could have come loose inside. I don't think I can tighten the axle enough to stop that, especially with the tubing spacer I needed to space the dropouts. I will inspect for wear on the axle and maybe make up some thicker torque arms to bear on more surface area. Also the derailleur bracket is sandwiched in there and makes for one more point of movement maybe I will mount it separately somehow or weld it to the torque arm/plate so it contributes rather than detracts from the stability.
Also I guess I should ask as I haven't delved very deep into programing my controller yet, is there any way to soften the onset of braking torque. My ques is that it would take a hardware hack rather than more sophisticated programing.
Alex

 

[999zip999]

Disconnect regen and try to isolate. Had a clunk with my 3200 watt setup thinking it was tight , but retighten and went away. Regen at 3200 watts only with clamping T.A. maybe later, lazy I guess.