Running Belt slows at 14kph then speeds up again

I was looking for some advice in troubleshooting a problem with my treadmill. When I run above about 14kph it slows down to walking pace, then I get off the belt because something is clearly wrong, but after a few seconds starts speeding up again. It does not do this when inclined at 7% and I can run at 16kph for a while without the slowing down. To me, this implies too much friction over the belt and deck etc. or a worn motor.

I tried a shimmy test after applying a fresh layer of silicone under the belt (and running the treadmill for a while to allow it to fully spread). I could hardly get the belt to move. I also set the treadmill to 15% and tried a slide test. I had to push hard to get started and only moved about a third to half way down the deck before stopping.
I bought the treadmill 2nd hand (Nordic Track T18) and the console indicated that the previous owner had done very little mileage on it. The belt does not look worn but I wander that if it is old it may have lost its suppleness resulting in more friction.

I have checked the rollers and there is nothing obviously causing friction here. The other possibility may be the motor and I have thought about trying to replace the brushes.
Can you offer any advice?


  • it sounds like a worn belt but it could be that the lower board is not sending voltage to the console and the only way to know this is if you have a voltmeter and can test the red wire & the black wire.

    You should have anywhere from 8vdc to 12vdc on those two wires.

    If you have that voltage then the console is bad.
    If you do not have the voltage then the motor controller is bad.

    here is also a link for checking the brushes!
  • Thanks very much for your feedback. I will check what you have suggested above.
  • Thanks again for your advice.

    I was able to test the red and black wire at LR5 and LR6 on the board and was getting about 40V at 4kph. These were the motor connections. Should I be testing at a different position for the console?

    Wasn't sure about the 8-12V you mentioned. Is this the expected voltage as you have mentioned:

    If you have that voltage then the console is bad.
    If you do not have the voltage then the motor controller is bad.

    I did try the coast test and when I pulled the key I barely traveled a step which would point towards the belt again.
  • The walking belt is worn out.
    Once you've added items to your Cart, and you are ready to Check out and you put all your shipping info in. Use this code 1982 at checkout for a 5% discount on your order.

Sign In or Register to comment.