Head shake when using the front brake

[sprok]

This is a 2014 Taotao Paladin 150 with about 600 miles on it. I have been getting an increasing amount of head shake when using the front brake. It feels similar to a tank slapper with the bars swinging left and right and it gets worse the more front brake I apply. Anyone experience something like this?

My head bearings are adjusted correctly and the front axle is correctly torqued. Nothing seems loose or binding in the front.

I'm going to disassemble the front and start checking things. I'm thinking:

• Could be glazed or otherwise contaminated brake pads.
• Warped brake rotor.
• One or both front shocks could be bad.

Otherwise I have no idea what it could be. Any other ideas?

[bikerdoc]

From the description sounds suspiciously like a warped brake rotor/disc. Can you elevate the forks so that the front wheel is off of the ground (e.g. set of axle stands or a race/paddock stand), then using a block of wood/or some such to place close to the surface of the brake rotor/disc. Spin the front wheel to check how true the disc rotor is...

[prince666]

Could be glazed or otherwise contaminated brake pads.
Warped brake rotor.
One or both front shocks could be bad.

Most lightly all 3 with Chinese made bikes
Good luck hope you sort it out

[ZMC888]

You say you checked the head bearing, but I'd double check it as it sounds the most likely, although I've never had a warped enough rotor to feel anything you are describing.

[galenernest]

Check the front wheel bearings, too.

[sprok]

Thanks! Yeah, I will double check the head bearing and wheel bearings. I have checked them externally and there is no looseness in the wheel or the head but I'm left with having to disassemble things at this point because I can't figure it out.

I checked the rotor runout and it's not warped.

I noticed if I grab the front wheel between my legs and pull the handlebars it's relatively easy to twist the forks/triple-tree. I'm guessing it probably did this even when it was new but there is the chance the triple-tree could be getting metal fatigue. Its a pretty crappy part, very thin and only has one bolt holding the forks unlike most that have two.

[galenernest]

You'll need to remove the front wheel to check the wheel bearings. But, it's pretty easy to do that. An over-tightened front wheel axle can cause a bearing to fail, usually because the spacer is either too long or too short. Not uncommon on Japanese bikes... probably even more common on Chinese bikes.

[sprok]

Just to follow up (even though no one ever does this), I disassembled the entire front-end and tightened the head-bearing and forks "hand" tight (30+ years experience working on bikes here) instead of following recommendations for torque (which are inconsistent in the first place for China-bikes). It's now much better. I will need to put on a few hundred more miles to say it's fixed but so far so good after about 100 miles. In other words, if you experience this then tighten the head bearing and/or fork clamps. It seems to work.

[ZMC888]

Thanks for the update Sprok.

Most Chinese torque settings are just plagarised settings from similar Japanese bikes and are often misprints and may not actually practically the right torque. If it seems like less torque or more torque works well double check a few similar Japanese bike torque settings and use Loctite.