Bike drops abruptly when lowering on jack

[Jim Bronson]

I've been playing with new shocks. I noticed that while lowering the bike, as the rear tire just barely touches the ground, the bike abruptly drops for a moment and then resumes slowly lowering. It is almost as if there is something in the way of the swing arm that hangs it up briefly. I don't recall ever seeing this before. Any clues? I'm thinking about reinstalling the old shocks and trying it again.

[hbkeith]

a flashlight and look , stop thr jack when bike gets to that hung up point and inspect

[Bikerscum]

Loosen the shocks & pull them outward.... does it still do it? Sounds like a shock body that's not clear of the frame/swingarm.

[Jim Bronson]

Thanks. Can I remove both shocks and move the swing arm up and down to check for freedom of movement? Do I need to support the swing arm to prevent it from dropping to the floor when I remove the shocks?

[Hossamania]

Yes. And yes.

[Jim Bronson]

Thanks Hoss. I'm on it.

[calif phil]

Make sure the shocks are not in a bind.   Mount the bottom or top bolts tight. and then look at the opposite end.  If they have to be pulled in when tightened then there needs to be some spacing issues figured out. 

[Jim Bronson]

There's no binding that I can see. They were furnished with spacers, so there's plenty of clearance.

[04 SE Deuce]

Just to clarify the reply's are referring to alignment without bind between top and lower mount...have to smug/tighten the shock at top or bottom and see how close the opposite end is aligned,  in or out...hence the spacers.

Physical clearance during the entire suspension stroke also needs to be verified...sounds like you may have done this.

[rbabos]

Possible there's an internal issue with the shock. Testing them off the bike will show if there's a problem. Long 2x4 as the press.
Ron

[Jim Bronson]

I removed the right one to check carefully for binding but found none. I worry about removing the right one too, as I'm afraid the wheel will crash to the floor. I know that can't happen if the tire is already touching the floor, but it freaks me out for some reason.

[Hossamania]

Put a jack under the bike, lower it until the tire is touching, loosen and pull the bolt out of the shock. You may have to raise or lower the bike slightly to relieve some stress on the bolt, and it will pull out with slight resistance.

[Maddo Snr]

Hoss is onto this i think...

Sit the bike upright under its own weight. Then loosen the shock mount bolts (both ends) and then re tighten to specified torque. Before torquing up the bolts take them out one at a time and grease the threads.

The symptoms sound like the squirm bushes are loading up and twisting the shock-eyes as the bike is lowered. Worth a look, free fix if that's the issue.

[Jim Bronson]

Thanks gents. I'll get on this first thing. About the greasing of the threads, the service manual calls for blue Loctite on the threads. I'd hate to have them back out under load, but I guess I can just re-torque them occasionally.

[Maddo Snr]

Thanks gents. I'll get on this first thing. About the greasing of the threads, the service manual calls for blue Loctite on the threads. I'd hate to have them back out under load, but I guess I can just re-torque them occasionally.

As long as the threads are clean (wire brush) Jim, you can give them a light mist of WD40 and put a dab of thread locker on the end. That way the thread locker won't contact the lubed threads.

ALL torque specs are for lubed threads, pulling dry threads up with a torque wrench will always result in under torqued fasteners...possibly your initial issue?

I've noticed what you described in the OP, especially with lowered shocks.

[hbkeith]

hopefully you have shoulder bolts on your shocks , don't grease your threads , lube the shoulder if you like . then do as Phil said

[Jim Bronson]

They aren't shoulder bolts. They are regular bolts with no threads where they pass through the shock eyelet nearest the head. I'll just lube that area and still use Loctite on the threads. Sounds like a good idea. Thanks.

[PoorUB]

No reason to lube the body of the bolt. It clamps down on the steel sleeve in the rubber bushing.

[Jim Bronson]

I took a video and sent it to the manufacturer. I reinstalled the original shocks for now. It is either a shock problem or swing arm bearings.

[Hossamania]

If it were swingarm bearings, wouldn't it do it with the original shocks too?

[Jim Bronson]

If it were swingarm bearings, wouldn't it do it with the original shocks too?

Maybe not. The original shocks are the HD manual adjustment 'premium' models. The LH one is the compression side, and it compresses very little when the bike is lowered. The new shocks compress noticeably when it is lowered. If there is a problem in the swingarm such that it occurs only as the bike is well loaded, it may never happen except on the road with the bike loaded down. I will be returning the shocks to the manufacturer tomorrow to have them checked out. They have been very cooperative.

[Hossamania]

I understand now. Glad they are taking care of you.