Loose shock bolt?

ebarker9

Well-Known Member
Starting to lose my mind with this. I'm working on my new downhill bike, a Scott Gambler with a Float X shock. I've swapped out the wheels and brakes, which meant running new lines through the frame. Currently I have a clunk if I drop the back of the bike from a few inches or cycle the suspension through the first part of the travel by pushing on the saddle. It's very much like what I've experienced with a loose shock bolt or work out bushing in the past but it's a new bike...

I have pulled the chain to confirm that it's not drivetrain related. Pulled the shock and greased every possible surface, torqued everything to spec. Played around with the shock to see if there was anything obviously loose. I pulled the internal cables out and repeated to see if it was actually cable rattle. Checked the dropouts, rear hub bearing preload...basically everything I can think of.

I don't have another shock to try, but I do have another rear wheel so I could try that. Feel like I'm at the point where it's either out of spec shock hardware or an issue with the shock itself.

Any other troubleshooting steps that I should take? It's a trunnion mount shock for reference.
 

ebarker9

Well-Known Member
Shock came with the frame so it should be correct.

I can measure the bushing. Makes sense, hard to imagine that there's play on the trunnion side. I can feel a small amount of lateral play in the bushing connection when the shock is unbolted at the top.
 

Steve Vai

Endurance Guy: Tolerates most of us.
Shock came with the frame so it should be correct.

I can measure the bushing. Makes sense, hard to imagine that there's play on the trunnion side. I can feel a small amount of lateral play in the bushing connection when the shock is unbolted at the top.

Is it a new frame and shock?
 

ebarker9

Well-Known Member
Came fully assembled. I did a few things on it (different brakes and wheels) so there was some amount of disassembly, mostly for the pain in the ass internal cable routing but really struggling to see where I would have changed something that would impact this. Lower shock eyelet bore is 8.14mm and shock bolt is 7.97mm. I don't know what the normal tolerance on this should be but obviously there has to be some allowance for assembly.
 

serviceguy

Well-Known Member
Came fully assembled. I did a few things on it (different brakes and wheels) so there was some amount of disassembly, mostly for the pain in the ass internal cable routing but really struggling to see where I would have changed something that would impact this. Lower shock eyelet bore is 8.14mm and shock bolt is 7.97mm. I don't know what the normal tolerance on this should be but obviously there has to be some allowance for assembly.
That’s almost 2/10 of a mm, way too much, the bolt will burrow into the bushing and make it increasingly worse. Let me check what my X2 looks like and report back…

So bolt is 7.93 and bushing is 7.96. I had to replace the bolt that came with the brand new frame as it started wearing and making clunking noises shortly after I started riding. New bolt never gave me an issue and I also replaced the bushing, I guess it’s a question of production tolerance…I’ve been thinking about replacing the bushing with needle bearing but seems a little too much.
 
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johnbryanpeters

Well-Known Member
That’s almost 2/10 of a mm, way too much, the bolt will burrow into the bushing and make it increasingly worse. Let me check what my X2 looks like and report back…

So bolt is 7.93 and bushing is 7.96. I had to replace the bolt that came with the brand new frame as it started wearing and making clunking noises shortly after I started riding. New bolt never gave me an issue and I also replaced the bushing, I guess it’s a question of production tolerance…I’ve been thinking about replacing the bushing with needle bearing but seems a little too much.
Needle bearings for shocks are not so hot - bearings are designed for rolling motion, not for impact.
 

serviceguy

Well-Known Member
Needle bearings for shocks are not so hot - bearings are designed for rolling motion, not for impact.
They supposedly eliminate the friction generated by the shock rotation during compression/extension. Also, they’re supposedly designed to resist impact. Supposedly.
 

ebarker9

Well-Known Member
You can put your hand around each shock mounting point and pull the bike off the ground. You'll easily be able to feel the play in the mount if that's where it's coming from.

Yup, nothing that I can notice. It's not as severe as what I've experienced with worn bushings in the past.

Did you hold the bike by the seat and bounce it slightly on the rear tire looking for play?

Yup, that's where it's the most noticeable in terms of sound but I haven't been able to locate any obvious play.

Video with slightly non-PG shock squish noise audio.

 

ebarker9

Well-Known Member
Do it slower and inspect every pivot point. set the tire down lift slowly watch for play between joints.

That's definitely what I've been doing, just tried to make the sound more obvious in the video.

Appreciate everyone's thoughts, I'll keep messing around with it.
 

ebarker9

Well-Known Member
Prob bad shock imho

I've definitely seen all of the X2 issues so certainly a possibility. Before I try Gearworks, anything that I can check? I'd have to pick up some of the shock fluid to do an air can service but I should have that anyway.
 
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