Loose shock bolt?

Dave Taylor

Rex kwan Do
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.
As a machinist that sounds within spec for the size.
 

JonF

Well-Known Member
I would check the sleeve that the shock bolt passes through (and the DU bush in the eyelet. I've had the OD of that sleeve wear down to the point that it was responsible for the same type of clunking sound you're describing. Wasn't the steel bolt, nor the ID of the sleeve, rather the OD that was either machined too small or wore down too much. A new lower eyelet kit from Fox will fix that.
 

ebarker9

Well-Known Member
I would check the sleeve that the shock bolt passes through (and the DU bush in the eyelet. I've had the OD of that sleeve wear down to the point that it was responsible for the same type of clunking sound you're describing. Wasn't the steel bolt, nor the ID of the sleeve, rather the OD that was either machined too small or wore down too much. A new lower eyelet kit from Fox will fix that.

I may order one just to have as a backup even if that isn't the issue. I've definitely experienced similar (had an Intense years ago that completely ate shock bushings), just never on completely new hardware.
 

Cassinonorth

Well-Known Member
I got nothing to recommend trying but being down this road a couple times recently I wish you the best 🙏. Well worth the effort for a quiet bike.
 

sundaydoug

Well-Known Member
I'm not sure if it's the case with your bike, but it sometimes helps to loosen all pivot and shock hardware then then tighten things down in a very specific order. Starting with the main pivots and ending with the shock bolts. It's worth a shot.

Also, if you haven't identified the location of the problem, it would definitely help to have a friend lift the rear of the bike up and down while you check at all pivot/shock locations by hand for play. You can also grab the rear brake lever with your right hand and the top of the rear wheel with your left, and with the brake pulled try to flex the rear wheel laterally. That will usually make the play more pronounced. It may be slight, but you'll feel it somewhere. Then, once you've identified where the play is, loosen everything and start by tightening the trouble area and see what effect that has.

The fact that it's a new bike makes me think there's play somewhere that can be solved by the above methods.
 
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ebarker9

Well-Known Member
I had to put this aside for a few days due to my level of annoyance. I ordered an air can service kit and also replacement shock bushing hardware, figuring it wasn't a bad idea to have those on hand even if they weren't necessary to solve the current issue.

Interestingly, the inside bore of the new lower mounting hardware is 8.05mm, which is a full 0.1mm less than the ID of what is currently installed. The bolt obviously fits much more snugly with the new one. However...I can't can't the old hardware off.

Has anyone done one of these 7 piece crush washer assemblies? Fox shows removal of the black delrin spacers just using a flathead screwdriver, but there's zero gap to get anything in there and they're press fit on pretty tightly. I get that it would be more expensive, but if they had machined some wrench flats on there it seemingly would be pretty easy. Ultimately I may just try pressing the interior pin out instead there are o-rings in there that I'd ideally like to save and feels like a lot of force would be required.

PXL_20230526_163903502.jpg


IMG_5321.jpg


(Fox instructions, lol)
 

serviceguy

Well-Known Member
I had to put this aside for a few days due to my level of annoyance. I ordered an air can service kit and also replacement shock bushing hardware, figuring it wasn't a bad idea to have those on hand even if they weren't necessary to solve the current issue.

Interestingly, the inside bore of the new lower mounting hardware is 8.05mm, which is a full 0.1mm less than the ID of what is currently installed. The bolt obviously fits much more snugly with the new one. However...I can't can't the old hardware off.

Has anyone done one of these 7 piece crush washer assemblies? Fox shows removal of the black delrin spacers just using a flathead screwdriver, but there's zero gap to get anything in there and they're press fit on pretty tightly. I get that it would be more expensive, but if they had machined some wrench flats on there it seemingly would be pretty easy. Ultimately I may just try pressing the interior pin out instead there are o-rings in there that I'd ideally like to save and feels like a lot of force would be required.

View attachment 214274

View attachment 214275

(Fox instructions, lol)
Once you press the inner spacer out the black (aluminum?) spacers should fall out, then I slip a cutter blade between the white bushing and the actual shock. Full disclosure I did break the o-rings, but I believe those where between the black and the white bushing (I maybe wrong). Once the cutter blade is under the lip of the bushing try and slide it around the perimeter of the bushing and it should loosen enough to come out.

P.S. it's always easier in the pictures/videos of the manufacturer, dang!

PP.SS. or, alternatively...fire + hardtail! LOL
 

ebarker9

Well-Known Member
I was able to press everything out without too much issue. And...no change, still something knocking. Guess I'll try a shock air can service next since I at least know how to remove the hardware!

Edit: didn't replace any of the air can seals because everything looked fine. Going to see if I can track down a 225x75mm trunnion shock to swap in to continue the process of elimination. Noise definitely sounds like it's coming from the shock.
 
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Ryan.P

Well-Known Member
Team MTBNJ Halter's
I was able to press everything out without too much issue. And...no change, still something knocking. Guess I'll try a shock air can service next since I at least know how to remove the hardware!

Edit: didn't replace any of the air can seals because everything looked fine. Going to see if I can track down a 225x75mm trunnion shock to swap in to continue the process of elimination. Noise definitely sounds like it's coming from the shock.
For test purposes only any trunion shock that is shorter would work just to compress a lil and see if its any different
 

ebarker9

Well-Known Member
Came across this, which is basically identical to my problem (they test it the same way that I did just before the 2:00 mark):



Going with the expensive option of a new Ohlins shock, mostly because it's an excuse to buy a fancy shock, but I'll be sending in the Float X to Fox for service/repair.
 
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