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Replaced the original worn aluminium one with a stainless one from Bounce in March, all snug, lovely. Noticed it is knocking again which I thought was strange. Pulled it apart and measured, width still 22mm, internal bore 8mm, shock bolt diameter 7.5 and obviously there is play between the two. I can only think that the bushing is a harder grade of stainless and has worn the bolt, guess that would make sense for the original aluminium bush to be the sacrificial wear part. Anyone else come across this? If that is what's happening and it's a new bolt every 3 months or a new bushing every couple of years guess I'll be changing back to alu!
Bump in case still needed, bit of a niche question though.
I see BETD also sell stainless bushes, maybe it's just that the bolt has had it's day too. Had over 3 years and 4500km on an ebike, suppose everything wears out eventually
At a guess the bolt is M8, 7.5 is close. However the bolt should be tight enough to prevent any movement relative to it & the bush. Any wear should be on the outside of the bush not on the inside. Are you applying the correct torque & threadlock to the bolt? Sounds like the bolt is coming loose & the bush is moving on the bolt. This isn't a good situation as the ends of the bush will be fretting on the frame & making the play worse.
Please ignore my ramblings if I've got the wrong end of the stick.
D.
Did you change the actual bush? Sounds like you’re just describing the reducer, the bush should always wear out first and be changed if you’re changing the reducers out
I've used a few different sets of the bounce hardware and never had problems like this.
I've had two years of very heavy use on one bike and the bolts are still very snug.
Sorry, yes I was referring to the reducer. Yes changed both, was all snug but now there is play between the bolt and the reducer
The bolt should be able to float inside the reducer, it’s not plugging the gap. Instead it’s being used to pull the two sides of the frame/linkage mounts together to sandwich the reducer, which then turns inside the DU bush.
Is the reducer moving inside the frame/linkage mount area?
davosaurusrex
Full MemberI can only think that the bushing is a harder grade of stainless and has worn the bolt, guess that would make sense for the original aluminium bush to be the sacrificial wear part.
None of these parts are a wear part; the only part that is, is the bushing in the shock. If the other parts are wearing in your setup something's gone really wrong, the shock hardware shouldn't move on the bolt.
Aluminium shock hardware isn't supposed to be a wear part either, but you're right, in practice it often is because they tend to be rubbish. Especially the "two top hats" design with the join in the middle, they're not fit for purpose and just shouldn't appear on a quality bike
Good info guys, ta. Need to check a few more things including the chainstay shaft, not replaced that yet although I have a spare, didn't really investigate properly before dismantling. Might not be the shock hardware at all
Put it all back together and all good again! No idea really. I'm 100% everything was nipped up as I had been round it a few times, maybe something was catching and not actually done up properly. Dunno.