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Ok so ive taken my rear shock out (factory CTD) adn after removing the bolts the actual shock appears to be a little stif in between the mounting plates. Im guessing this isnt right as it will obviously stop the shock from having small bump sensitivity.
Apart from bending the plates out has anyone noticed this before? or have a solution?
That's normal. Leave your bike alone.
as rickon says.
The plates clamp the reducers, the shock spins on a bush around the reducers. Step away from the bicycle.
Im guessing this isnt right as it will obviously stop the shock from having small bump sensitivity.
yup. i love that rattle of a loose shock mount.
Thing is the bushings in the shock don't seem to rotate in the shock so it appears to be just the pin and metal sleeve in the middle that its pivoting on. That cant be right.
it appears to be just the pin and metal sleeve in the middle that its pivoting on. That cant be right.
Its not, but if your bolt is tightened correctly (use a torque wrench!) you should see the shock does rotate on the reducer. They are designed to be tight to prevent them knocking and causing damage to the shock and frame.
[u]IF[/u] the shock is not rotating on the reducer, you might need a new reducer and shock bush, take it to a shop.
I'd stay away from trying to 'fix' your bike......and if possible thinking too much.
This is supposed to be a helpful place not a centre of abuse. It appears the OP is ignorant of the operation of the shock bush, we can educate him or just be horrible. I know what I would prefer.
Cheers guys and gals.
tbh i had expected the bushings to turn similar to bearings. Infact i expected that they would have a bit less friction due to some of the norglide type used.With the bush not turning in my fingers i then assumed that it was a fixed type bush and something you would not expect to see on something that was rotating like a shock. Even with the bush acting the way it does the excessive sideways pressure from the mount stops the shock moving freely.Its definatley not a "sliding fit" and i would have expected something free er running but not sloppy to cause the shock to rattle.
I do torque all my bolts using a number of calibrated torque wrenches. I expect they they are better specked than most.
Cheers for the help.
Get a drill bit and enlarge it. Nice and loose...
oh ffs guys
if you let out the air in the shock, or remove the spring, do you feel any stiction from the bushings?
Having just changed the bushings in a 5 I can confirm that the bushings do not turn by hand, however with the front mount in the frame the back moves stiffly but smoothly - the shock turns on the bushings but the bushings do not turn against the frame.
There was no evidence of this affecting the swingarm movement.
There would not be any sideways pressure tho, the reducer (the bush bit is in the shock) is either a single piece or two 'top-hat' shaped pieces which bottom out on each other. You can buy needle-roller bearing kits to fit, they have far less friction but have far shorter lives.
They do tend to fell quite stuff but the rotation of the shock is very small so strict ion would not have a noticeable effect on your suspension. You will probably find after a bit of time it get free-er as it wears, but make sure you don't let it get loose or it can cause significant damage to your shock and frame.
You see molgrips thats the exact thing i was looking for. Thank you both Stato and molgrips for talking sense!!
I would have expected them to be a lot freeer however. People spend big bucks on a gold coloured shock because its smoother and the sticktion in these was quite surprising!
actually, this ^ wee test proves the point. Undo the swingarm end and you'll be able to rotate around the front end of the shock and vice-versa
we can educate him or just be horrible. I know what I would prefer
true, horrible is much moar fun.
rebuilt with some super low friction graphite based grease and it now spins freely in my hand. happy days.
Didn't think it was right.
Hmm well when I tried it there was no stiction, it was just stiff.
same difference really.
No - there's a world of difference between stiction and friction. That's why they have different names.
Very true. but in this instance were talking about what is essentially a stiff mounting effecting movement.
It will affect it, but not in terms of stiction.
Didn't think it was right.
POSTED 1 HOUR AGO # REPORT-POST
but it was right. Not sure that smothering a dry fit bush on an interference fit with grease is the best idea for a long and happy bushing life
I can tell you its not.
I made a similar mistake aged 14 on my newely aquired marin b17 - it was squeeking....
It no longer squeeked - it did knock and bang after about 2 days......
Why's that then? Genuine question.
Is it because there's a low friction surface on the inside of the bush?
generally because the grease will attract dirt and create a grinding paste.
Breaks down the ptfe impregnation on the bush.
rubbish!
Report back in a week then .
Then there’s those odd bits that really you don’t want to lubricate at all. Most rear shock bushings disintegrate if exposed to grease and are designed to be self-lubricating so leave them clean and dry. And sealed cable sets like Gore-Tex Ride-Ons and Avid Flak Jackets have low-friction Teflon liners and shouldn’t be lubed either – lube just attracts grit and damages the liners.
Read more at http://bikemagic.com/how-to/mountain-bike-maintenance/lube-it-up.html#gUz4bsPQmRFldurk.99
yes grease and oil will attract dirt. The fact that grease breaks down ptfe is utter rubbish. Ptfe is used in all sorts of applications where it comes into contact with grease oils etc and it excels in those applications.
Ok , i see from your earlier posts on this subject you clearly know better .
As you were.
To be fair in this instance I clearly know more than you 🙂
Isn't PTFE the same as Gore-tex? The stuff that is so sensitive to oil that they have to coat it in polyeurethane?
And anyway I didn't think the bushings were in fact PTFE. There are the plastic ones, they are white, but the metal ones have a dark coloured layer on the inside.
EDIT ah these seem to be something called DU which is a layer of bronze then some PTFE. The internet says you don't need to lube them, but it does not say if anything bad will happen if you do.
Similar stuff but different applications. The oil blocks it up so in things like a jacket it doesnt breathe as gore is basically a perforated gasket. Virgin PTFE is quite resistant to a lot of things and its often suspended in oils and greases. I use it a lot for seals for hydrocarbon gasses (you know like oils) and it performs very very well. Youll also find it on bearings seals that, you know, contain grease.
Im not sure what DU is. Looking at the bushings in a shock i would be surprised if they were infact PTFE as they are to hard. look like a PEEK material to me.
http://www.ggbearings.com/en/products/metal-polymer/du
This is DU. the bushings are not this material.
If you must lube a plastic bush I'd use a silicon grease.
[url= http://www.tftuned.com/tech-help/71-mount-kits-and-bushings-for-rear-shocks-a-guide ]good pics down the page[/url]
your link says DU shouldn't be lubed, or at least that the performance is not as good as when dry.
however TF go on to say they'll supply DP, rather than DU, and refer to them being OEM from Fox [url= http://www.tftuned.com/dp-eyelet-bushings-127mm-bag-of-4/p518 ]here[/url]
going back to the site you linked to: [url= http://www.ggbearings.com/en/products/metal-polymer/dp31 ]dp31[/url] says that greased or dry provides similar performance. i didn't get as far as checking the other DP types though.
no wonder people get confused about this!
I went away for a few hours, and all hell breaks loose.
Ill repeat my first statement
That's normal. Leave your bike alone.
All shock hardware has a slighty tight fit, theres absolutely no need to lube it.
Dont worry about your bike so much, go ride it 🙂
What made you remove the shock in the first place?
This is DU. the bushings are not this material.
Yours might not be but it is common. Mine were, I think.
Rickon, im stuck at work on 12 hour shifts getting no overtime doing fugitive emissions testing. Tinkering with something keeps me sane. I just fancied taking the shock apart and giving it a clean up.
I think were getting confused between the bush in the eyelet and the plastic top hat bushes?
Plastic top hats? I have alu top hats...
Better pic/explanation here.
http://www.tftuned.com/low-friction-mount-kits-127mm-m6/p2927#tabid1
Different to what many of us have probably seen. A split bush with specially sized pin/reducer, with all parts fitted by hand, no bushing tool needed. Not sure i like the idea of a push-fit bush, id be concerned about it rotating in the shock and causing damage.