Fox Shock Bushes

[Johan Bornman]

A cursory inspection should reveal ridges of wear.

[jugheaddave]

yea, i can see bad wear on the reducer.

 

what would cause this premature wear??

 

[Brad@TheRiot]

 

yea' date=' i can see bad wear on the reducer.

 

what would cause this premature wear??

 

[/quote']

 

It's not necessarily premature. How many km's did you do? In what conditions? How regularly do you clean the bike? Is the shock pressure setup correctly for your mass?

 

As mentioned before, usually.. it's both reducers and DU bush. If you get reducers made up, ensure that they're 100% perfect fit. Otherwise, as JB says, just get them from your local Fox dealers. It's better than damaging your shock or frame.

 

[jugheaddave]

The bike inn question has done 1552k's since new.

 

All of this has been in the dry. The bike get cleaned +/- every two weeks with gentle running water and prepsol. No hp cleaning.

 

As far as I know the shock pressure is set correctly, in terms of sag (about 25% sag)

 

Maybe I am missing the point, but I still don't understand how having these reducers machined to fit could damage the shock and frame??

 

[Brad@TheRiot]

 

The bike inn question has done 1552k's since new.

 

All of this has been in the dry. The bike get cleaned +/- every two weeks with gentle running water and prepsol. No hp cleaning.

 

As far as I know the shock pressure is set correctly' date=' in terms of sag (about 25% sag)

 

Maybe I am missing the point, but I still don't understand how having these reducers machined to fit could damage the shock and frame??

 

[/quote']

 

It wont, if the reducers are exact matches to the OEM spec ones.

 

 

 

 

 

[jugheaddave]

why not just match them to what the external diameter of the shock bush? ie make a nice tight fit, but not to tight that they cant move??

[Johan Bornman]

The bike inn question has done 1552k's since new.

All of this has been in the dry. The bike get cleaned +/- every two weeks with gentle running water and prepsol. No hp cleaning.

As far as I know the shock pressure is set correctly' date=' in terms of sag (about 25% sag)

Maybe I am missing the point, but I still don't understand how having these reducers machined to fit could damage the shock and frame??
[/quote']

 

These bushes are pretty crude, with aluminium running on aluminium. This is a recipe for quick wear. Further, there is nothing in there to exclude dust, so they're not only a poor bushing material, but also are prone to dust and water intrusion that forms grinding paste.

 

A properly designed bush will weigh 7 grams more and that's apparently more than the weight-weenies can handle, hence the poor design.

 

I agree, I dont see how a badly fitting bush can cause damage outside the bush itself. It will be as irritating as hell, with knocks and clicks, but not damaging.

 

 

 

 

 

 

[Brad@TheRiot]

 

 

 

I agree' date=' I dont see how a badly fitting bush can cause damage outside the bush itself. It will be as irritating as hell, with knocks and clicks, but not damaging.

 

 

 

 

 

 [/quote']

 

Outside the bush, no, it wont. But the bush will wear quicker. That there is the problem. Also, if you destroy the bush, then you'll be running reducer to shock.. a recipe for disaster. I know most of us would stop long before the reducer is completely destroyed, but I have seen some weird things before

Brad@TheRiot2009-08-31 11:27:52

[jugheaddave]

OK, so maybe I should pop down to my friendly machine shop in the morning  and ask him to make some for me.

 

Now for the real question, would vesconite be a better option than alu??

 

[brussel]

OK JB you said "A properly designed bush will weigh 7 grams more and that's apparently more than the weight-weenies can handle, hence the poor design."

 

 

 

give me the design..I am keen to experiment. My thought is to design it with o-ring seals on either side to stop dust ingress.

 

 

 

after bragging previously in this thread about how mine are not worn I took my shock apart yesterday to find they are screwed!! the only thing stopping the rattling was the amount of crud in them

 

 

 

I have two extra sets of reducers and can turn up more if I need. The bush itself is stuffed. What is the bush made of? it has a reddish colour to it.

 

 

 

As per the last question from Jughead, what about alternative materials? Vesconite/acetal/brass

[jugheaddave]

HI

 

I had mine made up of vesconite. They seem to work just fine.

The guy who made them for me said that it is a far superior material than the original aluminum ones, in fact he said he was surprised to see aluminum!

 

Vesconite is pretty cheep, I bought a section 100x18 and it cost me R30, the engineering guy charged me R80 labour.

 

[brussel]

thankfully I am the engineer and I have a lathe

 

 

 

where did you get your vesconite? plastics seem to be so bloody expensive these days too, that sounds quite reasonable.

[jugheaddave]

I bought my vesconite form a company in East London called Euro Steel (maybe national) Ask the suspension guys were to get it from, sure they could help.

 

If you don't come right, I can send u some.

 

[Johan Bornman]

OK JB you said "A properly designed bush will weigh 7 grams more and that's apparently more than the weight-weenies can handle' date=' hence the poor design."

give me the design..I am keen to experiment. My thought is to design it with o-ring seals on either side to stop dust ingress.

after bragging previously in this thread about how mine are not worn I took my shock apart yesterday to find they are screwed!! the only thing stopping the rattling was the amount of crud in them

I have two extra sets of reducers and can turn up more if I need. The bush itself is stuffed. What is the bush made of? it has a reddish colour to it.

As per the last question from Jughead, what about alternative materials? Vesconite/acetal/brass[/quote']

 

I was a bit facetious with the 7grams but my thoughts were: "Where's the oilite brass?"

 

I don't have a design, unfortunately. I don't have a dual suspension bike otherwise I would have experimented long ago.

 

Aluminium is such a poor bushing material that the few grams extra for oilite brass will surely be worth it - particularly as an upgrade. I bet that manufacturers can supply their shocks with both bushes - alu ones for races and brass ones for training - and score points in the process.

 

Even nylon should perform better in those conditions although I doubt it will be hard enough.

 

Vesconite is the option that everyone is throwing about. I have no experience with the stuff other than seeing that it looks like nylon and has about the same density. Is it harder? I dunno.

 

I can think of some design parameters though.

 

1) Don't use O-rings where there is movement between the two surfaces it has to seal.

 

2) If there is movement, the O-rings require lubrication.

 

3) A labyrinth seal that moves freely even when the bushes are tensioned, may be required. Look to your jockey pulleys for inspiration there.

 

4) A proper bush will weigh a few grams. It's all for a good cause.

 

5) Don't use cartridge bearings.

 

That's all I can think of.

 

Edit: I just thought of one more thing. What harm can a grease nipple on either side of the shock do? Greased bushes last forever.

Johan Bornman2009-09-12 05:05:13

[Johan Bornman]

Buy your vesconite, nylon and other nice stuff here.

 

http://www.maizey.co.za/

[jugheaddave]

Hi J

 

I "think" vesconite is a little harder than nylon.  Not sure, as I have never machined/drilled it myself.