Fox Rear shock eyelet replacement

[Alouette3]

There is some play in my DU bushing on the rear shock of my Giant Trance X2 (2011). I replaced the DU bushing before, but the play returned a couple rides later.

 

Suspect that the 2 part eyelets are what is causing the play and the DU bushing to where out quickly. They not in great shape any way. Can one get a different "upgrade" eyelet system to replace the one that is in there now, was thinking something along the lines of a single through pivot with a spacer slipped on each side to keep it lined up?

 

Anyone know of anything, have one for me, or know where I can get? Spacing is 22mm (21.85mm) x 6mm through bolt.

 

You can also get a needle bearing kit, but would prefer to steer clear of that as they don't take kindly to dirt.

 

That's what is currently fitted

[Johan Bornman]

Your first crime was to replace the DU bushings but not the reducers. If the reducers were worn, they may have felt OK when installed but there would have been a bit of lash under pressure. This lash then quickly destroys the DU again.

 

Always (well almost) replace both at the same time.

 

Further, there are several alternative systems but not acceptable to the average Joe.

 

1) Steel through axles. Work extremely well but apparently too heavy for the gram counters.

2) Needle bearings - a very poor application for needle bearings this. They don't outlast other systems and are considerably more expensive. Besides, they require steel axles which are heavy. See point one.

3) Polymer sleeves. Expensive and crap.

4) Spherical bushings like in Spez and DT shocks. These work well but can't be retrofitted to Fox and Rox shocks.

 

Guess what it leaves you with...unless you're not a gram counter. If you want a pair, contact me offline and I'll machine a custom pair for you, guaranteed for life.

 

Edit: I've added the word "offline"

[Brighter-Lights]

Vesconite bushes + aluminium through pin been lasting for ages on our bikes... I turned them myself. Stock DU bushes lasted less than a year.

[Skylark]

 

1) Steel through axles. Work extremely well but apparently too heavy for the gram counters.

If you want a pair, contact me and I'll machine a custom pair for you, guaranteed for life.

 

What is that exactly, my shock axle is already steel?(RP23 on a morewood shova) and how many mandelas?

[Johan Bornman]

Vesconite bushes + aluminium through pin been lasting for ages on our bikes... I turned them myself. Stock DU bushes lasted less than a year.

I'm interested in that solution. I even bought the vesconite but since I don't have a full suspension bike and don't know any guinea pigs, I've never done it. When it eventually did wear, where did it manifest?

[DirtyFrank]

I have had the same problem on both my bikes.I think the brass bushing on the shock is the culprit as it also wears slightly , you can replace the aluminium bushings but within a short time the small amount of lash as suggested elsewhere ,wears them out again. The Endura needle bearing upgrade is well worth the upgrade but you have to press out the brass bushing on the Fox shock to fit this, It`s reasonably straightforward.

My Trance has done 10000+ km on the bearings and they are as tight as new.

You can order this online from Real World Cycling, I have attached my invoice for contact details but you will find them on the web.

 

Item Quantity Description Amount

---- -------- ----------- ------

NBKRWC2185BLU 1 RWC Shock NB Kit, 21.85mm span, Blue 30.99

 

Subtotal 30.99

Tax Rate 0.00%

Tax 0.00

Shipping/Handling 9.14

Total $40.13

 

 

Shipping Policy for Orders Outside the United States:

 

First Class Mail International does not include insurance and DOES NOT

PROVIDE TRACKING. Normal transit time for FCMI is 7-21 days, but it

can take up to a month.

 

Priority Mail International includes insurance and tracking. Normal

transit time for PMI is about 10 business days.

 

Express Mail International includes insurance and tracking. Normal

transit time for EMI is about 6 business days, although it is

sometimes no faster than Priority Mail International.

 

Once the package arrives in your country, any time spent in customs is

not included in the stated transit time.

 

 

Thank you for your business!

Real World Cycling, LLC

Customer Service: chris@realworldcycling.com

Phone: 877-363-8761

[Johan Bornman]

Frank, those are not brass bushings but plastic-coated (brown) steel inserts called DU bushings. I can't find a source reference for the meaning of DU other than it seems to have been one of the first brand names of such bushings. Maybe it passed into the generic domain some time ago.

 

Nevertheless, they are not the problem, the design is the problem. the Two reducers that fit into either side of the DU are not radially stable. Since the shock is part of the structure of the bike, it flexes with the frame. These two reducers therefore move relative to each other and wear out quite rapidly. We can predict the kind of movement not by some fancy CAD modeling but simply looking at the end result - two bushes showing conical wear with the smallest part of the cone in the middle of the shock eye.

 

The solution - the easiest one in anyway, is to put a straight reducer right through - lets call this a through axle for argument's sake. In other words, a piece of smooth, polished and chromed round bar with a 6 or 8mm hole through.

 

In addition to the through axle, you now also need some spacers at each shoulder so that the shock can't move laterally in the bike. It is as simple as that. I cannot think of one single disadvantage to this solution, but I'll be happy to listen to experiences.

 

My experience is that this lasts incredibly long. The DU just goes on and on, thanks tot he fact it isn't being graunched by two sharp edges playing against each other with each pedalstroke.

 

Like with any installation inside a DU, the inserting tip has to be nicely champhered to not damage the DU when inserting.

[Skylark]

So you use/leave the normal DU bushing that's pressed into the shock eye but you throw away the 2 alu half bushings and rather use one continuous piece of metal sleeve over the pivot bolt turned at the same OD of the alu bushings + spacers to keep the shock in its properly centered position?

[Johan Bornman]

So you use/leave the normal DU bushing that's pressed into the shock eye but you throw away the 2 alu half bushings and rather use one continuous piece of metal sleeve over the pivot bolt turned at the same OD of the alu bushings + spacers to keep the shock in its properly centered position?

Yes, goes into the standard DU bushing.

 

Here's the picture.

 

 

What you see here is a couple of things. A collection of half-and-half alu reducers - standard on most shock.

 

Back left standing upright, a length of chromed, chrome-steel shaft with either 6mm or 8mm hole drilled through it. I cut these to size as required

 

Then lying flat in the foreground, is the above shaft, with a DU bushing in the middle and black anodized aluminium tubing I cut to length to make up the correct spacers so that the shock doesn't move laterally over the chromed shaft. This could be just about anyting, including a stack of plastic washers.

[Alouette3]

Your first crime was to replace the DU bushings but not the reducers. If the reducers were worn, they may have felt OK when installed but there would have been a bit of lash under pressure. This lash then quickly destroys the DU again.

 

Yip LBS didn't have stock of the 22mm eyelet when I bought the DU bushing. Have just bought new DU's from my bearing supplier for 25% of the cost! Haven't fitted them yet.

 

1) Steel through axles. Work extremely well but apparently too heavy for the gram counters.

 

Not much of a gram counter so this will do.

 

Will get in contact.

[Johan Bornman]

So you use/leave the normal DU bushing that's pressed into the shock eye but you throw away the 2 alu half bushings and rather use one continuous piece of metal sleeve over the pivot bolt turned at the same OD of the alu bushings + spacers to keep the shock in its properly centered position?

The ODs and IDs are important here. It is a bizarre mix of units.

 

The DU's ID is 1/2 inch, The OD is 15mm.

 

However, the ID could be anything practical if you are going to implement your own system.

[DirtyFrank]

Frank, those are not brass bushings but plastic-coated (brown) steel inserts called DU bushings. I can't find a source reference for the meaning of DU other than it seems to have been one of the first brand names of such bushings. Maybe it passed into the generic domain some time ago.

 

Nevertheless, they are not the problem, the design is the problem. the Two reducers that fit into either side of the DU are not radially stable. Since the shock is part of the structure of the bike, it flexes with the frame. These two reducers therefore move relative to each other and wear out quite rapidly. We can predict the kind of movement not by some fancy CAD modeling but simply looking at the end result - two bushes showing conical wear with the smallest part of the cone in the middle of the shock eye.

 

The solution - the easiest one in anyway, is to put a straight reducer right through - lets call this a through axle for argument's sake. In other words, a piece of smooth, polished and chromed round bar with a 6 or 8mm hole through.

 

In addition to the through axle, you now also need some spacers at each shoulder so that the shock can't move laterally in the bike. It is as simple as that. I cannot think of one single disadvantage to this solution, but I'll be happy to listen to experiences.

 

My experience is that this lasts incredibly long. The DU just goes on and on, thanks tot he fact it isn't being graunched by two sharp edges playing against each other with each pedalstroke.

 

Like with any installation inside a DU, the inserting tip has to be nicely champhered to not damage the DU when inserting.

 

Hi Johan, Sorry man, you are right but the brass colour of the bushing internal finish had stuck in my head, the body is clearly steel/plated as you say, I assume the red residue is the plastic coating that did not wear awaydue to the space left by the taper on the ends of the alu bushings.This problem gave me the complete ****s as you could feel the slight clunk/movement when you picked the bike up by the seat post,even on my wifes bike which had barely done any mileage.I still reckon the Endura needle bearing solution is ace( if a bit expensive)

[Johan Bornman]

 

Hi Johan, Sorry man, you are right but the brass colour of the bushing internal finish had stuck in my head, the body is clearly steel/plated as you say, I assume the red residue is the plastic coating that did not wear awaydue to the space left by the taper on the ends of the alu bushings.This problem gave me the complete ****s as you could feel the slight clunk/movement when you picked the bike up by the seat post,even on my wifes bike which had barely done any mileage.I still reckon the Endura needle bearing solution is ace( if a bit expensive)

 

That one does look rather brassy, doesn't it?

 

Nevertheless, I've never tried the Enduro solution but had come across it in one of the shocks...can't remember which.

 

Those needle bearings are also standard industrial bearings which you can use to replace yours.

 

The reason I haven't tried to place them onto steel shafts is that it would require a shoulder seal either side that has to be waterproof. A bit too sophisticated for a low-price job. But you now have all the fancy seals and stuff, I'm sure it is just an o-ring living in a spacer with a recess. Measure the bearing up and buy local spares once it goes. I'd be interested to see how it wears. Needle bearings don't like small oscillating movements. They prefer full rotations. Also needle bearings prefer oil to grease.

[mazambaan]

I agree about needle bearings Johan but just note that most dirt bikes (the motorised ones) have needle bearings for the swing arm and suspension pivot points. They do have simple seals and a few have a provision for greasing but generally last well despite being properly abused.

[Brian Fantana]

So you use/leave the normal DU bushing that's pressed into the shock eye but you throw away the 2 alu half bushings and rather use one continuous piece of metal sleeve over the pivot bolt turned at the same OD of the alu bushings + spacers to keep the shock in its properly centered position?

 

Most rockshox mounting hardware are three piece as well. The mounting hardware on my Monarch RT3 High Volume (mounted on my Morewood Shova) is three piece aluminium which has a black coating. Could be anodised. Anyway, it has been going strong for 4000km now.

[Johan Bornman]

I forgot to caution against attempting to make the insert from aluminium. When that little insert corrodes, it freezes the bolt like a good welder can't do and makes it impossible to remove the shock. We had to make a special jig to hold the frame inside a hydraulic press and press the bolt out. By then we have already received one frame where the bike shop hammered at the bolt until the shock mount flange broke off the carbon frame.

 

I'm happy to know that there are lots and lots of bikes that's not happening to, yours included. But the two incidents in our workshop were enough to convince me once again, that aluminium should not be used in close tolerances if it will be exposed to water.