Wrong fork bushings installed at factory - heavy wear ensues

[duenan]

Eh... on second thought, I think I'll just wait a few months and pay for one of your retrofit services and slip that in as well. I was always meaning to get rid of the pogo stick effect.

[sorkyah]

@pattonme... Im kinda curious what the lower bushing looked like off my set. 14.5k miles may have put a nice wear pattern on it.
Also loving the upgraded forks... thnx again dude

[pattonme]

@sorkyah the one had very little wear, surprisingly. The other one had nearly 2 inches worth worn at least half way thru with lots of shiny showing.

[rick]

Does anyone know if this is still happening? Is this part re-used for cartrige kits? I've got an Advanced Andreani cartridge kit and Ohlins shock from Dave at FBI enroute and a local shop for the install. Im wondering if I need to advise my install guys at Mach 1.
 
 
thanks

The end gap on the wrong bushing is so big, they'll likely see it. But it won't hurt to give them a heads up to actually look. . 

[fzonly1]

My lower bushings weren't worn at all at 2500 miles. But I'm replacing them anyway as I'm dropping in this Mātris set up. The gap is quite large on the oem bushings.

[rick]

mine had a small amount of wear right at the end gaps at 1800 miles -but you had to look close at the correct angle. The end gaps on the proper bushings is perhaps 1mm. The OE ones were more like 4mm and even looks wrong.

[pattonme]

Yes, always replace the bushings with the correct item regardless of what mods you choose to do. I don't believe you @fzonly1, *grin*. I had one set that had no wear on one leg and just ginormous wear on the other leg. Wipe them clean and inspect under good light. If you see copper peaking thru, they are improperly worn.

[fzonly1]

 

Yes, always replace the bushings with the correct item regardless of what mods you choose to do. I don't believe you @fzonly1, *grin*. I had one set that had no wear on one leg and just ginormous wear on the other leg. Wipe them clean and inspect under good light. If you see copper peaking thru, they are improperly worn.

Lol. Well I haven't torn down the other tube yet. So we'll see. I was certain the way my chunky ass was squishin the fork down at every red light that I was wearin something out in there.

[etorty]

My lower bushings weren't worn at all at 2500 miles. But I'm replacing them anyway as I'm dropping in this Mātris set up. The gap is quite large on the oem bushings.

I'm really curious to know the wear of my bushings... At this time I'm at +20k km (near 13k miles). Good to know that the gap on your bushing is large... That characteristic seems to be a really wrong choice at the factory.
Let's see in the next months (I hope, at least... ).

[ilie1977]

I just took apart a <3000 mile set of forks and the lower bushings are already heavily worn. Kayaba has made this mistake before (EX650 I believe) by using the wrong bushing. The correct one is from a ZX6F or SV650 Gen2. 
You can buy an All Balls bushing kit (38-6095 which includes a lot of stuff) *BUT* it has the WRONG lower bushing. You want to buy the 95-97 ZX6F or 98 Yam XV650 V-star kit (38-6096). Yes, the upper bushing is the same part# as the one found in -6095.
 
Yes, you CAN buy the bushings individually for $5.50+ship from All Balls but it might be best to do a group-buy since they don't really want to. They want to sell kits, not individual parts.
 
If you have more than 5000 miles on your bike, get it replaced as soon as you can.
Note how the Teflon has been completely worn off and the copper is showing.
 
worn:
 
new:
 
 
Click the link for picture. I'm guessing the original is too big for the forum to allow it's inclusion...
 
The diameter of the bushing seat is 39.98mm. The OD of the WRONG bushing is 41.1mm. The bushing itself is 1mm thick. When installed you get a absolutely massive gap of ~5mm between the ends of the bushing.
 
The correct bushing has an OD of 42mm. When installed the gap is ~1mm.

 

My fz07 after 16k miles. Rebuilt all bushing and service.

[paulibiker]

I had the incorrect bushings as well. They did have a little wear at 2600 miles.
 
Don't think I would have messed with them if I wasn't installing Andreani cartridges.

[paulibiker]

I had the incorrect bushings as well. They did have a little wear at 2600 miles. 
Don't think I would have messed with them if I wasn't installing Andreani cartridges.

How do you like your cartridge kit? What rear do you have?
 
Thanks

Still in the middle of the install, waiting for seals, bushings, seal tool, & extra light fork oil. 
Ohlins and haven't done that yet.

[twf]

Funny you should mention 'the gap equalizes pressure'. I've been having the exact same conversation with a Traxxion rep. Traxxion drills a hole in the stanchions when you send them in for the AK-20 treatment so oil bleeds out from the inside into that outer area. 
I'm not convinced this pressure thing is something that really matters. The top bushing is hardly air-tight and forcing fluid into that space along the stanchion wall isn't a concern. Air can fill the area between the 2 tubes just as well.
 
Even with the 'tight' (properly fitting) bushings, oil can get by since there still is a ~1mm gap. I think the 'wide-gap' proponents are making excuses. If a more than minor gap was really necessary, then the proper thing to do is cut the correctly fitting bushing so it has a wider, native gap, and not force a gap by installing an under-sized bushing and distorting it. The highly concentrated wear pattern results from the bushing no longer being round.
 
Said rep was of the opinion the factory installed bearing was doing it's job wearing the fork lower into 'shape' (think piston rings finishing the wall) and so heavy wear was perfectly acceptable. And that owners should install new bushings "soon" after buying their bikes and that the next set of bushings wouldn't wear nearly as much. I say BS.
 

It does matter and why there is gap in bushing. There is no air getting in there, you don't want air in there or vacuum or hydraulic lock. You want free oil flow in and out. 

[pattonme]

If these fork parts were precision items, then sure the gap width would be more important. But as a practical matter the grossly excessive wear of the ovalized bushing (as low as 300 total miles) is a much bigger problem than a theoretical pressure imbalance. I'm not aware of a ready-made bushing that is the right size AND has the 'desired' gap. Now if you've got telemetry that shows spikes due to pressure gradients, I will concede the point.
 
If anyone wants me to put bleed holes in the upper tubes just to "be safe" I will happily do it. No charge. But so far some 15+ sets in, this is not an observed concern.

[twf]

What is not precision about them? They are precision once we put cartridges in
fyi. some gsxr forks have bushing gap almost twice that of fz.
Stock bushing is correct size and when installed on tube perfectly round, I have measured that. They are oval when not installed because they are designed to be round with that gap.
Forks with no gap on bushing have holes drilled for oil. Bushings need to be lubed, more oil there the better.
 

[pattonme]

Did I **** in your Wheaties, Zoran?
 
the lower leg diameter is 42.07
the fork tube is 40.93
the OD of the 'wrong' bushing is 41.97-42.00 not counting the 5mm flat spot due to the gap
the OD of the 'right' bushing is 41.94-41.95 not counting the 1mm flat spot due to the gap
 
So the 'wrong' bushing would appear to be a tighter fit except it cants considerably more than the 'right' bushing which is why it shows wear like this. (merc16's forks - tonight's victim)
 

[JanM]

There are other things that can give this uneven wear - one of them is not using the correct assembly and tightening sequence when installing the forks, wheel and brakes.

[rick]

There are other things that can give this uneven wear - one of them is not using the correct assembly and tightening sequence when installing the forks, wheel and brakes.

The bushings used OE do not have a 5mm gap when sitting on the bench. The end gap is small, just like the proper bushing when installed. When opened up to fit our fork tubes, this causes the shape of that wrong bushing to be distorted just a bit resulting in it being no longer round - especially at the gap ends. This is why almost every one that's been looked at is worn prematurely - at the ends. 

[JanM]

Just looking at other potential reasons. It would also be good to know if the replacement bushing shows much less wear at similar use - aka does it fix the problem?
If there isn't a lubrication hole in the stanchion, I would very much consider adding one. Also, the difference in measurements of the bushings doesn't really indicate a big problem - I would be more concerned with the fit of the bushing, like is it allowed to move or is it fixed when fitted, which could be a problem.

[pattonme]

The OE bushing is VERY tight. The 'right' doesn't spin exactly but doesn't take much to slide it.
For whatever reason this set of forks the OE bushing wasn't visually distorted and the calipers agreed. Other sets I've had you could see it wasn't round just by the amount of material peeking out when looked head-on. That's what actually prompted me to examine the issue in the first place.
 

[twf]

There are other things that can give this uneven wear - one of them is not using the correct assembly and tightening sequence when installing the forks, wheel and brakes.

Or gap been on load side. On gsxr we used to mark tube where gap is and turn it away from load. 
Matt, not here to argue with you, just posting why gap is there and info I find. I did few sets recently and none had wrong bushings, just what you guys call big gap.
One set had bent tubes and wear on bushings, not at gap area.
Last couple sets I also measured things for round, after hearing about this, and did not find anything wrong. Will do same on all I do in future.
For now gap is not my concern, not problem for me.    
  
Rick, I measured that. Bushings I measured here measure perfect round when on the tube and they are oval and small gap when on the bench. 
They are made that way, just like piston rings are oval until you put them in cylinders, or plain bearings that are pressed in to cases. 

[rick]

Just looking at other potential reasons. It would also be good to know if the replacement bushing shows much less wear at similar use - aka does it fix the problem? If there isn't a lubrication hole in the stanchion, I would very much consider adding one. Also, the difference in measurements of the bushings doesn't really indicate a big problem - I would be more concerned with the fit of the bushing, like is it allowed to move or is it fixed when fitted, which could be a problem.

Actually have wondered if that little slot in the bushing was enough to let fluid up the side of stanchion to lube that upper bushing.  
After less than 2k miles, my lower bushings both had noticeable wear, right at the end gap. The new bushings slid in place easily enough. 
 
I'll be back inside at some point - at least to put slicker fork seals in and probably deal with that Andreani compression valve.
Pattonme, I'll send you a PM to discuss that project tomorrow. 
 
 
 
  
 
 
 

[twf]

Here is few forks I have here handy. The ones with holes have small gap, the ones without have bigger gap.
Second picture is bushing inside gsxr fork. That one is 04/05. 06/07 is same way and most up side down with both bushings in outer tube will have gap. Even bigger than fz/sv because they need to be installed in there.
 

 

[rick]

Interesting.
 
I own a drill press - might not be a bad idea when I get back in there sometime in the next month or so. .
 
 

[markstertt]

7800 miles on s/n 0008xx 2015 model, I just pulled the forks to take a look inside. The bushing gap is 4mm on the right side with a slight visual wear on either side of gap though not real apparent. Back when this topic was being discussed, I bought an All Balls 38-6096 bushing kit so was wondering if this was still considered to be the way to go or if there was any new info to consider? Also, would it still be a good idea if using the tight gap bushing to drill the stanchion and if so where exactly and how big a hole? Thanks, Mark