Ask the experts

[jdadour]

This guy sells a nice one:
https://www.pinkbike.com/buysell/3236867/

Thanks. Before I go further down this rabbit hole, is there any simple test to see if your bushings may need to be burnished?

[Jtlange]

Been reading a lot about burnishing bushings lately. What tool did you use? Pretty straightforward process?

I bought from Oliver at Blue Liquid Labs. He has them in stock and ready to go, took Venmo and Paypal and shipped the same week. Tool is nice, and that's from someone with a machining background.

The process itself is really simple, you put some Fox 20wt gold (or whatever slippery oil you have) on the tool head and push and twist in until you go through the first bushing, repeat with the second one in the same leg which is below the first one, then pull it out while still twisting, then do the other leg. You hold the lowers with your foot on something soft.

I worked up a little sweat doing it and did each bushing 2x in and out. Took 20 minutes after you get your lowers off. Reason I do it twice (or more if its still really tight) is because the first pass will get rid of any shape imperfection (oval, high spot, etc), and the second pass will finish the sizing. Let them cool off between passes as well because the bushing will bounce back in size as it cools due to the material.

To see if you need it, take the air out of your fork and see if you can compress it all the way without any resistance. if you feel it hang up, its likely a bushing. Also if your fork has no suppleness no matter what air pressure you run, that's a pretty good symptom as well.

[J. Barron DeJong]

Thanks. Before I go further down this rabbit hole, is there any simple test to see if your bushings may need to be burnished?

From Roxtar’s link:

“If your CSU requires any sort of push to compress into the lowers or does not sink into the lowers under its own weight with the seals out, then the fork will benefit greatly from burnishing. A properly burnished fork should have the CSU drop into the lowers under its own weight with zero resistance (no seals installed), and should drop about 3" into the lowers from a very light touch from a finger with the seals in.”

[J. Barron DeJong]

It’s mind boggling to me how many people think suspension intervals are this magic black box with no clue how they actually operate.

I agree that internals aren’t that complicated, but tuning does seem to be a bit of a black art. I saw some pretty funky shims/shim stacks being used by the Ohlins motorsports guys.

No idea if any of the bike tuning guys are legit or not from a re-shiming perspective.

[Jtlange]

Kind of begs the question of how all these forks are making it on to many-thousand dollar bikes if the problem is so easy to diagnose and fix with a simple (but precision machined) tool…

In all my years of riding and shooting lots of bikes each year for catalogs I’ve never ran across a fork that needed bushings burnished. Or a modern fork that needed “aligned” It’s also standard operating procedure to tear a brand new fork down give it a good cleaning before riding it and give it a proper lower service and grease the seals. It’s amazing how many forks ship with dry lowers….

It’s mind boggling to me how many people think suspension intervals are this magic black box with no clue how they actually operate. It’s the same folks that tend to get taken for a ride by various snake oil sales man in the suspension “tuning” business. There is very very few people I’d actually pay money to to properly “tune” a setup. And even fewer suspension mods I’d pay for. Vorsprung and Push are the only two.

At the end of the day, its manufacturing variation of the materials that is the cause of this. If you can only control a process 0.05" and you need it to be controlled to 0.04" you will have the majority of the forks that are ok but not perfect and a minority that are not working as intended. Oversizing a bushing is worse than under sizing it from the perspective of the manufacturer because then you have to replace the bushing instead of just pushing a specific sized hunk of metal through it.

Bushings are not metal and are harder to control shape and size and are hard to measure down in the lowers. When installed from the factory the manufacturers count on the uppers to burnish the lowers a bit during the break in period but I have had forks that I could just never get to feel right that I am pretty sure is a bushing issue (those have been sold). I've had uppers that don't go into the lowers because the bushings are so tight, took 2 burnishing passes and its the smoothest fork I have ever felt. All of the race teams do this as a regular process for new forks too. Its real. You can see how WRG could tell the difference immediately.

At the end of the day, burnishing bushings is just making the fork work as its intended without extra friction. Its not a damper or air spring mod. You are just fixing manufacturing tolerances. I really like Fox products when they are working as intended.

[climberevan]

Question regarding chainline:

]

We just covered this. You need a 6mm offset ring to get back to 52mm.

Why not just get a power meter spider for your current cranks? P2Max ones are on sale right now and the total cost will be less with zero fuckery. It's prob a better PM as well.

[MegaStoke]

We just covered this. You need a 6mm offset ring to get back to 52mm.

Why not just get a power meter spider for your current cranks? P2Max ones are on sale right now and the total cost will be less with zero fuckery. It's prob a better PM as well.

Where are you seeing the P2Max spiders for sale?

[beaterdit]

It's most likely bushings being too tight. I had same issue when I got my EXT Era and spent months trying to figure out why I couldn't tune it to use more than 60% travel. Sent it in, and they found one of the lower bushings was tight.

Mine's in for i's first overhaul right now and they tell me the bushings are tight. Been wondering for a year why I couldn't get it to feel better than just ok. It was either too firm or too soft with no in between.

Also think it's crazy that every $1000 fork needs an overhaul right out of the box to feel good. Has it always been like this and we were just less picky? Or has quality control really just gone to shit? Prolly a little bit of both I guess.

Anyway, excited to feel how good this fork can be, finally. It's also going from 150 to 170 for the new bike, w00t!

[Andeh]

The thing that really pissed me off with the EXT is that it was marketed as a super premium fork, made in Italy, with lots of QC and appropriately sized bushings etc. And priced accordingly. Except apparently it was waved through QC just like all the Fox/RS forks made in Asia.

The bushings were so tight on mine that I could let all the air out of it, and put my full weight on the fork, and it still wouldn't bottom out.

[Gunder]

At the end of the day, its manufacturing variation of the materials that is the cause of this. If you can only control a process 0.05" and you need it to be controlled to 0.04" you will have the majority of the forks that are ok but not perfect and a minority that are not working as intended. Oversizing a bushing is worse than under sizing it from the perspective of the manufacturer because then you have to replace the bushing instead of just pushing a specific sized hunk of metal through it.

Bushings are not metal and are harder to control shape and size and are hard to measure down in the lowers. When installed from the factory the manufacturers count on the uppers to burnish the lowers a bit during the break in period but I have had forks that I could just never get to feel right that I am pretty sure is a bushing issue (those have been sold). I've had uppers that don't go into the lowers because the bushings are so tight, took 2 burnishing passes and its the smoothest fork I have ever felt. All of the race teams do this as a regular process for new forks too. Its real. You can see how WRG could tell the difference immediately.

At the end of the day, burnishing bushings is just making the fork work as its intended without extra friction. Its not a damper or air spring mod. You are just fixing manufacturing tolerances. I really like Fox products when they are working as intended.

Any hack even with a manual mill and lathe can easily maintain a tolerance of .04 or .05". In modern production a .001" is quite normal if not even higher.

In fact direct from the source correct bushing tolerance is a diametric clearance of 0.0015”– 0.0090”.. Bushings are sized before installation and re-checked for size after installation

Bushings too loose are way more problematic than a bushing thats at the upper end of the tolerance range IE: 0.0015 Now that tolerance level is quite fine, there is no way anyone is going to maintain a tolerance of that without using special fixturing and you are way more likely to do more damage then good trying to do this by hand.

Now all of the bushing tools people are selling online ( Fox just sells installation and removal tools) are all sized .07mm over. Thats 0.027" which is way off the charts for the factory spec.

If you really insist on doing this, then purchase a good bore gauge and actually measure it before and after.

[Huskier]

Fork wizard experts, riddle me this: Brand new Fox 36 Fit Grip came with the new bike, in the process of tuning with a shockwiz. Set up, calibrate, etc. All good. Set pressure to 85 psi, cycle the fork anddddd the fork locks up. Shockwiz reading upwards of 160 psi despite me setting it with a hand shock pump. Fork might as well be fully rigid, Wtf man. I cycle the fork a few -more- times, a little harder, and all of a sudden something "gives way" and it's back to the pressure I set. Weird, whatever. Fast forward to riding: SW is again reading 140-150 psi. It definitely...still feels like 85. Do I have a bad fork, and if so, how do I get it to replicate for my LBS such that they'll initiate a warranty?

[toast2266]

Fork wizard experts, riddle me this: Brand new Fox 36 Fit Grip came with the new bike, in the process of tuning with a shockwiz. Set up, calibrate, etc. All good. Set pressure to 85 psi, cycle the fork anddddd the fork locks up. Shockwiz reading upwards of 160 psi despite me setting it with a hand shock pump. Fork might as well be fully rigid, Wtf man. I cycle the fork a few -more- times, a little harder, and all of a sudden something "gives way" and it's back to the pressure I set. Weird, whatever. Fast forward to riding: SW is again reading 140-150 psi. It definitely...still feels like 85. Do I have a bad fork, and if so, how do I get it to replicate for my LBS such that they'll initiate a warranty?

My guess is that, for the initial issue, the negative chamber just hadn't charged yet and you needed to cycle the fork a bit to get the chambers to equalize. No big deal - that's normal.

For the shock wiz reading high, I wonder if your valve core is bad. Quick and easy to replace the core.

[J. Barron DeJong]

Fox just sells installation and removal tools

So what is Fox part number 803-00-813 then?

Not sure if they’re currently selling it, but they did.

Edit:
https://m.pinkbike.com/news/race-prepping-a-fox-40.html

Seriously, WTF is the argument here?

[californiagrown]

My front XT brake has stopped working. I've tried different pads, and different rotor, had a shop try and fix it and still no luck. After 4 hard years of riding, it's time.

I'm thinking about just slapping on the OEM Guide R front brake the bike came with. Other than "GuideR sucks", any reason why I shouldn't have sram front, Shimano rear? Seems pretty easy to just swap the brake and rotor and have a rideable bike again? Just need to buy a $20 sram bleed kit off Amazon I think?

[Gunder]

So what is Fox part number 803-00-813 then?

Not sure if they’re currently selling it, but they did.

Edit:
https://m.pinkbike.com/news/race-prepping-a-fox-40.html

Seriously, WTF is the argument here?

Direct quote from what you posted:

“With mass manufacturing the tolerances for the bushings is tight, opening the bushings does have an effect on the life of the fork, which would mean the fork would need servicing much sooner”


So if you want your fork to start to feel sloppy sooner than go for it. While you are at it shave down the inner side of the dust seals too as they provide far more friction.

[J. Barron DeJong]

Direct quote from what you posted:

“With mass manufacturing the tolerances for the bushings is tight, opening the bushings does have an effect on the life of the fork, which would mean the fork would need servicing much sooner”


So if you want your fork to start to feel sloppy sooner than go for it. While you are at it shave down the inner side of the dust seals too as they provide far more friction.

I feel like the goalposts are being moved…

[beaterdit]

The thing that really pissed me off with the EXT is that it was marketed as a super premium fork, made in Italy, with lots of QC and appropriately sized bushings etc. And priced accordingly. Except apparently it was waved through QC just like all the Fox/RS forks made in Asia.

The bushings were so tight on mine that I could let all the air out of it, and put my full weight on the fork, and it still wouldn't bottom out.

Mine's hasn't been quite that bad but yeah, extra crappy considering the premium price.

My front XT brake has stopped working. I've tried different pads, and different rotor, had a shop try and fix it and still no luck. After 4 hard years of riding, it's time.

I'm thinking about just slapping on the OEM Guide R front brake the bike came with. Other than "GuideR sucks", any reason why I shouldn't have sram front, Shimano rear? Seems pretty easy to just swap the brake and rotor and have a rideable bike again? Just need to buy a $20 sram bleed kit off Amazon I think?

No issue there, should be able to run the same rotor too. You'll likely notice a real lack of power from the Guide R though, especially if your XTs are dual piston.

[californiagrown]

No issue there, should be able to run the same rotor too. You'll likely notice a real lack of power from the Guide R though, especially if your XTs are dual piston.

Well, shitty power is better than no power. Plus, i really should get off the brakes more.

[beaterdit]

This guy sells a nice one:
https://www.pinkbike.com/buysell/3236867/

I see no 'blades' or abrasive surface, is that right? Does this tool just sort of 'stretch out' the bushings?

[beaterdit]

Well, shitty power is better than no power. Plus, i really should get off the brakes more.

Brakes just slow you down!

[snowaddict91]

No issue there, should be able to run the same rotor too. You'll likely notice a real lack of power from the Guide R though, especially if your XTs are dual piston.

Personally, I think the difference in "feel" between the two would drive me nuts more than anything.

[Meconium]

I have wore their underwear for 15+ years, and I have a few of their chamois. They are great, give them a try!

100% fixed my problem. No more cold, purple, reverse circumcision nub of a dick. Best chamois ever!!! 100% insane, thought it was a gimmick. If no one vouched for this, I wouldn't have paid full retail to guinea pig.

[J. Barron DeJong]

I see no 'blades' or abrasive surface, is that right? Does this tool just sort of 'stretch out' the bushings?

The engineers got into an argument about it in the Pinkbike comments:

[beaterdit]

Personally, I think the difference in "feel" between the two would drive me nuts more than anything.

Yeah I couldn't do it myself for that reason. No. Fuckin. Way. But not necessarily a 'problem'.

The engineers got into an argument about it in the Pinkbike comments:

LOL so the consensus seems to be that it "smears" the bushing material. Got it.

I'm all for it if it results in a noticable difference though.

[californiagrown]

Yeah I couldn't do it myself for that reason. No. Fuckin. Way. But not necessarily a 'problem'.

Eh, at least it will be the "safe" orientation with the off/on power of shimano on the rear and the modulation underpower of SRAM on the front. Im a run what ya brung kinda guy and not nearly good enough to be finicky about setup as long as it mostly works.