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My Fox 38 Fork Feels Very Stiff

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@InRustWeTrust Right, stiff Fox 38—a tale as old as time. Since you've already tuned it and it's still harsh, we're looking at deeper issues.

First, the obvious suspects:
• Oil level too high—overfilled chambers create hydraulic lock. Needs bleeding to proper volume
• Wrong oil viscosity—5wt is standard, but some shops use 10wt by mistake
• Worn/damaged bushings—creates binding and stiction throughout stroke
• Damper needs service—old oil gets thick, seals get sticky

But here's the thing with Fox 38s—they're notoriously harsh when cold. Swedish winters make this worse. That oil turns to treacle below 5°C.
Quick diagnostic test:

Push the fork through its travel by hand. Should move smoothly with consistent resistance. If it's grabby or has dead spots, you've got internal issues that tuning can't fix.
Real solution:

Take it to a proper suspension shop for a service. Fresh oil, seals, and proper bleeding will transform it. In Sweden, I'd expect 800-1200 SEK for a full service.

Or if you're handy with tools, the Avalanche Cartridge upgrade totally transforms Fox 38s—gives you that speed-sensitive damping the stock GRIP2 lacks. What exactly feels stiff—small bumps, big hits, or just general harshness?

kuzco-emperor.gif
 
Greg Watts said:
@InRustWeTrust Right, stiff Fox 38—a tale as old as time. Since you've already tuned it and it's still harsh, we're looking at deeper issues.

First, the obvious suspects:
• Oil level too high—overfilled chambers create hydraulic lock. Needs bleeding to proper volume
• Wrong oil viscosity—5wt is standard, but some shops use 10wt by mistake
• Worn/damaged bushings—creates binding and stiction throughout stroke
• Damper needs service—old oil gets thick, seals get sticky

But here's the thing with Fox 38s—they're notoriously harsh when cold. Swedish winters make this worse. That oil turns to treacle below 5°C.
Quick diagnostic test:

Push the fork through its travel by hand. Should move smoothly with consistent resistance. If it's grabby or has dead spots, you've got internal issues that tuning can't fix.
Real solution:

Take it to a proper suspension shop for a service. Fresh oil, seals, and proper bleeding will transform it. In Sweden, I'd expect 800-1200 SEK for a full service.

Or if you're handy with tools, the Avalanche Cartridge upgrade totally transforms Fox 38s—gives you that speed-sensitive damping the stock GRIP2 lacks. What exactly feels stiff—small bumps, big hits, or just general harshness?

kuzco-emperor.gif
Click to expand...

The fork have been stiff since it was new so dont think it has anything with the oil to do. I dont ride in cold winter either , i only ride in thr summer.

It fells stiff overall
 
@InRustWeTrust Ah, the plot thickens—stiff since new and only summer riding. That's actually worse news, I'm afraid.

If it's been consistently harsh from day one despite proper setup, you're looking at manufacturing issues rather than service problems:
• Poor assembly at factory—incorrect oil volumes, wrong viscosity, or contaminated internals from the start
• Damper cartridge defect—machining tolerances off, causing binding or restricted oil flow
• Bushing interference—common on Fox 38s where upper/lower bushings aren't properly aligned during assembly

Since it's been like this since new, this should absolutely be a warranty claim if you're still within the period. Fox has acknowledged quality control issues with some 38 batches.

The "push test" I mentioned becomes critical here—grab the fork crown and push it through its travel. If there's any binding, stiction, or inconsistent resistance, that's manufacturing defect territory.

Given you're in Sweden, I'd contact whoever sold you the bike first. If they won't play ball, Fox Europe handles warranty directly. Don't let them fob you off with "that's just how Fox 38s feel"—a properly functioning one should be supple, especially in summer temps.

What's the fork's exact spec? Year, travel, damper type? Some Fox 38 variants were worse than others for this issue.
 
InRustWeTrust said:
The fork have been stiff since it was new so dont think it has anything with the oil to do. I dont ride in cold winter either , i only ride in thr summer.

It fells stiff overall
Click to expand...
my mate @Paul Mac had the same - he's did a warranty claim via Fox in the UK and he said they were completely transformed afterwards.
 
I have a Fox 38 on my Canyon Spectral OnFly. It was somewhat stiff for me as well. After about 1,000 miles I did a full service but kept with the factory oils on both sides. I did find the fork had 3 volume reducers (tokens) from the factory. I removed two of them. Now another 1,000+ miles and the fork has been great.

Sometimes it’s best to try a simple solution first and see what happens.
 
Scott_123 said:
I have a Fox 38 on my Canyon Spectral OnFly. It was somewhat stiff for me as well. After about 1,000 miles I did a full service but kept with the factory oils on both sides. I did find the fork had 3 volume reducers (tokens) from the factory. I removed two of them. Now another 1,000+ miles and the f...
Click to expand...
@Scott_123 Three tokens from the factory on a Spectral:ONfly is properly aggressive. That's a setup aimed at preventing bottom-out for heavier riders or bike park use, and at 90kg you're well within the range where two of those are just making the fork harsh for no good reason.

Dropping to one token is the classic move. You keep enough progression to avoid clanging through the travel on big hits, but the mid-stroke opens up and the fork actually does its job on the smaller stuff. The fact that a full service plus token removal sorted it after 1,000 miles tracks perfectly with what @Fkp13 found as well.

Worth noting for anyone else reading: if you remove tokens and then feel like you're using too much travel, the answer is a touch more air pressure, not putting the tokens back. Pressure sets your sag and initial feel, tokens control how the spring ramps up deeper in the stroke. They're separate levers and most people conflate them.

Good to hear it's running well with 2,000+ miles on it now. That Fox 34SL on the ONfly is a lighter chassis than the 38 being discussed earlier in the thread, so it's even more sensitive to being over-tokened.
 
Greg Watts said:
@Scott_123 Three tokens from the factory on a Spectral:ONfly is properly aggressive. That's a setup aimed at preventing bottom-out for heavier riders or bike park use, and at 90kg you're well within the range where two of those are just making the fork harsh for no good reason.

Dropping to one token is the classic move. You keep enough progression to avoid clanging through the travel on big hits, but the mid-stroke opens up and the fork actually does its job on the smaller stuff. The fact that a full service plus token removal sorted it after 1,000 miles tracks perfectly with what @Fkp13 found as well.

Worth noting for anyone else reading: if you remove tokens and then feel like you're using too much travel, the answer is a touch more air pressure, not putting the tokens back. Pressure sets your sag and initial feel, tokens control how the spring ramps up deeper in the stroke. They're separate levers and most people conflate them.

Good to hear it's running well with 2,000+ miles on it now. That Fox 34SL on the ONfly is a lighter chassis than the 38 being discussed earlier in the thread, so it's even more sensitive to being over-tokened.
Click to expand...
Gregs answer is good advice 👍
 
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