Levo Gen 3 Fox 38 fork knocking.

[Renton]

I’m really not having much luck with forks on my bike.

After the Zeb issues I switched to a new Fox 38 performance elite just after Christmas.

Trying to set them up was hard as I just couldn’t get them how I wanted them to feel (Am always comparing to a mates ultra plush zebs that just seem to hoover everything)

Doing some research I read that the issue could be down to to much grease in the airshaft negative chamber. When I took the fork apart the oil levels were much lower than the should have been. Unfortunately whilst taking the airshaft apart I scored the inner road and so had to buy a new airshaft.

I rebuilt the fork and put the right amount of oil in both sides and then went and did the first ride on them (23 miles round FOD)

The issue now is that I have a knocking sound when lightly compressing and raising the fork, in the first inch of travel but also if I push them into the travel and do it then the same is happening.

Ive checked all the usual suspects so headset, disc, caliper, wheel etc and all tight.

The only was to get it to stop is to wind the rebound fully open so its at its fastest?? Then the more rebound you add the worse it gets?

Damper is Grip 2.

Does anyone have any ideas on what could be wrong? I didn’t touch the damper side

 

[Mina08]

watching this thread as i have a simular issue

 

[Mikerb]

check you have not lost the washer out of the low speed rebound knob..............and I assume you installed new crush washers on both legs when bolting them up.

 

[Renton]

check you have not lost the washer out of the low speed rebound knob..............and I assume you installed new crush washers on both legs when bolting them up.

Do you mean the little wavy washer? If so yes its there as I dropped it initially and spent half hour looking for it lol !

I have noticed that the HSR knob seems to jump a little between settings if I turn it quickly, does this indicate it isn't seated properly?

 

[Mikerb]

Do you mean the little wavy washer? If so yes its there as I dropped it initially and spent half hour looking for it lol !

I have noticed that the HSR knob seems to jump a little between settings if I turn it quickly, does this indicate it isn't seated properly?

hsr knob has a hex centre so no real way not to fit properly. The damper rod has a flat side which is where the securing allen screw fits.............maybe you did not line that up?

 

[Renton]

hsr knob has a hex centre so no real way not to fit properly. The damper rod has a flat side which is where the securing allen screw fits.............maybe you did not line that up?

Ah ok so they are both fitted correctly then.

When I adjust the HSR slowly it will click on every detent if that makes sense. If I try and turn it harder it sounds like it slips or jumps? Hopefully that makes sense?

 

[Mikerb]

Ah ok so they are both fitted correctly then.

When I adjust the HSR slowly it will click on every detent if that makes sense. If I try and turn it harder it sounds like it slips or jumps? Hopefully that makes sense?

recheck it then...sounds like it is spinning on the dampr rod which it can only do if it slips down.........both rebound knobs a re held in place by the allen screw so maybe the allen screw is not on the flat or is not done up tight enough. Sounds like you may have to remove the lower legs and refit them to check for the problem.

 

[Heated]

hey,
Reviving this, Did you ever solve it? I've had knocking 36's in the past and fox just say 'nothing wrong' which is bullsh1t!!
The reason i found this is my new 38 on my Reign E+ is knocking and on the reign it radiates through the frame which makes it very loud(yes its the fork as put in anther bike)

 

[KaeN]

I’m really not having much luck with forks on my bike.

After the Zeb issues I switched to a new Fox 38 performance elite just after Christmas.

Trying to set them up was hard as I just couldn’t get them how I wanted them to feel (Am always comparing to a mates ultra plush zebs that just seem to hoover everything)

Doing some research I read that the issue could be down to to much grease in the airshaft negative chamber. When I took the fork apart the oil levels were much lower than the should have been. Unfortunately whilst taking the airshaft apart I scored the inner road and so had to buy a new airshaft.

I rebuilt the fork and put the right amount of oil in both sides and then went and did the first ride on them (23 miles round FOD)

The issue now is that I have a knocking sound when lightly compressing and raising the fork, in the first inch of travel but also if I push them into the travel and do it then the same is happening.

Ive checked all the usual suspects so headset, disc, caliper, wheel etc and all tight.

The only was to get it to stop is to wind the rebound fully open so its at its fastest?? Then the more rebound you add the worse it gets?

Damper is Grip 2.

Does anyone have any ideas on what could be wrong? I didn’t touch the damper side

Hi. did you solve that problem? I have that knocking sound also and fork its almost new its the same issue.

 

[greengenes]

I have that knocking sound on my Fox 38s. Almost from new. Not resolved, as its almost impossible to replicate the experience when shop tries to replicate sound, from a limited ride test.

 

[guglez]

Do you have any fenders installed on the fork? I removed a fender from my fox36 Performance Elite 2023 and it seems that knocking sount is gone. But I need to ride the bike to confirm that. I had an original Fox XL fender.

 

[greengenes]

Thanks, I will try that

 

[elesdee]

There are two common reasons why 2021 to 2025 Grip2 36’s and 38’s knock.

1. Bushing play. Some forks developed bushing play pretty much right out of the box. It was such a common problem that Fox specced new bushings in 2025 around the same time as GripX and GripX2 dampers got released. The new bushings are backwards compatible. Bushing play feels identical to a loose headset or loose rotor/caliper. Assuming headset, axle, caliper, etc. all tight, hold front brake and rock back n forth while holding one of the fork legs just below the dust wiper. You will feel it! One side is usually much more obvious than the other.

2. VVC rebound piston assembly not preloaded enough - this is almost 100% the issue OP is describing especially after mentioning that it goes away with rebound open. Another way to zero in on this and eliminate all else is to take out the damper and test it by itself with rebound open/closed. The VVC assembly has a leaf spring that needs to be preloaded the right amount. If it’s too much the HSR shims will be reluctant to flex open - basically equivalent to HSR closed at all times regardless where the clicker is. If it’s too loose, the VVC leaf spring and the adjuster plate have up and down play. When LSR is relatively open, compressing the fork on the floor lets most of the oil go thru the LSR circuit and the VVC assembly is just sitting there. The more LSR is closed, the more oil will try to flow thru the HSR as well and that’s when the knock is felt due to up and down play. Fox’s preload instructions in the Grip2 service manual are stupid, asking for a gap of 0.7mm if I remember correctly. This almost always sets it up too loose. The VVC rebound assembly is best adjusted using common sense. Tight enough so there is no play, especially when HSR is open because that’s when the leaf spring is least loaded. But also loose enough that the leaf spring isn’t being flexed too much when the HSR is all the way closed.

 

[mild_bore]

I once had a head-scratcher knocking on a Pike fork, eventually found that one of the tokens had come loose and was rattling in the fork leg. Something easy to check

 

[greengenes]

Thanks, very useful information

 

[nickf]

There are two common reasons why 2021 to 2025 Grip2 36’s and 38’s knock.
hold front brake and rock back n forth while holding one of the fork legs just below the dust wiper. You will feel it! One side is usually much more obvious than the other.

Very useful info!

I've been having that "slightly loose headset" feeling on my almost new Fox36s with Grip X2 that hasn't gone away after tightening the headset further. I've just done as you suggested above, holding the fork leg below the dust wiper and with my thumb on the fork stanchion just above it. Sure enough the play in the LHS fork leg is very noticeable.

Looks like another repair required by Fox under warranty after I've literally just got my Float X shock back which had air infiltration into the oil. My first brand new bike with Fox suspension, and both shock and fork are faulty. Not impressed!