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Discussion Starter · #1 ·
I have a 2019 Fox 32 SC w/ 100mm travel (code DHKX) that I thought would be a relatively easy conversion to something similar to the Fox AX but with 50mm of travel instead of the AX's 40mm. I thought this would be as easy as shortening the 100 travel air shaft by 50mm. The resulting non-standard A-C would be accommodated by a custom frame design. After digging through Fox's drawings (very helpful but not 100% accurate) I still had enough questions that I thought I should just email fox to see what other parts I should swap.

This is the bulk of the email I sent:
"I have a Fox 32 SC, ID DHKX that I would like to convert to an AX model. With the exception of the shorter air shaft can you confirm that the only other parts necessary are:

234-44-050, Neg Plate Spacer, only used in the AX 40mm travel fork and 820-02-414-KIT, Neg Plate Subassembly, Short Travel ?

Are both of these included with the 820-02-456-KIT, Air Shaft Assy ?

What do I need to do to order these parts?
I've attached the drawings with links in the attached Word doc"


I received this reply a day or two later:
"The CSU and lower leg assembly for fork tune id DHKX cannot be lowered below 80mm of travel. There is no way to convert this fork to match an AX fork. The parts are just too different and not compatible to run lower than 80mm."

The reply was disappointing because I had seen a 100 to 40mm conversion previously on a 2018 fork and the implication was that swapping the air spring assemblies was all that was necessary. Here:

I've included several of the drawings for the air springs as well as a picture of the air spring assembly that I have.

Can anyone tell me why I cant just shorten what I have by50mm and move forward?

Part number: 910-20-562, Short ID: DHKX, Description: 2019, 32, K, FLOAT SC, 27.5in, F-S, 100, 3Pos-Adj, FIT4, Matte Blk, Orange/Matte Blk Logo, Kabolt 100, BLK, 1.5 T, 44mm Rake, AM

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Discussion Starter · #3 · (Edited)
Were ever you able to find an answer?

Nothing definite. The frame design this is going to be used for is on financial hold unfortunately. I'm pretty handy so I was going to simply trim the air shaft to give the travel I want. Fox used an uncommon thread to couple the air shaft to the base stud so I ordered the correct tap (shown above). I haven't done the machine work on it yet. If you are trying to do something similar I might be able to help and it'll motivate me to at least do the work I need for the shaft.

Worst case scenario is it doesn't work like we think it should and I just have to buy a new shaft.

I'm not sure what to think about the difference in the negative plates. I'd have a better answer if I could take a look at an actual short travel negative plate. I suspect that the short travel plate just reduces the air volume on the negative side. If I knew what the target volume was I could likely 3D print a filler for the long travel plate I have on hand and accomplish the same thing.

You might try copying the email I sent from above and asking Fox again. Maybe they'll give a better answer and we can both learn something. ...or just ask what the difference in the two plates is, maybe??

This is still of interest to me so I'll help with what I can.
 

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Discussion Starter · #5 ·
I'm curious about what your build is and what your goals are.

I had to spend more time time than expected to find the fork I thought I wanted on eBay and ended up finding a Fox 32 SC 27.5 15x100 fork on Pinkbike for $550. The A-C difference between the 27.5 and the 29 is only 10mm. I correctly predicted a larger than spec tire would clear the bottom of the crown at full compression but unfortunately I found that the arch is the most limiting factor on the 27.5. My goal was to fit a 2.2" tire and it doesn't even come close. The 29" is spec'd to fit a 2.2" so it should have plenty of clearance.

Additionally, the 27.5 is only available in 44mm offset. The 29 comes in 44 and 51. My preference would have been for a 51 but I compromised to get the extra 10mm, not sure I'd do that again.

Also, since you haven't already bought a fork... you are aware that Fox has since come out with a more purpose built short travel, lighter weight (3 oz maybe??) version of the AX, correct? It even comes in a 50mm version but It's still cost prohibitive for someone like me. My intent is to build a titanium framed bikepacking/gravel machine. If the new AX also had 3 bolt mounts I might consider it but it doesn't so...

Anyway, I'm curious what you have in mind for such an odd sized A-C fork. In case it's relevant to your project. Evil sells their Shammy Hagar fork separate, 430mm A-c with an unconventional 57mm offset (also 12x100 but that's workable). It's a well built full carbon jobber with 2 bolt mounts. I have one on hand if you need any specifics.
 

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Discussion Starter · #6 ·
...also, here's the email I sent Fox. I used [email protected] for the email address. Good luck.

Hi,
I have a Fox 32 SC, ID DHKX that I would like to convert to an AX model.

With the exception of the shorter air shaft can you confirm that the only other parts necessary are:
234-44-050, Neg Plate Spacer, only used in the AX 40mm travel fork
and
820-02-414-KIT, Neg Plate Subassembly, Short Travel ?

Are both of these included with the
820-02-456-KIT, Air Shaft Assy ?

What do I need to do to order these parts?
I've attached the drawings with links in the attached Word doc
 

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I have seen stuff on the newer fork, but clearance on that is less than I want. I'm looking to fit at least 29x2.3 tire for a modernized 90s style mtb/atb type bike with multiple mounting points for racks bottles, & bags. Want as little travel as possible while being able to fit 29x2.3 tires. As for rigid forks the Kona Sutra ULTD is also around a 430mm a-c, has 12x100 spacing & can fit 29x2.6 tires. It be my choice if I can't do a 40mm fork with 2.3 clearance.

One thing to keep in mind is will the tire during compression hit the stanchion of the fork?
 

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Discussion Starter · #8 ·
The Fox SC 29 fork is spec'd to fit a 2.2 so I'd guess a 2.3 will fit but maybe not much bigger. I'm guessing arch clearance will be the limit before anything else. I'm sure Google has an answer.

Were you going the SC or non-SC route? Non SC should have plenty of clearance even with the 32mm models.
 

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I guess that would depend on what I can find in the budget I have in mind. Ifound some AX forks for $300 in decent shape. I would have to find a shop that would be willing to do the work. I would prefer the regular 32. But I think the concern would be with a 29x2.25 tire would the tire & stanchion meet during compression? Would it be better to use the AX damper on a 32 SC & lower travel from that starting point?
 

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Discussion Starter · #10 ·
If you're willing to use a non-SC fork I'd do that (for tire clearance purposes) and shorten the air shaft to limit travel as desired.

An AX fork definitely won't clear the tire you want to run. It won't even come close to clearing a 2.2 due to the arch.
 

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There's no specific AX chassis for the first generation. The parts list doesn't show anything specific to that platform except maximum volume spacers and the proper air shaft. They achieve the different tire clearance by using the 27.5 32 SC chassis with the short shaft and quoting clearance for 700C wheels. The damper should be filled to a different level vs normal, but that's essentially purging excess fluid so the bladder is in a relaxed state at full extension. Perhaps the bushing heights are adjusted lower, but I really doubt they would bother. They never sold a 29 AX fork because it would be confusing and it ends up longer than they wanted.
 
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