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Adjust travel on Fox 831 and Float 32-36mm forks

info

This was originally posted at Pinkbike at 2012-10-09: https://www.pinkbike.com/forum/listcomments/?threadid=140305.

warning
  • This guide is old, newer Fox Float forks might be different.
  • I'm not responsible for any damages. This is your own doing. You have been warned.
    • If this looks too hard, get your fork to a professional bike shop instead. Fox forks are damn expensive.

Background​

Lowering Fox Float forks is really easy, but getting the needed information on how to do it, is hard. I wanted to lower my Fox 831 32mm from 100mm to 80mm, and wanted to document the process while I did it. The result is a guide which I hope others might enjoy for similar purposes.

Here are my before and after shots, for inspiration:

  • Before before
  • After after

F.A.Q​

What forks?​

This guide should work for all Fox Float forks, including:

  • Fox 831 (32mm, 34mm, 36mm)
  • Fox Float 32mm, 34mm, 36mm, for 26", 27.5", 29.5" wheels.

Why should I change the travel of my fork?​

Shortening the length of the fork will effect the geometry of the bike. Making the forks longer will do the opposite.

Geometry changes:

  • Lower BB (bottom bracket) / more BB drop.
  • Steeper head tube angle.
  • Longer reach, shorter stack.

Practical consequences:

  • Less available suspension travel: Might need more air pressure to not bottom out.
  • Lower BB: More likely to hit things with your cranks and pedals.
  • Lower handlebars: Less upright position.
  • Steeper head tube angle: More responsive and twitchy, less stable.

How much can I change the travel?​

The fork can be lowered from the given max travel on the fork, and theoreticly down to 0mm of travel (Which will leave the fork completely useless..).

How much spacers do I need to get the fork the height i want?​

If you want to lower it 20mm, you just use one 20mm spacer.

If you want your fork 20mm higher, you just take out one 20mm spacer

Example pictures taken from Fox Tech Center.

WhatPicture
Fox 32fox-32
Fox 36 160mmfox-36-160mm
Fox 36 180mmfox-36-180mm

I need help with a different Fox fork​

Fox has made a whole lot of information available to customers directly. Links can be found in the resources section.

Requirements​

Stuff you'll need:

requirements

Tools​

  • 24mm wrench or socket key for Fox 32 forks, 32mm wrench or socket key for Fox 36 forks.
    • An adjustable wrench is not recommended, the air top cap is made of soft aluminium.
    • A dedicated flattened sockets for fork/suspension use is recommended.
  • 10mm socket key.
  • Shock pump.
  • Hex or torx keys (to remove the stem and headset).
  • Cups (to gather the oil).
  • Toilet paper.
  • Torque wrench, which measures newton meter (nm). Check ridefox tech sites to find recommended torque.
  • Measuring cup or syringe.

Parts​

  • Spacer (Ø25mm is used for 32mm, 34mm and 36mm.

parts-spacer

Lubricant​

  • Fox Float Fluid Anti-Friction Lube (for the seals and top chamber, Fox says this is ESSENTIAL to prevent air leak).
    • How you need depends on your fork, check Fox Service Procedures in the resources section.
    • Fox 831 / Float 32 FIT needs 5mL/cc.
  • Grease, lithium based (for nuts and threads).
  • Fox Gold 20wt or Fox Green 10wt
    • What type and how much depends on your fork, check Fox Service Procedures in the resources section.
    • Fox 831 / Float 32 FIT needs 20ml/cc Fox Green 10wt.
    • You can reuse the old oil, but new oil is always better).

How much oil + how hard the bolts need to be tightened will be covered later!

Process​

Let's start.. The whole process ONLY involves the air side of the fork:

1. Remove fork from the bicycle​

Remove stem, headset and front wheel from the fork

remove-fork

2. IMPORTANT: Let the air out​

danger

If you skip this step you'll likely damage the forks and yourself.

let-air-out

3. Condense the fork​

condense-fork

4. Unscrew the 10mm nut in the bottom​

CHILL: No oil will get out yet.

unscrew-bottom-nut

bottom-nut-removed

5. Unscrew the air top cap​

warning
  • The air top cap is made of soft aluminium and is easily damaged.
  • Adjustable wrench is NOT recommended, even though I used it.

unscrew-air-top-cap

6. Get the oil (float fluid) out at the top​

If you don't have new oil: Keep it for later.

warning

IMPORTANT: The oil at the top differs from the oil at the bottom. Do not blend!

remove-top-oil

7. Push bottom bolt​

Press the bottom bolt in to the fork by tapping it gently with a hammer.

Let the oil drain out from the bottom afterwards.

push-bottom-bolt

8. Get the assembly out​

Use something to press the whole thing from the bottom and out at the top. As soon as you can grab the top with your hands: Do so, and drag the whole thing out.

get-assembly-out

9. Prepare spacers​

You should've already decide how much you want to lower/rise your fork.

  • I want to go from 100mm to 80mm, so I use a 20mm spacer.
tip

TIP: Measure the spacers just in case!

measure-spacer

10. Make room for more spacers​

Slide the old spacers down to get space for the new one(s).

  • If you are going to extend the travel of your fork; remove spacers and jump to step 12.

make-room-for-spacers

11. Put the spacer in place​

spacer-before

It should look like this:

spacer-after

12. Prepare Fox Float Fluid​

Take some Fox Float Fluid in a small syringe. This is the easiest way to lubricate gaskets and stuff.

prepare-float-fluid

13. Stick the whole thing back in​

Not so much that the bolt get through the whole at the bottom. Get some float fluid on gaskets, seals, and stuff.

reinsert

14. Fill oil through the bottom​

Fox Gold 20wt or Fox Green 10wt.

  • What type and how much depends on your fork, check Fox Service Procedures in the resources section.
  • Fox 831 / Float 32 FIT needs 20ml/cc Fox Green 10wt.

fill-bottom

15. Fasten bottom nut​

Press the whole thing further down, so the bolt gets out at the bottom. Grease the bolt, and get the nut back on

NB: The nut is made of aluminium, therefore it's very important that you don't over tighten it! Fox says 5.7 newtonmeter. fasten-bottom-nut

16. Fill Fox Float Fluid to the top​

  • How much you need depends depends on your fork, check Fox Service Procedures in the resources section.
  • Fox 831 / Float 32 FIT needs 5mL/cc.

fill-top

17. Lubricate the top cap with some Fox Float Fluid​

Both seals and threads.

lubricate-seals

18. Mount the air top cap​

Tighten it to 24-25 newtonmeter.

mount-air-top-cap

19. Add air​

When everything is tight, get some air in that fork

add-air

20. CONGRATS! You're almost finished​

finished

21. Reassemble your bike​

Step 1 Remove fork from the bicycle in reverse.

Resources​

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