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Fox 40 fulfill project AKA MOAR schraders

englertracing

you owe me a sandwich
Mar 5, 2012
1,573
1,069
La Verne
So i have two coil 40s and one air
I cant ride for a while so i decided to whip my junk air fork that came on my used mondraker summum into shape. I had ridden it once or twice with the air fork and it felt like shit, so i swapped my coil on.

The air fork came with 200 volume spacers in it and was filthy inside and out. I decided I wanted to give it the best shot against the coil forks, make it a dual air.

A. Positive and negative chambers can be adjusted seperately
B. The seal wont have to slide across a notch, prolonging seal life and likely less friction.
C. Float or gold oil can be used instead of slickoleum and wont migrate to the negative
D. Air volume can be adjusted by adding moar of the aforementioned oil.

IMAG3434.jpg


Machined a "butted stancion" that is/was for the damper side or coil forks, normally they have a short recess for the coil topout plate and a groove for a spirolock type snap ring. Had to machine the recess larger and deeper for the air sealhead and the odd air snapring. This was done to get a stancion with no internal dimple. I also checked some of the "non butted" way way old like first kashima stancions and the ID is much smaller and would not be possible to use with the air piston.
IMAG3432.jpg


IMAG3431.jpg

I drilled the center hole.
The piston on a 40 does not connect the negative with the piston rod. In stock configuration the footbolt vents the rod to the lower, on a 36 the inside of the rod does contribute to the negative spring and the footbolt is sealed fron the lowers. Im not sure why fox decided not to use the rod for negative volume on the 40, maybe the gigantic negative bulb on the piston is amply sufficient. But for better or worse the 10cc of rod volume is incorporated into the negative volume on my fork. Although i could add moar oil to the negative to change the volume if i felt the need. I drilled the center of the piston in the lathe and installed the mrp fulfill valve in place of the footnut can be seen in the background
IMAG3435.jpg


For the damper I used an NBO fit RC2, the new rebound pistion, the newer sealhead, MOAR shimz, i usually add one face shimz, on this one I added two, hoping to have enough damping to run without the HSC adjuster donking up the curve.

Im recovering from a surgery so no ride report, but putting 5psi moar air in the negative than positive sure does seem to make the thing more supple makes it "more coil like"

It cost about 50$ for the fulfill valve which is pretty expensive for what it is. and a 24 pack of corona to get my friend to chuck the stancion in a big lathe (my 10" lathe doesnt have a big enough throat to allow a long part like a stancion to pass through)


IMAG3441.jpg

This fork carrys two more secrets, on the outside
Can you spot them?
 
Last edited:

englertracing

you owe me a sandwich
Mar 5, 2012
1,573
1,069
La Verne
when i first read dual air for some reason i thought dual positive air (ala the manitou IRT). durrr.
I thought about it.
Chris porter did it long ago...
Wouldnt be extra hard to make the first generation air cap into a dual positive system
I wasnt going to bother as i usually feel air is too rampy anyways. But we shall see
 

jonKranked

Detective Dookie
Nov 10, 2005
85,573
24,192
media blackout
I thought about it.
Chris porter did it long ago...
Wouldnt be extra hard to make the first generation air cap into a dual positive system
I wasnt going to bother as i usually feel air is too rampy anyways. But we shall see
i have the IRT in my mattoc. if definitely takes some time to get adjusted properly but i do like it alot. on the mattoc at least it actually makes the fork less rampy, so the fork will rely more on the HBO than the air pressure ramp.
 

englertracing

you owe me a sandwich
Mar 5, 2012
1,573
1,069
La Verne
what's up with the blue thing at the bottom of the left side?
looks like a sticker. no?
Sticker,
Slik graphics...
I like them so i put on their stickerz
perhaps, the shitty picture makes it hard to tell. but there also appears to be an adjuster knob connected to it as well...
What are you talking about my htc takes chrisp photos....NOT....
Lol
Isn't it the cap of the negative air chamber?
On the bottom yes.
 

vinny4130

Monkey
Jun 11, 2007
450
207
albuquerque
Not as complicated of process but I have converted an older pike to dual air and it worked great. As air forks go I think positive and negative tuning is well, a positive. It’s cool to see someone still willing to tinker with stuff. I’ll never forget seeing Dave Camp’s old boxxer.
 

englertracing

you owe me a sandwich
Mar 5, 2012
1,573
1,069
La Verne
Test ride.
Did a slow poke dh run....
Collar bone and shoulder feel like shit still and arent fully signed off by the doc so i shouldnt be riding really....

So
I might be biased, but fork feels good. Usually my setups are for flat out and tend to feel bad when plonking along because i never do that except maybe on a trail ive never ridden. Felt good for plonking along.... Didnt use more than 75% travel. Probably will have to add Moar air and Moar comp when I start riding faster.

"Sssss" It feels rather coil like "Ssssss"
Insert lizzard here
 

englertracing

you owe me a sandwich
Mar 5, 2012
1,573
1,069
La Verne
So after some ride time the air spring is all good.

Two extra shims in the damper is at least one too many.
Lots of mid and high speed damping.
The goal was to not need to use the high speed loader and I certainly don't need to dial in any extra hsc with the adjuster.

Its fineish on steep with drops.... short runs
Long runs on loose its harsh and lacks grip

Pulled s shim out last night need to try again