Quantcast

Why no more Coil forks?

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
Maybe best to measure one then hey, I have both to compare but it'd mean pulling a working fork apart and I cbf.

Could always lathe a new plug or whatever (and just re-use the float retaining ring if it's different), it's a very basic assembly down there. I make up my own spacers and re-use the air topcap.
 

kidwoo

Artisanal Tweet Curator
What year van do you have? I realize I'm mostly thinking of pre 2015 ones. I might be wrong if it's a newer van. And even then the 26" version might be different than a 27.5".

They did some weird things with pieces once they started selling the 36s again. I've got a 2016 26" talas that is literally the same CSU and lowers as the old 'freeride' 180mm vans from 2012. If I'd bought it this year they'd be the lighter design.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
Thanks everybody for the inputs so far!

From 2015, Floats use a high retaining ring, see picture below, instead of the flatish one used earlier, see third picture bellow.
2015-36-140-180mm-FLOAT-NA-Air-Spring-Assysa.jpg
And since the negative chamber has to be airtight, there are a seal and a guiding bushing in the neg plate assy which would cause unnecessary friction if a coil was used as the main spring, see picture below. Nonetheless, the Float's neg plate assy could be easily drilled out in order to reduce friction!
2015-36-FLOAT-NA-Air-Shaft-Assembliesq.jpg
The plunger shaft assy for coil with the brown dildo is not available for sale any longer. I searched for the 180, 170 and 160mm and none can be had online... and that is even before knowing what length the shaft needs to be!
2011-2014-36-Van-180-Blue-Coil-Spring-Assyb.jpg
I might use the Float air shaft but I would have to source a top out spring and machine a dildo which is easier said than done
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
I would have to source a top out spring
After some well needed night sleep, I realised that I could use the top out bumper instead of the top out spring! :D
The dido dingy might not be necessary on its complete length but something needs to be done in order to hold the spring centered at least. As I understand it, the dildo helps to avoid the spring bowing (not sur if it is the right term..? )
 

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
I'd recommend trying to replicate the stock setup, including the topout spring - to be honest the reason I suggested the factory setup is because in my opinion it's flawless (how often do I say that...), I'd go to the trouble of robbing it from another fork if needed. But it probably doesn't matter if you're not as picky as me.

Yeah the dildo is to keep the spring from bowing and centered. It's not completely critical IMO, I cut both my 40 and 36 ones down to around 2/3 of the length (and re-chamfered) to knock off some dead weight. It's a neat solution though, I do rate it. If you put the spring isolator (singular) in the right place the old pre-dildo rod still worked quietly though.

There is no pressure buildup on the coil forks in my experience, I press those release buttons on my 40 lowers and nothing ever comes out. But hey if it's useful then great.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
Thanks @Udi , very informative as usual!

The irony is that I do own a 2013 36 Van RC2, it's a 26" 180mm freeride monster! The fork is in great shape and it did not get so much use and even less abuse. I never found it to be very supple, it is smooth right after a lower leg service but the feeling disappear quickly... it doesn't feel wrong when riding 100% tho but it is on the harsh side when riding with less commitment. I run a medium spring (70 to 82kg), weight 71kg without equipment and manage to bottom the fork on a few rare occasions.
It feels a bit like there a little too much friction somewhere. Any tips where that could be?
I never service the damper yet so that it might be overfilled...
 

Flo33

Turbo Monkey
Mar 3, 2015
2,057
1,298
Styria
Check for the SKF seals! I dunno if they where introduced before or after 2013 models. Made a big difference in my 2009 Float.
 

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
SKF seals came in 2012, did you buy it brand new @Happymtb.fr ?
You can just check for the SKF logo on the seal for that.

Definitely a chassis issue otherwise though, what you describe is usually the symptom of bushings that are too tight. Fox came out with new tools to set clearances in 2014/2015 so that's not really an issue anymore, but before that occasionally you'd get a tight one and it'd take forever to break in. There's always a chance it could just wear out too (prematurely) if something is way out. If you have a good Fox distributor they can probably just size the bushings with the new tools if you actually have a use for the fork.

Maybe you could use the spring rod otherwise, would just need to add 20mm of plastic spacers under the piston (above the topout spring) and subtract that from the spring spacing under the topcap if able.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
Thanks again!

The fork has SKF seals and even Gold oil in it :brows:
So that tight bushings sounds like a given culprit.
The distributor for Sweden is actually based in Danemark and does not have the best reputation but there are a few lbs approved by Fox in Sweden that might have the tooling. I will check.

The fork is new from 2013 and does not have the SKF seal head at the bottom of the RC2 damper. Will that make a noticeable difference too? As mentioned before the damper could do with a service and if I have to send the fork away for the bushings I might as well ask the lbs to service the damper too and change the seal head. If the SKF seal head does not make a big difference, I might as well serve the damper myself.

I'm not sure about taking the Van apart in order to convert the Float to coil... if I do that, I will not have a bike park bike any longer for the few occasions I use it. I will see what my options are, converting the Yari might be easier...
 

kidwoo

Artisanal Tweet Curator
Don't hold your breath if you're in a hurry for a SAR/stendec 36 spring kit. I sent them an email yesterday and just heard back. "Aiming for August"

Considering they started promoting this last september that seems a little nuts.

Anyway. @92SE-R, all you bud!


@Udi: what year van do you have and what travel config? I think most people have 160mm forks who are asking about this but they haven't made a van version of one of those since before the break in production. I'm assuming most are 27.5 too. So the only potential option for fox manufactured parts is from an old 160 mm 26" version that is definitely going to be a different CSU/lower design.

Drop them lowers and get some measurements man!

I can compare main spring length, neg spring assembly length, dummy rod length, diameter etc with my float.
 

FarkinRyan

Monkey
Dec 15, 2003
611
192
Pemberton, BC
Show of hands from all the people who are interested in coil conversions here; how important to you is the ability for the fork to ever be used as an air fork again? The idea is simple to implement but not in a way that doesn't damage the inner bore of the stanchion, which I imagine is what is slowing down the release of some of these products. It's part of what makes the Ohlins solution so great as well, a sealed air cartridge allows you to swap a spring in and out of the same leg with no issue.
 

FarkinRyan

Monkey
Dec 15, 2003
611
192
Pemberton, BC
I don't think it's an issue either, if I took the plunge and converted a fork I'd be perfectly happy for it to be coil only forever more. I just wonder if some of these guys are worrying about solving a problem that 99% of the people who would actually buy these don't care about.
 

kidwoo

Artisanal Tweet Curator
Resale is the only thing I could think would be a reason.

Go swing by vorsprung and bounce up and down with your arms down by your side and whine "but steeeeveee, we neeeeeed theeese"

The fucker's got a cnc setup now doesn't he? Dildos galore! He's probably already got the necessary dimensions memorized. (of the fork, not dildo dimensions NTTAWWT)
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
Well it seems that I will kind of jeopardise this thread until I can taste the feel of a proper coil fork... I hope it's OK for you? ;)

I have now opened the damper cartridge on my 2013 36 Van RC2 which was quite revealing.
As written before, the fork was not very supple and @Udi adviced that tight bushings might be culprit, but moving the shaft of the cartridge was requiring more effort than with any other cartridges I had the chance to "work" on and the movement was not smooth but instead kind of gritty... I also compressed the fork without the cartridge and it didn't felt as restricted as with the damper.

After removing the bladder I found small metallic shavings left on the cartridge body, like very fine glitter. This would explain the gritty feel, I assume.
On the picture below you can see the cartridge body with 2 scratches below where the bladder sits, there are 2 identical on the other side. There are also marks where the lower part of the bladder seals against the cartridge body, these are kind of "sedimented" shavings that could easily be swiped away!
2017-06-06 10.58.12.jpg

I tried to find signs of wear inside the cartridge, wear that would have generate the metallic shavings and find some around the base valve assy, see below
20170605_093534.jpg
The inside of the cartridge body and the rebound shaft look fine.

The warranty fork this fork has expired so that I don't expect Fox to do anything about it. I intend to rebuild the cartridge with the following: Fox Seal Kit for 36 / 40 FIT Damping Cartridges - 803-00-501.

Anything else I should check or do?
 
Last edited:

HAB

Chelsea from Seattle
Apr 28, 2007
11,580
2,006
Seattle
@Udi: what year van do you have and what travel config? I think most people have 160mm forks who are asking about this but they haven't made a van version of one of those since before the break in production. I'm assuming most are 27.5 too. So the only potential option for fox manufactured parts is from an old 160 mm 26" version that is definitely going to be a different CSU/lower design.

Drop them lowers and get some measurements man!

I can compare main spring length, neg spring assembly length, dummy rod length, diameter etc with my float.
All the internals between 26" and 650b 36s are the same, at least for the 2015+ ones. They just add more crown offset and move the dropouts down on the lowers for the 650b ones. I can't confirm that the diameter of the spring shaft hole in the lowers, or the threads in the crown for the top cap are the same on the older 26" 160mm coils, but there's no change in length for any of that stuff for the 650b so that part of the equation would be fine.
 
Last edited:

kidwoo

Artisanal Tweet Curator
All the internals between 26" and 650b 36s are the same. They just add more crown offset and move the dropouts down on the lowers for the 650b ones.
They're the same now. But I'm trying to match 160/26 then with 160/whatever now. Don't forget the production break though. For as many old fox 36s that I owned, I'm kicking myself for not having a 150 dollar worth fork sitting around right now so I could check. Udi doesn't want to answer me for whatever reason but I do remember the bottom stanchion caps being a good bit different. What I think is that the stanchion walls are different between now and then if we're talking about the 160mm forks. The newer van setups are only 180mm which is an entirely different setup than the 160. Modern day 36s ain't what they used to be in terms of stiffness and weight. I've owned probably 10 of these things since about 2003 when they came out and I really suspect that a 160mm spring assembly (mostly that bottom cap) wont' work. I've been cruising pinkbike and ebay for an old 2010ish vanilla to just buy but I'm kind of blown away that there really aren't that many out there. If any of you crusty bitches have one of these corroding in your basement somewhere, let me know.
 

HAB

Chelsea from Seattle
Apr 28, 2007
11,580
2,006
Seattle
There's a good chance that the damper side is different, since those older forks had the compression adjusters at the bottom, but I'm pretty sure the spring side is the same, at least at the bottom. I just dug up the service instructions for a 2011 36 Vanilla off their website.

Capture.PNG


Definitely the same general configuration, and it's a 10mm socket for the nut, which is the same as the current forks. That's clearly one of the 160mm forks too, since it doesn't have the lowers extending way past the dropouts like the old 180mm ones did.
 

kidwoo

Artisanal Tweet Curator
The damper side is definitely different. But I think most people are just looking at messing with spring sides (and modern RC2 setups are better so we should keep that regardless).

The cap that holds the dummy rod at the bottom of the stanchion is what's giving me some reservation from the 2012 ilk of vanilla forks. But truth be told, those wouldn't be hard to duplicate or just fabricate with the difference to make whatever you needed.

I know if I was re-releasing a product I'd go to the old dimensions because easy. But there's also a chance that some of the dimensions are different in lower space, total spring length etc. I'm willing to take that chance though because I doubt that's different between 2012 and the 2015 stuff. They'd be morons to be starting from scratch.

Anyway.......cheap busted 160mm vanilla. Need one.
 

HAB

Chelsea from Seattle
Apr 28, 2007
11,580
2,006
Seattle
Yeah, I don't really remember how that part works. I think there has to be some sort of retaining ring kind of deal like they have on the newer Float forks to give the negative spring something to push against, but I don't know exactly what it looks like. Like you said though, you just need something captive for the negative spring to push on, and since the stanchions have provisions for that retaining ring, it can't be that hard to hack something together.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
@kidwoo and @HAB the drawings for the Float and Van spring assys can be found in post #125
As Kidwoo suspect the retaining mechanism is different and a bit of machining of the Van's bottom plate might be required to fit the float stanchion. I have both forks and might check if I find some spare time of the internet...
 

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
All the internals between 26" and 650b 36s are the same, at least for the 2015+ ones. They just add more crown offset and move the dropouts down on the lowers for the 650b ones. I can't confirm that the diameter of the spring shaft hole in the lowers, or the threads in the crown for the top cap are the same on the older 26" 160mm coils, but there's no change in length for any of that stuff for the 650b so that part of the equation would be fine.
Yeah that's true for the 2015+ ones, and from before that the length of the spring side internals is the same but the damper has different threads (even the inverted FIT that looks the same as the current dampers) to match the different crown threads, and the 2015+ damper is slightly longer too IIRC.

The spring rod lengths are same for all 160 36s though from memory, maybe happymtb can check confirm the stanchion plug thing.

Fun fact worth repeating for all owners of all 36s too: they all fit 650b which is really cool, people with really old bikes can whack a big wheel in the front. Offset isn't critical (as I think kidwoo has mentioned, some may prefer the old offset too).
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
Post #120 too.

I'm looking for the 160mm part numbers.
Check the old Fox website. Under 2012, I found 820-02-084 for the 160 Plunger Shaft Assembly.

I just cleaned my RC2 cartridge and put back together my 36 Van. I must admit that I had a small orgasm when pushing the fork first time. :) The front now seems to match the plushness of Stoy, but some riding need to be done before final approval! ;)

While at it, I took some measurements of the fork. Please notice that mine is a 180mm and is thus a slightly different animal than a 160mm.
2017-06-08 15.39.08.jpg


The next image is some measurements I took earlier this year on the Float.
20170608_144113.jpg


I hope you can read my scribble and find some of the data you're looking for. I did not drop the lowers on the Float and try to fit the neg plate from the Van today.
The Van's neg plate seems very similar to the Float's neg plate from before 2010, if you have on of those lying around...
 

kidwoo

Artisanal Tweet Curator
Just got off the phone with fox. I was correct, the ID of the stanchions is different, at least between a current float and an old vanilla. So the old preload caps and the plunger shaft guide/stanchion plug won't work. That's for the 160mm.
 
Last edited:

HAB

Chelsea from Seattle
Apr 28, 2007
11,580
2,006
Seattle
Downer.

I still bet you could ghetto hack one together pretty easily. You wouldn't get preload adjustment, but a Float top cap with the transfer shaft removed would support a spring fine, and the negative spring plate can't be that complicated either. There's already a good grove to hold the retaining ring for the Float one.