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If you were thinking of reducing the diameter of a 35mm fork's rebound damper (a Yari like I did, or a 35mm Revelation) - it won't work down to a 32mm steel stanchion. There's too much diameter to remove and the piston head doesn't have enough material; you'll run out of solid material next to the ports and destroy it.

The current 32mm Bluto + Reba rebound damper (11.4018.025.011) is shimmed as well, and the piston head is plastic. There are plenty of older shimmed 32mm rebound dampers as well, but that was a time when SRAM had some pride and made the piston from aluminium.

The Bluto/Reba rebound damper shaft (and other RockShox rebound damper shafts) are 12.5mm in diameter.

Here's the Bluto/Reba rebound damper, top, next to a 2010-2013 26"/27.5"/29" Revelation rebound damper (11.4015.545.030).

View attachment 1930929

View attachment 1930930

The piston head diameters are:
- OD of the piston measured over the split glide ring: 27.7mm
- OD of the piston with the glide ring removed: 27.45mm
- OD of the glide ring channel: 23.9mm

View attachment 1930931

For what it's worth, the same measurements over the aluminium-piston 11.4018.025.011 are:
- OD of the piston measured over the split glide ring: 27.6mm
- OD of the piston with the glide ring removed: 27.08mm
- OD of the glide ring channel: 23.63mm

View attachment 1930933
Many thanks for taking the time to post this. There seems to be bad news here. These are the measurements of the 2021 Recon TK/RL rebound damper. Note the OD on the piston and metal shaft; are there any shimmed rebound dampers that are either a drop in fit or can be turned down to suit this OD?

For clarification the 203mm length is for the TK rebound port orifice damper and the 183mm is for the RL PO rebound damper supplied with the RL MoCo damper.

I'll triple check the measurements (when I get home tonight) and confirm on the damper shaft in the hope I've mis measured it.

1930990
 
Discussion starter · #102 · (Edited)
Many thanks for taking the time to post this. There seems to be bad news here. These are the measurements of the 2021 Recon TK/RL rebound damper. Note the OD on the piston and metal shaft; are there any shimmed rebound dampers that are either a drop in fit or can be turned down to suit this OD?

For clarification the 203mm length is for the TK rebound port orifice damper and the 183mm is for the RL PO rebound damper supplied with the RL MoCo damper.

I'll triple check the measurements (when I get home tonight) and confirm on the damper shaft in the hope I've mis measured it.

View attachment 1930990
The Yari's rebound shaft diameter is also 12.5mm OD. On the other hand, the 35 Gold's port orifice rebound damper shaft is 12.7mm OD. The 35 Gold's seal head has a 12.9mm hole with a standard o-ring that seals against the 12.7mm shaft; the o-ring's ID inside the seal head is exactly 12mm. I think it shouldn't matter if you have a 12.5mm or 12.7mm shaft running through it, the o-ring should still seal fine. Presumably the TK setup will be vaguely similar.

The measurements you posted up are probably correct, the steel stanchions are a bit thinner than aluminium. And the differences to the 35 Gold's rebound damper are small, they are:
  • OD of the piston with the glide ring removed: 29.50mm
  • OD of the glide ring channel: 26.6mm

So, basically the 6061 aluminium grade 35 Gold's stanchion ID matches the 32mm steel stanchion ID. Amazing....

So..it looks like you can probably work down a Yari rebound piston after all. Or a 35mm Revelation rebound damper. And probably use your existing lower seal head as well, depending on the ID of the o-ring around the shaft. The Yari rebound damper is 215mm edit 230mm in length, so you'll give up 25mm maximum travel in your fork (leaving it at 125mm max I think). The 35mm Revelation rebound damper is 215mm long, you'll lose 10-15mm possible travel.

I've seen complete Yari damper internals sell for as little as CA$40 on PinkBike Buy/Sell.
 
The Yari's rebound shaft diameter is also 12.5mm OD. On the other hand, the 35 Gold's port orifice rebound damper shaft is 12.7mm OD. The 35 Gold's seal head has a 12.9mm hole with a standard o-ring that seals against the 12.7mm shaft; the o-ring's ID inside the seal head is exactly 12mm. I think it shouldn't matter if you have a 12.5mm or 12.7mm shaft running through it, the o-ring should still seal fine. Presumably the TK setup will be vaguely similar.

The measurements you posted up are probably correct, the steel stanchions are a bit thinner than aluminium. And the differences to the 35 Gold's rebound damper are small, they are:
  • OD of the piston with the glide ring removed: 29.50mm
  • OD of the glide ring channel: 26.6mm

So, basically the 6061 aluminium grade 35 Gold's stanchion ID matches the 32mm steel stanchion ID. Amazing....

So..it looks like you can probably work down a Yari rebound piston after all. Or a 35mm Revelation rebound damper. And probably use your existing lower seal head as well, depending on the ID of the o-ring around the shaft. The Yari rebound damper is 215mm edit 230mm in length, so you'll give up 25mm maximum travel in your fork (leaving it at 125mm max I think). The 35mm Revelation rebound damper is 215mm long, you'll lose 10-15mm possible travel.

I've seen complete Yari damper internals sell for as little as CA$40 on PinkBike Buy/Sell.
Awesome. Regarding the travel: The Recon Silver TK longest travel in my particular guise is 120mm after having removed a spacer from the SA assembly. The stock TK rebound shaft length is approximately 203mm. I'll pull the MoCo damper at the weekend and measure the remaining clearance (at bottom out) to determine whether the longer 230mm Yari rebound assembly will fit without fouling the underside of the MoCo damper assembly.
I do apologise for the thread hijack as I realise it's bad manners but I'm genuinely pleased that I can improve the forks behaviour. I recently dusted my old bike off after it being in storage for many years and its a 26", 1-1/8" straight steerer with 9mm QR and v brake post mounts. The existing PACE Pro Class EVO 2 were well past their best hence I required a replacement. The 26" 2021 Recon TK 26" were the only thing I could find on the market that fitted and after the very first ride I though 'Oh hell no these are utterly rotten in terms of damping performance'. I serviced them to check the bush drag and replace oils and was pleasantly surprised that there was very little drag on the bushes and I also replaced the TK damper with the MoCo unit at the same time which marginally improved their behaviour. You might ask why bother - Well I've just bought a new house and I also have a 10 month old daughter so can't justify (for now) spending £4K+ on a new MTB only to use it 95% of the time just to cycle to work. In hindsight it probably would have been far better either buying a used old fork or buying an appropriate Gold CSU that I could use to easily upgrade the internals. The former I won't rule out quite yet but I need to determine what would be a good used base unit to purchase.
 
Discussion starter · #104 ·
Awesome. Regarding the travel: The Recon Silver TK longest travel in my particular guise is 120mm after having removed a spacer from the SA assembly. The stock TK rebound shaft length is approximately 203mm. I'll pull the MoCo damper at the weekend and measure the remaining clearance (at bottom out) to determine whether the longer 230mm Yari rebound assembly will fit without fouling the underside of the MoCo damper assembly.
I do apologise for the thread hijack as I realise it's bad manners but I'm genuinely pleased that I can improve the forks behaviour. I recently dusted my old bike off after it being in storage for many years and its a 26", 1-1/8" straight steerer with 9mm QR and v brake post mounts. The existing PACE Pro Class EVO 2 were well past their best hence I required a replacement. The 26" 2021 Recon TK 26" were the only thing I could find on the market that fitted and after the very first ride I though 'Oh hell no these are utterly rotten in terms of damping performance'. I serviced them to check the bush drag and replace oils and was pleasantly surprised that there was very little drag on the bushes and I also replaced the TK damper with the MoCo unit at the same time which marginally improved their behaviour. You might ask why bother - Well I've just bought a new house and I also have a 10 month old daughter so can't justify (for now) spending £4K+ on a new MTB only to use it 95% of the time just to cycle to work. In hindsight it probably would have been far better either buying a used old fork or buying an appropriate Gold CSU that I could use to easily upgrade the internals. The former I won't rule out quite yet but I need to determine what would be a good used base unit to purchase.
PinkBike BuySell has some surprising finds at times. Like this old Recon that was for sale for 2 days and would fit your lowers, is coil sprung, and takes the best 32mm dampers RockShox ever made. But, there's strong demand for forks like these and you have to move quick.
 
PinkBike BuySell has some surprising finds at times. Like this old Recon that was for sale for 2 days and would fit your lowers, is coil sprung, and takes the best 32mm dampers RockShox ever made. But, there's strong demand for forks like these and you have to move quick.
Damn! My issue at present is that I don't know what I need to look for in terms of a usable CSU - I'm literally stumbling around in the dark and I don't know what I don't know if you follow. Would E*ay item number 224466277317 be of any use?
 
Discussion starter · #106 · (Edited)
Damn! My issue at present is that I don't know what I need to look for in terms of a usable CSU - I'm literally stumbling around in the dark and I don't know what I don't know if you follow. Would E*ay item number 224466277317 be of any use?
Yes, it would be - that's a 2011 model year.

With that CSU and 120mm travel you can go straight to this damper (or the RCT3 moco + rapid recovery rebound - 11.4018.025.003 or 11.4018.025.011 or possibly this but not 100% sure of the length of that old Reba rebound shaft - since 32mm charger 2 dampers are not often found at reasonable cost) and a much better Dual Air spring like this (it comes with a 10mm travel spacer you'll need, add another 10mm to reduce travel to 120mm).
 
Yes, it would be - that's a 2011 model year.

With that CSU and 120mm travel you can go straight to this damper (or the RCT3 moco + rapid recovery rebound - 11.4018.025.003 or 11.4018.025.011 or possibly this but not 100% sure of the length of that old Reba rebound shaft - since 32mm charger 2 dampers are not often found at reasonable cost) and a much better Dual Air spring like this (it comes with a 10mm travel spacer you'll need, add another 10mm to reduce travel to 120mm).
I'll PM you if that's ok to save cluttering up this thread nay more?
 
I am new to the forum and have struggled with this fork too. I don't feel like dropping 800 plus on a new fork right now but need a viable solution. It is marginal at best with the upgrades on this wonderful thread so thank those for that. My question is since Faast racing can cut the threads on a yari compression damper from .5 to .8 pitch my thought was well why can't I take a charger damper with a .5 thread and have it machined to .8 pitch as well and solve most of the equation since the rebound damper is junk. The problem is I am still waiting to find out from my machinist if this is even possible and I also don't know which charger damper I would attempt this on for this 150mm fork. Any help would be greatly appreciated. Wonderful site and wish I had joined years ago.
 
Discussion starter · #111 · (Edited)
I am new to the forum and have struggled with this fork too. I don't feel like dropping 800 plus on a new fork right now but need a viable solution. It is marginal at best with the upgrades on this wonderful thread so thank those for that. My question is since Faast racing can cut the threads on a yari compression damper from .5 to .8 pitch my thought was well why can't I take a charger damper with a .5 thread and have it machined to .8 pitch as well and solve most of the equation since the rebound damper is junk. The problem is I am still waiting to find out from my machinist if this is even possible and I also don't know which charger damper I would attempt this on for this 150mm fork. Any help would be greatly appreciated. Wonderful site and wish I had joined years ago.
So it can be done - here is an example. The new thread is not quite M32 x 0.8 so the shop has to custom measure and cut. You'll have to disassemble the damper - of course.

These forks, uppers and lowers, are dimensionally identical to the Yari, Lyrik and Pike B1. I'll post up some Charger part numbers a bit later.

Photo below is 35 Gold CSU top, 2019 Lyrik CSU below.

1936044
 
Discussion starter · #112 · (Edited)
I am new to the forum and have struggled with this fork too. I don't feel like dropping 800 plus on a new fork right now but need a viable solution. It is marginal at best with the upgrades on this wonderful thread so thank those for that. My question is since Faast racing can cut the threads on a yari compression damper from .5 to .8 pitch my thought was well why can't I take a charger damper with a .5 thread and have it machined to .8 pitch as well and solve most of the equation since the rebound damper is junk. The problem is I am still waiting to find out from my machinist if this is even possible and I also don't know which charger damper I would attempt this on for this 150mm fork. Any help would be greatly appreciated. Wonderful site and wish I had joined years ago.
As far as which part numbers could potentially work, all of this is of course experimental.

Any Charger, Charger 2 or Charger 2.1 for a 2016+ Lyrik or Yari will functionally work, have M32 x 0.5 top cap thread, and will give you the fork's maximum 160mm travel (if you can get the topcap thread cutting part right) but quite expensive $250+.

The 29" non-boost (15 x 100mm axle) Pike A1 and Pike A2 Chargers (original, 2.0 and 2.1) are the cheapest and will give you a maximum ~150mm travel in this fork. These are cheap since there is no demand for them, they have a course M32 x 1.0 top cap thread that you won't be able to rethread. What you can do is get a non-boost 29" Pike A1 original version Charger RC like this for $99 and also a bladder assembly with the finer M32 x 0.5 top cap thread like this separately for $57, and after rethreading the bladder assembly's top cap take your Charger apart, change some shims around (you'll find threads about re-shimming the Pike Charger RC to improve it here on mtbr and also at ridemonkey and mtb-news.de) and re-assemble it with the new top cap. Over on mtb-news.de there's also 3d printer STL files for a revised Charger RC compression piston design.

The 2014-2017 29" boost Pike A1 and Pike A2 Chargers (original, 2.0 and 2.1 but excluding # 00.4018.783.015) are also cheaper and will also give you a maximum ~150mm travel in this fork. These forks have M32 x 0.5 top cap thread that's fine enough to rethread. Here's a Charger 2 RCT3 (# 00.4018.783.017) for $170.

The 2017 boost Pike A2 and 2018+ Pike B1 and 2018+ Revelation B1 Charger 2.0 and Charger 2.1 will give you the full 160mm travel in this fork but these are also expensive (for example part # 00.4018.783.015 is the first Charger 2 RCT3 but they're still $250+)

There's an assortment of Charger 2.1 for Pike B2, Pike B3 and Pike B4 that will all give you either 150mm or 160mm (I'm not sure) but are also $$$

Then on PinkBike you get things like this for $30 - no details on what fork wheel size and clearly not a 2020 (it's an original Charger RC) but zooming in I can see it does have the fine 0.5mm top cap thread - so it's for either a 27.5" or 29" boost Pike A1 or Pike A2.
 
Rete, Thank you so much for this extensive work. I really appreciate all that you did here. I spoke to my machinist this morning and said it shouldn't be an issue to pop it into a lathe and cut the threads to .8. I just don't know the main difference between the original pike charger performance for $30 bucks and the newer A1 dampers at $170 bucks. I will message that person to see what it went into and what travel that pike was.
 
Discussion starter · #114 ·
Rete, Thank you so much for this extensive work. I really appreciate all that you did here. I spoke to my machinist this morning and said it shouldn't be an issue to pop it into a lathe and cut the threads to .8. I just don't know the main difference between the original pike charger performance for $30 bucks and the newer A1 dampers at $170 bucks. I will message that person to see what it went into and what travel that pike was.
If you do get an original Charger RC you have to disassemble it in any case to remove the top cap. That's the time to remove the preload from the shim stack before reassembly. About halfway down here and same thing somewhere on mtbr. Video here. If you get more adventurous you can also print your own compression pistons (here - use translate in Chrome if your German is rusty)
 
Very Interesting rete. Why can I not just throw the whole damper in a pro lathe and turn down the threads without having to disassemble the unit? I certainly can take it apart as I work on ktm suspension in my spare time but It would be nice to turn and go lol. If the stacks are too firm I totally get that though and it would have to be dissasembled. Thanks for that!
 
I think I am just going to go for the A1 damper from Ebay like you suggested. I guess the air side I understand is an entire other ball of wax where there isn't any upgrades possible from what I understand as there are some internal differences in the air side assembly but I could be wrong. Thanks again for your guidance and I will of course let you know how it all turned out!!!!
 
Discussion starter · #117 ·
I think I am just going to go for the A1 damper from Ebay like you suggested. I guess the air side I understand is an entire other ball of wax where there isn't any upgrades possible from what I understand as there are some internal differences in the air side assembly but I could be wrong. Thanks again for your guidance and I will of course let you know how it all turned out!!!!
There are things you can do on the air side to increase the negative chamber size, again involving a bit of diameter reduction on the lower air spring seal head. I'll post up a few photos when I get home.
 
Discussion starter · #119 ·
This is the current layout of the air spring assembly at 150mm travel.

1936206


With this setup the o-ring of the negative seal head is around 20mm above the lower edge of the lower guide (which is secured at the bottom of the stanchion with a large circlip).

1936200


From the bottom edge of the lower guide to the bottom edge of the piston is around 86mm at topout.

1936201


At topout the negative chamber length, center of lower seal head o-ring to center of piston o-ring, is ~99mm.

1936202


You need a lower seal head from a pre-Debonair Lyrik for this modification. I have a bunch of these lying around, but if you get yourself the 200 hour Lyrik/Pike B1 service kit part # 00.4315.032.621 it comes with a negative seal head that seals right at the bottom of the stanchion, with the o-ring about 3mm from the bottom of the stanchion. This kit also comes with a set of low friction dust wipers which is a useful improvement on these forks.

1936203

For this specific modification you also need a 20mm travel spacer instead of the old 10mm spacer - I use a part from the Rockshox travel spacer kit part # 11.4015.450.000. Alternatively you can re-use the old 10mm spacer and the 5mm rubber bumper that sat in the old orange lower guide plus some additional hardware store o-rings.

Individual parts of the new assembly with ~150mm travel:

1936204


The new negative chamber length at topout.

1936205


The new Lyrik lower seal head has an external diameter of about 32.4mm...

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...and you need to get it down to ~31.5mm to fit into the 35 Gold's lower stanchion.

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That's where the additional machining comes in. I just use a threaded rod and two nuts in a drill with a sanding block (and gorilla tape wrapped around the rod threads where it sits inside the seal head), which took no longer than 5 minutes. If you do it this way, remove the seal inside the seal head first.

1936210
 
Fantastic write up Rete. My machinist is breaking my chops about taking the cap from .5 to .8 pitch. I know it can be done but I am going to have a deeper conversation about it. He is nervous about how much thread contact will remain and that I am unsure about. If he won't do it maybe you or someone knows someone that I could send it to worst case. Thanks so much for your help!!!!
 
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