hifiandmtb
Sphincter beanie
Awesome work!
Specialized rear shock "Brain" rebuild with pictures & now forks too
- Thread starter link1896
- Start date
link1896
Mr Greenfield
out for a shake down ride tonight.
link1896
Mr Greenfield
Thanks gents.
Fork cartridge bleed tool in all its glory. Screw the tiny unc no 4 end into the IFP, then set the IFP height with the first ally part engaged into the body, then turn the second ally part down to lock. Sets IFP depth and strain relieves the no4 tip (2.8mm diameter )
Profile on the left is nitto air fitting to allow the whole assembly to spin as needed to prevent hose kinking. Unusually long end, I found nitto fittings JUST couple with enough overlap and rely on positive pressure on the inside for a seal but don't usually work with vacuum.
Fork cartridge bleed tool in all its glory. Screw the tiny unc no 4 end into the IFP, then set the IFP height with the first ally part engaged into the body, then turn the second ally part down to lock. Sets IFP depth and strain relieves the no4 tip (2.8mm diameter )
Profile on the left is nitto air fitting to allow the whole assembly to spin as needed to prevent hose kinking. Unusually long end, I found nitto fittings JUST couple with enough overlap and rely on positive pressure on the inside for a seal but don't usually work with vacuum.
hifiandmtb
Sphincter beanie
Too stiff as in it needs too big an impact to unlock?
link1896
Mr Greenfield
Yep. With the brain fade threshold on 6, with IFP at 120 psi, it's too stiff. Going to experiment with pressures next ride.
redbruce
Eats Squid
What air spring pressures?
link1896
Mr Greenfield
90pos, 110neg. Same as always.
link1896
Mr Greenfield
Specialized rear shock "Brain" rebuild with pictures & now forks too
Have now had contact from the fourth suspension shop from around the world who have reached out and thanked me for the results of this project. Two of them I have made them tools (bleed port adapter, shaft clamps, sample Schrader valve stopper)
Over 30 rear brains rebuilt.
Woopieeeeee. That's the ultimate result.
Have now had contact from the fourth suspension shop from around the world who have reached out and thanked me for the results of this project. Two of them I have made them tools (bleed port adapter, shaft clamps, sample Schrader valve stopper)
Over 30 rear brains rebuilt.
Woopieeeeee. That's the ultimate result.
Z
Zaf
Guest
That's fantastic, and this thread has been a fantastic read through.
hifiandmtb
Sphincter beanie
Have you rebuilt over two dozen rear Brains?! Congrats Linky - what a champion! Great to see all your good work making a difference.
link1896
Mr Greenfield
No no, I've rebuilt about 5. These shops have rebuilt in excess of 30.
link1896
Mr Greenfield
Specialized rear shock "Brain" rebuild with pictures & now forks too
My current focus is on electronic means. Many short comings of the mechanical system, but electronic systems like ferrofluid based dynamically adjusted viscosity are a mine field, I've got 180ish patents from EU and the USA to read.
IFP pressures, minimum starting point is full depth so it's touching the valve gate above it when shock is at the ZERO travel position, and pressure is set at expected positive air can pressure (at sag position) plus 20psi. This works a lot better then a fixed arbitrary value.
An sworks style race tune is an extra 100psi, so for me that's 280psi. Running schrader valves rated at 800psi now, which allows trail side tuning.
Tuning IFP pressure on the trail side is pretty cool.
Specialized already have their parents covering the inertia mass, valid even here is Aus. I've not sold anything, all of my work has been for free so I can gain further experience. Plus the patents do not specify o ring sizes, shim stack dimensions or oil viscosity, so these are not protected by the patents. (Would have saved a lot of time if they did)
My current focus is on electronic means. Many short comings of the mechanical system, but electronic systems like ferrofluid based dynamically adjusted viscosity are a mine field, I've got 180ish patents from EU and the USA to read.
IFP pressures, minimum starting point is full depth so it's touching the valve gate above it when shock is at the ZERO travel position, and pressure is set at expected positive air can pressure (at sag position) plus 20psi. This works a lot better then a fixed arbitrary value.
An sworks style race tune is an extra 100psi, so for me that's 280psi. Running schrader valves rated at 800psi now, which allows trail side tuning.
Tuning IFP pressure on the trail side is pretty cool.
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MarioM
Likes Dirt
Very impressive . I remember ferrofluid from way back and just had a google to catch up with what they are now doing . Wow .
Miguel75
Likes Dirt
That's a pretty cool result. Congrats on working through a problem and including us in the ride...
fantastic read
Having just spent $350 on a rear brain service for my 2011 SW Epic (fluid leaking into -ve air chamber, main seal leak, no internal pressure and low on oil. IFP topped out), I've come to the conclusion that this is too expensive to maintain commercially.
If you ever want to start making a kit, let me know.
I've picked up a brain damper cartridge from a Stumpy which I want to pull apart - I've got the schematic from Spec which provides a great start.
BTW, a few pages back in this thread there was some comment about catastrophic loss of pressure from the RS dual air spring, the answer is usually to remove the top cap and put some oil down the leg, cycle a few times and then you're good to go. It happened to me and the LBS couldn't figure it out so got me a new fork carbon upper and told me that there was a leak between the carbon crown and the legs (which would defy physics if it did happen). Bikie was under warranty and one of the uppers had a scratch so I wasn't sweating it. The the fix is really easy.
Once again, great read thanks.
Having just spent $350 on a rear brain service for my 2011 SW Epic (fluid leaking into -ve air chamber, main seal leak, no internal pressure and low on oil. IFP topped out), I've come to the conclusion that this is too expensive to maintain commercially.
If you ever want to start making a kit, let me know.
I've picked up a brain damper cartridge from a Stumpy which I want to pull apart - I've got the schematic from Spec which provides a great start.
BTW, a few pages back in this thread there was some comment about catastrophic loss of pressure from the RS dual air spring, the answer is usually to remove the top cap and put some oil down the leg, cycle a few times and then you're good to go. It happened to me and the LBS couldn't figure it out so got me a new fork carbon upper and told me that there was a leak between the carbon crown and the legs (which would defy physics if it did happen). Bikie was under warranty and one of the uppers had a scratch so I wasn't sweating it. The the fix is really easy.
Once again, great read thanks.
link1896
Mr Greenfield
Specialized rear shock "Brain" rebuild with pictures & now forks too
Can do a kit no worries if it's the same as one I've previously reverse engineered. It's the bleed port adapter that's is a bit more involved.
The forks with carbon crown and bonded in stanchions. The O-Ring on the cap seals on the leg, not the carbon. I've seen this silliness too where forks are warrantied for orings that are dry and getting stretched/mangled upon assembly and not holding air when a little lube will fix. Of course carbon isn't air tight. Wonder how many have been RMAed due to this?
Post up some pics of the offending shock and we'll see if it matches the shock off redbruces' epic of that vintage.
Can do a kit no worries if it's the same as one I've previously reverse engineered. It's the bleed port adapter that's is a bit more involved.
The forks with carbon crown and bonded in stanchions. The O-Ring on the cap seals on the leg, not the carbon. I've seen this silliness too where forks are warrantied for orings that are dry and getting stretched/mangled upon assembly and not holding air when a little lube will fix. Of course carbon isn't air tight. Wonder how many have been RMAed due to this?
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