Specialized rear shock "Brain" rebuild with pictures & now forks too

link1896

Eats Squid
As the title says, I'm embarking on rebuilding Specialized rear Brain shocks (and now forks too, see post 243 of this thread). This has been a long time coming, I've spent a fair amount of time on the couch reading the patent documents while feeding my son over the last few weeks.

There are valid Australian patents for the brain technology and autosag technology. Spare parts availability seems to be non existent. Between Specialized's patents and their bus load of lawyers, I've had some legal advice, but really need to spend an hour with a patent lawyer. Personally I find the cost of ownership too high if I can't service myself. I really like SRAMs style, full service documentation and parts availability. Until I embark on an electronically controlled shock to supersede the brain, I want to maintain it to top condition. Until I have clarity from a patent lawyer, this thread will only show what I have done, current IP law lets an individual use/copy patent protected designs or processes as long as there is no commercial consideration.

Inertial mass (aka brain) Australian Patent http://pericles.ipaustralia.gov.au/ols/auspat/applicationDetails.do?applicationNo=2011253723
Autosag Australian Patent http://pericles.ipaustralia.gov.au/ols/auspat/applicationDetails.do?applicationNo=2012227197

So far I have two shocks to experiment with, a 2012 S-Works Epic rear brain, and a 2014 Epic World Cup rear brain. I've started with the Sworks, have stripped and cleaned. I'm currently stuck getting the piston head out of the brain assembly. Will need to make a tool with multiple pins to engage the piston head to spin it out, using a circlip tool quickly burred up two ports. grrr.

Next step is to hunt down generic parts from my local bearing/hydraulic shop. Fingers crossed the seals, etc, arn't custom sizes. I have a bad feeling they are. Seals are all made by NOK but have very odd size markings.

Some revisions provide a bleed port for vacuum bleeding, the 2012 Sworks shock doesn't have a bleed port, I'm yet to work out how to bleed.

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link1896

Eats Squid
Thanks. Yep, thinking of adding adjustable preload to the spring and a Schrader valve so I can recharge with air for testing
 

Ivan

Eats Squid
Thanks. Yep, thinking of adding adjustable preload to the spring and a Schrader valve so I can recharge with air for testing

I had assumed that is what the adjuster did, adjust the preload on the spring. I'll have to go and look at some pictures to figure out whats actually going on.
 

link1896

Eats Squid
I had assumed that is what the adjuster did, adjust the preload on the spring. I'll have to go and look at some pictures to figure out whats actually going on.
The brain fade adjuster on the reservoir sets the needle height inside the damper shaft, the spring for the inertia mass is fixed. fEwgdq0.jpg
 
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SummitFever

Likes Bikes and Dirt
...the 2012 Sworks shock doesn't have a bleed port, I'm yet to work out how to bleed...
Any idea who makes the 2012 for Speci? Doesn't look like a fox shock. Earlier brain shocks made by Fox have to be assembled in a 2l ice container full of shock oil to solve the bleed problem.
 

link1896

Eats Squid
Any idea who makes the 2012 for Speci? Doesn't look like a fox shock. Earlier brain shocks made by Fox have to be assembled in a 2l ice container full of shock oil to solve the bleed problem.
It was fox. I've drawings with Fox's logo on them. I guess shesh wanted to differentiate and didn't use Fox's aesthetics.

The original brain with the inertial assembly threaded into the main housing was a bucket bleed job, possibly the older remote reservoirs, like this 2012 example, are too. It will be fun working it out.
 

link1896

Eats Squid

link1896

Eats Squid
Progress update.

damper shaft seal is rock hard, like rp23's of similar vintage I've had apart.
Dowel pins ordered for making a tool to unthread the reservoir piston head.
found small metal shavings around the main shim stack but nothing is damaged, this shock has been apart previously, score marks on housings around hose c clips.
 

rider124

Likes Bikes and Dirt
just thought id add to this thread
love the brains, and im just about to teach myself to rip them apart too i hope
when i was at specialized recently, i snapped this of a brain they had on display if anyone was curious on what they looked like
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will be following this thread closely!
 

link1896

Eats Squid
just thought id add to this thread
love the brains, and im just about to teach myself to rip them apart too i hope
when i was at specialized recently, i snapped this of a brain they had on display if anyone was curious on what they looked like
View attachment 314477

will be following this thread closely!

That's a reservoir circa 2012. There is a grub screw holding in a ball bearing for bleeding under the adjuster. This design has the shim stack between inertia valve and IFP, later designs have shim stack first, inertia valve in middle and IFP at bottom.
 

rider124

Likes Bikes and Dirt
Very cool. Spesh AU or USA?
Spesh AU
Hoping to go there again soon so i can learn more about the brain servicing too!!

looks like you have just taught yourself though! props to you,
quite an intimidating system if you dont know what you are doing
 

SummitFever

Likes Bikes and Dirt
Other than the brass mass, the system is very similar to every other piggy back shock (other than CCDB/twin chamber etc.) or remote resi shock. The rebound damping is handled on the piston in the shock body and the comp damping is in the remote (or piggy back). The brass mass provides a way to remove the platform once the rear wheel hits a bump but the transition never feels smooth - you always feel a little "spike" before the system opens up.

If it was me, I'd be looking at ways to remove the brass mass, modify the adjuster to preload a LSC stack or modify the adjuster to control the comp free bleed. Suspension tuning has come a long way from when the brain first came out. The super-digressive stacks and their easy DIY tuning that come in shocks like the latest Monarchs mean the brain has really had its day, even on horst-link bikes like the Speci. You can look to the info of tuning the RT3 if you want some comp shim stacks to try. Even though the shocks are different, fluid displacement on the comp circuit will be same as the damper rod is the same diameter. So provided the free bleed is similar, the reservoir (comp stack in the resi) will see the same volume of oil flow as what the comp side of the RT3 piston will see.

Also, there is really nothing in those pictures of your shock pull apart that looks like something made by Fox. If I had to take a guess, I'd say its made by Manitou. I can't imagine Fox making all new components just for a Speci brain. Take a look at some pictures of the Manitou Q series of shocks and you will see many similarities - from the air cans, to the rebound adjuster, to the same design and seals used on the seal head.
 

link1896

Eats Squid
Other than the brass mass, the system is very similar to every other piggy back shock (other than CCDB/twin chamber etc.) or remote resi shock. The rebound damping is handled on the piston in the shock body and the comp damping is in the remote (or piggy back). The brass mass provides a way to remove the platform once the rear wheel hits a bump but the transition never feels smooth - you always feel a little "spike" before the system opens up.

If it was me, I'd be looking at ways to remove the brass mass, modify the adjuster to preload a LSC stack or modify the adjuster to control the comp free bleed. Suspension tuning has come a long way from when the brain first came out. The super-digressive stacks and their easy DIY tuning that come in shocks like the latest Monarchs mean the brain has really had its day, even on horst-link bikes like the Speci. You can look to the info of tuning the RT3 if you want some comp shim stacks to try. Even though the shocks are different, fluid displacement on the comp circuit will be same as the damper rod is the same diameter. So provided the free bleed is similar, the reservoir (comp stack in the resi) will see the same volume of oil flow as what the comp side of the RT3 piston will see.

Also, there is really nothing in those pictures of your shock pull apart that looks like something made by Fox. If I had to take a guess, I'd say its made by Manitou. I can't imagine Fox making all new components just for a Speci brain. Take a look at some pictures of the Manitou Q series of shocks and you will see many similarities - from the air cans, to the rebound adjuster, to the same design and seals used on the seal head.


There are rebound and compression dampening shim stacks in the main body, and a compression stack in the remote reservoir in the 2012 shock I have apart. The patent documents otoh show comp and rebound stacks in both main body and res. unsure yet what I'll find in the latest 2014 version.

I've a love hate with the brain. Climbs like a hard tail yet opens with an annoying delay once a bump arrives. I have started prototyping up an electronically controlled equivalent with a single axis accelerometer.
 
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SummitFever

Likes Bikes and Dirt
...I have started prototyping up an electronically controlled equivalent with a single axis accelerometer.
That sounds interesting. I read somewhere that someone tried putting the brain/remote on their fork lower and that actually worked better as it opened the rear when the front wheel hit so by the time the rear wheel got to the bump it was fully open. You could do the same and chuck the accelerometer up front.
 

link1896

Eats Squid
That sounds interesting. I read somewhere that someone tried putting the brain/remote on their fork lower and that actually worked better as it opened the rear when the front wheel hit so by the time the rear wheel got to the bump it was fully open. You could do the same and chuck the accelerometer up front.
Yep, the plan is to locate the accelerometer further forward, probably on the front fork. I've been searching automotive patents for methods of adjusting valving dynamically from fully closed to wide open without shim stacks. Fun stuff
 

SummitFever

Likes Bikes and Dirt
Have you checked out the "magnetorheological fluid" stuff? That seems to be the way of the future for electronically adjustable damping.
 

link1896

Eats Squid
Have you checked out the "magnetorheological fluid" stuff? That seems to be the way of the future for electronically adjustable damping.
Aka ferrofluid. Yes, the lack of fail safe and its expense kinda put me off it. I was thinking of two piston heads with small ports, held apart by a thrust bearing on their outer, one rotated to adjust open area by a shaft leading out to a stepper motor. Check valve on one side. repeat for rebound
 

yuley95

Likes Dirt
Just dropped my 2010 brain shock off for a very expensive service so will be interested to hear how this turns out.

And for those questioning if fox make these - they have since 2010. I took mine to Tekin and they send them on to Fox to be serviced.
 
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