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

link1896

link1896

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

Revised orings. Have swapped from polyurethane O-Ring on the bearing to damping rod position to a n70 quad ring. This should delay air pushing into oil chamber when IFP pressure drops below air can pressure, plus there is no need for an O-Ring of this rigidity in this position. I would suggest this was selected by our friends to minimise service life.


PositionMaterialIDCSPN
brain adjust knobbuna 70A51.5
top outer of reservior can to machined headbuna 70A222
IFPbuna 70A17.073.53BS-209
nitrogen stopperbuna 70A192.65BS116
brain piston ODbuna 70A211.5
hose end x 2 (polyurethane)polyurethane4.51.8BS-008PU
metering rod to inside of damper shaftbuna 70A31.5
damping rod to inside of end capbuna 70A111.5
damping body to bearingbuna 70A201.8BS-019
bearing to damping rod Quad ringbuna 70a12.372.62QR-112
IFP bleed portbuna 70A31.5
autosag assemblybuna 70A341.8BS-027 or BS-028
airsleeve to bearing housing Quad ringbuna 70A24.993.53QR-214N70
backup ringsTeflonBU-214T
airsleeve to end capbuna 70A331.5
airsleeve quad ring to damper bodybuna 70A20.223.53AS568A-211
airsleeve quad ring to damper body backup ringTeflonBU-211T
airsleeve wiper sealUrethane0.812 AN 0.812" urethane
 
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link1896

link1896

Mr Greenfield
merc-blue, way back up this thread we were talking about tooling. Here is my tool for installing the bearing block onto the damping rod. Had to make this guy again, somehow lost the last one.




Rebuilding with a n70 quad ring in the bearing block to damping rod position
 
link1896

link1896

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

Rong Fu mills are not the sturdiest.

So a few support braces and it's eliminates a lot of the chatter. The lowest piece that makes contact with the mills post is turned up and belted into the post. Never ever coming out

 
swaz

swaz

Likes Bikes and Dirt
sweet! Thank you. Must take you a while to machine some of those tools with a non-motorised table on the mill.

Hats off to you for everything BTW, you're one clever dude.
 
I

imago

Likes Bikes
Hey Link,

Do you have any pointers on how to do a basic air can service on these shocks? The general guide I was looking at is here:
http://www.ridefox.com/fox_tech_center/owners_manuals/09/custprod/content/ivairsleevemaint.html

I've got a 2016 Camber, the questions I had were

-Does that Fox guide still seem about right?
-Would 2cc of float oil be about right still?
-Any pointers for taking the shock off the bike, and do you need to remove the brain resevoir?
-I've seen a video from Spec talking about reinstalling the resevoir on Epics & that it needs to be put back on at an 11 degree angle and 3mm from the back. Any tips on reinstalling the Brain resevoir & making it's on the right spot? Have you seen any reference to what position/angle they get put on for other bikes?

Cheers!
 
link1896

link1896

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

imago said:
Hey Link,

Do you have any pointers on how to do a basic air can service on these shocks? The general guide I was looking at is here:
http://www.ridefox.com/fox_tech_center/owners_manuals/09/custprod/content/ivairsleevemaint.html

I've got a 2016 Camber, the questions I had were

-Does that Fox guide still seem about right?
-Would 2cc of float oil be about right still?
-Any pointers for taking the shock off the bike, and do you need to remove the brain resevoir?
-I've seen a video from Spec talking about reinstalling the resevoir on Epics & that it needs to be put back on at an 11 degree angle and 3mm from the back. Any tips on reinstalling the Brain resevoir & making it's on the right spot? Have you seen any reference to what position/angle they get put on for other bikes?

Cheers!
Click to expand...
Howdy imago,

That guide shows how air cans work and come apart, good basis for your understanding. I've not had touch/play of a 2016 Camber, photos please.

The shock/brain assembly must come off the bike to get the air can off. Take plenty of photos before hand.

Remove both positive and negative Schrader valves with a valve core tool (ten bucks at super cheap auto) and the shock is easy to manipulate.

The yoke (aka clevis) that bolts to the shock must come off. This is an imperial hex bolt holding it on!

The hose can spin in the shock and brain, turn the hose so the S shape in the solid tube allows the air can to pass.

I never found any variation on brain mounting position, but measure the angle with a protractor to be safe. No reference to position or angles in any documentation I have, but I don't have everything.

Make sure the hose is not rubbing on carbon frame when you are done, it will cut thru Carbon in no time ( and Specialized will not cover by warranty)

A pillow pack of Fox float fluid is fine, I'd go all 5cc's. Let me know if you need something else fast, can send you some of my favourite air can lube ( Clevite engine bearing assembly lube )

Find the service document showing bolt torques for when it comes time to reassemble.
 
Lazmo

Lazmo

Old and hopeless
Hwy Mark... it's no bloody wonder you have to ride at night... not enough hours in the day for you ;-)
 
link1896

link1896

Mr Greenfield
Lazmo said:
Hwy Mark... it's no bloody wonder you have to ride at night... not enough hours in the day for you ;-)
Click to expand...
Combined with a crazy 20 month old kid who won't sleep, I am rather time poor. Just got back from some fun at lystie. Hot but not as humid as Monday night.
 
S

SARED

Squid
Fantastic Thread! Thanks Link for your patience and detail. Way above my technical ability for now, but there is only one way... start! Is there an easier way to refill the nitto myself.... or I must take it to Spez to pressurize.
 
link1896

link1896

Mr Greenfield
SARED said:
Fantastic Thread! Thanks Link for your patience and detail. Way above my technical ability for now, but there is only one way... start! Is there an easier way to refill the nitto myself.... or I must take it to Spez to pressurize.
Click to expand...
Any moto shop should be able to fill, or buy a schrader valve that will thread into the existing nitrogen fill port and use a shock pump and air.

Such a valve is here http://teknikmotorsport.com.au/Shock-Bladder-Valve-Schrader-Valve-Fitting-KYB-Alloy
 
S

SARED

Squid
Thanks for the link, I will look for a schrader valve fitting. I'll ad my own pressure guage and pop into my local tyre shop for a Nitrogen refill :clap2:
 
link1896

link1896

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

Spent an hour helping a top female veteran setup her Sworks Epic. I sure do feel fat and slow on the climbs, holy fuck!

Things get whacky with 50kg riders. Down to 70psi in the rear shock to achieve 15% sag, but comp damping is preventing full travel plus wheels are not leaving the ground for air time, as you'd expect . With rear Brain on full soft there is no signs of pedal bob, with rebound mid range. Rider weight being seriously low plus very good technique is impressive.

Fork brain at mid setting, rebound on mid stroke. 60psi in forks, could probably drop to 50psi.
 
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S

SARED

Squid
Well done helping her! Putting your good indepth knowladge to good use and she is very fortunate! I am shure she appreciate it. Kudus to you!
 
link1896

link1896

Mr Greenfield
I had a very productive day tinkering in the workshop on a doctor mandated rest day.

Rebuild redbruce's shock again searching for longer term reliability. My spare shock is up next.

Swapped hose, IFP and bearing to damper rod orings out for quad rings. Quad rings at 15-20% squeeze do a better job than an O-Ring at 30%.

All three positions have one and one size only that fit, all in the <20% squeeze range.

Rebuilt the hand dyno too, little nicer.

 
Nambra

Nambra

Definitely should have gone to specsavers
A few strawberry daiquiris on the go too Link? I'll bet you've got a machine to make those as well...
 
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