Specialized rear shock "Brain" rebuild with pictures & now forks too
- Thread starter link1896
- Start date
Bradley James Lawlor
Squid
Quite cool how you have taken the time to essentially do this step by step for everyone. Tekin is under a contract with fox not to release this type of stuff with their product (diagrams, how to's etc), but there was a very clear message that we are not to "provide servicing to consumers of specialized branded shocks". So we just send and charge what we get charged.
Good to see someone dangling their balls in the face of specialized, knowing they cant do anything to you.
Bravo
link1896
Mr Greenfield
Thanks Bradley. Nfi how I missed your post, subscribed to my own thread for instant email alerts. :noidea:
Anyway, I'm slowly progressing, a wife in a wheelchair and a 4 1/2 month old son, a 9-5 job and a business, I'm a little short on time. Today I got a little done until my pipe bender decided to fail.
After my pipe bender failed I farmed the pipe so I could see some progress.
link1896
Mr Greenfield
First post Bobunter, welcome!
you are correct, the system ( shock + brain ) works as a whole, you can't service just one. To get the oil into the shock you have to vacuum bleed it in via the brain.
link1896
Mr Greenfield
Main piston shim stack. Note this is a WC tune, labelled CNRD. There are more shim stacks around the inertia mass, there is no need to disassemble the inertia mass for a rebuild.
17 shims in total
Rebound side x 9
15.21 x 0.12
12.68 x 0.12
8.83 x 0.55
10.17 x 0.25
10.17 x 0.25
10.17 x 0.25
10.17 x 0.25
10.17 x 0.25
15.25 x 1.27
Compression side x 8
15.22. X 0.17
15.22 x 0.17
15.22 x 0.17
10.19 x 0.25
15.22 x 0.25
15.22 x 0.25
10.18 x 0.25
10.13 x 0.51
17 shims in total
Rebound side x 9
15.21 x 0.12
12.68 x 0.12
8.83 x 0.55
10.17 x 0.25
10.17 x 0.25
10.17 x 0.25
10.17 x 0.25
10.17 x 0.25
15.25 x 1.27
Compression side x 8
15.22. X 0.17
15.22 x 0.17
15.22 x 0.17
10.19 x 0.25
15.22 x 0.25
15.22 x 0.25
10.18 x 0.25
10.13 x 0.51
stirk
Burner
Damn that's a big needle!The beginnings of a bleed port adapter. This one is for the bleed port in the brain adjusting needle. Oh the joys of unc 8-32
link1896
Mr Greenfield
Nitrogen needle is Fuck off scary. Get that in your finger with gas flowing and its gas embolism time. Should call that first guy a rod, not a needle. Not at all sharp and only partially hollow.
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link1896
Mr Greenfield
There are a few methods of failure. When all's happy it should be silent.
Off the bike try and compress rear suspension. Should be no movement when brain fade is on full firm, squelch will probably correlate to the amount of travel, due to air inside the damping oil you have.
look very closely at the brain and hose ends for signs of oil leaking.
When you set autosag, a tiny amount of blue oil should escape at most. If it's a decent amount of green or yellow, oil has leaked past o rings into air chamber.
same for forks, should be silent. Mine are not, next on the rebuild list once I finish rear shock. Doesnt looks like I need tooling for forks.
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Ivan
Eats Squid
link1896
Mr Greenfield
Bugger. At my current rate of progress, im hoping to have a shock rebuilt and on the bike for testing around Xmas time.
O rings cost me under 3 bucks
Oil will be 15 bucks at most
probably 1 hrs labour
link1896
Mr Greenfield
Any signs of oil leaking from hose ends or brain fade knob?
Ivan
Eats Squid
No oil from either of those locations, but there does seem to be a bit more oil than I would expect on the shaft, that looks like it come out of the air can seal
hifiandmtb
Sphincter beanie
link1896
Mr Greenfield
The bearing housing to damping shaft oring is made of polyurethane. I suspect this o ring has suffered from extrusion failure ( where it gets pushed into the tiny gap between bearing housing and damping shaft and damaged) and is letting oil out and air in. The fox air chamber oil is a very thick blue oil, circa 90w, known as "pillow pack" or "float fluid" . I've seen brain shocks with a very thin oil on the damper body ( shiny shaft the air can seals to) that appears to be the damping oil.
My friendly seal shop that does hydraulic parts and repairs sold me high quality Parker polyurethane orings.
Part of the final how to, when I wrap this all up, will be part numbers of orings.
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