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

[hifiandmtb]

Hey RB - I had mine on max no-Brain & it still annoyed me. It became a bit noisy, and rattled a fair bit too. Yours the same?

 

[redbruce]

Hey RB - I had mine on max no-Brain & it still annoyed me. It became a bit noisy, and rattled a fair bit too. Yours the same?

Yep.

My next move will be to replace the forks brain with conventional damping guts. About $230 for bits I'm told.

@ next service.

I'm also waiting with baited breath for the outcome of the DIY brain shock service.

Still working fine but many 1000's of K's on it and yet to be looked at.

 

[link1896]

working through orings, measuring everything to calculate oring selection, metering rod oring rides on the rod, inside of damper shaft is threaded, only way to assemble is to remove Loctite that's holding in damper shaft into the eyelet assembly and pass rod in from adjuster end, not piston end.

grrr shaft clamp is needed.

 

[link1896]

L

Here is metering rod, can't press into damper shaft from this end, internal thread damages oring on the way past

 

[link1896]

Shaft clamp, didn't have an internal thread cutting tool for the lathe long enough and thin enough to bore out a 1/2" hole this deep so used a drill bit instead, had to clean up with wet and dry. Works, vice needs to be bloody tight to prevent damping rod turning.

 

[link1896]

Stroke reducer I had not spotted is a 5.8mm delrin ring on the shaft that didn't like the mapp torch

 

[link1896]

Dual air SIDs with brain cartridge. They have an air leak somewhere in the positive chamber, leaking down over 24hrs. Hopefully fixable, at the very least a brain cartridge to dissect. Carbon crown and steerer is very sexy.

 

[redbruce]

Dual air SIDs with brain cartridge. They have an air leak somewhere in the positive chamber, leaking down over 24hrs. Hopefully fixable, at the very least a brain cartridge to dissect. Carbon crown and steerer is very sexy.

I had the same leak issue. All fixed with a left leg service.

 

[hifiandmtb]

Those forks are so nice. Aside from Brain.

 

[pink poodle]

He said shaft clamp...

This has come a long way! Is the work continually frustrating and laborious? Or is it reasonably interesting and fun?

 

[stirk]

He said shaft clamp...

This has come a long way! Is the work continually frustrating and laborious? Or is it reasonably interesting and fun?

Looks a bit rough and way too small to be effective, might fit a hipster's shaft though...

 

[link1896]

Trust you two to get scared by the shaft clamp. Not at all laborious, it's quite a fun challenge to work through.

 

[link1896]

I had the same leak issue. All fixed with a left leg service.

fingers crossed

Those forks are so nice. Aside from Brain.

Same as yours by the looks. Brain cart is doing the right thing in these from a quick play.

 

[hifiandmtb]

And mine are 15mm lowers.

 

[link1896]

2012 and 2014 SIDS are dimensionally the same. The brain cartridges are dimensionally the same too. Top adjust cartridge will fit into 2014.

Donor top adjust cartridge is in more need of a rebuild then mine, top 15mm of travel is full of air.

Can't get my brain cartridge to make noises on the bench, no air has been ingested. :noidea:

Dual air assembly also fits. Bonus. :dance:

 

[link1896]

Not so sure I want to use a second hand carbon steerer and crown, but really want to try dual air. To avoid the solo air negative chamber equilization notch, going to swap air and damping sides over and try dual air in right leg.

 

[SummitFever]

If you can put up with a 10mm reduction in travel, it is possible to convert solo air CSU's/forks to dual air.

eg. if you take a 120mm solo air SID, add the 120mm dual air spring assembly, with a 10mm all travel spacer installed (110mm mode), then the piston head o-ring seal is now spaced further up the CSU and never gets low enough to cross the solo air dimple. You now have a 110mm dual air SID using a 120mm solo air CSU.

 

[link1896]

If you can put up with a 10mm reduction in travel, it is possible to convert solo air CSU's/forks to dual air.

eg. if you take a 120mm solo air SID, add the 120mm dual air spring assembly, with a 10mm all travel spacer installed (110mm mode), then the piston head o-ring seal is now spaced further up the CSU and never gets low enough to cross the solo air dimple. You now have a 110mm dual air SID using a 120mm solo air CSU.

Thanks SummitFever. Hadn't thought about staying in the left leg. Need to work out what parts I have a little more, eventually getting the brain fade knob on the top right would be a good idea.

 

[link1896]

swapped to dual air in the right leg for now.

between dual air and molykote55 for the air chamber, stiction is gone.

brain cart, while I can't hear noises, needs a rebuild, isn't locked out like it should.

 

[link1896]

back to the rear shock assembly.


WE HAVE A WINNER!! After triple checking, the bearing housing to damper body oring in two samples of the 2014/2015 shocks are incorrectly sized. The oring has no stretch at all over the damper body, it's a loose fit. I believe this is the cause of leaking damper fluid into the air chamber.