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

[redbruce]

It’s a 2011 Stumpjumper.. I didn’t even think that it was interchangeable?

Sent from my iPhone using Tapatalk

You will need one of these.

https://www.mountainbikesdirect.com.au/bikeyoke-yoke-to-suit-specialized-stump-jumper

 

[link1896]

You will need one of these.

https://www.mountainbikesdirect.com.au/bikeyoke-yoke-to-suit-specialized-stump-jumper

Wow, didn't know they had such extensive model/year coverage.

Definitely the best solution.

 

[tasty.dirt74]

You will need one of these.

https://www.mountainbikesdirect.com.au/bikeyoke-yoke-to-suit-specialized-stump-jumper

Just bought one.. Thanks for the link. Now the next step is to get a shock valved correctly i guess?

 

[link1896]

I love a good challenge. Rebuilding this guy early January.

 

[redbruce]

Just bought one.. Thanks for the link. Now the next step is to get a shock valved correctly i guess?

Shot would be to see what the OEM replacements from RS for later bikes run in tune as a guide.

I have the standard Monarch Debonair RT3 MM 320 and with my 100kg, it is a bit firm on compression. Ideally I would like the platform setting to be as firm as open is now.

At this stage because of the firm compression I get away without volume bands to ramp up spring rate at end of travel but when I get around to fitting an L comp tune will need them.

Having said that, it rides and climbs better than with the original brain, and no clunking.

I love a good challenge. Rebuilding this guy early January.

So that will be 4 of the 7 generations of brain you will be "specialized"in

 

[Oddjob]

Sucker for punishment.

Sent from my SM-G900I using Tapatalk

 

[tasty.dirt74]

Just bought one.. Thanks for the link. Now the next step is to get a shock valved correctly i guess?

So ended up going down a different path..

This uses the original hardware and yoke. So the aftermarket yoke gets returned with absolutely no complaints by shop it was purchased from.. Also a huge shoutout to NSDynamics who got the shock AND fork(woohoo) to me overnight!! That in itself is amazing, but they also included a t shirt a socks in the package.!!

Thanks guys..

Sent from my iPhone using Tapatalk

 

[redbruce]

Well spotted.

I'd not come across that option.

If I may ask, how much (rear)?

 

[tasty.dirt74]

Well spotted.

I'd not come across that option.

If I may ask, how much (rear)?

It is the same e2e as OE, so 120mm. But so much more usable travel and controllable. Transformed the bike..


Sent from my iPhone using Tapatalk

 

[redbruce]

Cost?

 

[tasty.dirt74]

Cost?

The shock was $699.

Got Beryl fork at same time for total $1400..

 

[Afonso Ramôa Jr.]

Nice thread!

Is it possible to service only the chamber by changing oil and o-rings without servicing the brain cartridge?

 

[link1896]

Nice thread!

Is it possible to service only the chamber by changing oil and o-rings without servicing the brain cartridge?

Thank you Afonso, where on this lovely
Planet are you from?

Sadly no, all variants need to be bled as a whole once reassembled, and if you've got the brain assembly apart, the main shock end is easy.

 

[link1896]

Strip down has commenced.

Need to turn up a custom shaft clamp for the damper rod to get the piston head bolt off. Bugger.

Also need to remove the chamfer on yet another 6 point socket.

 

[link1896]

Socket complete. The Action impact sockets are a nice steel, turns well.

 

[link1896]

Fuck it. Weird damper rod seal that's gone hard and failed. Now to measure the O-Ring grove width and depth and try to find an O-Ring and backup ring combo that can do the job.

 

[hathill]

Your secret coconut water damping fluid recipe is out.....

Fuck it. Weird damper rod seal that's gone hard and failed. Now to measure the O-Ring grove width and depth and try to find an O-Ring and backup ring combo that can do the job.

 

[link1896]

Your secret coconut water damping fluid recipe is out.....

still don't have a valid 100c cSt value to share for coconut water sorry.

 

[link1896]

And the fun continues.

I have a 2018 rear brain due next week from Brazil. Photos and measurements to follow.

I've had a failed 2018 in my hands once already, some new tooling will be required, but now Specialized (Rockshox?) are giving the tooling needed for a 50 hour aircan service to dealers.

The redesign now uses a bladder instead of an IFP, bladder pressure was dropped to gain small bump compliance. I'm hearing stories of a lot of failures, along with a damper rod or bearing head part needing replacement due to parts out of tolerance.

I'm perplexed at the moment how dropping bladder pressure to gain small bump compliance doesn't cause major issues with pressure loss at the main seal head after full stroke compression events that require more oil return then the bladder pressure and hose cross section area can satisfactorily achieve, letting aircan air pressure to pass the main seal into the oil side.

 

[link1896]

One 25-30 hour old MY2018 shock is in my possession.

Workshop is about to get all packed up in anticipation of selling the house as part of my divorce, unsure yet when the workshop will reopen, but I will work out orings and what tooling is required in the mean time.