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

link1896

link1896

Mr Greenfield
Reservoir apart, inertia mass assembly off with its adjuster needle. Freaking fine metal filings everywhere. A shock full of oil can't generate this much swarf, only feasible answer is a parts cleaning step was missed before assembly.

 
link1896

link1896

Mr Greenfield
Offending Orings. Very loose fitting in the receiving holes at each end. O rings have gone hard or were undersized to begin with.
 
S

SummitFever

Eats Squid
Looks like a much larger diameter shaft (and/or smaller diameter piston) than the RP series shocks:



(Ignore the spacer on the shaft - it's one I installed to short stroke the shock pictured).

That larger shaft will result in more oil being displaced which is probably what is required by the remote brain.

Have you had the piston off? Hard to see from pics what the rebound stack is like. How big is the rebound free bleed through the middle of the shaft? Just from the observable dimensions it looks like most of your rebound damping will be coming from metering through the free bleed. It's hard to imagine that whatever small shims could be hidden within that small piston could do a good job at a nice digressive rebound damping curve.
 
link1896

link1896

Mr Greenfield
SummitFever said:
Looks like a much larger diameter shaft (and/or smaller diameter piston) than the RP series shocks:



(Ignore the spacer on the shaft - it's one I installed to short stroke the shock pictured).

That larger shaft will result in more oil being displaced which is probably what is required by the remote brain.

Have you had the piston off? Hard to see from pics what the rebound stack is like. How big is the rebound free bleed through the middle of the shaft? Just from the observable dimensions it looks like most of your rebound damping will be coming from metering through the free bleed. It's hard to imagine that whatever small shims could be hidden within that small piston could do a good job at a nice digressive rebound damping curve.
Click to expand...

Quick draw mcgraw

ive an rp23 in the parts bin I'll dig it up later. Guess the shafts are the same, rp23 has bigger piston
 
link1896

link1896

Mr Greenfield
SummitFever said:
Looks like a much larger diameter shaft (and/or smaller diameter piston) than the RP series shocks:



(Ignore the spacer on the shaft - it's one I installed to short stroke the shock pictured).

That larger shaft will result in more oil being displaced which is probably what is required by the remote brain.

Have you had the piston off? Hard to see from pics what the rebound stack is like. How big is the rebound free bleed through the middle of the shaft? Just from the observable dimensions it looks like most of your rebound damping will be coming from metering through the free bleed. It's hard to imagine that whatever small shims could be hidden within that small piston could do a good job at a nice digressive rebound damping curve.
Click to expand...

Once I have everything apart and clean I'll publish shim sizes and positions in case someone wants to simulate in shim Restakor or messes up and muddles up shims.

From a quick observation the external res has rebound and comp stacks, and yes most rebound damping is via metering needle through the main shaft if this shock reflects the published patent drawings.
 
link1896

link1896

Mr Greenfield
link1896 said:
Once I have everything apart and clean I'll publish shim sizes and positions in case someone wants to simulate in shim Restakor or messes up and muddles up shims.

From a quick observation the external res has rebound and comp stacks, and yes most rebound damping is via metering needle through the main shaft if this shock reflects the published patent drawings.
Click to expand...



Thankfully the oring is on the metering rod, not on the damper rod. No need to turn up a rod clamp for the vice.
 
link1896

link1896

Mr Greenfield
piston shim stack


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



 
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link1896

link1896

Mr Greenfield
redbruce said:
Who makes the brain assembly?
Click to expand...

the only common part between all samples I've seen is the hose assembly.

I've drawings that have a proprietary/copyright notice on them so I can't post up, but the logo is fox, yet the dimensions match the Fusion-X I have. Maybe someone was careless with logos on drawings?

your Brian is also Fusion-X I believe.
 
link1896

link1896

Mr Greenfield
All parts finally clean, my first bottle of isopropyl had gone off due to plastic bottle.

next task is to turn up a Schrader adapter for the IFP charge port.

 
S

SummitFever

Eats Squid
There have been rumours in the past that xfusion were making Fox shocks. This may be why these "Fox" branded shocks are made from xfusion sub assemblies.
 
link1896

link1896

Mr Greenfield
Progress.
Orings and seals purchased, the odd coloured ones are polyurethane. Bloody imperial shit!

vacuume pump has arrived, frame for reservoir has been cobbled together. Waiting on vacuume gauge from aliexpress

turned up an adapter to connect to the bleed port in the IFP.

 
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