CBR600RR shock without airbox clearance issues

[JJ_08]

Progress has been slow on this project (I've only been able to find a couple hours here and there on weekends to work on it), but I wanted to report back.

I recieved a used '05 CBR600RR shock in the mail a few weeks ago.  I proceeded to tear it down, clean it up, and then sawed the thing in half, which felt very, very wrong: 

I fitted up some plates to block off the ports, and welded them up:

Drilled, tapped and fitted -4AN to 1/8 NPT fittings:

Reassembled, filled, and pumped it up to 150 PSI.  After a week, I discovered it had lost about 5 PSI.  I noticed a small spot on one of my weld beads where the fresh paint was missing, and realized that oil was leaking out of a tiny, tiny pinhole.

I suspect I had some porosity in my weld bead that was allowing a miniscule leak.  It was probably from not cleaning the shock well enough before welding (...in combination with running out of argon on a Sunday afternoon and being stubborn about continuing to weld on the last few fumes in the tank...).

Word of advice to anyone trying this in the future: make sure you grind the black powercoating on the shock well away from the area you're welding, including the area inside the port.  I think this might screwed me up (along with running low on argon...).

Anyway, I tore the whole darn thing apart again last weekend, cleaned it all up again, and rewelded...  It's been 5 days so far and it looks like I'm still sitting steady at 150 PSI!  Hoping to get it all back together soon and take it out for a test ride!

Edited January 27, 2023 by JJ_08

[JJ_08]

Got the shock back together today - still holding steady at 150PSI!  (I'm planning on bleeding it down to 120PSI before riding it, per the experience of @shinyribs)

.

Unfortunately, when I went to install it, I found interference between the clevis and shock linkage.  The OEM shock has about 30mm of clearance between the centerline of the bolt and the inside of the clevis, but the 600RR shock only has 25mm of clearance, so the inside corner of the clevis hits the linkage. 

I was thinking of grinding some relief into the clevis, but I'm worried about how much metal is there before I hit the rebound adjuster.

Has anyone else who's installed a 600RR shock run into this issue?  Am I doing something wrong?

[JJ_08]

I ended up shaving down the 600RR clevis to create clearance from the linkage.  I did it the low-tech way, by hand, with mill files - which went surprisingly quickly.

I also machined some spacers for both ends of the shock and superglued them to shock to make assembly easier.  (Especially important on the eye end of the shock, as the 600RR shock is narrower than the stock shock, and as others have pointed out, you will damage the engine cases if you torque down the RR shock without spacers.)

Anyway, after all of that work, I got the shock installed, but found that the clearance between the clevis and the linkage is extremely tight.  The hose fitting on the opposite end of the shock is also uncomfortably close to the engine case.  (For anyone attempting this in the future, I recommend carefully choosing the location for the hose fitting to make sure it clears the engine case.)

I wasn't comfortable with how tight the clearances are, and since I wasn't able to confirm clerances through the full range of motion, I'm worried that something could bind or have interference at certain points of travel...

So after all of this, I've decided to shelve the project for now.  At some point in the future, I might try griding away more of the clevis to increase clearance, and relocate the hose fitting.

For now, my conclusion and advice to others is:  buy either a 2018+ shock (budget option), or save up your money and get an aftermarket shock (Ohlins, K-Tech, YSS, etc). 

Between the used 600RR shock, hose fittings, and welding consumables, I'm probably about $50 into this project.  (If you have to pay for machining and welding, that will obviously increase your cost.)  It's been a fun project and I don't regret it -- but if you just want better suspension and don't care about having a project, I think the smart thing to do is to invest the $50-100 you'd spend on adapting a 600RR shock into buying a purpose-built shock for the FZ/MT.

I'll probably return to this project at some point in the future, but for now, I admit defeat! 

[AP996]

54 minutes ago, JJ_08 said:

I wasn't comfortable with how tight the clearances are, and since I wasn't able to confirm clerances through the full range of motion, I'm worried that something could bind or have interference at certain points of travel...

If you install the shock without the spring (with the bike supported in some way) it should make it easier to work through the full range of movement and check clearance of the hose and Clevis.