Cbr rear shock

[great white]

So I've read a couple old posts about guys trying an f4i Shock on the FJ.

I can't figure for the life of me how they are getting them to fit.

When I eyeball an f4i (have a couple lying around) it seems the integrated reservoir needs to be inside the airbox space. A Cbr1000rr (have a couple here also) has the reservoir sticking out the back where the batter needs to be.

An older f2 (yep, have one of those too) has the remote reservoir, I can see how that could be made to work.

Anyone care to share a picture of the f4i mounted in an FJ?

I'm well aware of differences in spring rates and valving for an FJ vs the Hondas, just wondering about the physical mounting aspect....

[chiz]

Fitted a Honda shock; seem to think it was an F4 but don't know for sure. Was not difficult to do other some needle bearings that someone from this forum sent me,,, cant remember who; thanks.Shock  has a yellow spring but many do guess that don't help; don't think it has a reservoir to the best of my memory which you must realize by now is awfull.
 Will try to remember to check it out in the morning.
Chiz

  http://www.fjowners.com/index.php?topic=6549.msg60184#msg60184

[giantkiller]

My f4i shock has a remote reservoir. I mounted it to an aluminum bar attached to the battery box mounting bolt. First used plumbing pipe straps, and pipe insulation. Then I found some red anodized rubber lined aluminum clamps, from fleabay. Also 900lb eibach spring. Heaviest spring for stock valving. Works great I weigh 260ish.

[great white]

... don't think it has a reservoir to the best of my memory which you must realize by now is awfull.

LOL! no worries. I completely understand the memory not as good as it was!

[great white]

OK, I think I'm in on giving the CBR shock a try. I had my versions of the "F's" all mixed up with the "RR's".



But since it's already been done, I'm going to try a few twists on it to suit my uses a little better.

I'm going to start with an F3 shock, since it's shorter than the F4 shock:


(not my pic, from the interweb)

This will give me more room to play with length when machining a clevis type adapter to get it similar to the OEM shock. Similar to what J. Daugherty does with shocks:



I'm going to machine a clevis/fork arrangement vice mounting it upside-down and welding as seen on a few other threads here.

The F3 shock also offers a longer remote reservoir hose, so more options on where I can stuff it. The difference is more obvious in this pic:



F4 and F3 shocks are the middle ones. Again, not my pic, taken off the web. Lots of CBR shock pics out there, they're pretty widely modified since they are actually a half decent quality unit.....

For spring mount collars, I'm going to machine my own. This will let me try different springs from different shocks and manufacturers.

Loosing the OEM remote spring preload adjustment is a dissatisfier for me. So I'm going to take the remote preload adjuster off a ZG1400 shock I have lying around and see if that can be adapter to the F3 shock:



It's actually a hydraulic lift arrangement. The collar just slips over the shock body and is kept from rotating by a simple tab, turning the handle on the small body pushes fluid to the collar which extended and increases preload.

For springs I've got several lying around the shop which I'll try. If none are satisfactory, I'll just order up an Eibach spring. They're inexpensive and quality. Being able to make my own shock spring collars means getting what I need won't be a problem.

Once I get the spring sorted, I'll have to adjust the valving. But that is pretty far down the road. Have to get it mounted and sprung first.

[great white]

Just popped out to the garage quickly and the ZG adjuster is the exact size of the F3 shock body, so it slips right on.

Cool.

Just a matter of getting the right spring length to fit.

Be at least a couple days before I can start any machining work though...

[giantkiller]

I'll be interested to see how the f3 works for you.  With heavier spring. I'm going to use 92-93 r1 swingarms on the 1350 and the turbo bike. Slightly longer than stock and braced. Needs a shorter shock.

[great white]

Hmmm, I also have a couple RR shocks here:



These are universally accepted as better quality units than both the F3 and F4 shocks. I've been inside a couple and there's some really nice nice bits in there.

Problem with the FJ and using the RR seems to be the piggy back reservoir and it's positioning where cast. I quick eye-balled it in the approximate position on the FJ and it looks as if the reservoir ends up square int eh middle of the airbox or where the battery is.

But; if that reservoir were somehow "divorced" from the housing, it could be mounted anywhere.

So, since I've had a couple hanging around for years doing nothing but gathering dust, I'm going to try something radical: I'm going to cut the shock at the mount and tap it for a hose to divorce the reservoir from the body.

I have two options. Cut high:



Cut low:



The low looks more attractive from a reworking perspective. More "meat to work with for tapping a hose and lower on the body for clearance concerns in the FJ frame. It would divorce the compression valve as well, but hydraulics don't really care too much if it's right next to the shock body or at the end of a hose.

Like I mentioned, I've got a couple, I may cut up two of them to see what I've got to work with. It will also means two sets of valves, shims, seals, etc to mess around with. I can polish and port a valve and still have a stock one if I go too far. I can always use a greater selection of shims to "tune" with too.

The Eye-end/clevis arrangement is also the same as the FJ, so I may get lucky and have that fit with some small adjustments. Gotta get in there before I can know either way.

The RR is the length of the F4, but if that clevis works, it should be a minimal height change in the FJ. Most bikes can benefit from a little" raise in the rear end" for handling and the FJ I find a bit of a heavy slow steering bike anyways.

Since the F4 shock has already been done, I'm going to direct my efforts to the RR. Better shock, custom built and (for me) "0" dollar investment. Well, maybe a few bucks, but not much.

And if it turns out to be a bust, it's just more spare parts to chuck in the shock cabinet.

 

[jscgdunn]

 

We are watching.....

[great white]

So, the lower clevis of the RR will fit the FJ lower mount.

I measured and I have maybe a mm or two to shim, but that's about it. It even looks like the bolt hole is the correct size.

No idea on the upper yet as the bike hasn't been taken apart.

The reservoir is a deal killer though. It ends up right in the middle of the battery. You can't turn it around and mount it that way either: the reservoir "arm" would have to come up through the mount and even if you could it ends up right in the middle of the airbox.

The next step is to pull the shock apart and see about modifying that reservoir....if only the 600RR had needed the reservoir angled down instead of up, this would have been a cake walk!

[great white]

Alrighty.

First shock is a pile of parts on the bench.

The reservoir presents a bigger problem than expected. Since the top is cast, they cast the fluid passage in as well. What this means is its a large square hole from the compression damping adjuster to the shock body. Shutting that and tapping for a fitting is a no-go.

Alright, what about above the damper valve?

Nope, not enough meat to cut the reservoir off and tap. Not only that, it's not a drilled hole either. It's a slot.

That only leaves me with one possible option: cut the reservoir off between the valve and the main body, invert the reservoir (so it points down instead of up) and weld it back on.

It may work, it may not. The weld doesn't have to be structural, but it does have to be pressure tight. I'll have to get a shop to do that. My mig isn't set up for aluminum.

For the zig adjuster, it's close. It almost fits on the shock body. The od of the body measures 51.42 mm, the id of the collar measures 50.10

So I've got to shave 1.43 mm from the body, that's a .71 mm cut on the lathe. Doesn't sound like much, but the boss that needs to be machined is also threaded on it's ID to accept the billet shock tube.

There's no room to machine the adjuster collar ID as its only 2mm thick steel whee the hyd ram seals. So that's a no touch zone.

I need to sit down and think on that one a bit more. I'll likely machine the od before doing the reservoir work. No sense relocation the reservoir if I can't get the collar on.

If I break through machining the OD, then I may just relocate the res on the second shock and just have to deal with the adjuster being under the swingarm and probably hard to get to....

[great white]

Best laid plans...

Well, the RR shocks are essentially scrap to me so I just said "damn the torpedoes":





First thought is to just flip it over:



Nope, looks like it will either hit the battery or the battery box mount that comes off the upper shock mount. It's just not enough of a downward angle to clear. Cutting the leg to a steeper angle isn't going to work and it would get in to the compression valve area too much when welding.

Second thought:



Little better. Reservoir would be in the "dead space" behind the shock and above the swingarm. But interference again with the battery box bracket, possibly the battery itself and no reasonably accessible way to adjust  the compression damping valve. I'd also have to make up a filler block as the angled cut opens up toward the rear of that picture.

Maybe:



I'd have to make up an aluminum "V" block to fill the gap. But it would give decent access to the valve, reservoir is in the open space behind the shock. But may run into slight problems with that damned battery box bracket again.

Last option I can think of would be to weld both holes shut then drill and tap for a hose to remote mount the reservoir. That would be a messy looking option. That would be pretty "bodged" looking. That would bug the bejesus out of me, even if you wouldn't normally see it...

Turning into a bigger headache than I had wanted, but I'm in to it now so might as well see it through to either glorious success or tragic failure....

[red]

Great White,

Why cut the metal?  Why not remove the bolt to separate the shock from the reservoir, and bolt in a connecting hose between them?  It may take custom adapters at each of the hose ends, but it should look like a production job when finished, with no welding.
-

[great white]

Great White,

Why cut the metal?  Why not remove the bolt to separate the shock from the reservoir, and bolt in a connecting hose between them?  It may take custom adapters at each of the hose ends, but it should look like a production job when finished, with no welding.
-

Err, what?

What bolt? The reservoir is cast into the top of the shock body on the RR shock:



If you mean the gold thingy under the reservoir, that's not a bolt. That's the compression damping valve:

[simi_ed]

GW, how about welding a plate with a 1/4" or 3/8" fitting on both the shock body & reservoir?  Then run your braided line as needed between both. Or am I too far off point?