Honda F4i shock

[movenon]

Hank,
Great info on the bearings.  I replaced all of mine in the shock linkage/swingarm (92) this winter.  "the relay arm end that bolts to the FJ frame" were the very bad (powdered rust and needles fell out) and the bushing had to be replaced as well.

Bearings from Yamaha were over $70.00 for this exercise.

Thanks,

Jeff

Yes those are the ones...... It requires a bit more labor to get them out. That's why they do not get serviced as they should. They are small cheap bearings. My bearing shaft also had a little marking due to the rusted bearings but still serviceable.  The aftermarket bearings are better in my opinion. And fill that sob with good grease.

On the F4i shock top bearing that I got. I had to open the shock eye a up little to press in the bearing (with a vise). About a  .5 mm
difference. I took a 3/4 wood dowel and wrapped a sheet of emery cloth around it and clearenced
it as required. The eye is Al. And "machines" easily. Take a little and test fit , took 15 min. I didn't want to force to hard.

George

[jscgdunn]

Thx George,
We are planning on getting down to Idaho this summer so maybe we can connect.  Last year we got to Cour de lane.  My son and I and found a great ride around Hayden Lake.


Jeff

[movenon]

Yes it is beautiful country up there.. Down here it is high desert at the base of the mountains. Are you going to the WCR ? Looks like there might be 4 of us linking up in route so far. The bike needs some minor mechanical attention but it will just have to wait until later in the summer. Where in Idaho were you planning to visit or go thorough in route ?

[jscgdunn]

WCR is pretty far for this year so I do not think we can make it. 

Probably back to Cour de lane via Kalispel/Glacier (the pic shown is at Glacier last year).  Great ride between Kalispel via Libby to Sandpoint.  Then to Cour de lane and maybe further south.

Jeff

[stua1959]

Ok, I have finally finished the Honda shock conversion on my 91 FJ thanks to the advice from members of this forum. I had some difficulty getting someone to weld the clevis onto the shock so I ended up doing it myself with the old stick welder. I  wrapped the shock in wet towelling and only welded a small section before letting it cool down. I made the clevis out of 6mm angle welded together to form the U shape as the original clevis was destroyed. I also formed a 6 mm thick half moon shape to go between the honda shock and clevis to add extra strength

The top mounting point was easy. I needed a bush with an inside diameter of 12mm for the original mounting bolt and an outside diameter of 16mm for the Honda shock bearing. As I had just replaced the suspension linkage bushes I had plenty of this size. I had my local friendly engineer cut a 40 mm length to fit the Yamaha mounting. As the Honda mount is about 38mm wide, I used a couple of stainless washers to stop any sideways movement.
The gas reservoir has been zip tied to the swingarm for the time being until I come up with a better solution

Because of my home made clevis and the extra length of the shock I had to make up some dogbones 25mm longer than standard. I used cold rolled steel 6mm thick, 40 mm wide. Should be strong enough
The rear wheel now sits about 20mm off the ground when on the centre stand but the stand cannot fold right up due to the extra length of the dogbones. I will leave it off and just use it as a work stand. The sidestand is fine and will not need to be lengthened.

This has been an interesting exercise but I wont be able to test the results until I get the bike finished and back on the road. I have returned the shock to the original Honda settings and my first impressions are that it is fairly soft initially and then hardens up. The rebound also seems a little slow. I am hoping that I didnt destroy a seal with the heat from my amateur welding or that the extra length of the linkage is not suited to the stroke of the shock

[ribbert]

25mm in the dogbones is a lot. If it was me I would make doubly sure that all the linkages worked as they should. In general terms linkages like that are designed to work in a certain arc and if you exceed that the leverage effect changes, particularly at the end of it's travel. In extreme cases they can even go over centre or exert and excessive load on the mounting points. I have seen this happen.

Not wishing to be a wet blanket on your mods or suggest that your bike is dangerous but there appears to have been sufficient change to some very short linkages to warrant caution. All is probably well but given the importance of it's operation and the consequences of a failure I would err on the safe side and check it before riding.

And, this comes from someone well known to have a cavalier attitude towards safety.

Noel

[stua1959]

Thanks Noel. I appreciate what u are saying. I will check everything and take it easy until I am sure of what is going on. Like I said. this is an exercise and if it doesnt work I will go back to a standard shock or if  I can afford it, a RPM shock

[movenon]

Good work ! 

The first set of bones I built, with my 1990 FJ on the center stand and rear tire was just about on the floor, they gave me a low riding position. Lower than stock. I wanted to raise the rear up. When talking dog bone length the shock length (mine 13" c -c ) and rear tire ( mine is 180/55/17 ) effects the dog bone length.

So I made another set of bones (center to center hole spacing 4 7/8 ", approx 123mm). Now while parked on the side stand the rear is about the same height as the old FJ was on the center stand. On the center stand with a 1 1/2 (38mm) broad under it,  the rear wheel has 3/4" (19.05mm) clearance from the floor.

For now that's where I am going to leave it, I wanted to raise the rear up. I estimate that it is up about 1.5 " (39.37mm) over the stock rear ride height. I built a 3/4 " (19.05mm) shoe to go under my kick stand and now it sits like a stock FJ as far as the lean angle go's on the side stand.

The center stand will have to be modified or removed before riding. Work in progress...

I like the work you did on the clevis. It looks  stronger than what I did.

I set my preload at "3" (mid position) and the first time I sat it down to do a sag measurement I found it had to much sag. I now have the preload set at 6 and the sag is still a little more than I would like but probably acceptable. Yet to be determined...  I have preliminarily adjusted the compression and rebound up firmer.  No real riding report yet.. I am still working on the bike.
My preliminary opinion is that the f4i shock probably has a rider max weight limit on the FJ of around 220 LB's. And that's where I am. And that is just an unfounded opinion...
The shock feels better than the stock shock but riding will tell the complete story. I am not there yet.

I ended up with my reservoir mounted in the same place as you. Eventually if the shock works out I would like to install a longer air line and mount it up where the old FJ adjuster went. Also I trimmed the front of the rear fender/splash guard giving more clearance for adjusting the preload on the shock.

Good point Noel on the arc and leverage. By eye ball and rough measurement it looks OK. BUT.... .  Arnie has been running this for a while along with a few others none have reported any safety problems (maybe there were no survivors  ).  Yet...     One instance of tearing up dog bones has been reported  but something was said about "bunny jumping"....

I guess if it doesn't work I to will be hanging around RPM's WEB site drooling for a new shock. 
George

[Dan Filetti]

WCR is pretty far for this year so I do not think we can make it. 

Probably back to Cour de lane via Kalispel/Glacier (the pic shown is at Glacier last year).  Great ride between Kalispel via Libby to Sandpoint.  Then to Cour de lane and maybe further south.

Jeff

Love that area on a bike!

Dan

[skymasteres]

So on the 89+ FJ's is the center to center measurement on the stock shock 12 or 13 inches? (I'm getting confused)
Or is the FJ 12" and the F4i 12". Or is it the other way around with the FJ at 13" and the F4i at 12" 

[movenon]

So on the 89+ FJ's is the center to center measurement on the stock shock 12 or 13 inches? (I'm getting confused)
Or is the FJ 12" and the F4i 12". Or is it the other way around with the FJ at 13" and the F4i at 12" 

Stock FJ shock ................=  285mm center to center

Stock unmodified F4i shock = 300mm (15mm longer) C to C

IF you modify an F4i shock for a 89+ bike you will end up with the F4i shock at about 13" C to C. (due to welding on a clevis to one end)
George

[Arnie]

Ribbert,

I finally caught up with the posts made while I was going to and from Bellingen.
My dogbones are 145mm C to C.  This gives me about 20 mm extra long dogbones which was necessary to correct the ride height change caused by the excess length of the F4i shock with the clevis added.
I now have over 18,000 kms on the bike set up like this and have had no handling problems I would attribute to the linkage being out of proper range.
I have had to remove the centerstand as it won't fully retract with this length dogbones.
Next time you're in the neighborhood, lets go for a ride, you can feel how it handles for yourself.

Arnie

[stua1959]

After riding around now for a couple of weeks I will give my impression of this mod.
The shock is set to standard and the spring is on the second hardest setting. I weigh 80 kg and rider sag is 65mm ( ideal is about 35 mm ) so the spring is way too soft. When I get around to setting the preload to its max I might get another 5 mm. Even with the excessive sag the bike still handles well, no wallowing or scary moments and it hasnt bottomed out even 2 up on a less than perfect back road. I have a favorite corner which I use to judge my suspension setup. It is an uphill sweeper that gradually tightens up before u hit a big mid corner dip. The fj wasnt upset at all and held its line well. Overall I am pretty pleased with this mod considering that it cost me bugger all and I didnt have much choice at the time if I wanted to stay within my budget. Until I can afford a better alternative this will do, although I am looking at the BMW shock mod thread to see how that pans out