R6 shock on late model FJ

[racerrad8]

Tell us more Steve.
What year shock did you get and specifically, what will you have to do to make it work?

Kurt's '93 vs. your '89 (both with dog bone linkage) should be the same.

Pat, actually the shock mounting positions are different between the two models, so the dog bone length will be different.

Steve, did Kurt say he would post up for the rest of the forum members to be able to know how the conversion worked?

I'm sure there are many others interested with the application, modifications required and end result if the shock is a viable option.

I see Kurt had a thunderace swing arm, does that have any additional modifications required.

As Pat already requested more than five years ago and again this week, a full write up would be a benefit for members looking for other options.

Randy - RPM

[Pat Conlon]

Randy, question RE: Different shock mounting points on '89 vs. '93. I'm aware of the upper offset the '93 shock has, which matches the offset on the '93 lower relay arm. The '89/90's do not have this offset.

Is that the shock mount difference you were referring to, or are there more?
They both use an upper eye mount and a lower clevis, correct?
Sure, correct length dog bones need to be made, that's no biggie.

I think the bigger issue is:
In looking at the Race Tech specifications for the 2008-2015 YZF-R6 rear shock, it shows that the oem spring rate on that shock is 9.8 kg/mm.
Thinking about the lightest spring Penske recommends for the '89 FJ is a 1,000 lb spring which is 17.8 kg/mm spring.

My point is, I'll bet a jelly donut there in no way in hell the oem stock compression/rebound valves on the R6 shock will work on a 17.8 kg/mm spring.
It's too big of a jump to go from a light 9.8 kg/mm to a heavier 17.8 kg/mm spring without custom valves.

Add up the costs: 1) used R-6 shock 2) New spring and adjuster collar 3) custom valves 4) labor for shock 5) machine lower relay arm 6) upper/lower bearings
.....that should give you the true cost of this shock.

[Little Pink Steve]

Kurt did mention that he was happy with everything.

I did start looking at Fazer 1000 shocks, but then read that owners were upgrading to R6 units, so I thought why not.  Found one cheap, so won't lose out too much.

So far as I my build is concerned, it's a project that will take a couple of years to complete.  The R6 shock looks doable, will need to remove the battery box mount (relocating my battery anyway) and some work will be required to the lower clevis. I will do a write up once I'm happy with the fit.

I can't attest to any performance gains.  It may work out to be a waste of effort, but it's my first build and I'm really enjoying it.  I've got a non yam front end and swingarm fitted, not your usual wheels in.  Brakes all sorted, really big and beefy.

Worth noting my donor appears to have a Hagon fitted.  Not stripped it down yet as I'm building this thing on a spare frame.  Once I'm happy with the rolling chassis I'll transfer all the stuff in need over then get the stance right before modifying the bodywork.  I've got clip ons and straight bars fitted to keep my options open.

I'll start a build thread once I'm happy with what I've done.

At last count it has parts from at least 8 different bikes, which will no doubt increase

[Millietant]

Thanks for the update Steve - photo's of the bike's progress so far would be great 

I bought my Hagon shock about 9-10 years ago, but had done only about 4,000 miles on it when I parked the bike up at the end of 2009 (I think). When i brought my FJ back into service, the shock started to leak oil immediately, so I took it to the Hagon factory and they rebuilt it and re-set it to suit me & my bike (£100), while I waited at the cafe next door for a couple of hours. If you choose to use the Hagon you've got on the donor bike, it might be worth calling them to arrange something similar (better to be safe than sorry).

Oh, and mine was handed back with a full warranty for the next 2 years (the same as they give for new shocks) - very worthwhile in my mind. Great product (bearing in mind the cost), great service 

[Pat Conlon]

Kurt did mention that he was happy with everything.

Steve, did Kurt mention what spring rate he used?

Your build sounds bitchen! We hope you get some good pictures and details for us as you progress.

Cheers

Pat

[Little Pink Steve]

Quote for Kurt’s PM

“The R6 shock got no modification. I used the stock spring and valving. I have the Thunder Ace swingarm on my 93. The dog bones were shortened as I recall. The bottom shock mount needs some work, one was 20mm and the other was 27mm. I don't remember the details. it works on the 91-95 and 89-90 years I think it was plug and play on the 89-90. I was super happy with it. It made the front feel weak”

Everything like this is objective and will depend on a number of things including riding style and one’s perception.   I’m certainly not thinking in will be guaranteed right for me, however it’s cheap enough to try.  Sometimes you just have to try and draw your own conclusions. 

Honestly I doubt Im capable of riding to this shocks limits and the adjustability is more of a want than a need.  Would be very happy with a tried and tested Hagon, just like to be different.

I’m using an 09 shock and is NOT plug and play, but I don’t think it will be that difficult.  The battery box mount will need chopping off as it fowls the reservoir.  The clevis on the shock will need a little work also.

[Millietant]

Sounds like a great excuse to go for a tiny Lithium battery, instead of the huge brick we all use as standard 

[Little Pink Steve]

Quick update.

Had a little time on this this morning.  Don't see this as an easy or safe mod.  With the shock in the frame, top end, the bolt holes don't align.  Which means more metal off the mount or eyelet, neither of which I'm convinced are safe options. The lower clevis will need some work also as it has square shoulders that will need rounding off.

Plus there's the hassle of spring rates and valving to consider.

So sorry guys I'm calling it a day on this one.  I'll sell on my shock before I butcher it and use the Hagon from my donor bike. (Looks like a Hagon a least).