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General Category => Modifications => Topic started by: Broggy92 on October 11, 2016, 08:47:25 AM

Title: Twinshock
Post by: Broggy92 on October 11, 2016, 08:47:25 AM
Just out of curiosity has anyone ever converted an FJ1200 frame from monoshock to a twinshock?

If so was it difficult, and which swingarm did you replace the FJ one with (a XJR perhaps)?
Title: Re: Twinshock
Post by: fj1289 on October 11, 2016, 09:10:47 AM
Quote from: Broggy92 on October 11, 2016, 08:47:25 AM
Just out of curiosity has anyone ever converted an FJ1200 frame from monoshock to a twinshock?

If so was it difficult, and which swingarm did you replace the FJ one with (a XJR perhaps)?

1. Why!?

2. The rear subframe is bolted in place on the FJ - I would think you'd want the upper shock mount to be to a welded part of the frame structure
Title: Re: Twinshock
Post by: Broggy92 on October 11, 2016, 09:31:32 AM
Mainly out of curiosity, but as a big guy (6'5 and 21st+) I find the monoshock is pushed especially when carrying a pillion, a twinshock would give that bit more support.

And also I have a spare frame and thought I might give it a try but thought I'd test the water first before cutting and welding a sound frame.
Title: Re: Twinshock
Post by: JPaganel on October 11, 2016, 09:35:55 AM
Quote from: Broggy92 on October 11, 2016, 09:31:32 AM
Mainly out of curiosity, but as a big guy (6'5 and 21st+) I find the monoshock is pushed especially when carrying a pillion, a twinshock would give that bit more support.

Maybe you just need a better shock?

FJ stock shocks are no great shakes, and pretty old by now.
Title: Re: Twinshock
Post by: Broggy92 on October 11, 2016, 10:12:27 AM
I currently have a Hagon shock with uprated spring in and it is always bottoming out, this is made even worse when carrying a pillion.
Title: Re: Twinshock
Post by: fj1289 on October 11, 2016, 10:25:37 AM
I'd suggest going to a heavier spring - I don't know how much rebound the Hagon has, but I bet it will handle the added spring rate fairly well.  May need to take it to a shock specialist to get the heavier spring installed without garage heroics/antics!
Title: Re: Twinshock
Post by: aviationfred on October 11, 2016, 11:40:07 AM
My thoughts are with the cost involved with sourcing the XJR parts, swing arm, shocks, wheel, brake caliper and such. Plus factor in the trial and error of stuffing up a swing arm and needing to get a second one.

RPM has a FJ purpose built shock. It can be had with a spring rated for single rider up to 275lbs/19.64 stone, or a stiffer spring rated for dual rider with weights greater than 275lbs/19.64 stone.

I personally have had this shock on my '89 for 2 years now and have absolutely no complaints. I regularly tour solo with fully loaded hard luggage. I also do 200-300 mile day rides with a pillion. I am sure I regularly exceed the 275lbs that the shock is recommended for. I have the spring preload adjusted to my liking and I rarely have the shock bottom out on me.

IMO the RPM shock performance and value far exceeds the cost and time of attempting a dual shock conversion.

http://rpmracingca.com/proddetail.asp?prod=M%2FC%3ARPMShock%2891-95%29 (http://rpmracingca.com/proddetail.asp?prod=M%2FC%3ARPMShock%2891-95%29)

Fred
Title: Re: Twinshock
Post by: racerrad8 on October 11, 2016, 12:55:37 PM
The problem would be the sub-frame more than the swing arm. The tubular subframe on the FJ is not made to support anything but rider weight. You would have to fab up some structural frame to be able to support the suspension load.

Randy - RPM