Rear shock alternatives; How to install R1 Shock w/pic

bigborer

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If I found a spring of the same length and diameter (but correct rate for my weight), the R1 preload adjustment should work perfectly- is this correct?

And is the R1 shock gas chargeable or does it need a valve retrofitted?
 

bigborer

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One more thing:

What about the cbr 600 f4i rear shock? According to what I've found online it has a 14.2 kg/mm spring rate (perfect for rider of 80-90 kg), and it's around 12" eye to eye long.

I'll search for a used one, as it seems a great option. No new springs, no spacers. It should just need a valve for recharging and a basic rebuild.
 

Motogiro

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I was just admiring the amount of dedicated documentation that is so informative.

Thank you for more great tech porn! Lol!
 

bigborer

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One more thing:

What about the cbr 600 f4i rear shock? According to what I've found online it has a 14.2 kg/mm spring rate (perfect for rider of 80-90 kg), and it's around 12" eye to eye long.

I'll search for a used one, as it seems a great option. No new springs, no spacers. It should just need a valve for recharging and a basic rebuild.

Here is the only documentation I could find of the f4i shock on the fz6:
https://www.sportbikes.net/forums/fz6-fz6r/298481-rear-shock-mod-long-term-test.html

I've spoken to a local parts guy and will try to meet him this week. If I'm lucky he'll also have an FZ6 shock and swing arm I could measure (reducing any downtime on my bike).

I'll try to file down the inside corners of the f4i shock nearing the swing arm (going around the rebound screw), as this should reduce the amount of filing need to be done on the swing arm.

Either way, I'm quite confident that resistance shouldn't be an issue. The maximum payload for 600cc bikes is around 180 kgs, and they leave at least some 20-30% margin; I'll never load this bike more than 160kg so even if removing a bit of material will eat through the safety margin, it'll still be on safe side.
 

itsx

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Here is the only documentation I could find of the f4i shock on the fz6:
https://www.sportbikes.net/forums/fz6-fz6r/298481-rear-shock-mod-long-term-test.html

I've spoken to a local parts guy and will try to meet him this week. If I'm lucky he'll also have an FZ6 shock and swing arm I could measure (reducing any downtime on my bike).

I'll try to file down the inside corners of the f4i shock nearing the swing arm (going around the rebound screw), as this should reduce the amount of filing need to be done on the swing arm.

Either way, I'm quite confident that resistance shouldn't be an issue. The maximum payload for 600cc bikes is around 180 kgs, and they leave at least some 20-30% margin; I'll never load this bike more than 160kg so even if removing a bit of material will eat through the safety margin, it'll still be on safe side.

I'm super interested and curious with your mod. I saw your post in the wilber shock thread too. I'm in a similar boat, planning on doing the r6 front fork swap, and the my rear shock is going to be on my list of things to be done as well.
 

bigborer

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I've now ridder over 1500km with this mod.

Overall I'd say that it's worth it, and a major improvement over the stock one, however I've found it VERY sensitive to adjustments, and it took some time to find the right balance (almost crashed at first).

Important warning: I do not recommend this mod for the street for riders under 80kgs.

There is quite a bit to say about it- I've already drafted some of it- can't promise you anything but I'll try to finish it this weekend.
 

DeepBarney

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I've now ridder over 1500km with this mod.

Overall I'd say that it's worth it, and a major improvement over the stock one, however I've found it VERY sensitive to adjustments, and it took some time to find the right balance (almost crashed at first).

Important warning: I do not recommend this mod for the street for riders under 80kgs.

There is quite a bit to say about it- I've already drafted some of it- can't promise you anything but I'll try to finish it this weekend.
My stock rear is absolutely roached (guess a 104k miles will do that) and needs a replacement. Since it needs replaced and a used F4i shock is about the same or less than any used FZ6 shocks I'm finding (on eBay at least), I'll be considering this. Notching the lower shock mount would be pretty easy with a bandsaw. Since I got this bike as a budget foray into sport touring I don't really want to throw much money at it in the event I turn around and sell off the bike after the first big trip. I also won't be riding super aggressively, my skill level just isn't there. Because of that I'm not going to R6 swap the front, just rebuild the forks and go with heavier oil (maybe play with oil levels too). So with that in mind would you recommend making this upgrade or would I be served as well by a good condition stock shock since I'm not really upgrading the front?
 

Gary in NJ

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Regarding the fork, heavier oil will help with the slow speed nose dive, but it will make the forks very harsh on faster bumps. Oil height mostly effects rebound damping.
 

DeepBarney

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The stock fork springs are the closest to the correct rate for my weight. In fact all aftermarket springs are higher than what I should need at my weight. And in searching on here it seems some have had good luck in going to 10 or 15 weight oil (depending on their weight and the springs used). Oil is, comparatively, cheap and I'll need new oil anyways when I replace the seals and bushes, so I figure that's where I should focus my efforts in regards to the front. Not trying to make it handle great, just good enough for my needs which admittedly aren't very demanding.
 

bigborer

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If you can live with the stock front end then it'd be easier to just get a "new" FZ6 OEM rear shock. To fit the f4i shock it takes a bit more work than just shaving the shock's mounts on a band saw. It also needs some shaving off the lower swingarm bracket, spacers for the top mount (it's thinner) and another bolt (different ID). AND you need to be +80kg. Which you probably aren't, as you mentioned that the stock spring rate is correct for you.

Better suspension isn't just for aggressive riding- proper suspension will benefit even a commuter. The thing with damper rod suspension is that all it does is pass oil through some holes in a metal rod, so no matter what you do to it, it's still shit, because as Gary explained, what will improve the low speed behavior will equally affect the high speed behavior, and vice versa. And if you're wandering- "progressive" springs won't do much either.
Cheapest route would be cartridge emulators (around 100 USD) + mounting the forks a few mm lower.
 

DeepBarney

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If you can live with the stock front end then it'd be easier to just get a "new" FZ6 OEM rear shock. To fit the f4i shock it takes a bit more work than just shaving the shock's mounts on a band saw. It also needs some shaving off the lower swingarm bracket, spacers for the top mount (it's thinner) and another bolt (different ID). AND you need to be +80kg. Which you probably aren't, as you mentioned that the stock spring rate is correct for you.

Better suspension isn't just for aggressive riding- proper suspension will benefit even a commuter. The thing with damper rod suspension is that all it does is pass oil through some holes in a metal rod, so no matter what you do to it, it's still shit, because as Gary explained, what will improve the low speed behavior will equally affect the high speed behavior, and vice versa. And if you're wandering- "progressive" springs won't do much either.
Cheapest route would be cartridge emulators (around 100 USD) + mounting the forks a few mm lower.
Thanks for the feedback. All of those modifications are all something I can handle, I'm decently set up tool/fabrication wise and have easy access to bigger machining equipment when needed. I'm familiar with damper rod suspension operation, I think all but one bike has had it. My Bonneville has it and after altering oil weight and height I've made it much more compliant (I might have drilled out some of the holes in the damper rod on that bike, can't remember for sure though). Geared up I'm close to 77kg and am hoping to get that number back down closer to 70kg. So that spring is going to be on the firm side, which won't help the situation up front. Guess I'll stick with a stock shock. Thanks again.
 

Aggromuffin

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Hey OP! First off, thank you so much for the detailed write up and pictures. This is my next project as I bought an 05 with 34k miles on it and the rear spring doesn't look all that hot lol.

I may have missed it but did your suspension guy every share his details? I live in a small town and I'm concerned that the shops here won't have the experience necessary to do this without some guidance.
 
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