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Stock spring is too stiff for you. My son and I both tip the scales at 170# as well. I found that the 09-12 zx6 spring at 9.2 kg/mm allowed me to set both sags correctly. I'm starting with 35mm on my sons and 30mm on my bike. I did not count threads but spent a couple of hours measuring and adjusting. I'm starting with just two turns of compression and zero turns of rebound on both. You can find the zx6 shock on Ebay super cheap too like the GSXR stuff. I hope this helps.
 

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This is pretty awesome.
Have a 600 shock on the way..for the price why wouldn't you?
 

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Compression damping: High-speed: 2.75 turns out; Low-speed: 1.75 turns out (I turned both all the way clockwise in, then came out or counter clockwise to the turns indicated)
Rebound damping, lower adjustment: 2.5 turns out, and turned it all the way soft and then came out 2.5 turns

6mm of thread showing up top, this is probably way low, but it felt good to me, I might move it down some and expose some more thread, seems it was at 10 probably before......but with sons help should get proper sag numbers
Ok, so for anyone who did this mod, did you set up the GSX-R shock with it's recommended OEM settings for rebound and compression and adjust it from there? Or did you zero everything out and start from scratch.

I'm trying to get an idea of where to start as I currently have everything set to OEM settings except for the preload which has 4-5 threads showing because it was way too stiff. (Trying to get some helpful t tips for a 170lbs/77kgs weight guy)
Way back on page 3 you can find my settings, whenever you set a shock/fork you zero it and then count the turns out......you can see all that in my post.

This is what worked for me, and might make a good starting point for you, or a good reset back to if you get it to far out of wack.
I know my sag needs to be more, but I like it and prefer it where it is.........I know Dave Moss would say otherwise and probably prove it on the track when I shave 2-3 seconds off my lap times with the setting he says :)
 

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Way back on page 3 you can find my settings, whenever you set a shock/fork you zero it and then count the turns out......you can see all that in my post.

This is what worked for me, and might make a good starting point for you, or a good reset back to if you get it to far out of wack.
I know my sag needs to be more, but I like it and prefer it where it is.........I know Dave Moss would say otherwise and probably prove it on the track when I shave 2-3 seconds off my lap times with the setting he says :)
After watching hours and hours of Dave Moss videos this week, I think he would say the best settings are the ones that make you happy and fast. But he has a great way of getting to a good starting point.
 

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I do not use stock settings since they are for a different bike with different geometry, spring and for an unknown riding situation. I first find my total available turns by turning each adjustment all the way in and count out. I also write on the shock total turns per adjustment for reference then log all settings in an excel file per track event. I mean "all" settings: temp, sunny, humidity, track temp, tire pressure cold, tire pressure fresh off the track, tire temps............ you get the picture. If you run out of adjustment then it may be time to upgrade with a RT shock kit or a name brand shock. I have a date this weekend with my local track if it happens (COVID rules) and will continue to update my findings with these shocks, so far I'm happy with the performance and really like the lack of $ spent.
 

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Update, I got six sessions in on the the "A" bike and have fine tuned the shock for Heartland Park Topeka. If you have not been there before it is a relatively smooth track with a drag strip on the front straight and good combination of fast sweepers and 2nd/3rd gear corners. I did get the Ohlins cartridges installed on the front so I was dialing in both ends of the bike but after the 2nd session I only had to adjust the rear one more time on rebound. High and low speed compression were close from the first outing. I think the only thing to complain about is the lack of ride height adjustment. Suzuki took care of that function with how it attached to the upper shock mount, I or we will have to fabricate / purchase adjustable or fixed shock mounts to get the desired geometry which is going to be more than the 12.2* I currently have. I think I am done with this portion of the shock swap and will update when the shock oil wears out and has to be rebuilt, then I'll post back here on which direction I go with rebuilding it.

Keep the rubber side down!
 

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Latest update for any of you wishing to save some $ and upgrade the rear shock inexpensively. The GSXR shock works fantastic, we had perfect weather yesterday for Fathers Day at the track ( my 81 year old dad even came and took a few pictures ). I made two sessions on my son's bike and made just one rebound change to the rear. ( this bike is set up a little softer due to his weight being less and nearly no track experience). I made 5 sessions on my bike and made only one change rebound on it as well and a couple of changes to the front end. Both bikes have springs off of a ZX-6 (9.2 kg/mm for a 160-175# rider) so a grand total of $60 ($30 or less for 4 shocks off of Ebay) spent for each bike to have a shock that is 3 way adjustable, rebuildable, finite preload capability but is lacking ride height adjustment. As mentioned much early in the post the stock upper shock mounts can me modified and flipped to get the ride height real close to a race set up. (so afraid to type the word " geom****" I don't want to wake up SDSS). Anyway I will be spending some time soon making new shock mounts to raise the ride height a bit more.

I managed to keep the rubber side down but did get a "finger pointing" for passing too aggressively ooops, anyway lots of smiles inside of my helmet again from the N4. REALLY enjoying the flickability of these bikes, so easy to ride and just go where they are pointed with no surprises.
 

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Great stuff, thank you all. Gixxer shock and Nortons adapter kit on the way! Some good info and recommended initial settings on Nortons page as well..
 

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Loving my rear GSXR shock, finally had it adjusted at the track by the suspension guru and it was almost spot on. He didn’t have to do much. My friends 400 with the GSXR shock was way too stiff, so he of course softened it up. The Norton adjuster kit looks very sexy and the price ain’t too bad!
 

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A giant THANK YOU to Scook, bOXcrash, Kiwi, yarddog, and everyone else who has done all the work to figure out this swap.

After reading the entire thread a couple of times I bought the Norton kit, and in the name of science I ordered three shocks from ebay. (I’m still amazed how cheap they are!) The first shock was listed as being from a 2017 GSXR 750 with 2,400 miles on it. I also picked up one that I’m told was a new take-off from a race team’s 2018 600, and another from a 2011-2016 GSXR 1000 that was supposed to have been ridden 1,400 miles. They all look pretty clean, and they all seem to have about the same nitrogen pressure judging from the amount of force it takes to compress them with the springs removed.
14469


In the photo above the 600 is on the left, followed by the 750 and the thou. As you can see from the picture, the 750 has five free coils compared to four on the 600 and a few degrees less than four coils on the 1000. I’ve noticed that some of the other 750 shocks on ebay have five coils, while some have four, which is what all of the 600s and ’09 -16 1000s seem to have.

If I have my information correct, this same shock came on the ’09 through 16 GSXR 1000, with a yellow spring used in the first few years and with a black one beginning in 2012.

I took all three springs plus the original Ninja spring to a local suspension shop and here is what the spring rates were:

N400 - 96 N/mm - 548 lb/in
600 - 101 N/mm - 577 lb/in
750 - 91 N/mm - 520 lb/in
1000 - 105 N/mm - 600 lb/in

Looks like the original spring tested pretty close to the 94 N/mm that it is supposed to be, which is probably way within its production tolerances. No way of knowing when the spring tester was last calibrated. I’m guessing just before it was placed in the box at the factory 20 years ago... ;)

Not surprising that the 750 spring was so soft considering its extra coil, but I do wonder why they would spec it so much different than the other two, assuming it’s the original. It does look like a good option for someone who needs a lighter spring. All the other dimensions of the springs were the same except that the 750 spring wire was 0.44” thick while the other two were 0.48”. All measured with the powder coating intact.
The free length was pretty close to 193 mm on all three.

I flipped the upper mount and installed the Norton ECU tray support kit. It came with spacer washers for the bottom end of the shock, and I also spaced out the linkage so it wouldn’t rub, just like you guys mentioned.

Since I had the springs removed I put one of the shocks in place and compressed the rear suspension. I had about 10mm less travel than when I tried it with the original shock.

With the shock and spring installed the rear unweighted height is 21mm higher than stock.

I really appreciate all the information you guys have shared to make this swap possible. I never would have guessed that I could have a three (four?) way adjustable shock that worked this well for 24 dollars!

I’ll try to post a review of of the shock, and how it works with my revalved forks before long.
 

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A giant THANK YOU to Scook, bOXcrash, Kiwi, yarddog, and everyone else who has done all the work to figure out this swap.

After reading the entire thread a couple of times I bought the Norton kit, and in the name of science I ordered three shocks from ebay. (I’m still amazed how cheap they are!) The first shock was listed as being from a 2017 GSXR 750 with 2,400 miles on it. I also picked up one that I’m told was a new take-off from a race team’s 2018 600, and another from a 2011-2016 GSXR 1000 that was supposed to have been ridden 1,400 miles. They all look pretty clean, and they all seem to have about the same nitrogen pressure judging from the amount of force it takes to compress them with the springs removed.
View attachment 14469

In the photo above the 600 is on the left, followed by the 750 and the thou. As you can see from the picture, the 750 has five free coils compared to four on the 600 and a few degrees less than four coils on the 1000. I’ve noticed that some of the other 750 shocks on ebay have five coils, while some have four, which is what all of the 600s and ’09 -16 1000s seem to have.

If I have my information correct, this same shock came on the ’09 through 16 GSXR 1000, with a yellow spring used in the first few years and with a black one beginning in 2012.

I took all three springs plus the original Ninja spring to a local suspension shop and here is what the spring rates were:

N400 - 96 N/mm - 548 lb/in
600 - 101 N/mm - 577 lb/in
750 - 91 N/mm - 520 lb/in
1000 - 105 N/mm - 600 lb/in

Looks like the original spring tested pretty close to the 94 N/mm that it is supposed to be, which is probably way within its production tolerances. No way of knowing when the spring tester was last calibrated. I’m guessing just before it was placed in the box at the factory 20 years ago... ;)

Not surprising that the 750 spring was so soft considering its extra coil, but I do wonder why they would spec it so much different than the other two, assuming it’s the original. It does look like a good option for someone who needs a lighter spring. All the other dimensions of the springs were the same except that the 750 spring wire was 0.44” thick while the other two were 0.48”. All measured with the powder coating intact.
The free length was pretty close to 193 mm on all three.

I flipped the upper mount and installed the Norton ECU tray support kit. It came with spacer washers for the bottom end of the shock, and I also spaced out the linkage so it wouldn’t rub, just like you guys mentioned.

Since I had the springs removed I put one of the shocks in place and compressed the rear suspension. I had about 10mm less travel than when I tried it with the original shock.

With the shock and spring installed the rear unweighted height is 21mm higher than stock.

I really appreciate all the information you guys have shared to make this swap possible. I never would have guessed that I could have a three (four?) way adjustable shock that worked this well for 24 dollars!

I’ll try to post a review of of the shock, and how it works with my revalved forks before long.
Good solid info there bud. Thanks for posting this. The stock shock was too stiff (and crude) for myself at 130lbs. My rear end was kicking off every square bump in the road. I'm running a 80 N/mm spring in my K tech with better results.
 

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Huh - interesting info on the 750 shock spring. I had read in multiple places it was stiffer than the 600 shock spring, which made sense to me.

I have to say, with 2 Track Day Schools down, on a bumpy track, that the 600 shock has been awesome. I am right smack in the weight range for the stock 600 spring according to Jesse's chart, and this thing has been so good, it is forgettable, since the suspension doesn't worry me, and I only get good solid feedback, no bouncing, hopping, skipping, or extra squatting with power application. :D Best $45 shock upgrade evah!
 

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I've been doing a bunch of online research. Looking up part numbers, eBay auctions/pics, etc. It looks like all of the '11-'19 GSXR 600/750s and the '09-'16 GSXR 1000 use the same shock housing, so they will probably all fit in the 400 and be able to swap springs. The '17-'19 1000 is mostly the same, but has the reservoir angled upward, which could hit the underside of the battery tray. It also comes in a Race model, which has a shock that looks quite different and costs a lot more.

There are multiple shock part numbers used throughout the run of each model. It looks like the 600 may have kept the same spring rate the whole time, but the 750/1000 both had multiple spring rates. The 600 is a little bit stiffer than stock. The newer 750 (with the 5-coil spring) is softer than stock. The older 750 and the 1000 are stiffer than the 600, in varying amounts.

I'm trying to fill in the last few gaps, then I'll post a new chart similar to the one before.
 
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ok, I'm jumping in for my first non-cosmetic mod so I have a 2014 GSXR 600 shock from ebay ($50) and the Norton kit on the way. Dallas roads suck and I am 5'7" 165..will the stock 600 springs be ok for mostly commuting or should I look for softer? (BTW, thanks to you all for sweating out the details these last couple of years..)
 

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ok, I'm jumping in for my first non-cosmetic mod so I have a 2014 GSXR 600 shock from ebay ($50) and the Norton kit on the way. Dallas roads suck and I am 5'7" 165..will the stock 600 springs be ok for mostly commuting or should I look for softer? (BTW, thanks to you all for sweating out the details these last couple of years..)
I'd say too stiff for 165lb but bang it on and try it first, nothing to lose. Getting someone to measure your rider sag while your sitting on the bike (with your helmet and gear on) is useful.
 

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I'd say too stiff for 165lb but bang it on and try it first, nothing to lose. Getting someone to measure your rider sag while your sitting on the bike (with your helmet and gear on) is useful.
I agree, too stiff but not much different from stock so give it a try and see how it feels.
 
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