Oldheimer noob spring help - Suzuki GSX-R Motorcycle Forums Gixxer.com

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post #1 of 10 (permalink) Old 04-04-2019, 11:00 AM Thread Starter
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Oldheimer noob spring help

I don't have gixxer just shock on ex300. I'm 73 next month so please indulge a bit. 60+ yrs riding, raced RD400 in 70s, swapped Futura for EX due to need for lightness(getting weaker). EX has good stuff in fork and 2007 600 shock. It is stiffer than my boney arse likes. As I've done shock swaps on several other bikes in the past-my present ex250 has zx600 and sv650 a zx10.. I've surfed a lot seeking spring info but nothing answered my quest. Is there a softer spring from another year or model that will fit this shock? Thank you. Guzzijohn
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post #2 of 10 (permalink) Old 04-04-2019, 08:27 PM
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Re: Oldheimer noob spring help

Try the ninja forums.

Call a suspension shop like racetech...
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post #3 of 10 (permalink) Old 04-05-2019, 09:57 AM Thread Starter
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Re: Oldheimer noob spring help

I came here as you are Gixxer gurus and someone must have fiddled with the various stock bits over the years. I'll try the other gsxr forums too. With a lot of luck I might find a spring laying around as there is no $ for a new one. Thank you Mac.
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post #4 of 10 (permalink) Old 04-05-2019, 10:08 AM
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Re: Oldheimer noob spring help

You may need some more detailed info as it pertains to the specific shock swap you've done here. Remember, the rear shock works through a progressive linkage. Unlike the forks which the rate is going to be fairly consistently determined by your weight, the rear shock works differently. The spring that is on there is designed to work through the linkage of a 07 600. Not sure what the rising rate of the linkage on an EX 300 is by comparison.

I found this write-up that shows how to do the swap, but not really any technical details on setup beyond that point (not surprisingly).
https://www.ninjette.org/forums/showthread.php?t=170747

Where are you actually located? Rather than trying to build a Frankenbike flying blindly using random stock parts from different motorcycles perhaps try hitting up a local (if there is one) suspension tuner in your area to have him assess and setup the shock's adjustments (comp/reb/preload) for you and then determine what direction to go from there. I mean have you worked with someone to help get the suspension dialed-in at all.....it has adjustability built into it for a reason or did you just cobble together some parts and go ride it?
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post #5 of 10 (permalink) Old 04-05-2019, 05:57 PM Thread Starter
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Re: Oldheimer noob spring help

I'm just looking to see if anyone has ideas about a softer spring for this shock body. I know one could be ordered for hi $ but I can't do that. I have surfed widely for info but things like spring dimensions are hard to find. There is a suspension tuner who helped me w zx10 for sv so may visit him again-he's 50 mi from here. I am hooked to all Ninjette forums as well. Just trying all avenues. If I were a few decades younger the stiffness wouldn't bother as the 300 handles great w present setup. Thank you for replies.
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post #6 of 10 (permalink) Old 04-05-2019, 06:35 PM
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Re: Oldheimer noob spring help

First, you aren't giving us the right info.

You are asking for a softer spring because it rides to rough... for the most part, spring does NOT affect ride feel NEARLY as much as valving on a road bike in so much as to be considered negligible. Does the spring adjust properly for sag? What ARE your sag settings? What are your comp and rebound settings? Second, how do we know if it's the stock spring? What are the numbers on it?

Like SPL said, you are dealing with a frankenbike. Your first post was unclear both in content and in language. This is not a dig at you, but lack of info and lack of clarity nudged us to recommend a local suspension guy because you have a bike that has numerous aftermarket parts and settings that you have not specified.

Your linkage rate is different than a GSXR. You haven't given us info on sag, compression, or rebound, and you believe that the spring rate is making your suspension too hard. This tells us that you need to talk to someone in person, with the bike in front of you, and have the ability to converse back and forth.

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post #7 of 10 (permalink) Old 04-05-2019, 06:45 PM
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Re: Oldheimer noob spring help

Quote:
Originally Posted by guzzijohn View Post
I'm just looking to see if anyone has ideas about a softer spring for this shock body. I know one could be ordered for hi $ but I can't do that. I have surfed widely for info but things like spring dimensions are hard to find. There is a suspension tuner who helped me w zx10 for sv so may visit him again-he's 50 mi from here. I am hooked to all Ninjette forums as well. Just trying all avenues. If I were a few decades younger the stiffness wouldn't bother as the 300 handles great w present setup. Thank you for replies.
Well, 2 things. 1 you haven't mentioned whether or not you've done anything to try and adjust the shock as it sits currently. Have you tried turning out the preload and compression damping to soften the back end up to suit you riding needs.

2, you haven't mentioned how much you weigh.....in tandem with this you grafted a shock with a spring that generally suited towards a rider in the ~170-180 lbs range. BUT, you attached it to a bike that is around 50-60 lbs lighter in weight than the one its designed for. So coupling those 2 factors together is going to further complicate the issue of getting the correct rate shock spring into that bike.

A replacement shock spring from someplace like Racetech isn't exactly a high $ item. It's about 120 bucks....and you have the peace of mind in knowing that its the proper specs for the shock you are working with. Not to mention, do you know what the spring rate of an 07 GSXR-600 stock spring is (FYI it's 9.4 kg/mm and stock Ninja 300 spring is 9.3 kg/mm)? How are you going to know if the spring you are replacing it with is actually softer and not stiffer. Again, the particular linkage on the bike changes the relative rate of the spring that's being used.

To demonstrate this, on both my 07 600 and 05 1000 I essentially run the same .975 kg/mm fork spring rate in each. However, on the rear shock I run a 9.8 kg/mm spring on the 1000 and a 10.7 kg/mm on the 600.

Curious as to why you grafted a GSXR shock onto it in the first place as it sounds like you're not using the bike to push its performance limits and just want something cushy to cruise around on, I'm wondering if putting the stock shock back in place isn't a better route? If not I would look into getting the proper rate spring for your use case though based on your weight and your desire for a softer and more comfortable ride.

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post #8 of 10 (permalink) Old 04-06-2019, 01:23 PM Thread Starter
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Re: Oldheimer noob spring help

I have adjustments at minimum. I do weigh 235 wo gear. I still strafe apexes just a bit slower than years back. I do almost all back road riding. I did put racetech + emulators in front. Your spring numbers are interesting as the chart I see shows greater difference. The setup works great-just my butt complains a bit. I have gel pad + sheepskin to sit on. Perhaps I should build a new seat. I did that 2 yrs back for 250 and it is all day comfy. The stock setup was pogo stick soft so had to go. I was spoiled by how well the zx10 works on SV and had Wilbers on Futura. If your numbers are the real values then I'm in the ballpark for bike + rider weight. I did try a different gixxer shock 1st. Then put stock sv spring on it to try(was even stiffer). Now this is 2nd gixxer unit. Both from ebay. same configuration but not identical as 1st had disc w hole for nitrogen and blue adjuster ring around screw, 2nd has Schrader valve w red ring. It appears this unit was used for 4-6 yrs on 600/750 gixxers. I've found nothing on line showing any difference other than 600 having slightly heavier spring rate. As for frankenbikes my RD evolved (after a crash) to an xs500 fork, xz650 spoked al rims, 2 discs and RD250 rear brake. For trickness I added air valves to fork. I could hardly ride it stock as I'm 6'3". Using rear pegs TZ250 fairing and seat plus homemade clip-ons I sort of fit. W 5 yrs of trying got 1 2nd & 1 3rd. Not too bad racing rabid teenagers at 30.
Anyway thankyou very much for info. As the SV is really the Futura's replacement for longer rides and the 250 is tiddler and RV rack bike the 300 can be the backroad blaster for shot putts. GJ








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post #9 of 10 (permalink) Old 04-06-2019, 01:45 PM
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Re: Oldheimer noob spring help

@ 235 lbs without gear I definitely would NOT be considering going with a softer spring. In fact I'd be looking at a stiffer one and instead looking to adjust the shock's valving.
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post #10 of 10 (permalink) Old 04-09-2019, 10:52 AM Thread Starter
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Re: Oldheimer noob spring help

Had it out yesterday for 50 miler. You may be right about spring rate. It is fine until hitting rough pavement. The front to rear balance seems VG. There is something good about road feel through seat but my bony rear doesn't want to talk that much. The bike is sweet though- can play race granny shifting at 10k and not get into trouble. Just right for a riders twilight years.GJ
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