Fork and shock spring rate?

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throttleout
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Fork and shock spring rate?

Post by throttleout »

Should I go by Fredette's or Race Tech's spring rates? I weigh 150-155 lbs in my birthday suit, and probably somewhere around 170 with gear.



Fredette recommends:

Forks-.38 kg SPRING for riders that weigh between 140-190 lbs. A big range.

Shock- 4.8 kg SPRING for riders weighing between 150-180 lbs.
I assume his recommendations are based on a rider+gear weight.



Race Tech recommends:

Forks- .405 kg spring. They state to "use closest available", which is a .42 kg spring. This is a big difference from stock.

Shock- 5.009 kg spring. This is basically stock.



The forks are going to be the biggest improvement obviously, but is the stock shock close enough for my weight? I read on another thread that Fredette's recommendations are geared more towards racing, and they are a little light.
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Re: Fork and shock spring rate?

Post by 6 Riders »

When I had my forks built, he put .41 springs in it.....they are/where just right for 160# rider. Mine are set up for "slow "B" dessert/woods rider (I am unfortunately not a slow B rider, more like a Slow C). Given that, I think that Race Tech's calculator is a better choice to use.
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Re: Fork and shock spring rate?

Post by SS109 »

I personally would go with Race Tech's recommendation. I went with theirs and it has worked out good for me. They recommended for me (150lb B-rider) a .42/4.8 setup. I already had .41 fork springs and replaced the stock 4.7 up to a new 4.8.
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Re: Fork and shock spring rate?

Post by Bitteeinit »

If racetech recommends 0.405, then the closest would be 0.40 no? If they recommended 0.415 then the closest would be 0.42. I've just ordered a set of 0.44 for USD forks and I weigh 180-185 without any gear. Going to keep the stock shock for now and see how the bike handles. Should arrive anytime now.
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Re: Fork and shock spring rate?

Post by KDXGarage »

Did you check the sag with the stock spring?
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Re: Fork and shock spring rate?

Post by Bitteeinit »

Are you asking me or throttleout?
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Fork and shock spring rate?

Post by throttleout »

Bitteenit, Race Tech doesn't show any springs under the .42 kg. But, otherwise you're right.

Jason, I haven't set the sag yet. But, I see where you're going. I need to let the sag determine my shock spring rate...correct? I'm going to set my sag now, and then check it again when I replace my fork springs.

Since Race Tech doesn't offer a spring less than .42 I was looking at getting FRP's springs. FRP fork springs start at .38 and go to .42 kg.

I went back to playing with RT's calculator. Those original RT recommendations were based off of a B rider. I've never raced and don't know where I would land on that scale. I changed the rider level to c class, and now it recommends the same fork spring as FRP- .38 kg but the still the stock shock spring. :hmm: I don't understand how riding level affects the spring rate. ???
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Re: Fork and shock spring rate?

Post by Bitteeinit »

I've wondered that too. I suppose a more aggressive rider will want to go faster and as such want stiffer springs. I'm by no means a racer myself, and I think spring rates would also vary a lot according to the type of terrain you ride in and what you're accustomed to. Once I get the 0.44s on I'll report back. Kind of worried they might be slightly stiff but it should be fine. I haven't put many hours on the stock springs but can tell they're way too soft, so anything will likely make it more comfortable (and I can also let my 220-240lbs friends ride it... Though I'm not sure that's an entirely good thing as they might want to "borrow" it too often).
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Re: Fork and shock spring rate?

Post by KarlP »

I'm about the same weight and found that the stiffer of the XR400 springs was perfect for me.

I think they are .42 from the 97+ XR400? The nice thing about the XR springs is that you don't use that 5" steel spacer, instead you make a spacer about 5/8" long out of a PVC pipe fitting.

The rear shock rate turned out fine for me at 175 and my riding style.
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Re: Fork and shock spring rate?

Post by KDXGarage »

You may be fine with the stock shock spring. I can't see .38 being correct.

KarlP, 1996 / 1997 is .40 and 1998 - 2004 are .40 on the XR400R springs.
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Fork and shock spring rate?

Post by throttleout »

Thanks for all the input. I can't find any XR springs, and neither Race Tech nor Eibach offer a spring less than .42 kg. So, I'm gonna go with FRP's .40 kg fork springs. I have to assume his springs are quality. Surely they're manufactured by Race Tech or someone else big.
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Re: Fork and shock spring rate?

Post by newbbewb »

I don't know your riding experience, BUT, being a touch stiff on the front is not a bad thing. as you begin to get better you'll appreciate it. At least I did/do.
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Re: Fork and shock spring rate?

Post by chkdx »

I'm about 180 with gear, racetech recommended .44 fork springs, that's what I went with and think they're just right. Glad I didn't go softer.
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Re: Fork and shock spring rate?

Post by KDXGarage »

If you want .40 springs, here you go:

http://www.ronayers.com/Search.aspx?k=51401-KCY-761

buy 2
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Fork and shock spring rate?

Post by throttleout »

Bringing this thread back for fork set up advice. I was installing xr400 .40 springs, and had planned on doing the shim stack mod. To my pleasant surprise I have gold valves. The springs are engraved with .38 or .35 or something. Not very legible. Take a look and see what you think they may be.
Are these the stock .35's? Anyways, knowing I have gold valves threw a wrench in my plan. What weight oil should I use with which springs now?


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Re: Fork and shock spring rate?

Post by throttleout »

What length does my pre load spacer need to be for the xr springs??????
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Re: Fork and shock spring rate?

Post by throttleout »

I went ahead and installed the XR400 springs with a 7mm spacer. That was recommended to another very similar rider and setup on this site. I used a 50/50 mix to make 7.5wt oil. Got it done. I'm riding tomorrow at West Point, Tn. If I can tell a difference I'll give a ride report.
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