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Using a shim to increase Fork Spring Rate

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What would happen if I used a Shim to increase my OEM Fork Spring Rate on my DRZ400s. I a little confuse with the physics of a spring. Would it make the beginning of the stroke too stiff? I'm guessing I'd shorten my stroke. Has anyone tried this on a DRZ. I'm rebuilding a new style cartridge fork this winter to put on my 2001. Kind of debating if I should buy race tech springs. I weigh about 190lbs w/o gear.

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doesnt change the rate of the spring. you are just adding pre load. will make the fork ride higher in the stroke but not stiffer.

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It won't really make it worse, a lot of bikes have wedge systems to effectively do the same thing by cranking up the pre-load. I think I had a buck fifty in quarters at the top of each fork in my 1100, I'd have to check with the new owner. :smirk:

Steve

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At 190lbs your springs are to soft, if they are stock springs. The DRZ is set up for lightweight people. At the least go to the Race tech web page and use the calculator to figure the spring needed......or a better option send the forks to Eddie for custom work!!

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It won't really make it worse, a lot of bikes have wedge systems to effectively do the same thing by cranking up the pre-load. I think I had a buck fifty in quarters at the top of each fork in my 1100, I'd have to check with the new owner. :smirk:

Steve

I guess the preload thing is what is confusing me. Isn't the preload on my old forks doing the samething as adding shims?

The quarter mod seems kind of expensive.

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I have done the spacer thing with a couple of previous bikes...

It is a part fix ..I recommend you install the correct springs to suit your riding weight...

Edited by CraigoDRZ400sm
spelling error

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What would happen if I used a Shim to increase my OEM Fork Spring Rate on my DRZ400s. I a little confuse with the physics of a spring. Would it make the beginning of the stroke too stiff? I'm guessing I'd shorten my stroke. Has anyone tried this on a DRZ. I'm rebuilding a new style cartridge fork this winter to put on my 2001. Kind of debating if I should buy race tech springs. I weigh about 190lbs w/o gear.

go with the correct spring rate

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If you search around this site (and others) you will find that some add'l preloaded (washers on top of the springs), heavier weight fork oil, and a 'little' higher fork oil height will help your undersprung situation. Keep in mind, each of the 3 things I have mentiond all do slightly different things to the suspension. Even Race Tech recommends these things when installing emulators in old school forks (like Harleys). For $10 bucks you really will feel a difference.

To agree with the other posters - you can't duplicate the real fix = new springs.

As a side note - I just got a DRZ (e) to dual sport last fall. I have always ridden and raced true race type dirt bikes (I still have a CRF450R). I can't believe how good this DRZ is in the rocks STOCK, with just some improvement in the clickers, and I weigh 195 w/o gear.

Good Luck!

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As a side note - I just got a DRZ (e) to dual sport last fall. I have always ridden and raced true race type dirt bikes (I still have a CRF450R). I can't believe how good this DRZ is in the rocks STOCK, with just some improvement in the clickers, and I weigh 195 w/o gear.

Good Luck!

Well that brings up another thought. A lot of people say springs are the best mod, but they weigh 40 to 50 lbs more then me. I guess I wish I could test ride the difference. I know off road I don't bottom out often the way things are now and the front fork absorbs everything, real smooth, and on road the spring rate is good.

I'm just thinking that I'm probably missing out on something. No matter what my DRZ is a BLAST.

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A lot of people say springs are the best mod, but they weigh 40 to 50 lbs more then me.

So we can assume that your current springs are correct for you, if you were lighter, then once again the best mod would be the correct springs.

The whole point of the correct spring and/or adding preload is to have the bike sitting at the correct height in it's suspension travel.

Unlike a car, on a bike the rider is the the biggest influence on how it handles, where the rider can be anywhere between 1/3 and 2/3 thirds of the total mass.

This does not include dad @ 250LB riding his son's peewee 50:busted:

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Toadl:

Go ahead and dive in with playing around with the forks. Your forks are due for dismantling, cleaning, and tuning (by yourself). Depending on how much I get to ride my DRZ I plan to flush them twice a year. Hard riding will turn the fork oil black and runny as water! You will not believe the difference between 10 year old oil and new oil, you will be surprised how good new oil will feel even after a replacing 1 year old oil.

As stated, you want to play with the air pressure (if possible), pre-load, oil weight, and oil level. If you can afford the progressive springs then so be it, but you don't need to spend a lot of money to get your forks working well. I used to kick SV650s asses on my 25 year old GS400 due to the fiddling I did on the suspension and all it cost me was a couple bottles of fork oil.

Cheers, Steve

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