rear shock spring rate

9 replies to this topic
  • meanxr

Posted January 27, 2012 - 12:41 PM


Was looking to upgrade to a titanium spring for the rear shock on my 08 450. What is the stock or best spring rate that I should be looking for? Many are from the 4.8 to 5.0 kg/mm and over rating. I am 165lb and ride somewhat aggressive off-road. Also, is the lower the number the softer the rate? Tried searching this topic but no luck. Thanks guys!

  • MaxPower

Posted January 27, 2012 - 07:02 PM


I changed to a Ti spring a long time ago.My bike is a 04.If I remember right the WR spring is the same as the YZ spring.It will be a little softer as the bike is heavier. I weigh the same as you .With Factory Connection valving and the YZ spring I am very happy with the rate. On a MX track its a little soft. But my WR has no business on a MX track,The weight you save is a good amount.

  • GuyGraham

Posted January 28, 2012 - 02:42 AM


I thought the stock spring was titainium on the 08!
The stock spring is much lighter than the replacement I put on my 08
Stock spring rate is 5.5
I'd have thought that would be ok for a 165lbs rider
I'm 210lbs and run a 6.0 with 25/98mm sag

Have you measured you sag figures?
Don't get hung up on spring rates - its the sag figures that ulitmatley determine if you need a softer or harder spring, not the published rate

Edited by GuyGraham, January 28, 2012 - 07:08 AM.

  • 2grimjim

Posted January 28, 2012 - 11:02 AM


The stock spring rate on your bike is a 5.4 kg/mm rate. Race Tech claims that the OEM spring tests @5.3 kg/mm. For your weight, this is pretty close to ideal. If you use the Race Tech spring rate calculator, it reccomends a 5.35 kg/mm.

Checking the race-sag and free-sag is the best way to verify that the spring rate is correct for your weight.

The WR's have never been equipped with Ti springs from the factory.

There is really no reason to repring your WR unless you need the bragging rights that come with a Ti spring.

  • meanxr

Posted January 28, 2012 - 02:57 PM


Thanks for the responses. I guess the only reason I am thinking of going Ti is for the weight savings, and I wanted to make sure I got the right spring rate when doing so. Anyone got an estimate of how much weight difference there is between the two springs? Maybe the swap is not worth monkeying with. Thanks again!

Edited by meanxr, January 28, 2012 - 02:58 PM.

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  • 2grimjim

Posted January 28, 2012 - 07:11 PM


You might save one or two pounds at most.

  • GuyGraham

Posted January 29, 2012 - 07:32 AM


OEM workshop manual I've got states rear srping rate is 5.5kg/mm for 08 model - not sure where 2grimjim is seeing 5.4kg/mm

  • wrwest

Posted January 29, 2012 - 09:10 AM


Check out

  • 2grimjim

Posted January 29, 2012 - 10:32 AM


OEM workshop manual I've got states rear srping rate is 5.5kg/mm for 08 model - not sure where 2grimjim is seeing 5.4kg/mm

The 5.4 spec comes from Yamahas parts fiche.

Workshop manuals are often printed in advance of the bike being produced and changes made prior to the bike being produced may not be incorporated in the manual.

Race Techs spring rate search states that the OEM spring rate is based on their testing and not manufacturer data.

Edited by 2grimjim, January 29, 2012 - 10:34 AM.

  • Navaho6

Posted January 30, 2012 - 10:04 AM


I have an '06 and weigh 165lbs (185 with gear). Stock spring measured 5.3kg at the tuner's. I swapped it out for a 5.5kg titanium two weeks ago. 5.5kg was his recommendation for weight and the terrain I ride (tight single track).


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