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Ledrocnoc

Spring rates for heavier rider on 2008 WR450F

18 posts in this topic

What's the recommended spring rates for a rider @ 220LBS (in his birthday suit - so a lot more with all the gear, etc...) mostly for active trail rides (i.e. not racing speed, not dual sport riding either).

 

Thanks.

 

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You're probably looking at somewhere around .52 kg/mm up front and around 6.0 in the back. But call RT or run the calculator and that'll get you close.

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What's the recommended spring rates for a rider @ 220LBS (in his birthday suit - so a lot more with all the gear, etc...) mostly for active trail rides (i.e. not racing speed, not dual sport riding either).

 

Thanks.

 

08 WR450 forks come with the worst what I call defective base valve's in the forks. Especially with a heavier rider aboard they blow through the travel and no springs will help. Do yourself a favor and get new base valves.

 

http://www.thumpertalk.com/topic/683905-07-and-newer-wr450-base-valves/

 

http://www.thumpertalk.com/topic/683007-08-wr450-fork-valves/

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I'm around 210lbs and went with the following

 

RaceTech base valves in the forks (this is a must, as stock there are shite)

 

The stock fork springs are rated at 0.44kg/mm but rarely measure this. Mine measured 0.41kg/mm!

0.46kg/mm fork springs (this was after I tried real 0.44kg/mm springs which felt a bit soft). I also have some 0.48's still new in box and I have never fitted becuase the 0.46kg feel right

 

6.0kg/mm rear spring

I am near as damm it spot on with ideal rear sag of 25/100

 

HTH

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Thanks as always for all the great info guys!

 

I just ordered the race tech front (0.48) and rear (6.0) springs and the Gold Valve.   I just have a couple of additional questions:

 

  • Any specific things to be aware of for installation? (I rear spring is pretty straightforward but the font valves might be tricky)
  • What are the sag recommendation (without and with rider) for front and rear?
  • What kid of spacers do you use in front for sag adjustment (if any)?
  • Do you use the recommended fork oil weight or are these tricks there to?

Finally, (long story...), the bike is in Europe (France) and I am going there next week to ride, but the rear shock spring will probably arrive after I leave so someone will have to ship it to me.  To get an idea of the shipping cost, can anyone send me the dimensions (length, diameter) and weight of the rear spring?

 

Thanks again.

 

Denis

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Thanks as always for all the great info guys!

 

I just ordered the race tech front (0.48) and rear (6.0) springs and the Gold Valve.   I just have a couple of additional questions:

 

  • Any specific things to be aware of for installation? (I rear spring is pretty straightforward but the font valves might be tricky)
  • What are the sag recommendation (without and with rider) for front and rear?
  • What kid of spacers do you use in front for sag adjustment (if any)?
  • Do you use the recommended fork oil weight or are these tricks there to?

Finally, (long story...), the bike is in Europe (France) and I am going there next week to ride, but the rear shock spring will probably arrive after I leave so someone will have to ship it to me.  To get an idea of the shipping cost, can anyone send me the dimensions (length, diameter) and weight of the rear spring?

 

Thanks again.

 

Denis

 

 

  • Any specific things to be aware of for installation? (I rear spring is pretty straightforward but the font valves might be tricky) - follow the instructions and you will be fine. Also look at this thread http://www.thumpertalk.com/forum/showthread.php?t=776751
  • What are the sag recommendation (without and with rider) for front and rear? - rear is 25mm static / 100m rider. Forks have too much stiction to accurately measure sag, better done by fork travel and feel
  • What kid of spacers do you use in front for sag adjustment (if any)? - none, but i think you get some washers with race tech fork springs
  • Do you use the recommended fork oil weight or are these tricks there to? - use 5w oil. 2.5w is very thin and doesn't have much lubricational properties

 

I also struggled with lack of rebound with the stronger springs

I found when putting in the base valves, that the nut clamping the shims to the mid valve wasn't torqued down properly

After tightening the this nut and Loctiting it the rebound damping increased

I ended up running out of rebound damping adjustment so I added extra shims to the rebound stack to bring the adjusters back into range

 

You will get a shim stack sheet with the gold valves so you know how to increase or decrease the damping if you go out of range

 

The following info will be handy when trying to workout shims/thickness/strength

 

Shim thickness                 Strength

0.1                                    1

0.15                                  3.3

0.2                                    8

 

As you can see, a 0.2mm thick shim has eight times the strength of a 0.1mm shim

2 x 0.1mm shims do not give same strength as a 0.2mm shim - you need 8 x 0.1mm shims for this

The formula for the shim strength is material thickness cubed.

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One thing you will need to take these forks apart is a damper rod tool. I ended up making one, which was a pain in the butt being in the middle of working on the forks.

Something like this:

http://www.motosport.com/dirtbike/Motion-Pro-Damper-Rod-Fork-Tool

The only other advice I'd offer is follow the instructions and realize that your base valves will end up looking nothing like the stock set up. You will remove the crappy springs and cup washers they used and replace with shims. It will be much different looking but the set up works a lot better. Also, for oil height, I initially used around 120mm which I believe was recommended by RT at the time, but ended up going to 95mm to control bottoming better (I'm around 200 lbs no gear).

Those forks were definitely acceptable with the RT base valves and proper springs. I've since gone with YZ SSS forks, which are great.

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One thing you will need to take these forks apart is a damper rod tool. I ended up making one, which was a pain in the butt being in the middle of working on the forks.

Something like this:

http://www.motosport.com/dirtbike/Motion-Pro-Damper-Rod-Fork-Tool

The only other advice I'd offer is follow the instructions and realize that your base valves will end up looking nothing like the stock set up. You will remove the crappy springs and cup washers they used and replace with shims. It will be much different looking but the set up works a lot better. Also, for oil height, I initially used around 120mm which I believe was recommended by RT at the time, but ended up going to 95mm to control bottoming better (I'm around 200 lbs no gear).

Those forks were definitely acceptable with the RT base valves and proper springs. I've since gone with YZ SSS forks, which are great.

Thanks for the info.  

A pair of questions regarding the damper rod tool:

  • Is the one you link to the right one for the KYB 48mm fork?
  • Can you share more info about the one you made (ID / OD / Length / size of the teeth, material you used) so that I can make one myself?

Thanks again.

 

Denis

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Fork holding tool

Steel Electric Resistance Welded mild steel tube

32mm OD or 1 1/4" with 1mm wall thickness

Hole in the end is for the tommy bar

 

WR450forkholdingtool.jpg

 

Edit to my earlier post: -the stock OE springs are supposed to be 0.46kg/mm, not 0.44 as I said, but they did measure 0.41kg/mm when measured.

My suspension shop said WR's are notorious for having under strength fork springs and he was right

'Real' 0.46's feel great for my 210lbs

Edited by GuyGraham
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Fork holding tool

Steel Electric Resistance Welded mild steel tube

32mm OD or 1 1/4" with 1mm wall thickness

Hole in the end is for the tommy bar

 

WR450forkholdingtool.jpg

 

Edit to my earlier post: -the stock OE springs are supposed to be 0.46kg/mm, not 0.44 as I said, but they did measure 0.41kg/mm when measured.

My suspension shop said WR's are notorious for having under strength fork springs and he was right

'Real' 0.46's feel great for my 210lbs

 

 

Fantastic... I am going to scour the local hardware suppliers for a piece of 32mm OD tubing now!

 

Thanks!

 

Denis

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Ok, so a quick trip to Home Depot (really not hoping to find much) and surprise... I found the perfect piece of tubing.  It's a "1-1/4 x 12 brass threaded tube 20 gauge chrome" (UPC 0 41193 00581 6) , about $8.  It can be found in the plumbing section, it's basically an extension for sink drains.  It's 1 1/4"OD and a little less than 1mm wall thickness.  12" long so there is enough slack to cut the threads at least on one end to make the notches and the brass is stiff enough for what it's going to be used for and soft enough to be easy to cut.

 

  :thumbsup:  :thumbsup:  :thumbsup:  :thumbsup:

 

Now, any recommendation on the depth and with of the teeth (or notches, either way)?

 

557450_L.jpg

 

 

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Ok, so a quick trip to Home Depot (really not hoping to find much) and surprise... I found the perfect piece of tubing. It's a "1-1/4 x 12 brass threaded tube 20 gauge chrome" (UPC 0 41193 00581 6) , about $8. It can be found in the plumbing section, it's basically an extension for sink drains. It's 1 1/4"OD and a little less than 1mm wall thickness. 12" long so there is enough slack to cut the threads at least on one end to make the notches and the brass is stiff enough for what it's going to be used for and soft enough to be easy to cut.

:thumbsup::thumbsup::thumbsup::thumbsup:

Now, any recommendation on the depth and with of the teeth (or notches, either way)?

557450_L.jpg

3 or 4mm wide, 3 or 4mm deep, and evenly spaced at 90 deg apart and you should be in business. Don't forget to drill a couple of holes on the top to put a piece of bar stock or something through to make a T-handle for a little leverage.

I also used a piece of pipe extension, but one that was a little too fat at the teeth and ended up having to bend them inward to make them work. I also welded my bar stock piece on.

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One thing before you drill holes - if you don't have the forks right there, you might want to see if someone can get you the measurement for how deep the fork tube is to get to the cartridge assembly. Nothing worse than making the tool only to find it's too short. Otherwise, I will be home in a couple of hours and can measure the one I made.

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One thing before you drill holes - if you don't have the forks right there, you might want to see if someone can get you the measurement for how deep the fork tube is to get to the cartridge assembly. Nothing worse than making the tool only to find it's too short. Otherwise, I will be home in a couple of hours and can measure the one I made.

If you could do that that would be great.  I do not have access to the fork (bike's in Europe... going there end of this week, trying to get everything lined up before then).

 

If you send me all the measurements, I'll gather everything into a post that can be made into a sticky or added to the FAQ.

 

Thanks.

 

Denis

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So this was a hasty effort to make something that would work mid-project, and it included getting the wrong diameter pipe (this is 1-1/2", which is why I had to bend the teeth in to make it work), but it worked nicely. About 9" (or roughly 230mm if we want to stay with the metric system for some reason) from the T-handle to the end will work.

For the 14mm allen, I found it extremely difficult to find locally, so I found a nut and bolt laying around that measured 14mm and welded them together that I could then use with a socket. It also worked well.

IMAG0990.jpg

IMAG0993.jpg

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Super.  Got plenty of length so it looks like I am going to grab my saw, files, drill and get going!

 

Thanks.

 

Denis

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Ok, I got my tool made, here are the photos.  Hopefully it will work (won't know until next week as the place I bought the Gold Valves and rear spring from screwed up on the shipping and I won't be getting the parts until really late).

 

Length is 12" (300mm), OD 1 1/4" (32mm), 20 Gauge (< 1mm).  

 

The "teeth" are approximately 4mm wide and 4mm high.

 

I'll let you know how if went.

 

Thanks again everyone for the help.

 

 

Fork-Tool-01.jpg

Fork-Tool-02.jpg

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