Fork Spring Upgrade...DIY? + Setup Question - SV1000 Portal
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post #1 of 38 (permalink) Old 12th September 2019, 04:36 AM Thread Starter
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Fork Spring Upgrade...DIY? + Setup Question

In case you haven't noticed, I'm an excited new owner and full of questions.

I'm planning on servicing the fork fluid since my bike has sat for 13 years and thought, while I was at it, that I might as well upgrade the springs for my weight. So, I picked up a set of RaceTech linear 1.0 kg/mm springs and some new seals.

What I can't seem to confirm with certainty...is the fork spring change a "DIY" mod? I see special tools listed in the online service manual, but not sure what I need or if I really need any of them? I have a vise, decent mechanic skills and a good selection of common hand tools, wrenches, sockets, etc.

Also, I'm 240 lbs with gear. Was thinking of going with 5wt fork oil (possibly Maxima blue or Motul synthetic?) and setting a gap of 120mm-125mm from the top of the tube. For those in the know, does that sound about right for street riding?

Thanks!
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post #2 of 38 (permalink) Old 12th September 2019, 02:37 PM
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If you are wanting performance, go with a straight rate spring. If you plan on any two-up riding, a progressive rate spring may be an option. For my money, a straight rate spring, tailored for your weight is an excellent, not very expensive upgrade. Race tech has a great spring rate calculator site to determine your spring rate, sonic springs are a bit cheaper, but only if you know what rate you want. They donít have a calculator.
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post #3 of 38 (permalink) Old 12th September 2019, 09:01 PM Thread Starter
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Thank you for your input. I've already ordered the springs...RaceTech 1.0kg/mm (straight rate)

Now I need to figure out what oil and oil height I need. Seems 5wt and 120-125mm from top are ideal for 240lb rider fully kitted?

I've had the fork springs replaced in pretty much every bike I've owned, but I'm curious if it can be done easily by the home mechanic or if I need a bunch of special tools and would be better off taking to a shop?

I'm kind of over shops, to be honest, and looking for minimal downtime (this is my commuter)
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post #4 of 38 (permalink) Old 12th September 2019, 09:19 PM Thread Starter
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Also, will 1L (~1qt/32oz) of fork fluid be sufficient to do both forks?

Thanks!
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post #5 of 38 (permalink) Old 13th September 2019, 01:56 AM
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I did mine myself, and made my own cartridge tool out of a piece of square tubing. I made it by eyeballing down the fork tubes and trial and error cutting two tabs to fit into the cartridge slots. I have an 04, so it has different cartridges than 2005+ bikes to my understanding . Its not a difficult job at all. The cartridge tool can be purchased for about $50 though, so not catastrophic in price. My understanding is that 5wt is the oil to use. I used it, and proper fork oil level transformed my forks. Iím quite happy with the bike for street use. Also, fork oil level can be adjusted on the bike. Just fill them to an initial height. If you decide it could use more or less, measure at one place on each of the forks with the bike straight up and down on a rear swingarm stand. Make the adjustment in oil level, and measure in the sam place either up or down. Springs removed. Itís not rocket science. You can do it. I almost always replace seals and fork bushings while I have them apart, all balls racing makes a bushing/slider kit and a seal kit that arenít expensive. It keeps you from having to do it later. Conventional forks are hard on sliders/bushings in my experience, so I replace without question at rebuild time- Worth the $40 to me. Worth the $40 for seals too. The all balls kits are available amazon prime, the all balls site has the part numbers. Iíve had great luck with all balls kits on everything but an old first gen sv650s. The seals were fine, the sliders werenít right. Everything else has been good for four of my other bikes., and lasted a good long time. Some people say not to use them, but I do what I do. I have 8 bikes, and oem stuff can get really pricey x8 bikes.

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Originally Posted by Masta' C View Post
Thank you for your input. I've already ordered the springs...RaceTech 1.0kg/mm (straight rate)

Now I need to figure out what oil and oil height I need. Seems 5wt and 120-125mm from top are ideal for 240lb rider fully kitted?

I've had the fork springs replaced in pretty much every bike I've owned, but I'm curious if it can be done easily by the home mechanic or if I need a bunch of special tools and would be better off taking to a shop?

I'm kind of over shops, to be honest, and looking for minimal downtime (this is my commuter)
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post #6 of 38 (permalink) Old 13th September 2019, 02:09 PM
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Originally Posted by Masta' C View Post
Also, will 1L (~1qt/32oz) of fork fluid be sufficient to do both forks?

Thanks!
Racetech's web site says you need 2L

different springs displace different volumes of oil, so you should go with what Racetech says reil level rather than what the service manual says
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post #7 of 38 (permalink) Old 13th September 2019, 04:44 PM
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Quote:
Originally Posted by Masta' C View Post
In case you haven't noticed, I'm an excited new owner and full of questions.



I'm planning on servicing the fork fluid since my bike has sat for 13 years and thought, while I was at it, that I might as well upgrade the springs for my weight. So, I picked up a set of RaceTech linear 1.0 kg/mm springs and some new seals.



What I can't seem to confirm with certainty...is the fork spring change a "DIY" mod? I see special tools listed in the online service manual, but not sure what I need or if I really need any of them? I have a vise, decent mechanic skills and a good selection of common hand tools, wrenches, sockets, etc.



Also, I'm 240 lbs with gear. Was thinking of going with 5wt fork oil (possibly Maxima blue or Motul synthetic?) and setting a gap of 120mm-125mm from the top of the tube. For those in the know, does that sound about right for street riding?



Thanks!


What year bike? When I am setting these bikes up it can be different for the 03/04 bikes and the 05-07 bikes due to significantly different cartridges.

I would not run the fork oil level below 125 or 130mm as much below that and the air spring effect starts to go away pretty quickly. I have also never run higher than 110mm either.

In total you will need over 1 liter of oil. I think it turns out to be about 1.5 liters.

If you are not going to revalve, oil selection is critical, especially for a 1.0kg/mm spring. Oil weight is not a good value to gauge from brand to brand as one 5wt in some brands is 10wts in others.

You will likely have to cut you existing spacers or cut new ones from the material they supply. Make sure you calculate the proper shim length.

Also note that when setting the sag that with the stiff springs, you will be nearly at coil bind on the top out springs so set your your values taking that into account.
-ms


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post #8 of 38 (permalink) Old 13th September 2019, 06:05 PM Thread Starter
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The bike is a 2006

I went ahead and ordered 2L of Torco RFF 7 fork fluid. According to internet viscosity charts, the stock Suzuki L01 fluid (I assume that's what these came with) is rated at 15.50 [email protected], while the Torco is 16.10 [email protected]

I figure since the bike only has 600 actual miles on it that the original bushings should be fine, so I'm only changing out the seals/dust wipes (AllBalls).

Schmidt314: How do I calculate the proper spacer length? I assume when you say "shim", that's also what you're referring to?

Twag: Do you have any pics of the tool you made? Are there any other "special" tools I will need?

Junkie: Thank you for that! Probably should have noted that when I was calculating spring rates.
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post #9 of 38 (permalink) Old 14th September 2019, 12:17 AM
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The bike is a 2006



I went ahead and ordered 2L of Torco RFF 7 fork fluid. According to internet viscosity charts, the stock Suzuki L01 fluid (I assume that's what these came with) is rated at 15.50 [email protected], while the Torco is 16.10 [email protected]



I figure since the bike only has 600 actual miles on it that the original bushings should be fine, so I'm only changing out the seals/dust wipes (AllBalls).



Schmidt314: How do I calculate the proper spacer length? I assume when you say "shim", that's also what you're referring to?



Twag: Do you have any pics of the tool you made? Are there any other "special" tools I will need?



Junkie: Thank you for that! Probably should have noted that when I was calculating spring rates.


With 06 cartridges and 1.0 springs and that oil you will have poor rebound control in my experience. You will literally will be about 1/16 to less than 1/4 of a turn out, giving you poor granularity for your adjustments/tuning.

I see way too many pre mature failures with All-Balls seal kits and no longer use them. OEM or NOK (many OEM are NOK).

You need to calculate spacer length to set the initial spring preload to assure you will be in the dynamic range of your adjusters. You can cut new, or modify the stock plastic unit. I prefer to modify the stock one as it helps hold the spring on center.

I rarely need a cartridge holding tool. Smack the Allen socket you are going to use on the cartridge holding bolt several times with a deal blow hammer, crack loose by hand. Then zap with air and it comes right out w/o a holder. Holding tools will be different for 03/04 and 05-07.

-ms


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post #10 of 38 (permalink) Old 14th September 2019, 04:44 AM Thread Starter
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With 06 cartridges and 1.0 springs and that oil you will have poor rebound control in my experience. You will literally will be about 1/16 to less than 1/4 of a turn out, giving you poor granularity for your adjustments/tuning
Well, dang...What oil would you recommend then?

I was going off the chart below. I went back and highlighted the factory Suzuki fluid in Red and the other options I had considered, including RaceTech's recommended fluid and the popular Red Line "Light" fluid.

Looking through past threads, it seemed there was a trend of erring on the lighter side of oil weights for these forks.

Also, would I be better with 0.95 kg/mm springs? I've had 1.0's in other bikes and liked them, but the valving was tailored to those springs in most cases. I do ride 2-up occasionally, but not often.

Any thoughts are appreciated!

Thanks!
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post #11 of 38 (permalink) Old 14th September 2019, 06:29 AM Thread Starter
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Also, if I were to leave the stock fork seals in for now (Only 600 miles...they're not leaking), do I still need special tools to swap the spring?
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post #12 of 38 (permalink) Old 14th September 2019, 03:39 PM
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Iím sorry, I do not. It is also out on loan to a friend right now, so I canít get one. Iím rebuilding my RC51 forks this weekend, possibly into next week. I may end up making another tool, if I do, Iíll snap a pic. Itís supposed to be the same

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Twag: Do you have any pics of the tool you made? Are there any other "special" tools I will need?
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post #13 of 38 (permalink) Old 14th September 2019, 03:42 PM
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Also, if I were to leave the stock fork seals in for now (Only 600 miles...they're not leaking), do I still need special tools to swap the spring?
You would not. You would literally just be lifting the old spring out of the top. You would not be able to get the cartridge and valving as clean, but no special tool necessary.
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post #14 of 38 (permalink) Old 17th September 2019, 10:15 PM Thread Starter
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Cool!

So, I'm strongly contemplating ordering 0.95 kg/mm springs (to use instead of the 1.0 kg/mm I just got) and going with Bel Ray HVI 5wt...any thoughts?

Again, 2006 model, 235-240 lbs (~107kg) fully kitted, occasional 2-up, primarily street commuting/canyon riding.

Also, mm measurements for the oil are with springs out, correct?
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post #15 of 38 (permalink) Old 17th September 2019, 11:12 PM
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According to Race tech, stock spring rate is already .98 kg/mm. I would think the 1.0 would be better. Although their site recommends .96 for a 240 lb rider using their spring calculator.
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