Front Fork spring screwup - Wrist Twisters
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post #1 of 20 Old 06-06-2019, 09:00 PM Thread Starter
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Front Fork spring screwup

I have a 2002 Hornet and scored a set of front forks from a 2007 model, with the intention to install Ohlins 85kg springs. However when ordering I neglected to notice the 2002-2003 part number is 08686-85 while the 04-07 is -85b. My manual specified different lengths for springs between years. Should I go ahead and just install the 02-03 springs in the 07 forks? Or bite the bullet and eat the shipping?

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post #2 of 20 Old 06-07-2019, 03:00 AM
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How much difference in lengths? Can you adjust with spacers?

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post #3 of 20 Old 06-07-2019, 12:17 PM
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Quote:
Originally Posted by Andrew Puleo View Post
I have a 2002 Hornet and scored a set of front forks from a 2007 model, with the intention to install Ohlins 85kg springs. However when ordering I neglected to notice the 2002-2003 part number is 08686-85 while the 04-07 is -85b. My manual specified different lengths for springs between years. Should I go ahead and just install the 02-03 springs in the 07 forks? Or bite the bullet and eat the shipping?
What is included in those two PN's?
Just springs?
Or springs with precut spacers?
Or springs with raw lengths of spacers?
Regardless, something sounds very odd about it all.
The early and late forks have the same tube ID, so if you want 0.85s Ohlins and select from the correct family of free length and OD, it should be just a matter of determining the correct spacer length to get the installed preload you want.

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post #4 of 20 Old 06-10-2019, 11:39 AM Thread Starter
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The manual specifies a Fork Spring Service Limit of 276.7mm for 04-07 models and a Service Limit of 295.7mm for the 02-03. No spacers were included in my kit, and I decided to not take the chance with a 20mm difference.
On a completely unrelated note: anybody need some 85kg fork springs for an 02-03 model? 😆And hi, I’m new to the group and all that jazz

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post #5 of 20 Old 06-10-2019, 11:48 AM Thread Starter
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post #6 of 20 Old 06-10-2019, 06:08 PM
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How did you score a set of forks.. I have been looking for a set of 2004+ for years.. with no luck..

Quote:
Originally Posted by Andrew Puleo View Post
I have a 2002 Hornet and scored a set of front forks from a 2007 model, with the intention to install Ohlins 85kg springs. However when ordering I neglected to notice the 2002-2003 part number is 08686-85 while the 04-07 is -85b. My manual specified different lengths for springs between years. Should I go ahead and just install the 02-03 springs in the 07 forks? Or bite the bullet and eat the shipping?

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post #7 of 20 Old 06-10-2019, 06:19 PM
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Plenty of wrecked 919's in Australia.
http://www.ebay.com.au/itm/223146693850

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post #8 of 20 Old 06-26-2019, 08:45 AM Thread Starter
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So I apologize if I’m belaboring this, but what I ended up doing was using the 02-03
Ohlins springs at 281mm in my 2007 forks (07 springs were about 301mm) with the stock ‘07 spacers at 98mm. Did I screw up, and now have some wacky amount of preload?

(The Ohlins did not come with any directions or spacer material, but I have my original 02 forks apart and have the 150mm spacers I could cut down and use.)

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post #9 of 20 Old 06-26-2019, 07:17 PM
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Quote:
Originally Posted by Andrew Puleo View Post
So I apologize if Iím belaboring this, but what I ended up doing was using the 02-03
Ohlins springs at 281mm in my 2007 forks (07 springs were about 301mm) with the stock Ď07 spacers at 98mm. Did I screw up, and now have some wacky amount of preload?

(The Ohlins did not come with any directions or spacer material, but I have my original 02 forks apart and have the 150mm spacers I could cut down and use.)
There is only one way to do it properly.
Get a set of Racetech spring installation instructions, follow it, and determine what length of spacer you need for the amount of installed preload you want.
The OEM spring length + OEM spring length is irrelevant, as the goal is not to simply replicate the OEM installed preload.

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post #10 of 20 Old 06-28-2019, 09:02 AM Thread Starter
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Right, so instead of doing all that, I went on the forum dedicated to my model of motorcycle, and asked a question, hoping someone (who weighs around 180-190 w/gear) had also installed these same springs in their 919 forks and could save me the time and trouble by sharing their wisdom and experience and just TELL ME how long the spacers should be.

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post #11 of 20 Old 06-28-2019, 10:15 AM
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The likelihood of one of the remaining active members here of being in that same situation is small, unfortunately. Even if they have, they may or may not have recorded the spacer length. We can walk you through the process to calculate it; it really isn't difficult. It just requires some measurements to determine the overall length of spring/spacer you need to get the desired preload.

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post #12 of 20 Old 06-28-2019, 11:44 AM
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Quote:
Originally Posted by Andrew Puleo View Post
Right, so instead of doing all that, I went on the forum dedicated to my model of motorcycle, and asked a question, hoping someone (who weighs around 180-190 w/gear) had also installed these same springs in their 919 forks and could save me the time and trouble by sharing their wisdom and experience and just TELL ME how long the spacers should be.
Like Superdog said, anyone here who had done so and kept notes would have done so in a heartbeat.
Unfortunately, my 2004+ relevant notes re my 2005 don't help as the required spacer lengths are different for any given amount of installed preload in 2002/3 forks.

Should you ever get a set of 2004+ forks, with no change to the top out regime, a 90 mm spacer with Racetech springs (no buffer kit) nets 14 mm of installed preload.

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post #13 of 20 Old 06-28-2019, 12:14 PM Thread Starter
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I actually have 04-07 forks in my 02. So yes, that is somewhat helpful.

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post #14 of 20 Old 06-28-2019, 12:18 PM Thread Starter
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Any memory of the length of the RT springs?

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post #15 of 20 Old 06-28-2019, 12:33 PM
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Quote:
Originally Posted by Andrew Puleo View Post
Any memory of the length of the RT springs?
Unfortunately I have no record of that, as it wasn't necessary for the spacer length determination.
And my guess is that most others would be in the same boat.

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post #16 of 20 Old 06-28-2019, 12:35 PM
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Quote:
Originally Posted by Andrew Puleo View Post
I actually have 04-07 forks in my 02. So yes, that is somewhat helpful.
Have you established what installed preload you want?

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post #17 of 20 Old 06-28-2019, 12:58 PM
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Quote:
Originally Posted by Andrew Puleo View Post
Any memory of the length of the RT springs?
According to the racetech site, they are 315mm.

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post #18 of 20 Old 06-28-2019, 06:13 PM Thread Starter
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My Ohlins turned out to be 281mm (online claims 285) and I’m using the stock 99mm spacer. I’m aiming to run 15mm preload, that seems to be what everyone does.

So now correct me if I’m wrong, but as of right now I’m running NO (or even negative?) preload?

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post #19 of 20 Old 06-28-2019, 07:05 PM
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Quote:
Originally Posted by Andrew Puleo View Post
My Ohlins turned out to be 281mm (online claims 285) and Iím using the stock 99mm spacer. Iím aiming to run 15mm preload, that seems to be what everyone does.

So now correct me if Iím wrong, but as of right now Iím running NO (or even negative?) preload?
Some quick math tells me your front end should be collapsing about 10 mm before the spring even becomes active.

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post #20 of 20 Old 06-28-2019, 07:34 PM Thread Starter
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That’s what I’m thinking. So I’m going to take the longer spacers from my old 02 forks, cut them to 135mm, and drop them in. This *should* ballpark me to my desired 15mm of preload. Sound good?

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