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Shock preload vs. shim

Old 08-14-2013, 04:21 PM
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Shock preload vs. shim

This may have been answered already but I am not finding it. Reading through https://www.superhawkforum.com/forum...e-trail-24041/ I have learned that to make the bike more "flick-able" the key is to shorten the trail by decreasing the rake. I understand the common way is to shim the shock between the top mount and the subframe. How is this different than increasing the preload setting? currently I ride with the prelaod on the softest setting. Would setting it on a higher setting achieve the same effect, or would it also increase the stiffness of the sear suspension? Thanks ahead for your input or entertaining satirical remarks. KCCO
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Old 08-14-2013, 06:14 PM
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Originally Posted by KCCO View Post
This may have been answered already but I am not finding it. Reading through https://www.superhawkforum.com/forum...e-trail-24041/ I have learned that to make the bike more "flick-able" the key is to shorten the trail by decreasing the rake. I understand the common way is to shim the shock between the top mount and the subframe. How is this different than increasing the preload setting? currently I ride with the prelaod on the softest setting. Would setting it on a higher setting achieve the same effect, or would it also increase the stiffness of the sear suspension? Thanks ahead for your input or entertaining satirical remarks. KCCO
It would increase the stiffness of the rear suspension, which is not recommended if you are on the light weight side of humanity
The VTR comes with a very stiff rear suspension at the softest setting, also the reason for the JD F4I rear suspension upgrade Mod.
the shim is actually extending the rear shock (makes it longer Maxed at 6mm) and raise the rear a bit, enough to give you a bit better handling.
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Old 08-14-2013, 06:24 PM
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Thanks for the info! I'm 150 so the rear is quite stiff for me. I'm a pay check away from the F4 convert, so that will be in a month or so, just looking for a quick fix in the mean time. Looks like the shim it is! I figure I'll go 3mm first and go from there. I have the Jamie's fork parts and love them.
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Old 08-14-2013, 07:20 PM
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Originally Posted by KCCO View Post
Thanks for the info! I'm 150 so the rear is quite stiff for me. I'm a pay check away from the F4 convert, so that will be in a month or so, just looking for a quick fix in the mean time. Looks like the shim it is! I figure I'll go 3mm first and go from there. I have the Jamie's fork parts and love them.
As I said you are way light for the rear shock, just keep it at the softest setting for now.
3mm you may not even feel a difference, but you can play with that and see.
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Old 08-14-2013, 07:38 PM
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Worth going 6 first?
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Old 08-14-2013, 08:21 PM
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Originally Posted by KCCO View Post
Worth going 6 first?
I did, I just think that with 3mm it will be more difficult to measure the results, I like the results with the 6mm, also for my height preference.
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Old 08-14-2013, 10:52 PM
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KCCO, do the shim. It really changes the whole feel of the bike. Its like the bike looses 50lbs all at once. At 150 you sorta have a steel pipe for a spring at full preload. You want to shim and remove preload.

Try it you will like it.
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Old 08-15-2013, 12:26 AM
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Preload is all the way down as is right now. Shim will be made and installed later today. Thanks for the input all.
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Old 08-17-2013, 03:07 AM
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Are you guys saying back off the preload if you have a 6mm shim fitted?

I weigh 160-170 depending on what I'm wearing.(No sarcastic comments)
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Old 08-17-2013, 07:50 AM
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Yeah back it off so the shock actually works. At you wieght it will be way too stiff.
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Old 08-17-2013, 08:40 AM
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Originally Posted by kenmoore View Post
Are you guys saying back off the preload if you have a 6mm shim fitted?

I weigh 160-170 depending on what I'm wearing.(No sarcastic comments)
Youre exagerating...Nipple clamps don't weigh ten lbs
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Old 08-17-2013, 11:46 AM
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I'm using 3 washers as the shim, as a procedural question, do I need to remove the tank? If I can get a box end on the nut will that work or is it worth it to remove the tank for ease of operation?
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Old 08-17-2013, 02:49 PM
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Well mine do, I will take the nipple clamps of, and back of the preload before I go for a ride today.

Will report on how it feels after the ride.
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Old 08-17-2013, 04:11 PM
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To those confused by this, pre-load and shock shimming are fundamentally two very different things, and even if pre-load does affect ride height, it shouldn't be used for this adjustment.

Pre-load is a fine tune adjustment to your spring stiffness. Each spring can be made stiffer by compressing it (pre-loading) it a bit until the proper stiffness is achieved for that particular rider. Springs can only be loaded so much before travel and ride quality are affected, so a heavier or lighter spring is needed if it is maxed out. For bikes like the Superhawk, compromises were made in the suspension, and I suspect the engineers put a stiff spring on it to account for touring bags or a passenger. For many riders this is too stiff and pre-load should be adjusted all the way out.

Adjusting this load does affect ride height in that a stiffer spring will sag less under bike and rider weight. But it should be used to adjust for proper suspension tuning. Part of this is setting sag, which is effectively how far into the travel the suspension is with the rider and gear on. Many people on here know way more about this than myself.

This is not to be confused with adjusting overall ride height, and is very different from shimming the shock from a performance setting. When you shim the shock, you are shimming it above it's mount location. So you are not affecting the stiffness or travel of the suspension, and only affecting the geometry of the bike by adding a few mm of thickness to the bottom of your frame (mounting location). This is particularly important to the Superhawk, because it is already very stiff from the factory in the rear, and jacking the pre-load up more exacerbates this. Also note, that in shimming the rear, you shift the stock weight balance slightly more toward the front of the bike, making your already oversprung tail slightly lighter... and front end more sensitive from the decreased trail... it's all minor changes and the superhawk is relatively stable, but these things should be noted when changing stuff around.

Jamie is probably gonna eat me alive with corrections, but bottom line is that pre-load =/= ride height adjustment and shouldn't be used as such.
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Old 08-17-2013, 04:22 PM
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7moore7, great write up! I think that is the end all be all answer to this question.
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Old 08-17-2013, 07:41 PM
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OK, here comes the FNG in me: How do I do this? I have the shim made, placed the bike on a saddle and headlift stand, moved the tank, loosened the self locking thread, tried lifting up on the exhaust and cannot get enough space in between the shock mount and the bottom of the sub frame. What am I doing wrong?
Thanks all
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Old 08-17-2013, 08:00 PM
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You need to get the rear wheel in the air without using the swingarm. I made some crappy looking but awesome working wood stands.

I just put a barbell bar in front of the pass peg brackets and lift it onto these. Then the rear is hanging so when you loosen the shock nut it will make space to put the spacer.
Attached Thumbnails Shock preload vs. shim-6.07picomp-021.jpg  
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Old 08-17-2013, 08:03 PM
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Thank you! That I can do haha
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Old 08-17-2013, 08:22 PM
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Oh and is your spacer c-shaped like this? Goes in alot easier than round.

Pay no attention to the high tech tooling.
Attached Thumbnails Shock preload vs. shim-spacercut2.21-002.jpg  
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Old 08-17-2013, 09:04 PM
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Looks like what I did, took a washer (3) and a cut off wheel and went at it. Used jack stands and a bar under the subframe behind the shock to keep it off the ground. Shims went in great, tightened the shock mount up, went to put the tank back on and the hing bolt snapped. So the shim job is done, now I just need to get a new bolt and it will be done. Thank you all for the info and advise on the procedure!
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Old 08-17-2013, 09:09 PM
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Report back after you ride it.
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Old 08-17-2013, 09:11 PM
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Wilco.
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Old 08-18-2013, 01:42 PM
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Yeah, I backed the spring off, and can report that the bike is a lot more comfortable.

Thanks for the tip.
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Old 08-18-2013, 04:31 PM
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Went for a little test ride after shiming, removing 1/2 turn of damping (which is only 1/2 turn out) and 1 turn off the rear shock. the bike feels like it holds the front in the corners better = higher entry speed and more solid feel. The rear feels like it might be a little looser than before but nothing that would make me want to take the sims out. Does that go along the lines of how you all felt after the shim?
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