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Front or Rear suspension upgrade?

Old 05-30-2010, 08:39 PM
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Front or Rear suspension upgrade?

Hi,
I have a few questions for you guys.
I am going to do a suspension upgrade, but only have money to do 1 of them at the moment. So which one will I get the best initial results from...front or rear?
As far as the front goes I will be going with Racetech, since I weigh 155lbs. with no gear, and the calculator on racetech says .835 for the spring rate. So I will go with .85. Sonic springs go as low as .90, so that makes that decision an easy one.
As far as the gold valves, are they necessary for me? I really only ride for leisure. I don't do any twisties or any track days, so basically I leave my preload adjustment in 1 position.
Also, what weight fork oil should I go with?
As for the rear spring, the calculator on Racetech says the factory spring rate is actually right on for my weight. I know an aftermarket shock and spring will give the bike a much nicer ride, but is it worth it considering the spring rate is actually perfect with the stock equipment?
Also, when I do upgrade the rear spring, will the F4 conversion with ONLY the spring be adequate, or is the gold valve something I want to do?
Thanks for your input.
Mike

Last edited by superh1998; 05-30-2010 at 08:46 PM. Reason: forgot 1 question
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Old 05-30-2010, 08:55 PM
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Leave it stock. If you don't ride twisty roads there's really no reason for performance mods to the suspension.
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Old 05-30-2010, 09:30 PM
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Stock in the rear, or both?
Considering the front spring rate is so off, I think I should at least do the front.
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Old 05-30-2010, 09:33 PM
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Nah leave it stock, bottoming out the forks going into parking lots is fun. Do the front first, it gives more improvement in ride and handling.
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Old 05-30-2010, 09:35 PM
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Haha...yeah, that definitely gets old real quick.
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Old 05-30-2010, 09:45 PM
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It is always best to do the front first. With the way you have described your riding style you can try the stock valving to see how it works for you. I would still run 5wt with those springs as the stock set up is over damped to begin with.

As for the gold valves, IMHO I really don't think you would notice the difference. Just get the sag set properly and then go from there.
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Old 05-31-2010, 02:45 AM
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+1
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Old 05-31-2010, 05:48 AM
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i think its a toss up regarding which one you will feel the most given your riding style. the rear is just not very compliant so over sharp bumps, like you might notice even on the freeway or expansion joints, it just kicks you in the butt. that get transfered to the front also (like a rocking horse) - so they are both related. But the front is a much cheaper starting point. Personally I think the rear shock is what smoothed out the ride most - the front changes made it a better sport bike. for me at least.
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Old 05-31-2010, 07:27 AM
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I'd have to agree with Cliby on all points.

The two are related, and until you do both you'll not realize the full benefit of the work at ether end.

The shock will significantly help with comfort.. The front will help with performance more (though for me I'm more comfortable when the suspension is doing things predictable and not diving, bottoming out,,ect,,so it was one and the same)

Get a used F41 shock, send it off to Jamie.at Daugherty Motorsports ...for a rework... add some new springs and oil to the front.. you can hold off a bit that way and build up funds to do the font wright. Only thing you'll be out is the new oil.. springs will get re used.
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Old 05-31-2010, 07:29 AM
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Originally Posted by davidka View Post
Leave it stock. If you don't ride twisty roads there's really no reason for performance mods to the suspension.
Well thats a thought..

Do you use your brakes at all? When you do, have you noticed the front dive considerable?.. That reason alone is enough to rework the suspension.
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Old 05-31-2010, 08:53 AM
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Get the .85 springs. Change the oil and replace with same or slightly lighter oil viscosity than stock. Stock oil is Showa SS-8 at 36.47cSt. I wouldn't use anything lighter than about 30cSt. Maybe Redline medium (red). This will still allow you some rebound damping control.

See Jamie for a shock.
Attached Thumbnails Front or Rear suspension upgrade?-oil-data.jpg  
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Old 05-31-2010, 09:04 AM
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Cool, so it sounds like the front will be first.
I will change the springs to .85 and the oil as well. I will hold off on the gold valves, and hopefully notice a dramatic enough difference to maybe not even do them.
I already have an F4i shock, so when I get the funds, I will be sending that off to Jamie. So so you think I need to do the gold valve on the rear, or should I be OK given my riding style?
As far as the the front dive when I brake, I don't really notice it that much since I don't ride aggressively, but I have definitely noticed it when I have had to brake suddenly to avoid being killed by other drivers.
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Old 05-31-2010, 10:42 AM
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Originally Posted by superh1998 View Post
Cool, so it sounds like the front will be first.
I will change the springs to .85 and the oil as well. I will hold off on the gold valves, and hopefully notice a dramatic enough difference to maybe not even do them.
I already have an F4i shock, so when I get the funds, I will be sending that off to Jamie. So so you think I need to do the gold valve on the rear, or should I be OK given my riding style?
As far as the the front dive when I brake, I don't really notice it that much since I don't ride aggressively, but I have definitely noticed it when I have had to brake suddenly to avoid being killed by other drivers.
I my case it wasn't so much the fork dive, the real problem came when there were bumps in the road while trying to brake. The stock set up is so under sprung and over damped that the front end would lock up in those situations....

As for the rear, once again with your riding style, I don't think you would need a gold valve kit. It is nice but not really necessary.
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Old 05-31-2010, 12:37 PM
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Originally Posted by 8541Hawk View Post
....The stock set up is so under sprung and over damped that the front end would lock up in those situations....
You mean UNDERdamped? The problem is that the stock shimstack is so weak that the forks are limited in how much fluid they flow by the size of the orifices in the valves. Using a lower viscosity oil or different valving would the be ideal solution.

[Edit] The other problem is that once you blow through the entire stroke of the fork then what's left is the oil locks. These drastically raise compression damping at the end of the stroke to prevent hard bottoming. It would feel like the forks were locked solid.
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Old 05-31-2010, 12:42 PM
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Originally Posted by Hawkrider View Post
You mean UNDERdamped? The problem is that the stock shimstack is so weak that the forks are limited in how much fluid they flow by the size of the orifices in the valves. Using a lower viscosity oil or different valving would the be ideal solution.

[Edit] The other problem is that once you blow through the entire stroke of the fork then what's left is the oil locks. These drastically raise compression damping at the end of the stroke to prevent hard bottoming. It would feel like the forks were locked solid.
Sorry...... typing fast and hadn't finished that first cup o' coffee yet.....
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Old 05-31-2010, 12:43 PM
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Greg,
I am going with your suggestions.
I am going to use the .85 springs(already ordered), and the Redline medium (red) fluid(also ordered).
Do I need to change spacers, or anything else, or simply the springs and fluid?
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Old 06-02-2010, 10:42 AM
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Originally Posted by E.Marquez View Post
Get a used F41 shock, send it off to Jamie.at Daugherty Motorsports ...for a rework... add some new springs and oil to the front..
Does the year matter?
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Old 06-06-2010, 03:38 PM
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From reading numerous other posts about the fork oil level, I see there is really no specific air gap that everyone uses.
I was wondering if anyone has gone with the same or similar setup and has any suggestions for the air gap in my case.
Also, as far as cutting spacers...do I just measure the stock spring and spacer, the new spring and spacer, and cut off the difference?
Thanks,
Mike
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Old 06-06-2010, 05:36 PM
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No, it's not quite that simple. Hehe, I wish it was! You are shooting for 15mm preload on the spring. If you get your springs from Sonic then your approximate spacer length will be 66mm. It might take a few cuts - trial and error before you get it. They give plenty of spacer material. Sonic sends PVC. RT sends aluminum. Ensure you get all burrs and stuff off the cuts. Don't want that **** getting stuck in your valving.
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Old 06-06-2010, 05:42 PM
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Yeah, I definitely dont want to get metal burrs in the forks...that wouldn't help anything.
I got the RT sonce sonic didn't list .85...If my memory serves me correctly (and usually it doesn't) Sonic started at either .90 or .95.
So any approximate length for the RT spacers? or suggestions on where to start for the air gap?
Thanks Greg!
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Old 06-06-2010, 05:45 PM
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Go 155mm on air gap, fork bottomed, spring out, cartridge bled. No data on the RT stuff. It's been too long since I used them. Sorry.
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Old 06-06-2010, 05:48 PM
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No Problem...thanks again for all the info!
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Old 06-06-2010, 07:19 PM
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Originally Posted by superh1998 View Post
Yeah, I definitely dont want to get metal burrs in the forks...that wouldn't help anything.
I got the RT sonce sonic didn't list .85...If my memory serves me correctly (and usually it doesn't) Sonic started at either .90 or .95.
So any approximate length for the RT spacers? or suggestions on where to start for the air gap?
Thanks Greg!
I have .90 RT springs, spacer needed to be 72mm based on RT instructions, I used 7wt Belray oil, I do not remember the height. It all works great.
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Old 06-06-2010, 07:21 PM
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Sounds good...I will start out somewhere areound there.
Thanks for the info, JB.
Mike
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Old 06-06-2010, 07:24 PM
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trail and error with pvc first, then cut aluminum. i used a chop saw with die cutting disc
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Old 06-06-2010, 07:27 PM
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Thats exactly what I was thinking...just need to get the die cutting disc.
But just like everyone else on here...I love having an excuse to buy new tools, or accessories for them...haha
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Old 06-11-2010, 06:00 PM
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Well, I got a stipend check for my clothing allowance from work the other day. I figured since I already paid the credit card bill, I may as well spend the money for the gold valves since the shocks are already off the bike, right?...haha
There's always a way to justify it!
Anyway, now I am thinking I may be over my head with the install...taking off the top part of the shock for the springs was easy, but I seem to be lacking the confidence to go any further.
I think I may have to wind up sending the stuff to Greg or Jamie.
I guess I'll wait for the valves to arrive, take a look at the instructions, and go from there.
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Old 06-12-2010, 08:03 AM
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Send 'em to JD if you've got GVs. He's the resident expert on them. I like using the stock stuff for revalves. 6 of one, half dozen of the other....
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Old 06-16-2010, 07:45 PM
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Quick question...Since I am going with the gold valves, should I now use a lighter weight oil (5wt), or can I stay with the Redline medium (10wt)?
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Old 06-16-2010, 08:04 PM
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No, if you use Gold Valves, their shimstack and valve are designed for the Racetech US2 10wt oil. Depending on the spring rate you go with, and since you already have everything apart, use some of the extra shims they give you and build a stiffer rebound stack.
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