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Upgraded Front Suspension Dilemma

Old 06-09-2014, 11:50 AM
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Upgraded Front Suspension Dilemma

Hello all,

I have a 2001 Superhawk and I'd like to upgrade the front suspension before a trip to CO I have coming up next month. I've been doing some research but have come across conflicting theories.

I've read about the single rate spings and internal mods as outlined here:
http://www.ablett.jp/bikes/vtr/vtr_sus.htm and
http://www.vtr1000.org/phpBB3/viewtopic.php?f=31&t=29710. What I gathered there is that by grinding the taper off the rebound rod along with drilling an extra hole then setting the sag and everything else, you'll have a much better handling bike.

After speaking with Jamie at Daughtery Motorsports however, I feel these might be in error? Here is what Jamie said in response to my questioning the above-mentioned sites:
"Well, my professional advice is not to change only the springs. I know that is a common approach but in reality it causes as many problems as it fixes so it is at best a net zero gain. That said, I also realize that not everybody is able to go "all out" and get the forks setup properly so doing springs would be a step in that direction at least. If you wanted to change only the springs that would be ok just please understand the real problems with the forks lie in the valving."
"Yes, that is info that has been around the 'net for a long time. My advice is not to do any of those things. In fact, some of that will hurt the performance significantly. There isn't anything you can do with those forks that will help unless you replace the valving. Sorry, no free lunch!"
"The taper on the adjustment needles doesn't really hurt anything, but it also doesn't really help either. You would spend effort with no return, plus you would have the chance to screw something up in the process. I never change the taper on the stock needles when I revalve forks in case that helps.
The hole in the cartridge tube is the worst thing you could ever do. One of the problems with the stock valving is a lack of low-speed damping due to excessive free bleed. You would be adding to that problem. In the end you generate what is essentially a set of damping rod forks so you would be stepping back 20 years in technology."


My question now is what to do??? I'm not trying to bash anyone, just trying to get to the reasoning why some would say that doing it one way yields awesome results, while a known and trusted suspension guru says the total opposite. Thanks!!
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Old 06-09-2014, 11:59 AM
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Trust Jaime, that's what you should do.
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Old 06-09-2014, 12:08 PM
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That's what I'm thinking, but I just wanted to see if anyone had insight towards the completely different ways of thinking!
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Old 06-09-2014, 12:20 PM
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Do what i did on my dirtbike: research valving for a couple days. Find out things like: shim thickness and how it affects things, crossover shims, tapered stacks, seats, etc. once you understand the terminology, and how the Superhawk stack is constructed you will find it pretty easy to design a shim stack based on your needs.

I found shims from a local shock guy for about $.50 each, and i needed 10 of them to modify the high speed compression stack on my yz125.

James
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Old 06-09-2014, 12:33 PM
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I'll probably end up sending them to Jamie as my time is a bit cramped lately. i'll take a look at that though, good idea.
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Old 06-09-2014, 01:53 PM
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If you have the means to get the fork legs off, send them to Jamie and know it's going to be right for you and your riding conditions. His prices are more than reasonable and his reputation is beyond reproach.

Last edited by davidka; 08-25-2014 at 07:03 AM.
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Old 06-09-2014, 02:01 PM
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I have the means to do this. I have to replace the neck bearings and I'm doing an projector retrofit, so removing the legs is part of the process as is. Thanks for the insight.
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Old 06-09-2014, 05:33 PM
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wannab, trust Jamie period. And if you're doin head bearings, go w/ tapered rollers.
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Old 06-09-2014, 06:02 PM
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Got the all ***** kit ready to install.
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Old 06-10-2014, 03:27 AM
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Ive often wondered why that hole is drilled. I had thought it was to allow for the lack of flow at high shaft speeds. But yes its a constant bleed. May be better to drill the piston for higher flow or do what I did and fit RT Gold Valves. Or Jaime's version of.
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Old 10-06-2015, 04:19 PM
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Did anyone notice this original information (tapering the step out of the needle, and drilling the bleed hole) is from ROGER DITCHFIELD, courtesy of CyberCarl on VTR1000.org?

Roger even goes so far as to reply specifically about these mods on that forum.

So are you guys saying we should NOT do what Roger suggested with the stock front forks?

He did race VTRs a while, and was called in by Honda to help with the handling issue (in pre-production).... Seems like that warrants our consideration....


James
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Old 10-06-2015, 05:12 PM
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I think the key thing to remember with a set of "Rogered" forks is that these are effectively zero-cost and simple to do.

I don't personally buy in to changing the needle profile as the bypass size is generated in the annular orifice between the needle and it's seat; what happens further along the needle is irrelevant.

The standard compression valve body has quite restrictive ports, so adding the extra free bleed would take some of the harshness out of the forks I think, but perhaps at the expense of high speed compression control. A better solution would be to replace the valve body for one with bigger ports, but again, the Roger mods are effectively free.
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Old 10-06-2015, 06:45 PM
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Okay couple questions then:

Would removing the step help keep the oil flow moving well, instead of the oil running into a wall (the step) and having to change direction?

Also, wouldn't it be an effective "free mod" to "port" the stock valves instead of buying Gold Valves? Seems similar to the "should i port my heads or buy new ported heads" question... I realize purchasing ported heads from trusted companies typically yield fantastic results, but a lot of the fun is in the DIY, along with all the money saved.

Thoughts?

James
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Old 10-06-2015, 07:52 PM
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Originally Posted by thedeatons View Post
Okay couple questions then:

Would removing the step help keep the oil flow moving well, instead of the oil running into a wall (the step) and having to change direction?

Also, wouldn't it be an effective "free mod" to "port" the stock valves instead of buying Gold Valves? Seems similar to the "should i port my heads or buy new ported heads" question... I realize purchasing ported heads from trusted companies typically yield fantastic results, but a lot of the fun is in the DIY, along with all the money saved.

Thoughts?

James
The oil does not run along the needle anyway; it passes axially through the centre of the damper shaft and then makes a right angle turn to come out through the ports just above the rebound valve body. You can look through the ports and see the needle (but not in this photo).



It's probably worth reminding ourselves that we do want some restriction to the oil bypass; you need some, but not too much or too little. Hence the adjustable needle valve.

Regarding porting the stock valve body, I think these are made of sintered metal, and it takes very little for this to crumble. I tried this (fortunately, I had a spare) and the edge of the port just broke away.

Here are the OEM valve bodies, and the Showa 3-port bodies that I use. The difference in port size is pretty big. Gold Valves would be a bit bigger again.


Last edited by Cadbury64; 10-06-2015 at 07:55 PM.
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Old 10-06-2015, 08:01 PM
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It would be really cool if you had a gold valve for the superhawk in that picture too. Would be neat to see/know the difference. Too bad no one has a flow bench kind of thing for these valves

Where did you get the 3 port showa valves? Are they easy to find/inexpensive?

What makes you think the gold valves have bigger ports?

P.S. Did you try porting the stock valves with a high speed tool, like a dremel with a high speed cutting bit?

James
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Old 10-06-2015, 09:06 PM
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The 3-port Showa's I bought off a local suspension tuner. He probably pulled these out and slapped some Gold Valves in their place.

Here's a picture showing a Gold Valve next to the HMAS valves. Note that Gold Valves are not necessarily model specific; the same valve body will be used in any cartridge that has a 10mm shaft and 20mm id.



I tried using my battery drill and a steady hand to drill out the stock valves. I went as fast as I could!
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Old 10-06-2015, 11:37 PM
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The 3 port valves are out of Suzukis. Same as my bandit. I just Ported a HMAS valve up to 2mm fom 1.6. Also ground a sealing edge out to give a bleed. Should go into the fork next week.
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Old 10-07-2015, 06:19 AM
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So you did away with the bleed shim in favor of grinding out an edge?

James
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Old 10-07-2015, 06:39 AM
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Originally Posted by thedeatons View Post
Did anyone notice this original information (tapering the step out of the needle, and drilling the bleed hole) is from ROGER DITCHFIELD, courtesy of CyberCarl on VTR1000.org?

Roger even goes so far as to reply specifically about these mods on that forum.

So are you guys saying we should NOT do what Roger suggested with the stock front forks?

He did race VTRs a while, and was called in by Honda to help with the handling issue (in pre-production).... Seems like that warrants our consideration....


James

Also note, in the same post, that Roger comments that he makes more modifications than just those posted - so the posted solution on the VTR board may not be all the modifications done. Unless I knew what else he does - i.e. changing the shim stack or the valve bodies - how do you know what is posted is going to be an improvement?
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Old 10-07-2015, 04:29 PM
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I just got off the phone with Race Tech... They have some 3 port Suzuki Showa pistons (take-offs) on hold for me

They said i need 20mm OD/6mm ID valves for Superhawk forks.

I'll report back when i receive them.

James
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Old 10-07-2015, 08:10 PM
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New email reply from Roger Ditchfield.

Me:
This winter i plan to work on the stock fork legs a bit to hold me over for a while. I have fork springs on the way, and i ran into your and Cyber Carl's discussion on drilling the 1mm hole and grinding a taper into the rod (instead of the step).

Roger:
This description is 95% of all I do to the OEM forks for Street & Occasional T/Day usage. If you follow this article carefully including the set–up info it will make a real and tangible difference to the ride quality of your bike.


Me:
I was just hoping you could shed some light on why exactly you do those couple tricks, so i can understand the concepts.

Roger:
1) The purpose of tapering the damper rod is to allow a more controlled release of oil through the Rebound valve. The OEM design allows oil to bleed through initially and then as the “Step” lifts clear of the valve orifice the oil rushes through and all rebound damping is instantly lost. The mod allows for a longer and more metered oil control and therefore a more adjustable Rebound damping effect. By 2002 Honda amended the stepped taper design to a long taper on all CBR600s that used the same internal damper cartridge and damper rod as the Superhawk. Confirmation of its benefit!
2) The purpose of the bleed hole is two fold. First, it makes the “feel” more compliant with the road surface which helps build rider confidence in the front end. Second and more importantly, it alleviates the problem of “Hydro-locking” which is fairly common with the Superhawk forks. If you research Forums around the World I am sure you will find many references to this especially in the early years.

James
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Old 10-07-2015, 08:51 PM
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Thanks for sharing that James.
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Old 10-07-2015, 09:34 PM
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Thank Roger. He gave me permission to share

James
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Old 10-08-2015, 01:44 AM
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Sounds to me then, that with the 3 port Suzuki valves, the extra bleed hole is, therefore, unnecessary.
I am really interested in seeing how these Yamaha springs workout for you James. I love these cheap upgrades, that is, if they work. ;D

Last edited by Aquasnake; 10-08-2015 at 01:48 AM.
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Old 10-08-2015, 06:21 AM
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I'm pretty excited too...

Are you referring to the 1mm bleed hole that needs to be drilled in the Race Tech gold valves?

I've seen people drilling the 3 port Showa valves on other forums, so i'm still researching this aspect. Initial thoughts are the original Superhawk bleed shim may be too small in diameter because of the larger orifices.

James
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Old 10-08-2015, 07:51 PM
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The bleed shim on the standard compression valve is there to create a free bleed (I guess that was obvious) by packing the first 17mm diameter shim 0.1mm clear of the valve sealing face. The other ways to do this are the recessed slots in the face of the 3-port Showas, or a drilled hole through the valve wall so that fluid can pass around the shim stack. You only need to use one of these methods. If your Showa valves have a recessed slot(s), then don't use the bleed shim.
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Old 10-08-2015, 08:13 PM
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I'll take pics of the Showa pistons when i get them

James
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