Handling on a reasonable budget

[ZG]

Then again the Ohlins setup would be nice if I were as rich as Jay.

Nope, not rich TJ, just priorities... Ohlins suspension and PB&J/TopRamen for all meals... 

[556ALPHA]

So what do you have on the horizon?   

[tim61]

Sorry for the delay. The holidays always seem to put my projects on hold!!

Anyhow...here are the numbers. The fork revalve kit which replaces the compression and rebound cartridges with ones that are much more adjustable runs $186.00. The replacement fork springs run $110.00. With labor, seals, oil, waste fees, etc. the total for the fork mod installed is $361.00.

For that amount you get adjustable compression, rebound, and quality progressive fork springs. Barry convinced me tire life would be improved through better, more accurate fork control.  While I am no expert, if I understand correctly, the stock set-up is a series of compromises that leads to excessive tire wear. The stock for has limited damping control. So, as a band-aid, Kawasaki installs a really stiff spring in an attempt to control compression, but that heavy spring in turn puts heavy loads on the tire. With better control of the damping, you can run a lighter spring and put less force on the tire.

The shock I am going to try is the new Penske 8975 series. This shock has adjustable compression and rebound without the need for an external resevoir. Too cool! It has the new "floating piston" design, with adjustable preload, adjustable rebound, adjustable compression, and adjustable high speed compression. And we ordered it with the all important adjustable ride height.

The 8975 runs $725.00. The adjustable ride height option is an additional $75.00. Pretty amazing when you consider that entry level aftermarket shocks like Progressive run something like $500-$600.

In order to get a fair comparison, I am not replacing everything all at once. One thing I learned from years of racing is that you don't want to change more than one thing at a time, so you know if it worked or not! First up, I am going to re-install the forks and ride it a few weeks with the stock shock. Then I will add the shock and see how that changes things.

Lastly, I want to be clear I am not trying to start a debate on GP vs. Traxxion, Ohlins vs. Penske, etc., etc. I am just reporting what I have tried. I am certain there are many options on the market that can improve upon the OEM suspension.

Ok, now back to the shop. This forum stuff takes way too much time away from wrench stuff!

Happy New Year!

Tim

[gPink]

Thanks for the update Tim. Keep'em coming.

[Daytona_Mike]

Thanks so much for the update. I spent yesterday riding my C14 down to Titusville for the Last Blast and today I rode my C10 on the same roads.

The C10 , (all upgraded suspension) is much more compliant than the stock c14 (and I have stiff  1.2kg front springs with gold emulators and a new ZZR1200 rear shock which I think I will sell and put back the Progressive shock I just removed-the Progressive is better)

So what I am saying is I gotta do something with this C14. I miss the C14's power  when I ride the my C10 and I miss the compliant ride on bumps when I am on the C14. The C14 is pounding  me constantly.
So , I think I need to start with the easy one, the rear spring/shock.  $725+ 75 for ride height option or  $1,0xx.00 for the Ohlins? hmmm.. what to do?   
I thought pre-load and ride height were the same thing.

[stevewfl]

http://www.zggtr.org/index.php?topic=10019.0

[jsa]

Anyhow...here are the numbers. The fork revalve kit which replaces the compression and rebound cartridges with ones that are much more adjustable runs $186.00. The replacement fork springs run $110.00. With labor, seals, oil, waste fees, etc. the total for the fork mod installed is $361.00.

For that amount you get adjustable compression, rebound, and quality progressive fork springs.

The shock I am going to try is the new Penske 8975 series. This shock has adjustable compression and rebound without the need for an external resevoir. Too cool! It has the new "floating piston" design, with adjustable preload, adjustable rebound, adjustable compression, and adjustable high speed compression. And we ordered it with the all important adjustable ride height.

The 8975 runs $725.00. The adjustable ride height option is an additional $75.00.

Thank you for the update.  How are you getting adjustable compression damping on the forks?  Is this similar to Traxxion with compression adjustment on one leg and rebound adjustment on the other leg?

Regarding the shock, I have reviewed all of Penske's literature about the 8975 and can't find anything indicating that it has adjustable high speed compression damping, it is actually called the Street Double which also suggests there are only 2 damping adjustments.  Does the $725 price include the $75 ride height option?  The reason I am asking is that it isn't too hard to find the 8983 with external reservoir and ride height option for $800 or a little less.

[tim61]

Thank you for the update.  How are you getting adjustable compression damping on the forks?  Is this similar to Traxxion with compression adjustment on one leg and rebound adjustment on the other leg?

Regarding the shock, I have reviewed all of Penske's literature about the 8975 and can't find anything indicating that it has adjustable high speed compression damping, it is actually called the Street Double which also suggests there are only 2 damping adjustments.  Does the $725 price include the $75 ride height option?  The reason I am asking is that it isn't too hard to find the 8983 with external reservoir and ride height option for $800 or a little less.

I got the info I posted directly off of Penske literature. It says Adjustable Rebound (40 clicks+), Adjustable Compression (40 clicks+), and Adjustable High Speed Compression (65 clicks). I don't actually have the shock in my hands yet, so I can't verify the literatures claims.

The adjustable compression and rebound in the fork kit is accomplished through shim stacks in the cartridges. The rebound damping is adjusted the same as a stock fork with the adjuster mounted on the fork cap. The compression adjustment is achieved through altering shims in the compression cartridge. It is not externally adjustable like a ZX1400. This mod would have been prohibitively expensive. And the damping adjustments are the same for both forks.

Tim

P.S. The shock is $725. The ride height adjustment option is an additional $75

[tim61]

Thanks so much for the update. I spent yesterday riding my C14 down to Titusville for the Last Blast and today I rode my C10 on the same roads.

The C10 , (all upgraded suspension) is much more compliant than the stock c14 (and I have stiff  1.2kg front springs with gold emulators and a new ZZR1200 rear shock which I think I will sell and put back the Progressive shock I just removed-the Progressive is better)

So what I am saying is I gotta do something with this C14. I miss the C14's power  when I ride the my C10 and I miss the compliant ride on bumps when I am on the C14. The C14 is pounding  me constantly.
So , I think I need to start with the easy one, the rear spring/shock.  $725+ 75 for ride height option or  $1,0xx.00 for the Ohlins? hmmm.. what to do?   
I thought pre-load and ride height were the same thing.

Spring pre-load and ride height are not the same, although I can see how they could be confused. The pre-load is used to set your suspension sag, while the ride height can raise (or lower) the back of the bike, thereby changing the effective rake of the front fork geometry. You could acheive that by cranking up the preload, but then it would be sprung too stiff and would no be compliant. The correct way would be to set your suspension sag with the pre-load, and alter the height with the ride height adjuster. Basically, the adjuster lengthens or shortens the oevrall length of the shock.

Gawd, that almost sounds like I know what I am talking about! I don't, really. But I know if you can raise the back of the bike, a couple cool things can happen. You can transfer more weight to the front of the bike, so it turns in better, and you can steepen the rake, so the bike turns in quicker and can flip back and forth quicker and easier. All the way up to the point where you raise it too far and it gets real nervous under hard braking or at high speeds.

The simple explanation is that on all my really good race bikes, the final icing on the cake came when we got the ride height dialed in. That is when the real magic happened, because everything becomes very balanced and stable, yet quick and aggressive.

Tim

[tim61]

http://www.zggtr.org/index.php?topic=10019.0

That is a REALLY cool set-up! I have a very similar suspension on my 2006 Honda RS125GP. And I absolutely love it.

But, it is also more than double what I was hoping to spend on my street bike. But, if you have the cash, it is pretty hard to go wrong with a full race suspension!

Tim

[jsa]

I got the info I posted directly off of Penske literature. It says Adjustable Rebound (40 clicks+), Adjustable Compression (40 clicks+), and Adjustable High Speed Compression (65 clicks). I don't actually have the shock in my hands yet, so I can't verify the literatures claims.

The adjustable compression and rebound in the fork kit is accomplished through shim stacks in the cartridges. The rebound damping is adjusted the same as a stock fork with the adjuster mounted on the fork cap. The compression adjustment is achieved through altering shims in the compression cartridge. It is not externally adjustable like a ZX1400. This mod would have been prohibitively expensive. And the damping adjustments are the same for both forks.

Its not worth arguing about but when I go to the Penske website (http://www.penskeshocks.com/Motorcycle-8975_Series.php) the 8975DB shock has only two damping adjustments.  The shock you are describing sounds like the 8970 Formula One Shock which has an external reservoir and costs about $1600.   As you said, we will find out when you have the shock in your hands.  Regarding the forks, I don't know how you can say they have adjustable compression damping when the only way to change that damping is to change the internal shim stacks, and that is commonly referred to as re-valving.

[jsa]

Spring pre-load and ride height are not the same, although I can see how they could be confused. The pre-load is used to set your suspension sag, while the ride height can raise (or lower) the back of the bike, thereby changing the effective rake of the front fork geometry. You could acheive that by cranking up the preload, but then it would be sprung too stiff and would no be compliant. The correct way would be to set your suspension sag with the pre-load, and alter the height with the ride height adjuster. Basically, the adjuster lengthens or shortens the oevrall length of the shock.

Gawd, that almost sounds like I know what I am talking about! I don't, really.

No, you really don't.  Preload does not make a spring stiffer (http://www.sonicsprings.com/catalog/preload_tech_article.php), it just changes the amount of force it takes to initially make the spring compress.  Once the rider's weight is put on the shock, the spring's total compression will be the same as it was before the spring was preloaded.  Preload does change suspension sag but the purpose of setting sag is to achieve the correct ride height after the rider's weight is added (sag also tells you how much travel is being used and how much is left).  You can achieve the same result by using a ride height adjuster although preload has a secondary benefit in that it increases the amount of available travel after the riders weight is added.....which allows the spring to compress further (than before preload)....and that gives more spring resistance at the end of the stroke....helping to prevent the suspension from bottoming if the spring rate is softer than it should be.

If you are using the correct spring rate then your sag should also be correct, bottoming should not be a problem, and ride height (assuming you have ride height) should be used to fine tune the steering geometry.

[Daytona_Mike]

Ok. Thanks jsa.  I got it now. I had to read some more to understand ride height. Most every bike does not have a ride height adjustment so we use pre-load to do two things. Set the sag correctly which puts the stroke of the shock in the  correct position for proper travel. You don't want to run out of travel up or down but you do want to try and use most or all of it.  Hopefully when using the correct rims and tires the ride height is close after setting the correct sag because most of us dont have a ride height adjustment.
Ride height adjustor  leaves the sag the same but changes the chassis geometry. That makes sense. I may want to use very low profile tires (or smaller diameter rim) so I would need to increase ride height to restore proper geometry and not change the sag as that was already correctly setup.
Got it!!     

[stewart]

Subscribed.

I'm interested to hear the results...saving my pennies to do something.

[slerickson]

 Just reading this it sounds a little odd but I dont know enought to even be dangerouse. Please post up some info.

[tim61]

The forks are installed and I have only had a chance to ride it once, so I won't comment on my impressions yet. But, lets just say things are looking VERY favorable at this point.

Tim

[tim61]

Wow! I can't believe it has been 11 months since my last post!

UPDATE.....

I decided to install the modded forks and Penske shock and leave everything else as is. Didn't want to throw on new tires and then tell everyone how awesome the suspension is. So I left the shagged, cupped Road 3's.

First thoughts were that the suspension is much more supple over typical pot holes, cracks, bumps, etc. after about 500 miles, I had pretty. Uh decided I was happy with the changes. Then, an interesting thing started to happen....

The cupped out Road 3's started wearing round again. No kidding. In fact, to date I have put over 4,000 additional miles on them!!! And they have worn perfectly round again...no cupping. Granted the tread is getting thin, and I will be spooning o. A fresh set soon, but....DAMN! 4,000 more miles???!!!! I never would have guessed.

I quizzed Barry on why they would wear like that. He told me the Concours is way over sprung in stock configuration. Once he put in lighter fork springs, and a lighter spring on the Penske, the suspension moves over small stuff easier, rather than pushing the tread blocks, distorting them and causing cupping.

Pretty cool! I am completely satisfied with the transformation. I have had the bike othe local race track at a decent clip, and have gone for day long rides. It excels at both, although it could use a few hundred pound weight reduction for the track days!!!

All in all, I would rate this mod as a complete success!!!!!

TimO

[VirginiaJim]

Wow! I can't believe it has been 11 months since my last post!

Neither can we!  Thanks for the update.

[pistole]

Barry convinced me tire life would be improved through better, more accurate fork control.  While I am no expert, if I understand correctly, the stock set-up is a series of compromises that leads to excessive tire wear

You mentioned the above almost a Year ago. Seems to fit with what you are reporting now.

.

[maxtog]

The cupped out Road 3's started wearing round again. No kidding. In fact, to date I have put over 4,000 additional miles on them!!! [...]I quizzed Barry on why they would wear like that. He told me the Concours is way over sprung in stock configuration. Once he put in lighter fork springs, and a lighter spring on the Penske, the suspension moves over small stuff easier, rather than pushing the tread blocks, distorting them and causing cupping.

My tires are cupping now.  Fascinating.  So in the long term, the money spent on changing the fork springs might actually pay for itself in having to buy/balance/mount fewer tires?