Front suspension upgrade-terminology/questions etc

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jc100

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Apologies if this should be in technical-I thought the subject matter might help those with suspension set ups like mine.

Looking to see about cheap suspension upgrades for the front end of my Z750S since I just found myself a cheap 636 rear shock to swap in to do the rear suspension.

My Z750S (06) doesn't seem to have any options for adjusting the front suspension.

A couple of questions:

What's an emulator (emulator valve)?
What's the benefit of swapping the stock springs out for new springs from a different manufacturer? What types of springs are popular etc?
What's a preload kit?

Given all the choices what's the best bang for the buck improvement over stock I can get?

Other info: I'm 195lbs and my budget is around $200...less if I can get away with it but I'd spend a little more if I were to see a massive improvement.

What am I looking for? Just an improvement overall, I know my bike came with cheap suspension items so I'm looking to add a little adjustment etc for my riding style/weight.

Thanks.
 
I'm not sure $200 is worth the investment over stock. The best thing you can do is to get the correct spring for your weight if you're riding aggresively. You can go to the Racetech website and get the "correct" spring for your weight. You also should revalve the fork for the spring to control it. This will give you some adjustment for rebound and compression damping. I don't think you can do both for $200..that's about the price of the springs alone.

Same goes for the back..you might be able to get a used unit..or your stock may be rebuildable..but you should change the spring for your weight. You want to make sure the suspension is balanced..both ends working correctly..or you'll get some mystery handling.
 
The Racetech spring rates suggested are predicated on you getting the whole package. Generally it's not a big deal for the shock unless it's reallllly old, but for the forks it makes a big difference.

Stock forks that use a damping rod are generally undersprung. This is to offset the fork's tendency to react stiffly/harshly to bumps or other high speed movement. This is also the reason why bikes with damping rod forks dive more under braking. If you get Racetech springs according to your weight without installing the fork emulators, your bike will now react even worse over bumps.

Not sure what a preload kit is, I haven't heard of anything by that name before.
 
swap a set of 636 forks on, and forget about the crappy damping rod setup that bike comes with.

The 636 has a true cartridge fork and is FAR superior in OEM trim than your original fork will ever be, no matter how many parts and how much money you throw at it.
 
reciprocity said:
swap a set of 636 forks on, and forget about the crappy damping rod setup that bike comes with.

The 636 has a true cartridge fork and is FAR superior in OEM trim than your original fork will ever be, no matter how many parts and how much money you throw at it.
Click to expand...

OK I've read about that mod too but it looks a little complicated-ish. Or is it?

Checking Ebay and they seem to be running about $450ish with delivery including the lower triple tree. That's a little too rich for me right now unless there's a cheaper source for these things.
 
reciprocity said:
swap a set of 636 forks on, and forget about the crappy damping rod setup that bike comes with.

The 636 has a true cartridge fork and is FAR superior in OEM trim than your original fork will ever be, no matter how many parts and how much money you throw at it.
Click to expand...

Listen to this, he's spot on. I used to ride an SV650s, and the best investment I made was buying a used 20xx ZX10R rear shock for $80 on Ebay. I forgot the year, but it was exactly the same length as the stock SV one, even the dog bones fit. A whole lot of modding later, I had a superb rear end setup on my bike.

The problem is that i went with a cartridge emulator and progressive springs on the front tailored for my weight. Yes, they stiffened up my suspension, but the bike still felt like a pogo stick. I know the geometry is different, but on my new GSXR600 the front suspension is soooooooo much better even though it's still stock.

So save up some more money and get real 636 forks and whatever else you need. You won't regret it.

Edit: I noticed the kit you linked doesn't even have progressive springs. You'll likely not see any difference over stock except harder springs.
 
jc100 said:
OK I've read about that mod too but it looks a little complicated-ish. Or is it?

Checking Ebay and they seem to be running about $450ish with delivery including the lower triple tree. That's a little too rich for me right now unless there's a cheaper source for these things.
Click to expand...

Check Cherrypickerracing.com

or ask some of the stunters, there is TONS of this stuff hanging around in canada.
 
OK I checked a little...it's not just the forks to swap out is it?....need new calipers, wheel..upper triple tree, rotors and fender...optional brake line upgrade to make use of the better brakes etc. Looks to be about $700ish. Swapping the forks means swapping for an entire front end?

Seems although the forks fit in OK, the wheel bearings and axle are different and an upper yolk(?) (is that the top triple tree??) is needed.
 
Yes, I believe you need the whole front end.

There was a comment made above that the springs were not "progressive". You don't want progressive springs if you're the rider dedicated to that bike. Progressive springs are okay for situations where you don't know the weight of the rider because they'll resist bottoming a bit more, but that's the only advantage. They have a higher spring rate when the suspension is compressed. Straight-rate springs that are correctly selected for the rider's weight and riding style are a better choice. Relative to a progressive spring, straight-rate springs are more compliant when the suspension is compressed (leaned over in a corner - when you need the compliance). They're stiffer when the suspension is not compressed, but so what, it doesn't matter so much. The downside, of course, is that if you change the weight of the rider, you really ought to change the springs to the proper spring rate for the new rider weight.

Every (serious) race bike has straight-rate springs in it ...
 
The positive thing about the front-end swap is that the fork will actually work well. And you'll get some extra goodies along with it. If you go the Racetech emulator route, it will work ok but it's probably going to cost you the same amount of money in the end. That Recipe is a clever fellow..don't let his predilection for sammidges fool you.. :-)
 
I'd love to do the fork swap but I don't think I have that kind of cash lying about. It's coming up to valve adjustment time for the bike and I was going to have them do a few other small bits and pieces while it's in the shop. I was thinking they could install new springs for the front and swap out the shock in the back for the one I bought. If by some miracle I can lay my hands on the right parts super cheap I'll still do it but that's looking unlikely unless a 636 ridden by some charitable angel gets rear ended in front of me.
 
Brian P said:
Yes, I believe you need the whole front end.

There was a comment made above that the springs were not "progressive". You don't want progressive springs if you're the rider dedicated to that bike. Progressive springs are okay for situations where you don't know the weight of the rider because they'll resist bottoming a bit more, but that's the only advantage. They have a higher spring rate when the suspension is compressed. Straight-rate springs that are correctly selected for the rider's weight and riding style are a better choice. Relative to a progressive spring, straight-rate springs are more compliant when the suspension is compressed (leaned over in a corner - when you need the compliance). They're stiffer when the suspension is not compressed, but so what, it doesn't matter so much. The downside, of course, is that if you change the weight of the rider, you really ought to change the springs to the proper spring rate for the new rider weight.

Every (serious) race bike has straight-rate springs in it ...
Click to expand...

So would the Matris spring kit with preload options and a spring for my weight be a decent option? (There's a link above in one of my other posts) This is 150 euros or so and seems like it might be a decent stopgap? Would this be way better than stock or only a slight improvement?
 
I "refreshed" my VFR suspension with Racetech Gold valves and new springs and I still can't believe the difference.
It carves like a knife through butter.
About $400.
 
reciprocity said:
Check Cherrypickerracing.com

or ask some of the stunters, there is TONS of this stuff hanging around in canada.
Click to expand...
also pm ac in this board, he tends to have 636 parts laying around
 
If you want to stick to your $200 limit....

Buy a couple of suspension books = $50 each
Buy a shop manual for you model = $50 ( it was for mine )
Take the time to study them until you understand how suspensions work= $0
Change the oil in your forks and adjust the oil level to your liking/needs = $40
Adjust the suspension compression and rebound damping settings and record the changes = $4 (for a pen and note book)

Send me the left over $6 for this valuable guidance.

If you really want to tune your suspension in to suit you, you can easily spend an entire riding season tweeking it for free. You will become a better rider as your make the suspension do what the bike is designed to do. I doubt many of us here can our-ride our stock suspension.

As you become comfortable with one setting you will want to change it because your riding ability grows and you will need to adjust the settings.

Then you can have something worth more than $200 invested - you will have knowledge about your sport.
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