Need help from the suspension guys

[Goforaride]

I posted over in the suspension forum and got a little input but I need more opinions. I am 30yrs, 5'6" 170#. 2014 yz450f. I have been struggling with this bike. I think I am a fast c rider but the suspension (mostly front) on this bike is kicking My ass and I can't maintain race pace for more than a lap or two. Forks are just way to stiff and transfer every little bump into my arms. The fc calc suggests .44 and 5.7 but a couple guys have said that .44 is to soft. Also I can't currently afford a 're valve. What are your thoughts?

[GuyGraham]

Springs only control the ride height. Its the valving whick controks how harsh ot feels.

You need a revalve to soften the compression damping

[grayracer513]

When I made you a 180 pound B rider, the calculators I used came up with .46 and 5.8.  They also recommended .44 and 5.7 for the weight/skill you listed.   If you imagine yourself improving to a B level (whether you're ever actually reclassed or not), go with the .46's and leave the rear.  Otherwise, consider replacing the springs at both ends with the lighter ones recommended.  Cut back on both high and low speed shock compression 2-3 clicks from baseline, and up about 2-3 on rebound.

 

At the front, open the compression up 2-3 from the manual listed base and start from there. 

 

The spring rate difference is enough to soften things quite a bit, but you still might want to relax the mid valve some.

[Goforaride]

I only race on occasion so I'm not actually classed. I just know that I can keep up with the fast c guys when I hit the open practice days. Currently I'm just trying to up my fitness and dial my bike in so that I can sustain speed.

At some point I am sure I will need to valve it but I can't afford to do it all at once. I can do the spring swap on my own so no shop rates there but I have never messed with valving and I am quite hesitant to attempt it on my own.

Edited June 30, 2015 by Goforaride

[grayracer513]

Springs only control the ride height. Its the valving whick controks how harsh ot feels.

You need a revalve to soften the compression damping

 

Not true.  Springs control the ride height, yes, but also the rate of suspension compression under a given weight.  For example, a 100 inch/pound spring will compress an inch for each 100 pounds of load or force applied to it.  A 200 in/lb spring, only half that far.  If both were mounted on identical bikes, each placing a 200 pound load on the spring, both could be preloaded to compress one inch under that load, but one will be noticeably softer while riding.

[Goforaride]

When I made you a 180 pound B rider, the calculators I used came up with .46 and 5.8. They also recommended .44 and 5.7 for the weight/skill you listed. If you imagine yourself improving to a B level (whether you're ever actually reclassed or not), go with the .46's and leave the rear. Otherwise, consider replacing the springs at both ends with the lighter ones recommended. Cut back on both high and low speed shock compression 2-3 clicks from baseline, and up about 2-3 on rebound.

At the front, open the compression up 2-3 from the manual listed base and start from there.

The spring rate difference is enough to soften things quite a bit, but you still might want to relax the mid valve some.

so if I were to put the .46's in front with the stock rear it wouldn't cause front to back balancing issues?

[grayracer513]

It shouldn't, not so much.  You'd only be one rate off of the recommended 5.8.  But it might still be a little stiff overall, too. 

 

Do you know how to judge the rear spring rate by checking the sag?

 

Read: http://api.viglink.com/api/click?format=go&jsonp=vglnk_14357606979728&key=fd4d0c8927dbf2331e83bbda32ac7c21&libId=ibkuu92z010004is000DL550qrjygbtju&loc=http%3A%2F%2Fwww.thumpertalk.com%2Ftopic%2F378677-common-threads-look-here-1st-mods-maintenance-common-issues-and-faqs%2F&v=1&out=http%3A%2F%2Fwww.tootechracing.com%2FStatic%2520Sag%2520Suspension%2520Tip.htm&title=Common%20Threads%3A%20Look%20here%201st!%20Mods%2C%20Maintenance%2C%20Common%20Issues%20and%20FAQ%27s%20-%20YZ%20400%2F426%2F450%20-%20ThumperTalk&txt=Use%20Sag%20to%20Check%20the%20

[Goforaride]

Yes. I am at 40mm free with 105 race. By the numbers, I could go s rate softer but I also like how the rear feels

[grayracer513]

Yeah, that shows a little heavy, but oddly, a spring too heavy can usually produce a plusher ride than a spring too light.  That's because the only compensation for too light a spring is too much comp damping, and there comes the harshness, right back in the picture.

 

In any case, you're only one step off at the rear, so I think you'll be happier at the very least with the .46's in front.  No matter what, the only way to know for sure would be to try both the .46 and the .44 and see, but that's mo' money.

[Speeddemon73]

An aftermarket lowering link does tremendous things for this bike. Pro-Circuit or Factory Connection make an aftermarket link that levels the bike out and drops the rear end about 8mm. The bikes seems to run with a stink bug stance and the link helps to level the bike out and take some pressure off the forks. I currently run the Pro-Circuit linkage on my 15' YZ450 and it helped a ton. When I asked Factory Connection what sag to run with the link, they recommended 108mm-110mm. Set my bike up with the proper spring in rear, set the sag at 108mm, and bike handles like a dream. No harshness in the forks at all. One thing to check if you are having trouble with front end harshness is tire pressure. When I first got my bike, the dealership put 19psi in the front and it felt like a rock. Check your tire pressure in the front because too much can have a negative effect on how your suspension feels.

[jcm3]

Are you the original owner of the bike?  Have you checked to ensure the spring rates are stock?

 

I bought a '14 YZ450 recently, and it had some work done to the rear (Enzo revalve with one spring rate softer than stock) and a stock front end.  The previous owner was not exactly sure what was done.

 

It would be good to verify that the suspension components are actually stock to give you a good starting point.

[Goforaride]

Are you the original owner of the bike? Have you checked to ensure the spring rates are stock?

I bought a '14 YZ450 recently, and it had some work done to the rear (Enzo revalve with one spring rate softer than stock) and a stock front end. The previous owner was not exactly sure what was done.

It would be good to verify that the suspension components are actually stock to give you a good starting point.

purchased New from dealer.

[GuyGraham]

Not true.  Springs control the ride height, yes, but also the rate of suspension compression under a given weight.  For example, a 100 inch/pound spring will compress an inch for each 100 pounds of load or force applied to it.  A 200 in/lb spring, only half that far.  If both were mounted on identical bikes, each placing a 200 pound load on the spring, both could be preloaded to compress one inch under that load, but one will be noticeably softer while riding.

 

I agree, but I was being simplistic so as to not over complicate the issue for the OP

If the valving is too much, and you put a softer spring becuase it feels harsh then, its still going to be too harsh as its the damping that is giving the harshness not the spring rate.

 

Yes the spring rate has go to be correct first, but the point I was trying to make in a simple way was that even with the correct spring rate, if the valving is too harsh then it will still feel harsh

the spring rate and the damping must be suitable for the rider weight and skill level

A trail rider will want softer damping than a SX rider

[GHILL28]

Stock rate in the rear is 6.0kg, front is.50kg.

 

Spring rates control natural frequency first and foremost, and ride height second (along with preload).  The bike is pretty well balanced in stock form, so I don't know that I'd drop the fork rate without dropping the rear as well.

 

The stock springs comes with a LOT of preload on them.  Correct that first and then see how they feel.  Back it off to about 5mm.  I found 10mm on my forks with the stock springs.

 

You're not as tall so you could get away with softer fork springs.  Taller guys usually need to stay up a rate from normal in the front because of the weight transfer.

An aftermarket lowering link does tremendous things for this bike. Pro-Circuit or Factory Connection make an aftermarket link that levels the bike out and drops the rear end about 8mm. The bikes seems to run with a stink bug stance and the link helps to level the bike out and take some pressure off the forks. I currently run the Pro-Circuit linkage on my 15' YZ450 and it helped a ton. When I asked Factory Connection what sag to run with the link, they recommended 108mm-110mm. Set my bike up with the proper spring in rear, set the sag at 108mm, and bike handles like a dream. No harshness in the forks at all. One thing to check if you are having trouble with front end harshness is tire pressure. When I first got my bike, the dealership put 19psi in the front and it felt like a rock. Check your tire pressure in the front because too much can have a negative effect on how your suspension feels.

 

Do you happen to have the exact length of that link?  I have a link for an '09 YZ450F, and I wonder if that would fit on this '14 just for shiggles.

[Goforaride]

Stock rate in the rear is 6.0kg, front is.50kg.

Spring rates control natural frequency first and foremost, and ride height second (along with preload). The bike is pretty well balanced in stock form, so I don't know that I'd drop the fork rate without dropping the rear as well.

The stock springs comes with a LOT of preload on them. Correct that first and then see how they feel. Back it off to about 5mm. I found 10mm on my forks with the stock springs.

You're not as tall so you could get away with softer fork springs. Taller guys usually need to stay up a rate from normal in the front because of the weight transfer.

Do you happen to have the exact length of that link? I have a link for an '09 YZ450F, and I wonder if that would fit on this '14 just for shiggles.

how exactly do you change the front preload?

[Speeddemon73]

Stock rate in the rear is 6.0kg, front is.50kg.

 

Spring rates control natural frequency first and foremost, and ride height second (along with preload).  The bike is pretty well balanced in stock form, so I don't know that I'd drop the fork rate without dropping the rear as well.

 

The stock springs comes with a LOT of preload on them.  Correct that first and then see how they feel.  Back it off to about 5mm.  I found 10mm on my forks with the stock springs.

 

You're not as tall so you could get away with softer fork springs.  Taller guys usually need to stay up a rate from normal in the front because of the weight transfer.

 

Do you happen to have the exact length of that link?  I have a link for an '09 YZ450F, and I wonder if that would fit on this '14 just for shiggles.

Front center of hole to center of hole its 143.5mm. Stock is 142mm.

[GHILL28]

how exactly do you change the front preload?

 

Machine off material from the top of the spring seat.

 

To measure preload, just measure the height/protrusion of the cartridge before and after you tighten the footnut (without compressing the spring, but still touching it).

 

 

 

Front center of hole to center of hole its 143.5mm. Stock is 142mm.

 

Excellent, thank you!

[Goforaride]

Machine off material from the top of the spring seat.

To measure preload, just measure the height/protrusion of the cartridge before and after you tighten the footnut (without compressing the spring, but still touching it).

yah I'm not about to do that! Beyond my mechanical comfort zone.

[GHILL28]

Get a measurement and bring it to someone then.  Takes <5 minutes on a lathe for someone to do both sides.

[GHILL28]

I fought the same compliance issues that you did and went through multiple revalves of the front end before I cut the seats.  The preload made one of the biggest noticeable changes.  It's not perfect yet, but it's a ton better than it was stock.  Feel like I wasted a bunch of effort doing valving without getting that corrected first.