[Pound sand]

Hello Yxz owners,

Sorry haven’t been here in awhile, tons and tons of work! Along with driving and tuning rediculous horsepowerd full size sand cars! The UTV market is exploding. More models of Polaris RZR cars, the CanAm x3, and add 4 seaters to this mix! And aftermarket Walker Evans, and Kings also! I drive and tune all these cars myself. These all must be tested and driven maytimes with lots of miles over different terrain. I don’t sell anything (shocks) in stock form.

As far as the yxz, nothing beats the revalve to get the most out of the yxz and Suspension. The stock Fox rc2 type shocks work great. Everything gets modified including the rear BOC to get a much wider spectrum of soft and firm, and smoother transition to blast those whoops and still have tons of bottom resistance.
some people like my Walker evans and or king set up also. The HCR kit uses Kings, so we bettered that set up tons. It’s nice to have shock choices.
But yes, revalve and springs to match the owner drivers needs, stock Suspension and or long travel. One size definitely doesn’t fit all. I have quite a few cars out there, get a ride or drive if you can? Then you will know exactly what your getting and how much more fun your car can be? You don’t need to believe me? The proof is in the drive and ride.

 

[Pound sand]

One of the biggest deals with the rear fox stock shocks is that the BOC, or bottom out cup is over harsh. It hits the breaks to hard and abrupt. So you end up with a compression kick in the rear. And the car does not soak up the bigger whoops and transitions as smoothly as it should. It should have a smoother transition. Some tuners are just out right eliminating the BOC altogether. We feel it is a good application once we came up with a plan to modify it and tone it down and work as a positive instead of mostly negative handling characteristics. Especially in dirt and dez.

 

[Zilla]

One of the biggest deals with the rear fox stock shocks is that the BOC, or bottom out cup is over harsh. It hits the breaks to hard and abrupt. So you end up with a compression kick in the rear. And the car does not soak up the bigger whoops and transitions as smoothly as it should. It should have a smoother transition. Some tuners are just out right eliminating the BOC altogether. We feel it is a good application once we came up with a plan to modify it and tone it down and work as a positive instead of mostly negative handling characteristics. Especially in dirt and dez.

So what's your opinion on the X2 shocks, you do anything with them or are they already perfect out of the box ?

 

[Pound sand]

So what's your opinion on the X2 shocks, you do anything with them or are they already perfect out of the box ?

Lol? Those bipass Foxes are only 2.0 main valve pistons inside. That shock has a lot of ports and small spaces and corners for the oil to travel through. This’s limits the oil speed from friction loss and takes away from the work the main valving on a larger piston should be handling. It as simple as that. The better the MAIN valving is, the better the adjustments will work on the car. Taking away main valving is not really an overall positive.
The Fox bipass shock is not new, it has been out for many years and used on full size cars. It was not close to the best. Usually to soft and required very firm valving to do its job because it is a smaller shock internally.
Can we make the stock bipass work for the Yamaha! Of course yes! We valve the stock fox bipass for the Polaris XP and stock X3RS with good results.

But i feel the non bipass yxz stock 2.5 rc2 type shock is a better shock overall and especially for the most aggressive race type driving.

Here is a 2.5 main valve piston, and a 2.0 man piston.

 

[Pound sand]

To add, for the stock X2

The stock valving is over hard right away.
Picture having just a regular firm mattress for a bed you sleep in. Nearly no padding. It’s good firm, but gets irritating because there is no plushness on top. Right? And that firm mattress is probably not that thick either. So when you jump into bed or bounce big, it bottoms out because it has no suport behind it.

The above is similar to the stock Fox valving.

So lets go get a new bed that works better and meets more of our needs. I personally like a bed that has a good plush pillow top with padding that introduces the user to a good firm thick mattress.
This is the type of valve job that goes into all our shocks. Softer beginnings mean less deflection off the terain and more control of the car.
Some tuners are valving the mattress to be softer to get the plusher ride. But that just makes it more difficult to control bottom out, and then the ride gets firm again as all the adjusters must be set to the firmest settings to compensate. Or valve to a firmer mattress to control bottom out, and suffer the harsh ride over the rough.

For both yxz Fox Compression hi/low adjusters, think of it this way. The 17mm high speed adjuster is for your “pillow top pad”
The low speed flat head screwdriver adjuster is for the “mattress”. For bottom out, you adjust the mattress, for a plusher Or rougher ride, adjust the mattress pad. Make sense anyone??
So, run that 17mm full open to start on all 4 shocks! We want the softest pad we can get with the stock valving. ONLY make adjustments using the flathead screwdriver mattress adjuster. If you end up with this adjuster full closed, then you can start using the 17mm mattress pad adjuster.
Next

The front end needs more ride hight ! And the rebound settings are to slow.
The rear is over firm to soon, and rebound is to fast.

For any one that has dirt bike or quad experience, this will make sense. Think about running through a rough or whooped out stretch. Where is your body? And throttle? Throttle is usually increased and your butt is back over the rear of seat or fender to keep some leverage on the rear end. You pull back on the bars a bit and use throttle to keep the FRONT END up and Bike level over the terrain, or else what happens??? You end up over the bars as the FRONT END DIVES and the rear high.

Same effects happen to the yxz. But we cant hang our ass over the rear fender now can we?? So we have to make adjustments to help keep the car level.
Front end needs to sit a little taller, move those crossovers lower on the shock to engage the bottom spring sooner to push the front end up sooner and faster after compression. Run faster rebound settings. Don’t forget the adjuster setting explained above. Start soft compression. But the low speed will need to be turned firm a few turns.

Rear can be started full compression soft to start. Part of the rear hop is because of over firm compression settings. (Compression hop).
Rear Rebound here will be run at much slower settings than stock to slow down the rebound after compressions. This will help keep the rear tires loaded and on the ground.
Use the rear crossover rings to help with bottom out resistance. The lower the crossover, the sooner it will engage bottom spring, and spring rate will increase much faster. This also adds to body roll control as the car is leaning on a firmer spring sooner As the crossovers come downward. rebound needs to be continually increased (slow down). Since the higher spring rates used will have more power to push and extend the shocks outward and rear end to the sky. These adjustments should be done with the compression adjusters pretty much full open. Only after these crossover and rebound settings are in a good spot can the compression setting start to get adjustments. This will get the softest ride posssible out of the stock valving.

Moto!

 

[Visionhvac1]

My shocks are awesome after your valving job for fireball long travel kit. No bottoming as fast as you want to go especially through whoops. Thanks ED the car is a blast to drive!!!!!

 

[Rocken Robin]

Just got back from three days in Arizona with Fireball LT and suspension completely redone by Pound-sand and all I can say is this man nows what he is doing . I was a little hesitant when he told me the weight of the springs he was using but he took into consideration my weight, spare tire and rotopax set up. I am impressed with this car now . It is a pleasure to drive its smooth in the chop and it will soak up a hit . Very happy with his work . THANKS ED.

 

[Rocken Robin]

I was just thinking of you Visionhvac 1 you were right about Pound sand and thanks for the feed back on your set up I basically copied yours and am very happy.

 

[JavaJack]

First, thanks very much for taking time to share your expertise. I am trying to make sense of the analogies used and what that means settings wise. Let me start by saying that I don't doubt anything you are saying as I am sure it is 100% correct. However, shock settings and crossovers are completely new to me so some of my questions will likely be quite ignorant...I'm just trying to learn. So, to ensure I am understanding your descriptions and recommendations, I would like to ask some questions and should you be so kind as to answer, it is extremely appreciated. I know the ride on my SS SE is can be vastly improved so I am hoping to gain some insight so I can improve the ride.

Open = CCW which means allowing oil to flow more freely. Result being softer ride and faster response from shock in/out?
Closed = CW which means restricting oil flow, i.e. stiffening the ride and slower response on shock in/out?

I am assuming by X2, we are talking about the SS SE shocks with the Internal bypass and everything that follows is guidance based upon that assumption.

To add, for the stock X2

The stock valving is over hard right away.
Picture having just a regular firm mattress for a bed you sleep in. Nearly no padding. It’s good firm, but gets irritating because there is no plushness on top. Right? And that firm mattress is probably not that thick either. So when you jump into bed or bounce big, it bottoms out because it has no suport behind it.

The above is similar to the stock Fox valving.

So lets go get a new bed that works better and meets more of our needs. I personally like a bed that has a good plush pillow top with padding that introduces the user to a good firm thick mattress.
This is the type of valve job that goes into all our shocks. Softer beginnings mean less deflection off the terain and more control of the car.
Some tuners are valving the mattress to be softer to get the plusher ride. But that just makes it more difficult to control bottom out, and then the ride gets firm again as all the adjusters must be set to the firmest settings to compensate. Or valve to a firmer mattress to control bottom out, and suffer the harsh ride over the rough.

For both yxz Fox Compression hi/low adjusters, think of it this way. The 17mm high speed adjuster is for your “pillow top pad”
The low speed flat head screwdriver adjuster is for the “mattress”. For bottom out, you adjust the mattress, for a plusher Or rougher ride, adjust the mattress pad. Make sense anyone??
So, run that 17mm full open to start on all 4 shocks! We want the softest pad we can get with the stock valving. ONLY make adjustments using the flathead screwdriver mattress adjuster. If you end up with this adjuster full closed, then you can start using the 17mm mattress pad adjuster.

I'm not sure I understand why the high speed settings are the pillow top pad and the low speed settings are the bottom out control. I had thought the high speed settings dictated how fast the shock would compress and rebound when driving fast over hard hitting terrain. So, I am not quite getting how a pillow top relates to high speed driving over rough terrain. Equally, I don't understand how the low speed settings equal the firm mattress. Am I thinking of this wrong?

I'm also confused by this sentence..."So, run that 17mm full open to start on all 4 shocks! We want the softest pad we can get with the stock valving. ONLY make adjustments using the flathead screwdriver mattress adjuster. If you end up with this adjuster full closed, then you can start using the 17mm mattress pad adjuster."

Does this mean CCW all the way on the 17mm (High speed) and once that is done, then start making small adjustments to the low speed. Only after you have dialed the low all the way in and cannot get the desired ride, go back to the 17mm and start adjusting?

To add, for the stock X2

Next

The front end needs more ride hight ! And the rebound settings are to slow.
The rear is over firm to soon, and rebound is to fast.

For any one that has dirt bike or quad experience, this will make sense. Think about running through a rough or whooped out stretch. Where is your body? And throttle? Throttle is usually increased and your butt is back over the rear of seat or fender to keep some leverage on the rear end. You pull back on the bars a bit and use throttle to keep the FRONT END up and Bike level over the terrain, or else what happens??? You end up over the bars as the FRONT END DIVES and the rear high.

Same effects happen to the yxz. But we cant hang our ass over the rear fender now can we?? So we have to make adjustments to help keep the car level.
Front end needs to sit a little taller, move those crossovers lower on the shock to engage the bottom spring sooner to push the front end up sooner and faster after compression. Run faster rebound settings. Don’t forget the adjuster setting explained above. Start soft compression. But the low speed will need to be turned firm a few turns.

Rear can be started full compression soft to start. Part of the rear hop is because of over firm compression settings. (Compression hop).
Rear Rebound here will be run at much slower settings than stock to slow down the rebound after compressions. This will help keep the rear tires loaded and on the ground.
Use the rear crossover rings to help with bottom out resistance. The lower the crossover, the sooner it will engage bottom spring, and spring rate will increase much faster. This also adds to body roll control as the car is leaning on a firmer spring sooner As the crossovers come downward. rebound needs to be continually increased (slow down). Since the higher spring rates used will have more power to push and extend the shocks outward and rear end to the sky. These adjustments should be done with the compression adjusters pretty much full open. Only after these crossover and rebound settings are in a good spot can the compression setting start to get adjustments. This will get the softest ride posssible out of the stock valving.

Moto!

The analogy of the bike over whoops makes perfect sense. So when you say move the crossover ring lower to engage heavy spring sooner, this means compress the heavy spring more (ie. more preload)? So, how far do you move it down? If you move it down, doesn't that opens up the tender spring more (less preload on the tender spring)?

If you change the crossover ring, you say you need to adjust the rebound. Does that mean that the steps you just did before are no longer valid? Should you do the crossover ring first so you don't have to go back and start tweaking the rebound settings again?

Yo said Rear can be started full compression soft to start. Is that the 17mm or the screwdriver? If the 17mm, didn't we do that in step 1 already?

Thanks again. I'm trying to wrap my head around the physics of each of these settings and perhaps that is the wrong way to look at it.

 

[JavaJack]

OK, doing more research...this is starting to make more sense now. My initial understanding was a bit off...so, the high speed settings do relate to how fast the shock compresses and rebounds but are not directly related to the speed of the vehicle. It is entirely related to the type of terrain and how hard/fast the terrain is making the shock move. The low speed then is related to flatter terrain that is not forcing the shock to react quickly so it is moving slower in/out in response to the terrain. So now the mattress analogy makes way more sense.

So, opening the high speed compression all the way will allow the shock to compress faster over washboard like terrain. Opening the high speed rebound all the way will allow it to reset faster. Then in the washboard whoops, it would soak up those quick, successive hits providing for a smoother ride. However, neither of the high speed settings should impact the take off of a jump or how it flies through the air, only the landing and how fast it recovers after it hits.

It should be the low speed settings (particularly the rebound) that would impact the take off and how flat it flies. So, as you hit the face of the jump as a gradual change and not a quick hit to the shock, the shock will compress and if the rebound is too open, as you leave the jump, it will donkey kick. Is that correct?

So, slowing the low speed rebound will help it fly straighter and not kick as much?

 

[Holeshot01]

OK, doing more research...this is starting to make more sense now. My initial understanding was a bit off...so, the high speed settings do relate to how fast the shock compresses and rebounds but are not directly related to the speed of the vehicle. It is entirely related to the type of terrain and how hard/fast the terrain is making the shock move. The low speed then is related to flatter terrain that is not forcing the shock to react quickly so it is moving slower in/out in response to the terrain. So now the mattress analogy makes way more sense.

So, opening the high speed compression all the way will allow the shock to compress faster over washboard like terrain. Opening the high speed rebound all the way will allow it to reset faster. Then in the washboard whoops, it would soak up those quick, successive hits providing for a smoother ride. However, neither of the high speed settings should impact the take off of a jump or how it flies through the air, only the landing and how fast it recovers after it hits.

It should be the low speed settings (particularly the rebound) that would impact the take off and how flat it flies. So, as you hit the face of the jump as a gradual change and not a quick hit to the shock, the shock will compress and if the rebound is too open, as you leave the jump, it will donkey kick. Is that correct?

So, slowing the low speed rebound will help it fly straighter and not kick as much?

From what limited knowledge I have about these shocks I believe you are on the right path, I understand the concept, I just would love to have a knowledgeable tuner around to make the adjustments......lol. Also if you ask FOX they tell you this is a "superior" shock vs the non internal bypass.....But tuners don't seem to think so?

 

[JavaJack]

From what limited knowledge I have about these shocks I believe you are on the right path, I understand the concept, I just would love to have a knowledgeable tuner around to make the adjustments......lol. Also if you ask FOX they tell you this is a "superior" shock vs the non internal bypass.....But tuners don't seem to think so?

Thanks. I will share as I learn this stuff myself. The engineer in me wants a much better understanding so I can dial this in better. As for whether it is actually better or not, I don't know. PoundSand seems to prefer the non bypass shock. I think it is because it is easier to tune without all the extra bypass ports so it provides a more consistent tuning experience. Whether other tuners feel the same way, I don't know as I haven't really spoken to others nor seen comments as such.

I plan on doing a lot of experimenting and documenting of this and will probably put it on video as I figure it out. Right now it feels a bit like a puzzle that needs to be solved.

 

[Holeshot01]

Thanks. I will share as I learn this stuff myself. The engineer in me wants a much better understanding so I can dial this in better. As for whether it is actually better or not, I don't know. PoundSand seems to prefer the non bypass shock. I think it is because it is easier to tune without all the extra bypass ports so it provides a more consistent tuning experience. Whether other tuners feel the same way, I don't know as I haven't really spoken to others nor seen comments as such.

I plan on doing a lot of experimenting and documenting of this and will probably put it on video as I figure it out. Right now it feels a bit like a puzzle that needs to be solved.

Great please share.....
I will be doing some extensive adjusting, as I am going racing, and this is what I have for now...Possibly change out springs, as just about everyone (shock tuner) wise says thats the biggest initial improvement....

 

[Rocken Robin]

Ed told me the 2.5 will hold up to compition better because they won't get as hot Because they are bigger .

 

[idiot]

From what limited knowledge I have about these shocks I believe you are on the right path, I understand the concept, I just would love to have a knowledgeable tuner around to make the adjustments......lol. Also if you ask FOX they tell you this is a "superior" shock vs the non internal bypass.....But tuners don't seem to think so?

All i can say is i have the fox x2 and i have 3 different buddies i run with and have ridden in and driven their machines that all have the rc shock and in the real world seat of the pants, the x2 is vastly superior in both ride quality and the ability of the shock to absorb big hits without bottoming or jolting the hell out of the passengers

 

[JavaJack]

It seems that Internal Bypass designs are certainly very popular as every shock manufacturer has them and promotes their qualities and a lot of professionals use IBP type shocks as well. Now, I'm sure the IBP design used in a trophy truck is probably quite a bit different than what is on the YXZ SE, but I would expect that some of the conceptual benefits would also carry over to a lower cost design like the X2. In the end though, it does not really matter to me as that is what is on my ride so that is what I have to work with and dial in. I'm not dumping the shocks to get something else, I will make what I have work for me. It is proving to be quite educational though for me and I can't wait to get out and start tweaking settings to see what the real world impact is. Should make for some interesting videos.

 

[Pound sand]

OK, doing more research...this is starting to make more sense now. My initial understanding was a bit off...so, the high speed settings do relate to how fast the shock compresses and rebounds but are not directly related to the speed of the vehicle. It is entirely related to the type of terrain and how hard/fast the terrain is making the shock move. The low speed then is related to flatter terrain that is not forcing the shock to react quickly so it is moving slower in/out in response to the terrain. So now the mattress analogy makes way more sense.

So, opening the high speed compression all the way will allow the shock to compress faster over washboard like terrain. Opening the high speed rebound all the way will allow it to reset faster. Then in the washboard whoops, it would soak up those quick, successive hits providing for a smoother ride. However, neither of the high speed settings should impact the take off of a jump or how it flies through the air, only the landing and how fast it recovers after it hits.

It should be the low speed settings (particularly the rebound) that would impact the take off and how flat it flies. So, as you hit the face of the jump as a gradual change and not a quick hit to the shock, the shock will compress and if the rebound is too open, as you leave the jump, it will donkey kick. Is that correct?

So, slowing the low speed rebound will help it fly straighter and not kick as much?

Ok Javajack!
Using the rebound will help balance the car. Faster front speed rebound coupled with slower rear speed rebound will let your car fly more level. The rear kick happens from both over hard compression and or over fast rebound. Think of rebound as faster or slower, NOT harder or softer.

And now to twist your mind some more. Two actions control how your shocks dampen. One is, the main valving that is set internally by arranging shims that flex open as fluid moves through as the shaft moves up and down with bothe compression and rebound control. Your bipass shocks have a smaller piston and less surface area to accomplish this. The external compression and rebound adjusters do not change or control this internal valving.

But these adjusters control fluid flow from the shock body into and out of the reservoir. This fluid movement comes from the shock shaft moving in and out of the shock body. Picture what happens when someone steps into a Jacuzzi full of water? Your body displaces water out of that Jacuzzi tub. Now picture a reservoir that water drops into that replaceable that water when you get out so the Jacuzzi pool is always full to the brim.

This is what your shock is doing as it compresses and extends. The main shock body is always loaded full
Of fluid. So fluid is shifting back and forth. The adjusters control or meter the speed the fluid flows back and forth from shock body to reservoir. This works in combination with the main valving.

The bipass shock adds a third concept.
Now picture your on a freeway that has 3 lanes of traffic. You moving along at 35 mph. Then you see a bipass lane approaching that adds one or two lanes to your regular 3 lane hiway. So, what happens? Traffic now is running faster and easier up until those extra lanes are taken away and all the same traffic must condense back down to 3 lanes and slower speeds.

This is exactly what is happening inside your bipass shock. A small amount of Fluid is diverted out and around the main valving so the shock can move a little faster and easier till the bipass area is taken away and the shock slows as the bipassed fluid must now join up with the full flo of fluid.

Some owners feel this is some type of superior shock to all others!? Well, not really! But people can have any opinion they like. Problem is, some of these opionions come from limited experience and loyalty bias is tossed in the mix also. It’s all good. We are not here to bash anyone’s opinions, just here to putout info for more informed choices and or opinions for our readers and vehicle owners.

Both the Fox Bipass and regular RC2 type shocks are great products. Each has its hi points and it’s lower points as compared to eachother. Depends on the intended usage. One doesn’t stand out more than the Other! (That’s another talk for another day). In the end, both shocks are a jumble of metal and parts. It comes down to how it all is managed and tuned and who does it is yet another huge piece of the pie!

 

[JavaJack]

Ok Javajack!
Using the rebound will help balance the car. Faster front speed rebound coupled with slower rear speed rebound will let your car fly more level. The rear kick happens from both over hard compression and or over fast rebound. Think of rebound as faster or slower, NOT harder or softer.

And now to twist your mind some more. Two actions control how your shocks dampen. One is, the main valving that is set internally by arranging shims that flex open as fluid moves through as the shaft moves up and down with bothe compression and rebound control. Your bipass shocks have a smaller piston and less surface area to accomplish this. The external compression and rebound adjusters do not change or control this internal valving.

But these adjusters control fluid flow from the shock body into and out of the reservoir. This fluid movement comes from the shock shaft moving in and out of the shock body. Picture what happens when someone steps into a Jacuzzi full of water? Your body displaces water out of that Jacuzzi tub. Now picture a reservoir that water drops into that replaceable that water when you get out so the Jacuzzi pool is always full to the brim.

This is what your shock is doing as it compresses and extends. The main shock body is always loaded full
Of fluid. So fluid is shifting back and forth. The adjusters control or meter the speed the fluid flows back and forth from shock body to reservoir. This works in combination with the main valving.

The bipass shock adds a third concept.
Now picture your on a freeway that has 3 lanes of traffic. You moving along at 35 mph. Then you see a bipass lane approaching that adds one or two lanes to your regular 3 lane hiway. So, what happens? Traffic now is running faster and easier up until those extra lanes are taken away and all the same traffic must condense back down to 3 lanes and slower speeds.

This is exactly what is happening inside your bipass shock. A small amount of Fluid is diverted out and around the main valving so the shock can move a little faster and easier till the bipass area is taken away and the shock slows as the bipassed fluid must now join up with the full flo of fluid.

Some owners feel this is some type of superior shock to all others!? Well, not really! But people can have any opinion they like. Problem is, some of these opionions come from limited experience and loyalty bias is tossed in the mix also. It’s all good. We are not here to bash anyone’s opinions, just here to putout info for more informed choices and or opinions for our readers and vehicle owners.

Both the Fox Bipass and regular RC2 type shocks are great products. Each has its hi points and it’s lower points as compared to eachother. Depends on the intended usage. One doesn’t stand out more than the Other! (That’s another talk for another day). In the end, both shocks are a jumble of metal and parts. It comes down to how it all is managed and tuned and who does it is yet another huge piece of the pie!

Thanks. So then what role does the preload and crossover rings play in how the car handles bumps, jumps and how it flies? I know that the preload impacts ride height but does it impact how the shock responds as well?

I also know that the crossover determines when the heavy and tender springs engage but not really clear on how changing that crossover point changes ride characteristics when jumping and bumping.

 

[sanddan52]

Poundsand, What are good starting ride heights for the X2 when used in sand? Have you looked at softer springs for the X2? The stock rates are a lot stiffer than the Eibach kit springs, I wonder if most of the tuning issues are due to over stiff springs.

Thanks for posting the info, it helps for those of us who don't have access to a tuner.

 

[Pound sand]

Thanks. So then what role does the preload and crossover rings play in how the car handles bumps, jumps and how it flies? I know that the preload impacts ride height but does it impact how the shock responds as well?

I also know that the crossover determines when the heavy and tender springs engage but not really clear on how changing that crossover point changes ride characteristics when jumping and bumping.

For preload,
For example purposes, these ARE NOT REAL NUMBERS TO USE ON YOUR CAR. let’s say you want your front middle of car to sit 15inches off the ground. You have 200 over 200 dual rate front springs. Both springs are 10 inches long. Total of 20 inches long plus 1/2 inch for the slider. Your preload is how much you must turn that top collar downwards to get the car to sit at the height you want. Say you turn that spring collar downward 5 inches, that’s 5inches off that 20 1/2. Or 5 inches from the point that the springs started to compress. With lesser rate springs means your spring rate increases at a lesser rate as the springs are compressed as you drive the car.
Say you now run 300 over 300 front springs. You may only need to preload these 2 1/2 inches to get the car to sit at the ride hight you want above. Point here is the higher rate springs can help your shocks resist bottom out and control more body roll because the firmer spring rate increases faster as the shock is compressed.
Lower or weaker spring rates will soften the ride But sacrifice bottom out and body roll. So, you may need more swaybar help to make up for weak spring rates. And valving ends up struggling to keep up also with the weak spring rates and can end up over soft or over harsh to control bottom out. valving must be set to pair up with your spring rates. If you wish higher spring rates, then the valving needs to match up so you can benefit from the higher rate springs and sometimes loose some swaybar action and gain more independence on the corners.

Crossovers enable you to decide when you want to get out of the progressively slower spring rate increases from the dual rate set up, and start increasing the spring rate more quickly as only a single spring is compressing increasing lbs per inch 2 times or more depending on the lower spring rate as compared to the top spring. These higher rates will assist the valving to slow the shock compression for bottom out resistance, and body roll and turning stability.

Helping with compression is all good and and great, but as you add higher spring rates, and or move the crossover further downward, will also increase the spring rate power to push the shock to extend outward faster!! So rebound control ( closed) must slow this down. Or make it faster (open) when weaker springs are used