Spring change or Aero

[White Snake]

So, i recently installed a set of KW shocks from a Gen 4 ACR-E on my Gen 5 GTS...
Now, I knew that the ride quality was going to suffer but what I did not realize was that the car would become scary to undriveable on the streets. Weight transfers are sudden and unpredictable...any bump at 110 or above might as well be a ramp pointing you to the nearest tree.
I have set the shocks to the "softest" settings but that simply does not help at all.
My quandary is this:
Replacement springs so that the rates are more in line with what a GTS should be OR drop 25k on all of the aero needed to remedy this issue OR just reinstall the original shocks.
Cheapest option is to reinstall the old set up (minus the 3k spent on the new shocks)
Mid-option is to replace the springs on the KW's (i assume someplace in the 2k area)
Full aero (which I do love the look of) but good lord the cost...(25k Min).

So, if I do decide to replace the springs, to whom would I speak to about this and what rates would be recommended?

[pMak26]

Step one, what rate springs are on the KWs you installed? Once you know this, a call to KW would be in order. Have your serial number handy and ask them about the valving in the setup you purchased.

[13COBRA]

Why did you switch to KW from the factory ones?

[SRT_BluByU]

want to be totally happy.. put back to stock, sell and buy ACR-E.. that might do it.. ;)

[Lawineer]

Something is wrong. I have ACRE spring rates in my GTS. It's harsh, bit it's fine. I just have an AP lip splitter, side skirts, diffuser and a TA spoiler.

Aero or not, under 70mph, you wont see much difference in weight on the springs.

Are you sure your alignment is good?

You might even be underdamped. Very stiff springs + very soft shocks can be a bad combo.

[Steve-Indy]

Just curious...What is a "Gen IV ACR-E"?

[RedTanRT/10]

I had KW's on my G3 coupe and had to play around with the spring rates. they were better on the track than the stock G3 set up.

I'm thinking you bought them to lower your Viper? Did you have your Viper aligned and corner balanced after the install?

Spring changes are fairly inexpensive. I know some of the KW models have the DIY spring swap option, one of their variants needs a crazy tool to get the spring off and you have to find someone who has that, or send them back to KW. If you can get the spring out, plenty of optional springs at $100 each from Hyperco or Eibach. Good luck, Mike

[TKO MOTORSPORTS TEAM]

So, i recently installed a set of KW shocks from a Gen 4 ACR-E on my Gen 5 GTS...
Now, I knew that the ride quality was going to suffer but what I did not realize was that the car would become scary to undriveable on the streets. Weight transfers are sudden and unpredictable...any bump at 110 or above might as well be a ramp pointing you to the nearest tree.
I have set the shocks to the "softest" settings but that simply does not help at all.
My quandary is this:
Replacement springs so that the rates are more in line with what a GTS should be OR drop 25k on all of the aero needed to remedy this issue OR just reinstall the original shocks.
Cheapest option is to reinstall the old set up (minus the 3k spent on the new shocks)
Mid-option is to replace the springs on the KW's (i assume someplace in the 2k area)
Full aero (which I do love the look of) but good lord the cost...(25k Min).

So, if I do decide to replace the springs, to whom would I speak to about this and what rates would be recommended?

First thing you have to figure out is what is exactly causing the problem. Was the car ok before changes? What changes did you do exactly?

You dont want to make spring changes until you check the basic easy stuff first. Start with the basics ( foundation) control arm bushings are good, ball joints good, steer rack is all good, stability control good, etc then move one
"weight transfers are sudden and unpredictable" taking the compression out will only make that problem worse ......" any bump at 110 or above might as well be ramp pointing you to nearest tree" this is most likely a bump steer problem or bad setup zero toe or not enough toe. There is a very small possibility of internal tire damage causing problems.

[White Snake]

Why did you switch to KW from the factory ones?

I was looking for a set up that would allow for dampening/recoil and slight height adjustments; those shocks were developed for the Viper by KW...and well the price from the seller was pretty good; no real reason to choose KW over any others on the market.

[White Snake]

Something is wrong. I have ACRE spring rates in my GTS. It's harsh, bit it's fine. I just have an AP lip splitter, side skirts, diffuser and a TA spoiler.

Aero or not, under 70mph, you wont see much difference in weight on the springs.

Are you sure your alignment is good?

You might even be underdamped. Very stiff springs + very soft shocks can be a bad combo.

I will need to verify the alignment...I did notice a slight pull to the passenger side, thanks for the reply!

[White Snake]

I had KW's on my G3 coupe and had to play around with the spring rates. they were better on the track than the stock G3 set up.

I'm thinking you bought them to lower your Viper? Did you have your Viper aligned and corner balanced after the install?

Spring changes are fairly inexpensive. I know some of the KW models have the DIY spring swap option, one of their variants needs a crazy tool to get the spring off and you have to find someone who has that, or send them back to KW. If you can get the spring out, plenty of optional springs at $100 each from Hyperco or Eibach. Good luck, Mike

No, I have not done a corner balance and alignment could be off; thanks for info!

[White Snake]

First thing you have to figure out is what is exactly causing the problem. Was the car ok before changes? What changes did you do exactly?

You dont want to make spring changes until you check the basic easy stuff first. Start with the basics ( foundation) control arm bushings are good, ball joints good, steer rack is all good, stability control good, etc then move one
"weight transfers are sudden and unpredictable" taking the compression out will only make that problem worse ......" any bump at 110 or above might as well be ramp pointing you to nearest tree" this is most likely a bump steer problem or bad setup zero toe or not enough toe. There is a very small possibility of internal tire damage causing problems.

So the car was just fine before the changes, there was obviously some room for improvement in the system and this what I was after.
When we pulled the shocks, we did take a look at the adjacent components/bushings control arms but did not see anything that would warrant replacement…everything seemed pretty solid and behaved as it should.
Thank you for the insights, I will certainly take the car into a place around here that can help me get things dialed in a lot better.

[Hawk]

Fyi

52378

[Lawineer]

First thing you have to figure out is what is exactly causing the problem. Was the car ok before changes? What changes did you do exactly?

You dont want to make spring changes until you check the basic easy stuff first. Start with the basics ( foundation) control arm bushings are good, ball joints good, steer rack is all good, stability control good, etc then move one
"weight transfers are sudden and unpredictable" taking the compression out will only make that problem worse ......" any bump at 110 or above might as well be ramp pointing you to nearest tree" this is most likely a bump steer problem or bad setup zero toe or not enough toe. There is a very small possibility of internal tire damage causing problems.

100% this.


Try this if there's a place you can do it safely.
Go fast and slam on the brakes (in a safe place). Does it pull hard to one side?
Keep in mind when you're doing this, IT MAY JERK TO ONE SIDE.

When I got my car, I was told it was recently aligned. It seemed fine because it drove straight in a line, but fuck was it fidgety and a bit squirly. Being my first Viper, let alone G5, I figured this was the "viper death trap" reputation. Plus it was on lowering springs, so I figured it was that.
My first lap at the track, where it has a hard right braking zone under compression, the car jerked to the right. Got it aligned and it was "lol, wtf, lmfao" off. It just, somehow, drove straight and didn't really show under "street loads". Under real load though, shit went in all kinds of directions.

[Mikey]

100% this.


Try this if there's a place you can do it safely.
Go fast and slam on the brakes (in a safe place). Does it pull hard to one side?
Keep in mind when you're doing this, IT MAY JERK TO ONE SIDE.

When I got my car, I was told it was recently aligned. It seemed fine because it drove straight in a line, but fuck was it fidgety and a bit squirly. Being my first Viper, let alone G5, I figured this was the "viper death trap" reputation. Plus it was on lowering springs, so I figured it was that.
My first lap at the track, where it has a hard right braking zone under compression, the car jerked to the right. Got it aligned and it was "lol, wtf, lmfao" off. It just, somehow, drove straight and didn't really show under "street loads". Under real load though, shit went in all kinds of directions.

Hmm, did it tend to grab on to every dip and curve in the road? I've had two alignments and the shittier the road, the more I have to fight to keep it straight

[Lawineer]

Hmm, did it tend to grab on to every dip and curve in the road? I've had two alignments and the shittier the road, the more I have to fight to keep it straight

That *can* be an alignment problem, but it could also just be an aggressive alignment. The symptom in and of itself isn't worth much diagnostic value. I *think* it's the toe that can cause that. It makes the tire want to "grab" into road groves. Obviously, you don't want zero toe on a performance setup. I had a more aggressive alignment with my C7 and it was a handful down a highway.
That's distinct from jerking to the side over bumps.


I will need to verify the alignment...I did notice a slight pull to the passenger side, thanks for the reply!

Does this mean you installed them and didn't realign the car? If so, I'd bet Darts to ACR's this is your problem.
Stiff springs won't cause the car to change direction over bumps like you're describing. It's a result of suspension geometry changing and going in different directions than what you want (such as bump steer as TKO pointed out).

What's probably happening over bumps is you are unloading the suspension and then loading the whole thing again and 4 different tires are twisting into 4 different directions.

Really, going straight is not at all a good indicator that your car is properly aligned. Heck, if it's going straights it's probably NOT well aligned as roads are crowned, divited, etc.

[Aevus]

So, i recently installed a set of KW shocks from a Gen 4 ACR-E on my Gen 5 GTS...
Now, I knew that the ride quality was going to suffer but what I did not realize was that the car would become scary to undriveable on the streets. Weight transfers are sudden and unpredictable...any bump at 110 or above might as well be a ramp pointing you to the nearest tree.
I have set the shocks to the "softest" settings but that simply does not help at all.
My quandary is this:
Replacement springs so that the rates are more in line with what a GTS should be OR drop 25k on all of the aero needed to remedy this issue OR just reinstall the original shocks.
Cheapest option is to reinstall the old set up (minus the 3k spent on the new shocks)
Mid-option is to replace the springs on the KW's (i assume someplace in the 2k area)
Full aero (which I do love the look of) but good lord the cost...(25k Min).

So, if I do decide to replace the springs, to whom would I speak to about this and what rates would be recommended?

Unless your rear spring rate is way above 1000, do yourself a favor and just get a bump steer correction kit from TKO. Then make a proper alignement with 7.5+ front caster (will limit camber to roughly -1.2), unless you track your car a lot and need that extra camber.

Will be day and night.

[White Snake]

Thanks again to everyone that replied, it has given me a lot of food for thought! I at least now have a road map for what order I will attach these issues!

[LATAMUD]

So, i recently installed a set of KW shocks from a Gen 4 ACR-E on my Gen 5 GTS...
Gen4 ACR or ACR-X?

The "ACR-X" KW3 shocks had stiffer spring rates than the base ACR.

[Arizona Vipers]

Let us know the spring rates. If you posted them for some reason I'm not seeing it. Once you post those I can try and help, I have done extensive spring rate testing. I can say small changes make a HUGE difference in how the car handles and puts the power down.

[str5010]

Gen IV ACR KWs
Front: 514 lbs/in
Rear: 1085 lbs/in

Gen IV ACR-X KWs
Front: 800 lbs/in
Rear: 1480 lbs/in

[Fulltilt]

Since it was brought up, does the TKO bump steer kit help? I've never heard anyone talk about this kit but I can't be the only one that is annoyed by the bump steer in these cars. I hate the fact my wheels sit nearly 2" inside the the wheel well but I know putting wheel spacers on will only make the bump steer worse.

[Arizona Vipers]

Gen IV ACR KWs
Front: 514 lbs/in
Rear: 1085 lbs/in

Gen IV ACR-X KWs
Front: 800 lbs/in
Rear: 1480 lbs/in

I wonder if the OP can see the model number on the springs on his car. They are on Eibach's and H&R's etc. If my car had 1480's it would be undrivable for me. The stock 1300's are ridiculous, I'm running 1200 now to not bottom out, but my car would be much faster with 900-1000 and some kind of setup to not bottom out.

[Aevus]

Since it was brought up, does the TKO bump steer kit help? I've never heard anyone talk about this kit but I can't be the only one that is annoyed by the bump steer in these cars. I hate the fact my wheels sit nearly 2" inside the the wheel well but I know putting wheel spacers on will only make the bump steer worse.

check out my thread ''Keeping the snake straight''

https://driveviper.com/forums/threads/28891-Keeping-the-Snake-STRAIGHT?p=446028&viewfull=1#post446028

I don't know about other gens, but the Gen 3's design and geometry is downright faulty. Every single gen 3 Viper on the road or on the track should be equipped with bump steer correction kit, TKO or else.

Of course good tires helps and in my opinion if you don't track the car, reduce front camber to push the max caster possible (9+ possible on some cars), stock alignement specs are NOT the ultimate answers at all.


also that thread:

https://driveviper.com/forums/threads/29069-TKO-bump-steer-correction-kit-Review?p=446031&viewfull=1#post446031

[Aevus]

I wonder if the OP can see the model number on the springs on his car. They are on Eibach's and H&R's etc. If my car had 1480's it would be undrivable for me. The stock 1300's are ridiculous, I'm running 1200 now to not bottom out, but my car would be much faster with 900-1000 and some kind of setup to not bottom out.

yeah, anything north of 1,000 is probably very difficult to enjoy, especially if you don't have the aero to justify it.

I ordered 950's Hyperco for my Penske double, I hope I won't regret it since it will be 100% street....

[Lawineer]

Did the OP check his alignment?
Fwiw I have acr spring rate and not much aero (side skirts, chin spoiler, ta spoiler) and it’s fine. Keep in mind, the gts is a good bit more sprung mass than the acr iirc so that probably helps a little, too.

[13COBRA]

I wonder if the OP can see the model number on the springs on his car. They are on Eibach's and H&R's etc. If my car had 1480's it would be undrivable for me. The stock 1300's are ridiculous, I'm running 1200 now to not bottom out, but my car would be much faster with 900-1000 and some kind of setup to not bottom out.

Why not run 900s and a spring stop?

[TKO MOTORSPORTS TEAM]

Since it was brought up, does the TKO bump steer kit help? I've never heard anyone talk about this kit but I can't be the only one that is annoyed by the bump steer in these cars. I hate the fact my wheels sit nearly 2" inside the the wheel well but I know putting wheel spacers on will only make the bump steer worse.

Our bump steer correction kit does help. Some customers who install see 1-3 second lap time improvements; We love our customers but we think 1-3 seconds maybe a bit generous and is probably really just driver confidence is improved and it feels like 1-3 seconds.
Wheel spacers wont really change bump steer to much and the general rule is dont use wheel spacers unless you absolutely have to. Spacers will change scrub radius and of course front track. Widening the front track is not a bad thing in most cases to a certain point. Changing your scrub radius because your using wheel spacers can cause problems like slow turn in , increased tire wear, and a heavy feel in the steering

[Arizona Vipers]

Why not run 900s and a spring stop?

Hey dude! Can you send me a link to exactly what you are talking about?

[13COBRA]

Hey dude! Can you send me a link to exactly what you are talking about?

Tons of options. It's not meant to act as suspension, basically just a bump stop to keep it from bottoming out.

https://grandprixauto.com/bump-stop-spring-2000lb

https://pitstopusa.com/i-23901183-landrum-bump-stop-spring-1000lb.html?ref=brand:4818

[TKO MOTORSPORTS TEAM]

Tons of options. It's not meant to act as suspension, basically just a bump stop to keep it from bottoming out.

https://grandprixauto.com/bump-stop-spring-2000lb

https://pitstopusa.com/i-23901183-landrum-bump-stop-spring-1000lb.html?ref=brand:4818

Just a heads up. Bump stop springs are really hard to work with and have alot of down sides to them in road race applications. You will also need to machine some parts so they dont destroy the shock body , cap and shaft. Only place we have ever used bump springs is offroad applications.

[13COBRA]

Just a heads up. Bump stop springs are really hard to work with and have alot of down sides to them in road race applications. You will also need to machine some parts so they dont destroy the shock body , cap and shaft. Only place we have ever used bump springs is offroad applications.

Correct, machine caps for above the shock and below the mount. Ideally, I'd like to try about 20 different sets of shocks in order to fine tune it to nearly bottoming out, but not haha I just don't have the time nor patience for that.

[TKO MOTORSPORTS TEAM]

Correct, machine caps for above the shock and below the mount. Ideally, I'd like to try about 20 different sets of shocks in order to fine tune it to nearly bottoming out, but not haha I just don't have the time nor patience for that.

Bump rubbers and packers is what all of us use. Super easy to work with, quick changes, limitless combos and cheap

[13COBRA]

Bump rubbers and packers is what all of us use. Super easy to work with, quick changes, limitless combos and cheap

I like the idea of bump rubbers, except they just become a wear item. I'm not 100% sold on spring stops either...still in the process of weighing my options.

Should be finally getting the measurements on my frame today, and will hopefully be ordering that pan.

[TKO MOTORSPORTS TEAM]

I like the idea of bump rubbers, except they just become a wear item. I'm not 100% sold on spring stops either...still in the process of weighing my options.

Should be finally getting the measurements on my frame today, and will hopefully be ordering that pan.

Since your a TKO customer you have access to all our support. Which includes race engineers, product engineers, install help, set up info , track data, etc. If you have questions, need trouble shooting or you just want to discuss an idea you can email or call we are always glad to help.

[13COBRA]

Since your a TKO customer you have access to all our support. Which includes race engineers, product engineers, install help, set up info , track data, etc. If you have questions, need trouble shooting or you just want to discuss an idea you can email or call we are always glad to help.

You guys are top notch.

[White Snake]

I wonder if the OP can see the model number on the springs on his car. They are on Eibach's and H&R's etc. If my car had 1480's it would be undrivable for me. The stock 1300's are ridiculous, I'm running 1200 now to not bottom out, but my car would be much faster with 900-1000 and some kind of setup to not bottom out.

Sorry for the long departure, my world had caught on fire since my last post...I will try to answer previous questions as best I can.
Shock assembly KW part # 95181595A. I am not sure if these are Gen 4 ACR-X or not and I am not really sure how to read the spring rates on the springs themselves.
The shock assemblies have upper and lower adjustable knobs (I assumed for rebound and dampening), initially we set them all to 0 or the lowest setting assuming that this would result in the softest setting...it appears that this assumption is vastly incorrect. So after playing around with some of these adjustments that has been some improvement in drive characteristics. I am still a bit hesitant to really push these tests.
No alignment check as of yet but it is on the agenda...like I said, it has been nuts over here lately!

[Lawineer]

I'd definitely start with an alignment.

[chiromikey]

Obviously you should perform an alignment any time you change suspension parts but I’m not sure why so many are suggesting this as a fix to what seems to be an obvious shock problem. Did you have the shocks tested before installing? Shocks are a wear item and buying used can be sketchy, especially if they were on a car that was run hard. I wouldn’t be surprised if these have an internal failure or aren’t valved properly for your spring rates.

Good luck and please keep us updated.

[Lawineer]

Obviously you should perform an alignment any time you change suspension parts but I’m not sure why so many are suggesting this as a fix to what seems to be an obvious shock problem. Did you have the shocks tested before installing? Shocks are a wear item and buying used can be sketchy, especially if they were on a car that was run hard. I wouldn’t be surprised if these have an internal failure or aren’t valved properly for your spring rates.

Good luck and please keep us updated.

What makes you say it's an obvious shock problem?

[chiromikey]

What makes you say it's an obvious shock problem?

His initial post with the description of symptoms. He talked about unpredictable and sudden weight transfers and the feeling of getting launched up a ramp over high speed bumps. This sounds more in line with uncontrolled damping. I’d expect alignment to be described as unpredictable in a lateral sense instead of weight transfers or getting launched upward.

I know others have far more suspension knowledge than I do and I’m hoping he figures this out and lets us know. My opinion is only based on my own experiences and the limited amount of information that we have from an internet post so right or wrong, I’m willing to learn something here.

[TKO MOTORSPORTS TEAM]

His initial post with the description of symptoms. He talked about unpredictable and sudden weight transfers and the feeling of getting launched up a ramp over high speed bumps. This sounds more in line with uncontrolled damping. I’d expect alignment to be described as unpredictable in a lateral sense instead of weight transfers or getting launched upward.

I know others have far more suspension knowledge than I do and I’m hoping he figures this out and lets us know. My opinion is only based on my own experiences and the limited amount of information that we have from an internet post so right or wrong, I’m willing to learn something here.

Un-controlled/incorrect dampening or damaged shock is definitely a possibility so your on the right track but just a little ahead. Dyno shocks prior to install is also a great idea.

[GTS Dean]

If you have shocks properly sprung and valved for aero loading control, then put them on a car with no aero, I'd opine that you're about guaranteed to be oversprung and overdamped. My guess is that the springs are too stiff to start with and the valving - particularly rebound - is too harsh. If you are unloading on the backside of a bump and the tires are going light because the shafts are not moving fast enough to follow the road, you will have daylight underneath the tires and zero control. It could also be bad bump steer at full droop. Not good Goose.

[Lawineer]

His initial post with the description of symptoms. He talked about unpredictable and sudden weight transfers and the feeling of getting launched up a ramp over high speed bumps. This sounds more in line with uncontrolled damping. I’d expect alignment to be described as unpredictable in a lateral sense instead of weight transfers or getting launched upward.

I know others have far more suspension knowledge than I do and I’m hoping he figures this out and lets us know. My opinion is only based on my own experiences and the limited amount of information that we have from an internet post so right or wrong, I’m willing to learn something here.

Under load, the suspension moves and if it's not aligned properly, it will likely move into a direction you don't want it to move into. My car was perfect example. When I frist got it it, under heavy braking, it JERKED HARD to the right, despite driving dead straight on a flat road. Now, that COULD have been suspension in one corner being busted, but it could also be alignment.

[TKO MOTORSPORTS TEAM]

Under load, the suspension moves and if it's not aligned properly, it will likely move into a direction you don't want it to move into. My car was perfect example. When I frist got it it, under heavy braking, it JERKED HARD to the right, despite driving dead straight on a flat road. Now, that COULD have been suspension in one corner being busted, but it could also be alignment.

Broken or warn out suspension for sure you nailed it. Most likely warn out front aft control arm bushing. This is great example of correcting the basic mechanical foundation of the car before going after the more complex problems like shock valving, spring rates, aero , etc