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loboboy

Shock Spring Length Question

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I purchased a Tatum Spyder and I sure could use some help with determining the spring length needed to properly setup the shocks. I have read the shock tuning posts but i haven't found where it addresses my issue.

The issue is and i will start with the front shocks, coil overs (no bypass on the front) King 2.0 Overall length eye to eye 32", 12" stroke with dual 12" coil spings of unknown rate (thats another issue in itself). Should i be running a 14" lower and 10" upper spring?

Same issue on the rear coil-overs but they are King 2.0 36" eye to eye length, 16" stroke with dual 14" length springs. Rear has 300/500 rates.  I was thinking i should run an 18" lower spring with a 12" upper spring. Any thoughts would be greatly appreciated as the setup from previous owners isnt correct in my eyes and i want correct these issues so i can move forward with the shock tuning.

In the current condition i will never get to the point of using the crossover as you could never compress the currnt springs afar enough for the sperator to get to the threaded parts of the shock body.

If you need any more info please ask and if you can help it would be greatly appreciated.

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This my next upgrade on my buggy if plans go in my favor.  I was told id a shock stroke is 14 then the spring should be 16. As you mentioned.  I will be reading this post. 

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the only reason to have different spring lengths is to position the crossover ring higher/lower on the threaded body.

Your pre-load and ride height adjustments will determine if you need a different spring height, but that may also tell you you need different rate springs if it's that far outa whack.

90% of the cars had equal length springs from the start.

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Ya I have a 10" shock and use an 8" spring and a 12" on the bottom, shocks lay inward alot but crossover adjustment was the reason for the different lengths. I like to run the secondary crossover about 1 inch away from the spring  divider at right height

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24 minutes ago, 2turbofords said:

Ya I have a 10" shock and use an 8" spring and a 12" on the bottom, shocks lay inward alot but crossover adjustment was the reason for the different lengths. I like to run the secondary crossover about 1 inch away from the spring  divider at right height

That sounds way to low.  you are using your bottom spring most of the time then and you should be getting a rougher ride than expected. 

loboboy springs sound like they should be fine as of length.  you can move your crossover ring up and down to figure when the bottom spring kicks in.   Most cars I have found run way to heavy a spring.  with 300/500 sounds pretty good for the rear.  Yes get your springs dialed in before you start on your bypasses.  I have changed springs 3 times and need one more change on the front to get me in the sweet spot.   

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 Always been told not have more than 100lb difference beteween spring weights on the same shock

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18 hours ago, Squatcher said:

That sounds way to low.  you are using your bottom spring most of the time then and you should be getting a rougher ride than expected. 

loboboy springs sound like they should be fine as of length.  you can move your crossover ring up and down to figure when the bottom spring kicks in.   Most cars I have found run way to heavy a spring.  with 300/500 sounds pretty good for the rear.  Yes get your springs dialed in before you start on your bypasses.  I have changed springs 3 times and need one more change on the front to get me in the sweet spot.   

Spring rate is what I am working on for sure. To clarify a little, in current state the springs could never compress far enough to use the crossover even if I was to lower the crossover rings all the way down on the shock body. Also when compressed the spring separator is below the shock body and has the potential to get hung up on the shock body as it extended in its travel. 

DBD41748-D414-4044-870D-D021C017C445.jpeg

765D4161-CDDC-4EAE-927E-59239B90B16B.jpeg

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how much preload is on those ?  I would get longer springs but you want to make sure you get the proper spring weight.  reason I would get longer spring is as they compress your spring rate increases.  longer spring will have less increase being compress less.   your ride will be softer and then you control the stoke with the bypass. 

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18 minutes ago, Squatcher said:

how much preload is on those ?  I would get longer springs but you want to make sure you get the proper spring weight.  reason I would get longer spring is as they compress your spring rate increases.  longer spring will have less increase being compress less.   your ride will be softer and then you control the stoke with the bypass. 

i have about 1 3/4-2 inches of preload right now (right now that is with just me in the car). I need longer springs regardless. The spring length was my main concern since i wasnt able to utilize the crossover. I think i will end up with a 18" lower spring and a 12" upper spring and since i installed an iron block engine recently i will up the upper spring rate to 350/500 and see how that works.

As for the fronts i dont know where to start with spring rates but on the front i have no preload and its stiff as a horny mans peter. I was thinking of trying a 150/250 rate on the front and change the lengths to 16" lower and a 10" upper spring. This will allow me to utilize the crossover.

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sounds like you got it going.  on the front you might go even lighter.   I went from a 250/350 front with my car and I am still to stiff at 125/150  I have zero preload on my front springs and need some lighter ones and that is on my car with 3.0 bypasses, boxed arms , windshield and about 2600.  my car is planted when driving just need to take out the chop more.   Jessie at JP design has a ton of used springs I think he charges around 60 to 80 a pair so get a few and try them out.  

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2 hours ago, Squatcher said:

how much preload is on those ?  I would get longer springs but you want to make sure you get the proper spring weight.  reason I would get longer spring is as they compress your spring rate increases.  longer spring will have less increase being compress less.   your ride will be softer and then you control the stoke with the bypass. 

"as they compress your spring rate increases"  .. not true.  spring  "rate" on a spring ,does not increase as it is compressed. Whatever it's stated  #/" rate is, it will take that amount of weight to compress the spring every "1"..  throughout the entire travel of the spring. This is true for most all standard offroad shock springs. This is unless it is a "progressively" wound coil, where some of the coils stack up to coil bind and are locked out. then as the coils stack up , and "less" coils are active, the spring rate will go up. But not what is involved here. What is more important, is determining "travel " of the springs, and how much is needed of each spring (top and bottom).. as you change rates of either one, the needed travel of the other will change. as in any dual-rate spring set-up, the amount each spring compresses per inch of shock travel is different ( unless both springs are the exact same rate) . 

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32 minutes ago, SCHMIDTY said:

"as they compress your spring rate increases"  .. not true.  spring  "rate" on a spring ,does not increase as it is compressed. Whatever it's stated  #/" rate is, it will take that amount of weight to compress the spring every "1"..  throughout the entire travel of the spring. This is true for most all standard offroad shock springs. This is unless it is a "progressively" wound coil, where some of the coils stack up to coil bind and are locked out. then as the coils stack up , and "less" coils are active, the spring rate will go up. But not what is involved here. What is more important, is determining "travel " of the springs, and how much is needed of each spring (top and bottom).. as you change rates of either one, the needed travel of the other will change. as in any dual-rate spring set-up, the amount each spring compresses per inch of shock travel is different ( unless both springs are the exact same rate) . 

schmidty glad you chimed in.  I do have a question since I am always trying to learn more about suspension.   here is an example.   say you have the same spring rate but your springs are 4 in longer.  if the shock still travels the same lets say 8" in a ride ( talking about while driving normal.) will the car have less rebound and feel softer with longer springs then with shorter springs?  is it kinda like less preload once the shock is "working though travel" hope I explained my question correctly.    besides shock size what determines the lengh of springs to use.  I would  think that when shock is mounted as long as you can adjust the spring to have zero preload when mounted I  would want the longest springs you can put on there.  would that be a logical choice to do? I wouldn't the ride be smoother than with say 6" of shock threads showing?

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Loving the info guys and thank you! At least i believe i am on the right track with the longer springs so i will be able to utilize the crossover for tuning. One of the things i noticed with mine was that i did have a significant amount of threads showing on the shock body above the springs which leads me to believe sum-ting-wong on the spring length. Then the cross overs were not utilized since the springs would be in coil bind prior to reaching a point to cross over. At some point in this cars life someone changed springs and didnt know what they were doing nor did they try to educate themselves on the proper direction to go. With any luck and your helpful input i will get it figured out and get it to ride the way i want it to. Not big into jumping, i want it to handle good and be smooth ride through choppy terrain and the whoops.

I really appreciate the input and i welcome any info anyone is willing to give.

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Springs should only expose about 3" of the shock body with no preload when correct length. The spring divider should ride completely on the shock body even at full droop with preload,and should not drop below the shock body during it's cycles. Jp Jessie(Patton prerunners)  has tons if springs and will swap with you also for what u already have 

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1 minute ago, 2turbofords said:

Springs should only expose about 3" of the shock body with no preload when correct length. The spring divider should ride completely on the shock body even at full droop with preload,and should not drop below the shock body during it's cycles. Jp Jessie(Patton prerunners)  has tons if springs and will swap with you also for what u already have 

awesome. i will try and find JP number and see what we can work out.

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On the back flip your crossover.  Long side up.  2nd.  Call tatum and ask what the put on the spyder.

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8 hours ago, Squatcher said:

schmidty glad you chimed in.  I do have a question since I am always trying to learn more about suspension.   here is an example.   say you have the same spring rate but your springs are 4 in longer.  if the shock still travels the same lets say 8" in a ride ( talking about while driving normal.) will the car have less rebound and feel softer with longer springs then with shorter springs?  is it kinda like less preload once the shock is "working though travel" hope I explained my question correctly.    besides shock size what determines the lengh of springs to use.  I would  think that when shock is mounted as long as you can adjust the spring to have zero preload when mounted I  would want the longest springs you can put on there.  would that be a logical choice to do? I wouldn't the ride be smoother than with say 6" of shock threads showing?

spring "rate" is spring "rate" whether it is a 4" or 18" spring. A spring is basically a "lever" , shaped in a spiral. the longer the wire, or the more active coils there are the "lighter" the spring rate will get.

Different wire diameters are needed to achieve different spring rates in different length coils.  A 4" 400# spring  may only have 3-3.5 total coils. and  have 2.5" range of travel.. a 14" 400# spring will have a lot more coils, and therefore wire diameter will need to go up to create the desired rate, which at the same time chews up real estate, and limits travel . so determining  the available  "travel" of a given spring is critical, when choosing a "length" for a coil over.  a lighter rate in any given length, will typically have more "travel" than one the same length but in a heavier rate.

Edited by SCHMIDTY

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I had the same issue....Mine had 16" and 12" in the rear and my crossover wouldn't engage until about 2" before I bottomed out.  The treads on one of the shock bodies didn't go down as far as the other.  I put 18" on the bottom and 10" on the top.  Same ride...but now my crossover engages in the right place and I can adjust it accordingly.  I just changed my spring rate to 450/550 from 450/500 so I have a set of 18" X 500 rear springs I can loan you to see if that gets you where you need to be?  They are Hypercoils.   Where are you located?  If you haven't priced them yet...18" springs are alot more expensive than 16" and 14" so you'll want to get the rate right before you buy some.  At least the Hypercoils were.

 

~jw

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On 11/28/2018 at 3:45 AM, loboboy said:

Spring rate is what I am working on for sure. To clarify a little, in current state the springs could never compress far enough to use the crossover even if I was to lower the crossover rings all the way down on the shock body. Also when compressed the spring separator is below the shock body and has the potential to get hung up on the shock body as it extended in its travel. 

DBD41748-D414-4044-870D-D021C017C445.jpeg

765D4161-CDDC-4EAE-927E-59239B90B16B.jpeg

from this pic you clearly need longer springs just to get them positioned up on the shock body for cross-over engagement

are you sure those are 16" stroke? based on the king site 14" is 35-1/12ish and 16 is 39-1/2" 
http://www.kingshocks.com/products/performance/coilover-performance-race/

 

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6 hours ago, DuneTrack-N said:

from this pic you clearly need longer springs just to get them positioned up on the shock body for cross-over engagement

are you sure those are 16" stroke? based on the king site 14" is 35-1/12ish and 16 is 39-1/2" 
http://www.kingshocks.com/products/performance/coilover-performance-race/

 

Your right in the length. I am 35 1/2ish and i rounded up due to quick measuring and not sure exactly where the bolt center was. They are 14" and 16" stroke though for sure.

 

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19 hours ago, jwest2sh said:

I had the same issue....Mine had 16" and 12" in the rear and my crossover wouldn't engage until about 2" before I bottomed out.  The treads on one of the shock bodies didn't go down as far as the other.  I put 18" on the bottom and 10" on the top.  Same ride...but now my crossover engages in the right place and I can adjust it accordingly.  I just changed my spring rate to 450/550 from 450/500 so I have a set of 18" X 500 rear springs I can loan you to see if that gets you where you need to be?  They are Hypercoils.   Where are you located?  If you haven't priced them yet...18" springs are alot more expensive than 16" and 14" so you'll want to get the rate right before you buy some.  At least the Hypercoils were.

 

~jw

I am in Oklahoma. I have 300/500 now and am thinking of trying the 450/600 option but if Hypercoils have the 18" in 550 i will try that.

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That's a pretty big jump....  I'd start smaller if the ride height was close to what you want.  Maybe 400/500 to start with an 18" lower spring.  the crossover collar really makes a difference and it doesn't look like it was even coming into play with your current setup.  With a 300/500 your effective spring rate is 188#.  When it hits the crossover it goes straight to 500#.  With a 400/500 your effective rate is 222# and then to 500# on the crossover.  There is a calculator on hypercoil's website.  You need to weigh your car and take some measurements and it can probably get you close to where you need to be. 

 

Here's a chart on how the stacked coil spring rates work.

http://www.advancedracingsuspensions.com/stacked-spring-combined-rates-chart/

 

~jw   

Edited by jwest2sh

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18 hours ago, jwest2sh said:

That's a pretty big jump....  I'd start smaller if the ride height was close to what you want.  Maybe 400/500 to start with an 18" lower spring.  the crossover collar really makes a difference and it doesn't look like it was even coming into play with your current setup.  With a 300/500 your effective spring rate is 188#.  When it hits the crossover it goes straight to 500#.  With a 400/500 your effective rate is 222# and then to 500# on the crossover.  There is a calculator on hypercoil's website.  You need to weigh your car and take some measurements and it can probably get you close to where you need to be. 

 

Here's a chart on how the stacked coil spring rates work.

http://www.advancedracingsuspensions.com/stacked-spring-combined-rates-chart/

 

~jw   

agreed i need to weigh the car. just need some scales! I Still have trouble finding the 18" springs. King only offers the 600# in the 18" long and i cant find the 18" springs in the right rate.

 

Edited by loboboy

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On 11/27/2018 at 9:39 AM, 2turbofords said:

 Always been told not have more than 100lb difference beteween spring weights on the same shock

I know some older builders tuned that way, but some of the newer guys are going with a larger difference, like 150 or 200 lb difference. This allows a lighter spring rate at normal ride height, then a more drastic rate increase when the crossover collar kicks in, allowing for more aggressive driving with less chance of bottoming out. 

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Does it feel like a kick in the pants when secondary spring kicks in? 

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