Questions on shock length
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Posting Guru
Joined: Jan 2012
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From: Indiana
Questions on shock length
So I am looking at shocks, and I have questions about length...
Is shock length measured from eye to eye of the mounts? That's how I measured what I have...
FRONT
Ride height- 21.25
Compressed- 16.75
Extended- 23.5
REAR
Ride height- 28.125
Compressed- 21.625
Extended- 31.5
If it's not measured eye-to-eye, how much do I need to subtract from my measurements?
Is shock length measured from eye to eye of the mounts? That's how I measured what I have...
FRONT
Ride height- 21.25
Compressed- 16.75
Extended- 23.5
REAR
Ride height- 28.125
Compressed- 21.625
Extended- 31.5
If it's not measured eye-to-eye, how much do I need to subtract from my measurements?
Laughing Gas
Joined: Jul 2018
Posts: 816
Likes: 7
From: Prescott, AZ
That seems to be the universal method, at least with all the shock manufacturers I've looked at. Bilstein for certain.
*edit*
I have heard that one should allow for at least 1/2" of travel at each extreme as you don't want to bottom the shock internally or overextend it either. Bottoming would seem to be a fairly "hard" figure, with some form of unpleasant contact being the ultimate limiting factor. I'm not sure I understand topping to be the same though - if it's simply the extension of the springs that stops the axle from dropping, this would seem to be a dynamic measurement that could vary with inertia (like if the truck "aired out" at speed as opposed to being lifted by a floor jack). Bottoming is a fairly easy measurement, but I'm still wrestling with which Bilsteins to put on the rear... I think I'm going to get the suspension installed and do actual measurements of fully topped before I make a selection.
*edit*
I have heard that one should allow for at least 1/2" of travel at each extreme as you don't want to bottom the shock internally or overextend it either. Bottoming would seem to be a fairly "hard" figure, with some form of unpleasant contact being the ultimate limiting factor. I'm not sure I understand topping to be the same though - if it's simply the extension of the springs that stops the axle from dropping, this would seem to be a dynamic measurement that could vary with inertia (like if the truck "aired out" at speed as opposed to being lifted by a floor jack). Bottoming is a fairly easy measurement, but I'm still wrestling with which Bilsteins to put on the rear... I think I'm going to get the suspension installed and do actual measurements of fully topped before I make a selection.
Lead Driver
Joined: Apr 2011
Posts: 8,259
Likes: 346
From: Northern California
Yes Eye to eye, make sure to subtract extended from collapsed to get your shaft travel.
There are 2 broad catagories in shocks to factor in, “Short” and “long” bodies.
Your front shock example, has a 6.75” travel Didn’t you go with a 8” travel spring ?
There are 2 broad catagories in shocks to factor in, “Short” and “long” bodies.
Your front shock example, has a 6.75” travel Didn’t you go with a 8” travel spring ?
Thread Starter
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Posting Guru
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From: Indiana
For the rear, I did the same thing to measure for extension. For compression, I measured similar to the front, based on where the bump stops I am fabbing up are going to be.
At any rate, I have been looking over tons of manufacturers' shock specs, and they all list compressed and extended length, but I don't see many of them listing travel. One thing I do notice is that most of them I look at have a compressed length shorter than my measurements and an extended length greater than my measurements. Would that mean I would be safe with those, as they would never bottom or top out?
Lead Driver
Joined: Apr 2011
Posts: 8,259
Likes: 346
From: Northern California
Sounds like you have a handle on it.
just out of curiosity what are your measurments front and rear.
edit......never mind, Post 1 is your measurments....I took it as the measurment of the shock you are considering
just out of curiosity what are your measurments front and rear.
edit......never mind, Post 1 is your measurments....I took it as the measurment of the shock you are considering
Lead Driver
Joined: Apr 2011
Posts: 8,259
Likes: 346
From: Northern California
Bilstein list travel and you can see the diffrent proportions of long and short body shocks.
https://cart.bilsteinus.com/Portals/...g-2018-WEB.pdf
https://cart.bilsteinus.com/Portals/...g-2018-WEB.pdf
Laughing Gas
Joined: Jul 2018
Posts: 816
Likes: 7
From: Prescott, AZ
I don't know what the travel of the front springs are (ATS X-Code/Zone mini pack). For extension, I checked it two ways. First, I jacked up the front end by the frame until both tires were off the ground and measured. Then I put another jack under one tire and compressed it on that side while letting the other hang. Either way I came up with 23.5 extended. For compression, I measured (on the ground) the distance from the spring plate to the bump stop and added in a half inch for bump stop compression- then subtracted that number from the distance between the mounts at rest.
For the rear, I did the same thing to measure for extension. For compression, I measured similar to the front, based on where the bump stops I am fabbing up are going to be.
At any rate, I have been looking over tons of manufacturers' shock specs, and they all list compressed and extended length, but I don't see many of them listing travel. One thing I do notice is that most of them I look at have a compressed length shorter than my measurements and an extended length greater than my measurements. Would that mean I would be safe with those, as they would never bottom or top out?
For the rear, I did the same thing to measure for extension. For compression, I measured similar to the front, based on where the bump stops I am fabbing up are going to be.
At any rate, I have been looking over tons of manufacturers' shock specs, and they all list compressed and extended length, but I don't see many of them listing travel. One thing I do notice is that most of them I look at have a compressed length shorter than my measurements and an extended length greater than my measurements. Would that mean I would be safe with those, as they would never bottom or top out?
I have the same question on picking a shock that has "a compressed length shorter than my measurements and an extended length greater than my measurements". My guess is that we are safe if there is a margin of at least an inch on either end - most of the shocks I have been looking at provide that on compression, but not sure yet on full extension. And I'm concerned that extension can be more than what is measured in the garage, given a situation where a truck fully compresses over a bump and then launches into the air at speed. I guess if your rebound is correct, the unsprung weight can't get too out of control and extend the springs excessively.
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Posting Guru
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From: Indiana
Now I am on to figuring out a budget shock that still performs halfway decent. I was trying to compare the Bilstein 5125's to the Rancho RS5000X, but Rancho don't seem to give any usable information on their valving. Plus, I spent an hour with Google comparing the two, and a lot of people aren't liking the Ranchos as much.
I also thought about a cheap set of Gabriel Pro Guards just to get by while saving for a higher quality shock, but they don't list much info either, and let's face it- they are 30-dollar shocks! I'm about half afraid that just taping $120 to the axles would have the same effect...
I also thought about a cheap set of Gabriel Pro Guards just to get by while saving for a higher quality shock, but they don't list much info either, and let's face it- they are 30-dollar shocks! I'm about half afraid that just taping $120 to the axles would have the same effect...
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Laughing Gas
Joined: Jul 2018
Posts: 816
Likes: 7
From: Prescott, AZ
In the grand scheme of things, spending $320 for parts that will last 5-10 years isn't that bad. I've been known to cheap out on some things, but shocks and tires I tend to go on the upper end of the quality scale.
But I totally get it, as I'm there right now - seems like it costs $500-$1200 every time I look at this truck. I keep telling myself that someday the list will be shorter. Hasn't happened yet...
But I totally get it, as I'm there right now - seems like it costs $500-$1200 every time I look at this truck. I keep telling myself that someday the list will be shorter. Hasn't happened yet...
Lead Driver
Joined: Apr 2011
Posts: 8,259
Likes: 346
From: Northern California
The diffrence between a Bilstein 5125 and a rancho 5000 is the Bilstein is a mono tube and the rancho is a twin tube....the twin tube is ok on soccer moms suv but will fade quickly on a washboard road.
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Posting Guru
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From: Indiana
Thanks pirate4x4 camo. Bilsteins it is then. They have one rear that fits my application (33-185576) and the valving is 255/70.
For the front, I have some choices. two of them have 255/70 valving (33-186542, 33-185552), two of them have 360/80 valving (33-230320, 33-230344), and one is intended for dual shock applications with a valving of 170/60 (33-104645).
Out of these options, which would be the best way to go with what I have up front? (ATS "X-codes" with the Zone mini pack).
Just for curiosity, when you run dual shocks, do you double the valving numbers or is there a formula or ratio that you use to figure the combined valving?
For the front, I have some choices. two of them have 255/70 valving (33-186542, 33-185552), two of them have 360/80 valving (33-230320, 33-230344), and one is intended for dual shock applications with a valving of 170/60 (33-104645).
Out of these options, which would be the best way to go with what I have up front? (ATS "X-codes" with the Zone mini pack).
Just for curiosity, when you run dual shocks, do you double the valving numbers or is there a formula or ratio that you use to figure the combined valving?
Lead Driver
Joined: Apr 2011
Posts: 8,259
Likes: 346
From: Northern California
the numbers Bilstein uses are in Newton Meter of force with the first number representing rebound and the second number being compression.
Now, while a shock setup can be roughly figured out by doing the math the reality is ride quality is subjective and leaves a good bit of subjective room for diffrent setups. ( ask 10 racers what the best setup is and you’ll get 12 diffrent answers )
that said, If I recall your front spring rate is off the charts stiff and as such you don’t need much compression dampening since the high spring rate will take care of that. The bad news is you will need a ton of rebound dampinging to control the high spring rate. Obviously that puts you in a custom shock valving catagory with something like 360/30 however if I were to choose one off the rack I would go with the lowest compression valving as that will give you the best ride, I’d choose the 170/60
fwiw.... my Ex is 4 linked and I run a Bilstein coilover, currently have a 600 lb spring and run 20 on the compression.
it rides ok on the street but not ideal, i’ll Be switching to a 450 inch lb spring rate with a 255/70 valving as a start as soon as I get around to
I used the spring because I had it laying around and was experimenting but got tired of shock tuning for the time being.
Lead Driver
Joined: Apr 2011
Posts: 8,259
Likes: 346
From: Northern California
Dual shocks.... I don’t run them they are for show, If you are fading a single 2” shock then get 2.5” shocks, if you are fading 2.5” then get 3” shocks, ain’t no excursion going to fade 3” shocks.
Shock running a single 3.5 shock.
(edit....full disclosure, I can’t tune that but I hang out with the guys who do and have been involved in the process )
Shock running a single 3.5 shock.
(edit....full disclosure, I can’t tune that but I hang out with the guys who do and have been involved in the process )
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