Help a nOOb set up his Coil-Overs in Winston

Oliver's

Oliver's

Drive Line & Gear
Joined
Jul 16, 2005
Location
707 E. 12 1/2 St. Winston Salem NC 27101
Anyone have any scales in or around Winston. Need to weigh the new buggy for coil-overs.

Thanks.
 
Mac5005 said:
Have you got any mock up springs/shocks on it currently?

If so work backwards and measure to get the actual load at the shock. This will be more accurate than using scales.
Click to expand...

Yes, it currently has C/O's and springs installed on it. I can read the weights on 3 of the 4 pairs of springs. It rides like a wagon. Unfortunately I'm out of my wheel house with this one, so any advise is welcome. Thanks.
 
When I was weighing mine for rear coilovers I went to the local cat semi truck scales. I parked with one side tires on the sidewalk just off the scale pad so just the other side tires were each on a separate scale pad. Then I parked the other side off the scale. It gave me the corner weights on each tire. I did some guesstimating to figure my unsprung weight and got it pretty close on the first shot.

Sent from my XT1254 using Tapatalk
 
Oliver's said:
Assuming this is the proper way to measure the load?
Off-Road Coilover Springs | How to Fix Your Coilover Springs
Click to expand...

Looks to be close. Just check and double check the measurements so you end up with similar load #s using upper and lower spring compression amounts.

Enter the measurements and spring rates in this calculator.

http://metalwerxdesign.com/files/springcalculatorv2.xlsx

Then enter the desired preload amount, and find the new effective spring rate.

Scroll down in the chart to find the spring combo that gets you the desired rate and proper step up #'s.

How much up/down travel are you going for?

What is the travel of the shock?

What brand shocks?

Post up the spring rates you know, current preload on coilovers, as well as amount each spring of each rate is compressed at ride height.

Swap springs around from the pair you do know, with the ones you don't.

Post your info, and I'll be glad to help.

Shoot for 2" of preload as a good starting point.

Shoot for 50 to 100 lbs of step up from the secondary spring to the main spring.

Doing it this way takes into account the angle and mounting location of the coilovers and any mechanical advantage or disadvantage the spring mass has on the shock.

In other words, you find out actual realistic load at the shock vs sprung weight.

For example:

You currently have 0 preload on fox 14s. 6" up travel. You want to have 7" uptravel.

Lower spring is 250lb spring compressed 4" at ride height. Upper spring is 175 lb spring, compressed 5.75 at ride height.
 
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As long as you realize that a 250 lb spring is not actually a 250 lb spring, you'll do just fine. Good enough for what you're doing though.

Scales are very accurate, but you need to do some geometry with them when you're starting with corner weights. It's very simple geometry though if you have solid axles front and rear, because then you just have a beam with a car attached to it and springs mounted at some angle between the two.
 
Fabrik8 said:
As long as you realize that a 250 lb spring is not actually a 250 lb spring, you'll do just fine. Good enough for what you're doing though.

Scales are very accurate, but you need to do some geometry with them when you're starting with corner weights. It's very simple geometry though if you have solid axles front and rear, because then you just have a beam with a car attached to it and springs mounted at some angle between the two.
Click to expand...


But as accurate as scales are, guessing at sprung weight % is a shot in the dark compared to measuring a compressed know rate.

Unless of course you weighed every item of unsprung rate, plus half of the link, coilover, and driveshaft weight while assembling, it is far less accurate.

Plus addressing the motion ratio and mounting angle.

I'm not saying the scales aren't accurate, I'm saying guessing your sprung rate, and factoring in motion ratio and mounting angle is less accurate.

Plus total weight doesn't help that much, when it's really easy to read a tape measure, on an already assembled rig.

More than one way to arrive at the same destination.

When you realize that the top nut is adjustable and 2" of preload may turn into 2.5 or 1.5, then the fact that an advertised 250 lb rate spring doesn't actually achieve a 250 lb rate, doesn't matter.



To the OP, also make sure if possible to get the measurements with driver and passenger weight in the rig, plus tools and fluids ready to ride.
 
I was able to get some quick measurements this evening.

Fox 2.0 14" on all four corners. All 8 springs are 14"

The fronts are 150 over 250. Sitting at ride height the lower is compressed to 12" and the upper is 10 7/8" 7" of shaft showing.

The rears are 110 over 200 ( I think? They appear to be an off brand and the weight was written in sharpie and was very faded)
At RH the lower is compressed to 12 1/4" and the upper to 11" 8" of shaft showing.

The buggy is a V8 (6 liter) front engine, single seater and is fairly nose heavy. 3K total weight.

I'm sure I'm forgetting something.

Thanks for the help.
 
Oliver's said:
I was able to get some quick measurements this evening.

Fox 2.0 14" on all four corners. All 8 springs are 14"

The fronts are 150 over 250. Sitting at ride height the lower is compressed to 12" and the upper is 10 7/8" 7" of shaft showing.

The rears are 110 over 200 ( I think? They appear to be an off brand and the weight was written in sharpie and was very faded)
At RH the lower is compressed to 12 1/4" and the upper to 11" 8" of shaft showing.

The buggy is a V8 (6 liter) front engine, single seater and is fairly nose heavy. 3K total weight.

I'm sure I'm forgetting something.

Thanks for the help.
Click to expand...


How much preload on the coils?

Meaning: when the shocks are at full extension, how far is the top but preloaded onto the springs.

Zero preload would be just barely touching upper spring.

Do you want to change the current static ride height?
 
Ride height is fine.

I'll check the pre-load this evening when I get home.

Thanks.
 
There are a lot of factors to look at when selecting rates, preload is one of many measurements.

The most accurate way to get weight carried by the springs is to take the following measurements:
Start with shock charged to desired pressure
Get vehicle to desired ride height without bump stops touching axle and without dual rate nuts touching the slider
Measure threads above upper spring perch
If tender coil, measure tender coil height
Measure shaft showing
Record upper and lower spring rates
Go to full droop (remove center limit strap, but not shock limit straps)
Measure shock shaft showing
If springs are tight - loosen upper spring perch until springs start to rattle
If springs are loose - tighten upper spring perch until springs stop rattling
If tender coil - measure new height of tender coil
Measure threads above spring perch

It's possible to compensate for not being able to reach the desired ride height, you just loose some accuracy, especially on emulsion shocks.

How much you moved the nut is preload (negative preload if the springs were loose)
Shaft measurements correlate everything

I keep a HUGE amount of component weight data so I can work with total vehicle weight.
 
TRD said:
There are a lot of factors to look at when selecting rates, preload is one of many measurements.

The most accurate way to get weight carried by the springs is to take the following measurements:
Start with shock charged to desired pressure
Get vehicle to desired ride height without bump stops touching axle and without dual rate nuts touching the slider
Measure threads above upper spring perch
If tender coil, measure tender coil height
Measure shaft showing
Record upper and lower spring rates
Go to full droop (remove center limit strap, but not shock limit straps)
Measure shock shaft showing
If springs are tight - loosen upper spring perch until springs start to rattle
If springs are loose - tighten upper spring perch until springs stop rattling
If tender coil - measure new height of tender coil
Measure threads above spring perch

It's possible to compensate for not being able to reach the desired ride height, you just loose some accuracy, especially on emulsion shocks.

How much you moved the nut is preload (negative preload if the springs were loose)
Shaft measurements correlate everything

I keep a HUGE amount of component weight data so I can work with total vehicle weight.
Click to expand...
@TRD got a diagram? or more detailed literature? I got sorta lost on this.....link to well written procedures or such?
 
@WARRIORWELDING , I was hoping to make a video but haven't had a chance. I'll write an article in the morning. Basically there are A LOT of ways to do it depending on your setup and ability to achieve the desired ride heigh. Accuracy varies with these as well. I'll stick with the straightforward and accurate methods.
 
My goal is to elaborate on the process to pick new springs based on a desired preload amount.

Huge thanks to TRD for elaborating on defining preload and how to measure it with those articles.

I will follow up with the concerns I have with Daves setup and spring choices for the sake of this thread.


First I take Daves current preload,

And multiply the spring rates by the spring compression amount to output the current load at the shock itself. This is similar to spring rate, but different in that it factors in the current motion ratio and compound mounting angle of the shock.

auploads.tapatalk_cdn.com_20160819_eadc899821d2c8301388aae250c80686.jpg



Once I know the current load at the shock, I figure out the new effective position of the springs.

Take the desired position of the shock: aka ride height, aka amount the shock is compressed,

And add the desired amount of preload.

auploads.tapatalk_cdn.com_20160819_d8a3d9ba4df783e925358ab8459bbab9.jpg



Next calculate your new desired combined spring rate, by dividing the load at the shock, by the effective new spring position.

auploads.tapatalk_cdn.com_20160819_d071bb55f8043b0f93d95c926320ccbc.jpg



Next take you new desired combined rate and pick out your new individual spring rates.

The rates listed below are what is commonly available in 2.5" diameter 14" and 16" long PAC springs. Different Sizes and vendors may obviously be different.

Rear

auploads.tapatalk_cdn.com_20160819_ba1f90f455828883a1b6a4080dc563d6.jpg


Front

auploads.tapatalk_cdn.com_20160819_57ca6457e87a875b70c1d4ac9b5ed6d9.jpg



Generally using this method, use a lower spring that is 2" longer than your shock travel, and an upper spring the same length as your shock travel.

This ensures that the dual rate slider stays above the bottom of the shock body and doesn't bind through the travel on the bottom of the shock body.

This also eliminates the need for a triple rate or tender spring.


If you don't want to do the math, or save some time, enter your info in this calculator in excel

http://metalwerxdesign.com/files/springcalculatorv2.xlsx

Which also includes instructions and an expanded chart of combined spring rates and individual rates.
 
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Reserved for my thoughts when I get to a computer.

I'm going to elaborate on preload, light springs, motion ratio, and overall how to pick new springs,

And then follow up with my thoughts on spring choice and Daves unique situation and setup.
 
Mac5005 said:
Reserved for my thoughts when I get to a computer.

I'm going to elaborate on preload, light springs, motion ratio, and overall how to pick new springs,

And then follow up with my thoughts on spring choice and Daves unique situation and setup.
Click to expand...
And just to emphasize that, spring selection is ONLY the beginning of the process. You need to be willing to go into the shocks multiple times for valving to get the most out of the shocks...not just a smooth ride back to camp. If any owner isn't acclimated to do so, I suggest you hire someone with experience to watch you wheel and tune from there.

It's a pretty serious study to get them right....and you won't be sorry, once you get there.

Matt
 
Got a cousin in winston that has a race car. I'm sure you could use his scales. Pm for contact info.
 
Weighing it once probably won't be enough.
Google weighing a vehicle with bathroom scales and build your own levers.
Paint the floor and weigh the vehicle in the same spot every time.


Matt
 
Thanks to everyone offering up scales on here and by PM.

Huge thanks to Mac and Ryan at Accutune. I now have some springs ordered and will report back.

Thanks again!


Dave
 
Gonna bump this.

I feel like I've gotten to the "80%" mark and want to fine tune it.

I really want to weigh this thing just to make sure, especially after some of the changes that have been made. Bigger fuel cell, added tubing, etc.

Any one willing to weigh my junk for me, in or around Winston? I'll come to you, beggars aren't choosers where I come from.

Thanks!


Dave
 
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