anyone used single-rate coilovers on a DD?? I searched but couldn't find any single rate coilover info... Thinking of using bilstein 7100 series 10 inch travel coilovers with a remote resevoir... Anyone got any info??

What is the application?

You may not be able to find a spring long enough and with enough travel for any single rate application over 8" travel, you will have to get good measurements to see if a single rate spring will work.

this would be on a 4 banger TJ... I'll email bilstein and see what they say...

give dave aka pig from www.polyperformance.com a call. not only does he sell coilovers for a fair price but he is a wizz at spring rates and suspension geometry.

Originally posted by GOAT1
You may not be able to find a spring long enough and with enough travel for any single rate application over 8" travel, you will have to get good measurements to see if a single rate spring will work.

Kind of what I was thinking, GOATguru.

Originally posted by camo
give dave aka pig from www.polyperformance.com a call. not only does he sell coilovers for a fair price but he is a wizz at spring rates and suspension geometry.

Thanks for the pimp mr glitter.

Okay, so as far as measuring at what not, what should I measure? And what would be the ideal setup of the coilover (position wise)? It seems the popular way is the rears angled and the fronts almost vertical, but those are for dual rates. PM me if you want PIG...

I ran some numbers and I doubt you will be able to get a light enough coil and one with enough travel for a 10" travel. You will probably have to go with a dual rate setup. Again you will have to have some good measurements of corner sprung wieght and shock travel at ride height before you can really know for sure

I know this is a stupid question, but I gotta ask it:

why can't you stack 2 coils of the same spring rate to get hte heright/travel you need?

Originally posted by Sundowner
I know this is a stupid question, but I gotta ask it:

why can't you stack 2 coils of the same spring rate to get hte heright/travel you need?

You can, but when you stack two springs of the same rate, their effective rate is cut in half, thats how the dual rate works, if he is after a 150 lb/in rate he would have to stack two 300 lb/in rate springs, if they are the same length, they will always keep the same rate because the top one will not bottom out before the bottom one will.

Originally posted by GOAT1


You can, but when you stack two springs of the same rate, their effective rate is cut in half, thats how the dual rate works, if he is after a 150 lb/in rate he would have to stack two 300 lb/in rate springs, if they are the same length, they will always keep the same rate because the top one will not bottom out before the bottom one will.

Are we in parallel, or is this the beginning of a serial (spring configuration, of course)?

Happy Trails!

Two springs in parallel (side by side), spring rate doubles.

Two springs in series (one on top of the other), spring rate is halved.

Originally posted by Philabuster
Two springs in parallel (side by side), spring rate doubles.

Two springs in series (one on top of the other), spring rate is halved.

Are you sure?

Two equal rate springs in parallel (side by side), spring force on each spring is halved (as is displacement, compared to the same force on one single spring).

Two springs in series (one on top of the other), spring force is (the same, displacement is halved for each spring compared to one single coil)?

What was the question: spring rate of coils in series & parallel, or displacement (of two equal rate springs in series, compared to one longer coil of the same rate)?

Happy trails!

Originally posted by Philabuster
Two springs in parallel (side by side), spring rate doubles.

Two springs in series (one on top of the other), spring rate is halved.

We are talking about series springs and they are only halved if they are the same rate, it is similar to resistors in parallel in an electrical circuit, product/sum.

Originally posted by GOAT1


We are talking about series springs and they are only halved if they are the same rate, it is similar to resistors in parallel in an electrical circuit, product/sum.

Yup,

if you cut a single 14inlong 300lb/in coil in half
you d then have two 7in 600lb/in coils

If you put the two 7in 600lb/in coils in series the spring would once again be 14in and 300lb/in.


got it :D

whats the performance difference between
1.running two 300lb/in 8in coils in series= effectively one 16in 150lb/in coils

2. running one 400lbin 8in coil in series with one 240lb/in 8in coil = effectively one 150lb/in coil but will the 240lb/in coil compress first for preload then have the stiffer 400lb for ride height?

3. or running a longer soft coil and stiffer short coil for the same efective 150lb/in. How do you figure the rate with different lengths??



For ride height Id want it stiffer with less up travel, and have a soft long throw down travel.

I was thinking of useing a dual rate coil useing two equal length equal rate coils both soft, then run a 1/4 eliptic leaf set up for that stiffer ride height, but it looks like thats not a good Idea and can be done with different rate, different coils in series?


how woudl you figure out how to set up #3 case thats kina tricky...

Originally posted by ashmanjeepXJ


Yup,

if you cut a single 14inlong 300lb/in coil in half
you d then have two 7in 600lb/in coils

If you put the two 7in 600lb/in coils in series the spring would once again be 14in and 300lb/in.


got it :D

whats the performance difference between
1.running two 300lb/in 8in coils in series= one 16in 150lb/in coils

2. running one 400lbin 8in coil in series with one 240lb/in 8in coil = effectively one 150lb/in coil but will the 240lb/in coil compress first for preload then have the stiffer 400lb for ride height?

3. or running a longer soft coil and stiffer short coil for the same efective 150lb/in. How do you figure the rate with different lengths??



For ride height Id want it stiffer with less up travel, and have a soft long throw down travel.

I was thinking of useing a dual rate coil useing two equal length equal rate coils both soft, then run a 1/4 eliptic leaf set up for that stiffer ride height, but it looks like thats not a good Idea and can be done with different rate, different coils in series?


how woudl you figure out how to set up #3 case thats kina tricky...


The lengths do not make a difference with the rates, you pick the lengths of coils based on how much travel you want out of themeffectively

Originally posted by Ed A. Stevens


Are you sure?

Two equal rate springs in parallel (side by side), spring force on each spring is halved (as is displacement, compared to the same force on one single spring).

Two springs in series (one on top of the other), spring force is (the same, displacement is halved for each spring compared to one single coil)?

What was the question: spring rate of coils in series & parallel, or displacement (of two equal rate springs in series, compared to one longer coil of the same rate)?

Happy trails!

Do you even know what spring rate is?

Basically, spring rate is the ammount of force (pounds) it takes to compress a spring a certain distance (say 1").

A 300lb spring rate means it takes 300 lbs to compress the spring one inch. It takes 150 lbs to compress it 1/2 inch. Two inches equals 600 lbs and so forth. This is for a single, linear rate spring.

Two springs [300lb spring rate], on top of one another, with 150 lb load, will compress 1" total, with each spring only compressing 1/2" each.

The same two springs side by side will take 600 lbs to compress 1" (each spring taking a load of 300 lbs).

Does this make more sense?

Originally posted by GOAT1



The lengths do not make a difference with the rates, you pick the lengths of coils based on how much travel you want out of themeffectively

I thought about my case #3 some more last night and for that case to happen the softer coil would have to fully compress metal to metal then the system would begin to compress thesecond "system" other stiffer coil.

What I was thinking, say you have a 10in coil over, how long would the total coil be? 20in so if you ran a stiff 16in coil and a soft, REALLY soft 4in coil, the 4in coil would fully compress metal to metal and you would have only the "stiff spring rate" for ride height. so a full 4in of yoru down travel would be really SOFT and the other 6in of up travel would settel some down to ride height and provide a stiff stable ride with good controlled drop.

Is that a practical set up?

Originally posted by ashmanjeepXJ


I thought about my case #3 some more last night and for that case to happen the softer coil would have to fully compress metal to metal then the system would begin to compress thesecond "system" other stiffer coil.

What I was thinking, say you have a 10in coil over, how long would the total coil be? 20in so if you ran a stiff 16in coil and a soft, REALLY soft 4in coil, the 4in coil would fully compress metal to metal and you would have only the "stiff spring rate" for ride height. so a full 4in of yoru down travel would be really SOFT and the other 6in of up travel would settel some down to ride height and provide a stiff stable ride with good controlled drop.

Is that a practical set up?

Yes, that's pretty much how a lot of the coil-over setups work.

Originally posted by Philabuster


Do you even know what spring rate is?

Basically, spring rate is the ammount of force (pounds) it takes to compress a spring a certain distance (say 1").

A 300lb spring rate means it takes 300 lbs to compress the spring one inch. It takes 150 lbs to compress it 1/2 inch. Two inches equals 600 lbs and so forth. This is for a single, linear rate spring.

Two springs [300lb spring rate], on top of one another, with 150 lb load, will compress 1" total, with each spring only compressing 1/2" each.

The same two springs side by side will take 600 lbs to compress 1" (each spring taking a load of 300 lbs).

Does this make more sense?


Yes, & I agree (brain fade on my part).

When you assemble a coil over (any spring system) that is a combination you typically want to determine the spring force at various displacements. It may help to identify the result in a graph of force (of the spring assembly) vs. displacement.

This will help select the combination of soft and rigid coils to set the static ride height and resulting compression/extension travel.

You can build a spreadsheet to make this easier, for the selection and the force vs. displacement graph of the spring assembly. The various component coil spring rates and lengths can then be selected by swapping them in the program and comparing the graph. You have to account for the soft coil (each spring assembly configuration), before and after bind, and the results can be well worth the short time to set the spreadsheet up.

Thanks for the help.

Happy Trails!

Originally posted by Ed A. Stevens

The various component coil spring rates and lengths can then be selected by swapping them in the program and comparing the graph. You have to account for the soft coil (each spring assembly configuration), before and after bind

"bind" is that a term for a fully compressed coil?

Whats the shortest softest standard size coil? 8in 50lb/in?

ok, back to the origonal question, i know you can get the 7100 series with a threaded body, so is anyone running this as a coilover? sure seems better than the 850 per pair for kings...
owen