So, I was looking at my coilovers, (shocks only at this point)
they are the 2.5" x16" sways...
I measured the total extended spring-length distance. it's right
about 36"+ the dual-rate spacer is 1", leaving me with 35+ inches of space for the springs. usually, as I've been told, you
just run the 16" travel springs X2. but that's only 32" worth of
springs..........
rather than "waste" that 3 invches of shock, why not run 18"
travel coils? at least on the rod end. (these would also have to be
the primary spring. might even run both 18" springs. that would
be at top height, 1" worth of preload.

so, what is the concensus of this all? coil-over guru's please reply.


and like the other current thread, (Top mount for coilovers)
I'm in the same boat as that guy. I don't know how much my
junk will weigh yet. it's all parts right now. I have an idea of
my desired ride height. should I just progress-on with the build
and get to the point when I can weigh the POS so I can buy my
springs?

--thanks in advance...............

--Sherpa

Choose a ride height, decide where in the shock travel you want your shocks at static ride height, then build your mounts accordingly. Finish putting the rig together, then weigh the unsprung corner weights. Since spings are rated at the amount of weight it takes to compress them one inch, (lbs. per in.) you then pick the springs that will compress to the height you need. I don't have it handy, but I am sure someone here has the little math formula for finding the rates you need for a dual rate setup. You will also have to factor in the mounting position of the shock unless it is mounted directly above the axle and not tipped in in any direction. There are formulas for this too.

Adjusting ride height by the moving the spring platforms is not the best way to go about it, because you move the position of the shock rod at static ride height. The ideal way is to get the upper shock mount in the correct position to begin with. Another option would be an adjustable mount on one end. the threaded shock platforms are a good tuning tool to play with different spring rates to acvheive the same ride height. A stiffer spring will have the platform screwed near the upper end, while a lighter spring will have the platform screwed down toward the shaft end.

18" coils are a bit more expensive and not available in as many spring rates.

often you can set it up with 16 in coils on the bottom so you get full compression without the coils binding and full droop without the spring going slack. Quality coils are key becuase the cheapies use larger diameter wire with more coils to get the same spring rate. So you can't get as much travel out of the cheapies. (the coils bind or hit into each other before it is compressed as much).

also with the 2.5" shocks you are going to pay alot more for coils. the logic of the 18" coils costing more might not hold true for the bigger diameter springs.

18" coils are not a standard coil so they are harder to find and more expensive. I run triple rates on most of the 16" shocks we use. Generally we set them up with a 5" 90# top coil, a 12-14" center coil and a 16" bottom coil. I don't know antyhing specific about your rig but on all the coil overs we run the adjustment nut is threaded down the shock body about 3 - 6". I think you are only really dealing with 32" or so.

First of all you kind of screwed your self by getting 2.5" shocks for your rock buggy. This is because the spring selection sucks for light rate 3" ID coils. That set aside, I would figure out how much up/down travel you want out of the shock. From there I would go ahead and buy a 3"-16" id coil from someone (Poly Performance for example) who will swap it out with you if it turns out to be the wrong rate spring once you finish building your rig. When it is done, weigh it and go from there.

Also, the reason I would stay away from 18" coils is beacuse th lightest 18" coil you can get is 400lbs which is way off. Give me a call if you want as I can give a little more insight if I can get some more details.

Dave
805-234-1760

Pig,

I had no idea the lightest 18" coil was 400#.... that's alot.

I've seen alot of 350# 16" springs on rigs, and they often use

a 200-or so tender spring. the tender-spring is almost always

3/4 compressed at ride height.... that's what I'm trying to

avoid. a waste of a 16"travel shock. live and learn. I'm

leaning towards 350/250 combo for beginning set-up, and

as most shops have told me, as long as you don't drive on

them, they'll swap them out for the desired spring you wish.

at least Mckenzies will... I hear King is not too nice about doing

that though.,..... hearsay? I dunno. thanks about the word.

--Sherpa

Originally posted by SHERPA
Pig,

I had no idea the lightest 18" coil was 400#.... that's alot.

I've seen alot of 350# 16" springs on rigs, and they often use

a 200-or so tender spring. the tender-spring is almost always

3/4 compressed at ride height.... that's what I'm trying to

avoid. a waste of a 16"travel shock. live and learn. I'm

leaning towards 350/250 combo for beginning set-up, and

as most shops have told me, as long as you don't drive on

them, they'll swap them out for the desired spring you wish.

at least Mckenzies will... I hear King is not too nice about doing

that though.,..... hearsay? I dunno. thanks about the word.

--Sherpa

250/350 sounds way too heavy for a rock buggy. What the hell are building? Pics maybe???

AFW frame rails,
350SBC/nv4500/atlas II
dynarape prorocks f/r 42 tsl's
cj7tub, most sheetmetal intact
8274-front, m8000rear
4 link front/rear

what else-?

--Sherpa

I've seen alot of 350# 16" springs on rigs, and they often use a 200-or so tender spring. the tender-spring is almost always 3/4 compressed at ride height.... that's what I'm trying to avoid. a waste of a 16"travel shock. live and learn.

Sherpa, no ofense but it sounds like you are a little confused. A tender spring is real light and short like the 90# 5" coil I spoke of earlier, some are alot lighter.

I think you are just mixed up with the terminology but you say the 200# tender (which I'm asuming you are talking about the center spring and not a tender) is 3/4 compressed and that's what you are trying to avoid. :confused:

If you run a lighter spring on top of a heavier spring that's what is going to happen, that's what it's suposed to do. The lighter spring will compress alot and the heavier spring a little just setting it down to ride height. The actual tender spring (if you are using one) will be totally compressed at ride height. When you compress the shock the lighter spring will compress totally or at least close to it before the heavier spring is forced to work. Granted 3/4 compressed at ride height doesn't sound right but if that's what you saw I'd gueas the rates on that rig were too light. The larger the weight diffrence between the two coils the more noticeable it will be.

I agree with Pig on the rates you were talking about, sounds toooo heavy. I'm thinking more like 250/250 or 200/250. That is if you are talking about the front. Just a verry uneducated gueas :p

I had that same problem with (2) 14" coils with about 31" between the the spring seats. With help from this board I ended-up using Eibach helper springs on top of the upper coil.
They are about 11 lb rate and 3/8" when compressed and 3" when extended, they fill the gap at full extension and are working great. You may not be able to get them in 3" ID.
I'm useing 350/450 rates with no preload and without dual-rate separators at all (4) corners on a 4200 lb cj with D60s, it weighs about 2000 on the rear and 2200 on the front. It rides and handles great , but, as I said, I'm not running the dual-rate separators, so you will be running a softer rate.
I would get everything designed and built based on the fully compressed length against compressed bump-stops (articulated) allowing for a 1/2"-3/4" of "wasted" travel (in case the bump-stop gets torn-off) then find a spring rate that gives the ride height you want.
I'd try to swap the 2.5" bodies for 2" if possible.