Flexy Coils and Mathematical Theory for Review

[Delancy]

Rear coils as noted by tag and my measurements.

PLEASE NOTE. I DID NOT HAVE A MICROMETER, so will remeasure the bar when I get it home

**DS Marked 585**
Free Length - 22.5"
(7) wraps .80 (see note above)
(3) wraps .625 (see note above)

**PS Marked 570**
Free Length- 22.75"
(7) Wraps .8125" (see note above)
(3) Wraps .375" (see note above)

At RH, the upper two coils do flatten.

 

[landtank]

I wasn't born then. Here is a quick history of Hunter. Here is a cool site with Hunter's history. http://www.hunter.com/company/history/ They introduced "Computerized" alignment in 1979. If you are using shops that have equipment that pre-dates that, I would strongly suggest a new alignment place

Well I did alignments for 9 months back in 1980. I'm quite sure we used the stops as an alignment tool for both caster and camber but that was more than a couple of years ago.

I have run into shops that just can't get the readings done for whatever reason.

However, in my opinion that doesn't negate the value of following the FSM to set the stops properly. One less variable that I would be worried about if things weren't going well for whatever reason. And considering the history with this truck it's something I would suggest.

 

[Delancy]

Well I did alignments for 9 months back in 1980.

Do they call the fire department when lighting up your birthday cake?

Rest assured, fellas.

The stops will be set according to FSM by a qualified technician and not the one at Toyota with a laser rack, that aligned my LT FJC.

 

[sleeoffroad]

What I am wondering about is how you measure those angles that you have to set the steering to? Scribe a line on the floor, then turn and do the same and measure?

With the new machines you really can's screw that part up much.
http://www.hunter.com/videos/index2.cfm?v=16

 

[Delancy]

**Process utilized to determine**

Removed Coils

Unbolted lower shock eye

Lifted to full droop and measured

Lowered and measured.

Disconnected sway and repeated the above.

Raised, finagled to achieve a 24" COH/F dimension on both sides and measured.

Raised 1".

**Components that aren't OE**

Christo's pan hard bar and Rick's upper and lower rear links, the uppers OE length with OE bushings, the lowers ~.25" longer than OE with OE bushings.

Sway bar drops (which will be disappearing soon enough, as will the OE sway bar)

It was a Monday in the real world and shop closes at 5:30, so wasn't expecting them to stay over for lift time.

Will complete front in the morning, in similar fashion, unless there's a flaw that is uncovered now.

Obviously the front is substantially different than an OE, caster corrected, so the information will be useless to all.

At the point, my shock order is still validated, as far as I can tell, on the rear with the following measurements:

Rear
760mm (30") extended
450mm (17.75") compressed
290mm (12.25") shock travel

At 24" COH/F measurement, the lower of the two discussed options, 5.75" available at RH, and at full bump, which probably isn't a reality, leaves 1".

Yes, I did skip #3, because it was pointless.

Subtract 2" from any given dimension and that'd be the same as stuffing without tires, but any coil would bind long before that'd be a possibility, even articulated it wouldn't matter, and the damn tires are heavy and cumbersome.

 

[TheBigBoy]

You are SOOO over thinking this whole thing. And making a huge issue out something small and trivial. What is all of this trying to acheive?

If the coils are too high. Swap them or sell them and get slightly smaller. If your trying to work out shock size, the only measurment you need to know is the shock distance at full tuck.

If you want to know what your caster is, go get a wheel alignment.

 

[AutoCraft Aus]

Rear Coil Measurements

**Spring Seat Dimension**

Full Extension No SB
DS 22.5" 571mm coil free height 585mm
PS 23.5" 597mm coil free height 570mm

An informed decision is only something you can make, when you have all the information

Based on this, trimming them isnt an option.

Moving the top shock mounts up would be an option, to trim the coil, and negate the need for big bump spacers for the compressed length, while keeping the same travel, but then more trimming may be required.

Juist what you needed, another variable LOL.

Can I see a pic of the rear coil in the car at ride height, to determine if the top dead coil section is actually fully compressed properly at ride height please ?

Im starting to think the car isnt compressing the dead coils fully.

 

[TheBigBoy]

Im starting to think the car isnt compressing the dead coils fully.

Its not. Its been stripped of all its weight along with no reserve tank.

 

[Delancy]

Based on this, trimming them isnt an option.

Think that was ruled already, due to your assumptions below.

Moving the top shock mounts yup would be an option, to trim the coil, and negate the need for big bump spacers for the compressed length...

Here's my screwed up way of thinking about this.

The shock travel is based on the rear linkages ability to compress/droop, with tire size a consideration, as well the links binding.

Now, seems I need to coil to fit that movement, no?

Coil that'll support at 24-25" COH/F dimension and with a free length of nominally longer than 597mm (23.5")?

Here's the deal. If I have to scrap the shocks I've ordered, I will, to get this right.

Can I see a pic of the rear coil in the car at ride height......

Im starting to think the car isnt compressing the dead coils fully.

Exactly.

As Shane stated, these were meant for a 4" lift on a lightweight 80.

I've got 6".

If they compressed 2" more, than that'd put all the smaller (3) upper rungs on top one another, possibly even onto the larger diameter bar, more like this on the FJC.






Need this many dead winds on a coil for the 80.

 

[Delancy]

You are SOOO over thinking this whole thing.

You know me well enough by now, Mark.

I have little choice but to over think it, because when relying on otters to do the thinking for me, the end result isn't what was requested.

It ain't right as it is, for these reasons discussed earlier in the thread, but I don't want a 6" rear/5" front lift and don't want a coil that binds before the balance of the already disadvantaged suspension should.

Not arguing, man. I want a solution and I'm not smart enough, in the area, to achieve it.

making a huge issue out something small and trivial. What is all of this trying to acheive?

I don't feel it's small and trivial, or I wouldn't have infested the time and fortitude it's taken to compose this thread, the data therein, nor the barrages of the stupidity of the issues from most all.

Trying to achieve a 24" or 25" level COH/F dimension with a coil that'll expand to ~23.5" and compress to a suitable dimension (not 9". I realize the lunacy, there)

If the coils are too high. Swap them or sell them and get slightly smaller.

To which?

I need a coil that'll suspend the four corners at a 24"-25" COH/F dimension, expand to ~23.5" and not bind long before the end of the links/shocks.

If your trying to work out shock size, the only measurment you need to know is the shock distance at full tuck.

Shocks are done, that's how determined, minus coils, and are as follows:

Rear
760mm (30") extended
450mm (17.75") compressed
290mm (12.25") shock travel


Front
768mm (30.23") extended
455mm (17.90") compressed
313mm (12.33") shock travel

If they won't work to see this through, then they'll be room for them on the next build or on someone else's 80, but think they're fine, at least they are on the rear.

If you want to know what your caster is, go get a wheel alignment.

I don't give two chits about caster, right now, that's Christo and Rick's debate, not mine.

 

[Delancy]

Its been stripped of all its weight along with no reserve tank.

No it hasn't.

There's no additional weight beyond OE, overall.

There's a 60-70lb additional bias to the front, sprung weight added above the OE front bumper and half of the removed flare/plastic weight removed.

The removed rear bumper is nearly the same weight at the OE, but have calculated and have additional weight in the rear to compensate for added tube.

There aren't reserve tank 80s in the US, or they're rare/aftermarket adds.

All of which was made aware to, and addressed when ordered.





Are you getting why I can't just order a shorter coil yet?

I'm not being condescending, but this was what I ordered, so I can't base the results, nor the experiences on whatever is a lightweight 80 in Oz, nor is it an easy task to ship over what is unknown.

THAT's the purpose of this thread.

Determining a coil for MY 80 that'll maintain a 24" or 25" level COH/F height, expand to the necessary length to remain captive at the fullest extension of the OE links, while not binding before any up utilization is achieved.

 

[Delancy]

I can't quote the yellow text.




The 585 and 570 must be part numbers and have little bearing on free length, because the coils measured, sitting on the ground, from the bottom of the lowest bar portion to the top of the trim tab exactly the following:

**DS Marked 585**

Free Length - 22.5" (571mm)
(7) wraps .80 (see note above)
(3) wraps .625 (see note above)


**PS Marked 570**

Free Length- 22.75" (578mm)

(7) Wraps .8125" (see note above)
(3) Wraps .375" (see note above)

Something else to note:

When I measured inside the bucket, it would be from the same location as where the coils where measured, from the furthest end of bar to the flat mounting portion.

I also had, as seen in this pic, the OE rubber installed, which may account for 1/2-3/4" I can't say, as I didn't measure that, at all.

 

[AutoCraft Aus]

Its not. Its been stripped of all its weight along with no reserve tank.

Then the primary rate must be well above 160 lb, which should be the absolute max for that rate, if you want them to be collapsed on a std 80 series, here, or over there.

The seller of the product should of realised the local set up, before confirming he was selling a product that should of been suitable.


As should anyone offering product, while helping out.


That isnt the buyers fault, when he specifies what he required.


Now if he is going to buy coils that sit lower, someone needs to make them, they arent "off the shelf" so thats a pretty poor option to offer up, really, when you have spent a heap of time guiding him to start with, and now your suggesting something that isnt possible.


Unless of course you have someone who could send him what he needs, and havent said anything as yet ?


Then to trivialise it by telling the purchaser its no big deal, when it obviously is to him, is really just rubbing salt into an open wound, when you have been involved from the start, it would seem?

 

[ChaseTruck]

Just out of curiosity:

How about adding weight to the back of the truck? In the form of a well-stocked tools and parts box (God forbid my AZ buddies see me post this...) maybe? And since the other thread on axles touts the advantage of having a fully assembled third available to fix a blown diff, how about a front and rear third, a set of front axleshaft assemblies, rear axleshaft, and a set of drive shafts?

Add to that the incontrovertible truth that if you carry a spare part around for 1000 miles, you will never need it, the insurance factor alone should smooth out the ride?

Just sayin'

 

[Delancy]

I wish it were that simple.

I'm laden with weight in the cargo bay.

The tailgate alone takes a lot of ass to close, 85-100lbs in spare tire and carrier, 40lb Co2 tank, trail spares (load when going, which hasn't been much. No thirds, but probably a good idea), and have put as much as 200lbs, purposely to gauge, will little to no height reduction.

Had the (4) Trail Ready's and (2-3. can't recall) several tires in it, not mounted, and nada.

I know no husky women. Not that husky is bad, but married, so I know no other women, period.

If one wanted a 6" lift that won't sag when loaded, but ride decent empty, even with Ls, these are the coils for you.

 

[AutoCraft Aus]

If you want to work out the coil rate, [aprox]

measure height.

add 100 lb to the rear.

measure height.

add another 100lb.

measure height.

add another 100lb.

measure height.

If its on the primary rate first, it will drop more for the first section of 100 lb, than the others, when it gets to secondary, it should drop the same amount [aprox] in comparison per 100lb.

A coil maker may be able to reset the coil 25mm lower in the secondary rate, and increase the free height of the primary for you.

Spring makers will quite often change the coil after manufacture, to get it within the spec required. It can depend on the material, and design if its long lasting, but the lighter the coil usually, and the load, the more chance of success.

Looking at the coil, it looks like a 200kg constant load coil [over the cars std weight] so it will probably drop 10-12mm for every 100kg [220lb] you add to the car and the thicker top section looks like it might be a 200-220 lb coil rate, on the primary.


Given your limits in tie rod ends, and suspension arm bushes etc, and the length of the shocks you have, I would say trimming the coil, and moving the shock mounts up, to limit the bump spacer sizes, and trimming some sheet metal will be the best all round set up, if you have gone this far, to fit the wider rim offset under there.

Or, not unlike *one we are working on here now, where we are moving the suspension mounts up, so our slinky long travel kit offers 1"" lift, in the suspension, butt he height will come from the 40" MTR's, with the fenders trimmed to fit them, and longer rear control arms to move the diff back, you could cut the rear floor out, weld it in higher, then cut out the rear coil and shock mounts, and move them up too, to lower the truck 8)

*Not actual truck*

We also use the cruiser rear set ups, when we put them in 79 series utes to make them coil sprung rear.

More confused yet ???

 

[Douglas S]

Why not just put coilovers up front and be done with it? Even with factory radius arms, they offer nearly infinite adjustment even if the articulation isn't extraordinary.

Shorter springs (or any of the multitude of options already proposed in the thread) for the rear and adjust front to match, heightwise.

 

[Delancy]

More confused yet ???

To some degree, by this.

A coil maker may be able to reset the coil 25mm lower in the secondary rate, and increase the free height of the primary for you.

Primary Rate = lower, heavy coils with high rate

Secondary Rate = upper, lighter coils with lesser rate.

Right?

These images seem to explain, pictorially speaking.








Based on that, wouldn't the following be true if communicating the changes to the exact coils I have:

Need to lessen the primary rate active distance within the coil free length while increasing the secondary rate within the inactive coils distance, right?

I would say trimming the coil, and moving the shock mounts up, to limit the bump spacer sizes, and trimming some sheet metal will be the best all round set up, if you have gone this far, to fit the wider rim offset under there.

Am I'm being optimistic in believing that a coil spec can result that can be given to a coil manufacturer to build a coil specifically?

 

[Delancy]

Is it lunacy to somehow expect to determine a specification that's relatable to a coil manufacturer, in a description that's as complete as this?



Wish there was a bottle jack type scale that could be inserted in the coil buckets at RH that could accurately weigh the corners that a coil was actually supporting.

Any creative means to do so?

 

[scottryana]

Delancy,

Your PM is full but here is the info you asked for,

I didn't really do a build thread but the one I did, the photos are gone because I got a divorce and changed my mac account. but it was here:
https://forum.ih8mud.com/fj55-iron-pig-preservation-society/119024-pig-coils-kind-3.html

Lots of photos in my for sale ad under flikr:
https://forum.ih8mud.com/fj55-classifieds-corner/390352-omg-cant-believe-i-am-doing-fj55-sale.html

And when it made the magazine:
https://forum.ih8mud.com/fj55-iron-pig-preservation-society/420307-55-made-4x4-garage.html