Flexy Coils and Mathematical Theory for Review

[LT]

Delancy, you need to reverse your upper rear links if the side that is mounted on the frame is a bushing. Your frame stays stationary your axle doesn't hence needing the mis alignment joint on the frame side so the link can move with the axle.

The coils you're showing on the 80 doesn't look like a progressive or dual rate spring just a straight up lift coil.

 

[Delancy]

Delancy, you need to reverse your upper rear links if the side that is mounted on the frame is a bushing. Your frame stays stationary your axle doesn't hence needing the mis alignment joint on the frame side so the link can move with the axle.

They're they same bushings on both ends.











landtank's Upper Rear Links

The coils you're showing on the 80 doesn't look like a progressive or dual rate spring just a straight up lift coil.

Doesn't appear to be and why I'm hesitant to cut.

There's two dead coils at the top and they expand, but due to overall length of the coil it's hard to say how relevant the upper rungs are.

Well, don't this suck. Back to square one.

What are my options for a coil that'll lift 4" yet not fall out at fullest extension of front and rear links?

 

[AutoCraft Aus]

The FJ coil design is prone to breaking at the area between the active, and dead coils, and really needs to be tapered wire to get the right result.

We spent lots of $ and lots of time, with many designs, to find that out.

We now have a coil we use with a 29" rear FJ shock that stays in there, with offset lower arms, to stop them contacting the housing.

The 80 rear, is a simple process for you to work out the details, I think.

Measure coil free height.

Measure distance between coil seats at full shock extension.

Cut the coils off and grind flat to within 10mm of your coil seat measurement when dropped with the shock.

Space the shock mount on the rear up 1" and that will give you more to trim the coil by, reduce your bump spacer an inch, same travel, just slightly different place.

Trim more than the distance beatween the coil seats, and fix the bottom of the coil to the housing seat, top will locate itself, if its only 10-20mm shorter than the seat distance.

Even if you dont like to do that, at least you will see/feel/try the set up, at the height, to see if it was worth it.

More than one way to skin a cat sometimes

 

[LT]

They're they same bushings on both ends.

landtank's Upper Rear Links

Doesn't appear to be and why I'm hesitant to cut.

There's two dead coils at the top and they expand, but due to overall length of the coil it's hard to say how relevant the upper rungs are.

Well, don't this suck. Back to square one.

What are my options for a coil that'll lift 4" yet not fall out at fullest extension of front and rear links?

On your fjc

 

[Delancy]

Pretty sure they're correct.

Have had them off several times since and replacing rear link and front control arm bushings is on the short list, so they'll be off again, soon.

Another opportunity for bloodying knuckles in the same spots that take forever to heal.

 

[AutoCraft Aus]

Need some of these

 

[newtomelx]

Nice gloves!!

 

[sleeoffroad]

OK, my suggestion on cutting coils was based on the assumption that your springs were like you showed for the FJ with a lot of dead coils at ride height. Did not realize that you actually have very little. Cutting those coils will probably not work very well.

 

[sleeoffroad]

Not every shop or every dealer has the most up to date equipment for alignment racks. I know one in RI that can't even measure caster. For that reason alone I stick with a shop I know has the latest stuff.

Still confused about your comments on this. So you use a shop that uses the latest equipment, and that equipment relies on the steering stops to determine the left and right turn while doing the caster sweep?

For the Hunter machines that we work with, I can not find any references to that. I did find some references that one really really old machines, the left and right turn could have been dictated by an angle measurement/dial on the turn plates on the front wheels.

So if you are going top take the time to adjust the stops why in hell would you not do it right?

Your comments said that incorrect steering stop adjustment will influence caster calculations by a alignment machine. I have not seen a single reference to this in the documentation we have with our alignment machine.

Adjustment of the steering stop is documented and the angles are 31 and 35 degrees. Most alignment machines require a 10 to 15 degree swing on the caster sweep, so that is way inside the steering stop limits. So they cannot affect caster calculations as you mentioned on any machine that gives the operator an reference on how far to turn the wheel.

For those that care to get into the math behind caster and how it is done, here is a good article.
http://www.disco3.co.uk/gallery/alb...eering-geometry-and-caster-measurement[1].pdf

 

[Delancy]

OK, my suggestion on cutting coils was based on the assumption that your springs were like you showed for the FJ with a lot of dead coils at ride height. Did not realize that you actually have very little. Cutting those coils will probably not work very well.

I figured and why I was hesitant to fire up the torch.

A picture is worth twenty five billion of my words, huh?

 

[sleeoffroad]

Yes, should have posted those pics in the beginning. Based on those pics, and your given free lengths it does not look like the are compressed a lot. What is the wire diameter and the number of coils on those rear springs?

 

[Delancy]

In continuation.

Allocated lift time, today with intent gather enough data to put this to bed.

My intentions, all with no coils and no shocks, and presenting for review. If I need more, please advise.

1. At full droop, measuring distance between coil perches.

2. Stuffing both axles with tires on before contacting fender, measuring between coil perches and axle to bumps.

3. Stuffing both axles no tires and measuring between coil perches and axle to bumps.

4. Lowering to a level 24" COH/F dimension and measuring between coil perches

5. Lowering to 25" COH/F dimension and measuring between coil perches.

I'd give anything to be weigh the four corners under at all four coil locations at a level ride height, but can't come up with any scales capable in all of Tulsa.

Any additional dimensions that might be relevant to determining information to potentially correct coil issue, I'd appreciate.

 

[Delancy]

Yes, should have posted those pics in the beginning. Based on those pics, and your given free lengths it does not look like the are compressed a lot. What is the wire diameter and the number of coils on those rear springs?

I thought I had, but think I got pissed off and deleted the post.

Will have them pulled within the next two hours, and will detail the best I possibly can.

For the record, I'm not cutting these coils. I'm seeking a more elegant solution.

They did ride nice, but believe they'll be available to purchase soon.....if I can get replacements to my liking soon enough.

 

[sleeoffroad]

While you are at it, measure the distances between shock mounts for all the cases you mentioned.

 

[Delancy]

While you are at it, measure the distances between shock mounts for all the cases you mentioned.

Already have about a month ago, but will replicate.

Shocks should be on my doorstep any day, travel criteria determined from previous, similar endeavor.

Ordered:

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

The compressed dimension isn't the actual dimension between the mounts.

 

[landtank]

Still confused about your comments on this. So you use a shop that uses the latest equipment, and that equipment relies on the steering stops to determine the left and right turn while doing the caster sweep?

how do you think they aligned cars prior to lasers and computers?

 

[scottryana]

Don't take your truck to places that dont have these. It makes no sense they are everywhere now.

how do you think they aligned cars prior to lasers and computers?

 

[sleeoffroad]

how do you think they aligned cars prior to lasers and computers?

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

 

[Delancy]

Rear Coil Measurements

**Spring Seat Dimension**

Full Extension No SB
DS 22.5"
PS 23.5"

Full Extension with SB
DS 21.25"
PS 21.75"

4" RH COH/F
DS 15.5"
PS 15.75"

5" RH COH/F
DS 16.5"
PS 16.75"

Full Bump (see pics)
DS 9"
PS 8.75"

By full bump, I mean.

 

[Delancy]

**Rear Shock Lengths**

Full Extension No SB
DS 30.5"
PS 31.25"

Full Extension with SB
DS 29.5"
PS 30"

4" COH/F
DS 23.5" PS 23.75"

5" COH/F DS 24.5"
PS 23.75"

Full Bump (see pics)
DS 18.75"
PS 18.75"

By Full Bump, I mean....