Old-timer finally joining the SFD bandwagon

[hawairish]

Well, I installed the Moogs with limited success...with about 1.75" from the spring perch and isolator, the lift amount was only about .25" taller than what my OMEs and 2" spacers produced.

 

Since that's not consistent with manufacturer-provided specs, something is spec'd wrong. OME's catalog says that OE spring rates for the 4Runner were 150 lbs/in, and that seems far more accurate than Moog's spec of 190 lbs/in. Go figure.

 

Still...that's not bad for an OE spring.

 

Overall, fitment was as good as could be expected. The ID of the OMEs were actually closer to 4.9", not 5.05" that R50 Moogs are spec'd, so the upper isolator was looser than expected. The OD of the Moogs do fit within the outer lip of the upper perch, so I don't have any particular safety concerns there. But, I think a poly-vinyl or rubber tube to wrap the ends might be beneficial to fill gaps and avoid the possibility of metal-metal contact.

 

The good news is that this is a more economical lift approach for those wanting about 3"-4" inches of rear lift. Figuring OMEs run about $170 and 2" spacers run another $100, my test setup was about $90 (springs, spring isolator, and the 2" body lift pucks used to center up the pigtail on the axle perch, bolts...the body lift pucks were a temporary solution, though, but I've seen it used like this before). However, I did not give this a road test, so I can't attest to ride quality. But a few jumps on the truck to help it settle, it did feel a little softer than OME...but hard to say of course.

 

For now, I don't have any other OE springs worth trying that get us into that range 4"-6" range. FJ springs seemed like the next best option, but given some cross-references, I think these might be about the same as what I tried.

 

I'll get some pics up later.

[hawairish]

Moog 81045 vs OME 2922:

 

 

Installed:

 

 

Upper perch:

 

 

Lower perch:

 

 

The body lift spacer isn't my plan; I bastardized it from my bumpstop extension. I think that it could work reasonably well.

 

I got to thinking that I could put Toyota spacers up top, but I'm wanting a no-cut/no-spacer solution.

Edited June 12, 2018 by hawairish

[jyeager]

First comment: The 4Runner spring is a variable rate spring by virtue of the lower diameter coiling at the pigtail. That could explain the discrepancy you see between advertised spring rate and your experience....when you installed it and the vehicle weight compressed it, you were using that lower spring rate first. If you then tested the spring rate by adding weight above your axle, you might have seen something closer to spec.

 

Second comment (actually question): Aren't there lift springs for the 4Runner you could simply swap in to this setup you have and get your desired lift?

 

[hawairish]

First comment: The 4Runner spring is a variable rate spring by virtue of the lower diameter coiling at the pigtail. That could explain the discrepancy you see between advertised spring rate and your experience....when you installed it and the vehicle weight compressed it, you were using that lower spring rate first. If you then tested the spring rate by adding weight above your axle, you might have seen something closer to spec.

 

Second comment (actually question): Aren't there lift springs for the 4Runner you could simply swap in to this setup you have and get your desired lift?

 

 

It wouldn't surprise me if Moog's specs were wonky in more ways than one, but these are spec'd as constant rate.

 

A pigtail isn't indicative of a variable rate spring, though. Steel hardness, coil diameter, coil thickness, and spring pitch are all factors of spring rates.

 

There are several variable and constant spring rate lift springs available. These were a no-risk purchase...I can even return them for free. It was a fitment test more than anything, but by the numbers, it should've yielded more than it did (math below).

 

I will still make spring perches and will eventually guinea pig actual lift springs. Even OME springs should be good for about 6" of lift.

 

(Warning: math!)

Here's why the Moogs should have yielded more...

 

My OMEs have a free height of 13.75" (spec is 14.17") and an install height of 9.75" (so 4" of compression). If 140 lbs/in is still accurate for them, then 4" x 140lbs/in = 560 lbs load supported per spring. For the Moogs, 560 lbs * in/190 lbs = 2.95" of compression, which means that Moog w/perch should have been 1" taller than OME w/2" spacer. I saw about a .25" difference, which is consistent with OME's OE spec of 150 lbs/in: 560 lbs * in/150lbs = 3.73". If my OME springs are worn (and to some degree they must be if the free height is nearly .5" below spec), then it would have equated to even more visible lift for the Moog setup.

[jyeager]

 

It wouldn't surprise me if Moog's specs were wonky in more ways than one, but these are spec'd as constant rate.

 

A pigtail isn't indicative of a variable rate spring, though. Steel hardness, coil diameter, coil thickness, and spring pitch are all factors of spring rates.

 

 

 

Is pigtail not the right nomenclature? At that one end where the coil diameter comes down to roughly half of the 5" diameter...For the last couple of coils. That part of the spring just will not yield the same rate as the rest of the spring.

If that entire section compresses under the vehicle's weight at that corner, then and only then does the spring become constant rate.

But you can't look at the spring's specs and plug those in to a spring rate calculator and get the correct answer on spring rate. You either include the full height in your calculation and it gets thrown off because part of the spring isn't the 5" diameter you are inputting, or you measure height as the free height MINUS the necked down coils in which case you get a bad result too...

 

Never the less, after test fitting and measuring spring height, then adding a known amount of weight to the spring and measuring again, you could then have an accurate rate.

And the spec's spring rate may be accurate in this sense. You just can't use the spec'd spring rate + free height + corner weight to predict your ride height.

 

Does any of that make sense?

[hawairish]

 

Is pigtail not the right nomenclature? At that one end where the coil diameter comes down to roughly half of the 5" diameter...For the last couple of coils. That part of the spring just will not yield the same rate as the rest of the spring.

If that entire section compresses under the vehicle's weight at that corner, then and only then does the spring become constant rate.

But you can't look at the spring's specs and plug those in to a spring rate calculator and get the correct answer on spring rate. You either include the full height in your calculation and it gets thrown off because part of the spring isn't the 5" diameter you are inputting, or you measure height as the free height MINUS the necked down coils in which case you get a bad result too...

 

Never the less, after test fitting and measuring spring height, then adding a known amount of weight to the spring and measuring again, you could then have an accurate rate.

And the spec's spring rate may be accurate in this sense. You just can't use the spec'd spring rate + free height + corner weight to predict your ride height.

 

Does any of that make sense?

 

Pigtail is the right nomenclature. But, keep in mind that as the pigtail's diameter gets smaller, its pitch also decreases slightly on these springs. It makes about 1.5 wraps in the same pitch height as any 1 wrap below it, but even then probably represents a trivial change in the spring's properties since bar thickness and material is unchanged. I can't quantify it using the household objects I have at hand, except maybe by comparing coil lengths in a given pitch, but I'd be pretty confident they'd net out to some degree if in fact it is a constant rate spring as advertised.

 

And you can look at a constant rate spring's specs and predict an answer. It's called Hooke's Law.

 

https://en.wikipedia.org/wiki/Hooke%27s_law

http://www.efunda.com/designstandards/springs/calc_comp_k.cfm#calc

 

Perhaps the pigtail has some degree of progressiveness, but if Moog's calling it a constant rate spring, I'm treating it like a constant rate spring. All I'm saying is that my observations are more consistent with OME's numbers than with Moogs.

[jyeager]

 

Perhaps the pigtail has some degree of progressiveness, but if Moog's calling it a constant rate spring, I'm treating it like a constant rate spring. All I'm saying is that my observations are more consistent with OME's numbers than with Moogs.

 

Fair enough.

Very interested in seeing the new swap approach you settle on (ie. specific part #s).

Thanks.