FJ80/FZJ80 Vs LX coil springs (1 Viewer)

[robinhood4x4]

So I've found the FAQ and did some searches, but I'm getting conflicting info. Are the rear coils from a LX different from a FJ80/FZJ80 (toyota)?

The FAQ says the coils are the same, but the shocks are softer on the LX. Slee's FAQ says the LX has a "softer suspension", which may imply both are softer.

The reason I'm asking is because I just installed some stock LX coils in my 4runner, but I'm getting less lift than I expected. I'm wondering if it's because the springs are softer, or because I have a really heavy custom bumper.

 

[tarbe]

... or because I have a really heavy custom bumper.

How heavy is really heavy? How did you come about your expectations for the lift?

Someone will chime in on the LC vs LX spring issue (don't know if there will be a consensus), but between your non-stock bumper and the uncertainties involved in the spring swap, I don't know how certain you could be of getting exactly X amount of lift.

 

[Tooth Fairy]

LX from my experience are much softer and therefore give a worse ride and ride heigth ( I forgot how to spell that). They bottom out terribly on an even stock rig over sligth ( man I'm havin' a total brainfart here ).

I've got some old stock '93 boingers and '97 LX's and there is now comparison. Less winds and the diameter is decreased too.

Hope that helps.

 

[robinhood4x4]

Most people who have done this swap get about 2" more than what I have now. This is my rear bumper:

The gas tank is empty, but the tool box probably has about 50lbs of stuff and the bumper itself weighs about 140 lbs, plus the hilift.

Tooth fairy, thanks, that does help. Dammit, now I have to look for new coils.

 

[syrinxstar]

Less winds and the diameter is decreased too.

Well the consensus used to be the springs were the same but the shocks were valved differently. If TF is saying he has a confirmed visual inspection of differences in pitch and wire diameter, then maybe the complete shock/spring combo is different.

 

[cruiserdan]

The part numbers for the LX450 springs are the same ones for the 96-97 80. The shock part numbers are different.

 

[robinhood4x4]

Here are the LX coils I got, LX on left, downey 4runner coils on right.

Can you guys see any differences between these and early 80 coils?

 

[Junk]

One is dirty and one is clean. C'mon sparky, if you are swapping springs on your 4skinner I'd hope you could at least figure into the calculation the amount of weight on your rear bumper. It ain't rocket science.

 

[cruiserdan]

I gave my original 1993 springs away years ago. I can tell you that the OME 863 wire diameter is larger and the OME 864 wire diameter is WAY larger than those.

 

[robinhood4x4]

One is dirty and one is clean.

I knew somebody was going to say something like that which is why I specifically said, "...between these [LX implied] and early 80 coils?"

Are there spring rates for the stock springs published somewhere? This spring swap is a fairly common thing and the consensus has been that I'd be higher in the rear than the front, even with heavy bumpers.

 

[Beowulf]

The stock springs have 16mm wire but I cannot remember how many coils. Those pictured have 5-1/2 coils so that must be the number if those are stock springs. Seems like they should have at least 7 or 8 coils though. The OME stock length springs (16mm) have about 10 coils.

-B-

 

[Junk]

Oh, hooded one, funny how just about every project you delve into has issues like this (and your 80 series axle swap). Not to be too harsh on you, but have you ever considered doing the research PRIOR to starting the project?

 

[robinhood4x4]

Junk, Ummm...I think you have me confused with somebody else. I don't know what you're talking about.

 

[cruiserdan]

Are there spring rates for the stock springs published somewhere?

Not that I have seen, at least not from the factory. Toyota does not typically publish that type of information. I can tell you that there are several different springs used on 80's depending on year model and equipment. Some 91-92 vehicles had "towing" springs and used the same height spring on both sides with a 10mm steel spacer on the left side. Most 80 series springs are left and right-handed with the left hand spring being taller. The 4Runner uses springs of the same height on both sides.
Logic dictates that a 4Runner should lean if a "pair" of 80 coils is used as opposed to 2 rights or 2 lefts. To elaborate it would seem that you would want to find 2 lefts from the same year model to have a rate match and maximum lift.


D-

 

[robinhood4x4]

I've measured my wire diameter and it's at 15.4mm. From the picture I posted above, one side has 6.5 coils and the other has 5.5 coils.

With these numbers, I've run the calculation to find the spring rate as they sit in my truck according to the equation:

k=(dG)/(8NC^3), where:

N=number of active coils=3.75 on driver side
D=mean coil diameter=6.4in
d=wire diameter=0.6063in
C=D/d
G=modulus of rigidity=11,600ksi

I come up with 200 lbs/in. HOWEVER, these springs are compressed to the point where the coils are touching each other at the ends, thus the small number of active coils used in the equation. The effect of this is the spring rate is artificially higher.

To back up the theoretical side of this, I also did some testing on my 4runner. The wheelbase is 102in and the distance from the rear wheel to my rear bumper is 42in. With 150lbs of me standing on the bumper, the bumper sags approx 1in. Doing some basic statics and free body diagram, I find the force the rear springs feel is around 211lbs and the deflection at the springs is 0.7in. That makes the spring rate 211/0.7=300lbs/in...but wait, there are two springs in parallel so that means each individual spring has a spring rate of 150 lbs/in.

So the theoretical comes out to 200lbs/in and the experimental is 150lbs/in. What does this mean? Well, unfortunately, a small error in measuring can make a big difference in the result so it's difficult to say how accurate the experimental result is. My conclusion is that the spring rate of the stock LX springs are somewhere below 200lbs/in and above 150lbs/in. I know, a huge difference, but it's a start anyway. I can take better measurements the next time I see my friend, it's kinda hard to measure things by myself.

Some of the spring rates for OME rear coils ranged from 220-260 lbs/in (I think 260 was the high?), per a past thread, so I'm in the ballpark. Please feel free to check my work above, that's why I posted it.

So, here's another comparison. This is a picture of coils from an earlier 80: http://community.webshots.com/photo/103759693/117565896PiWeOL

Compared to the ones I posted above, the early 80 coils have almost 7 coils, while mine have 5.5 and 6.5 coils. Also, the wire diameter appears to be thicker, but it's hard to be sure. This adds to the confirmations from toothfairy and beowolf.

Based on Dan's part number post above, I conclude that 96-97 FZJ80's and LXs have a softer spring, while the FJ80s and FZJ80s before 96 have stiffer ones. This contradicts some posts in the link in the 80 series FAQ.

 

[semlin]

I sold my 93 LC coils to a guy who got more lift than he expected on his 4runner but I think he used the front coils. You are using rear coils.

the stock uncompressed coils off my 93 were 19" high ds and 18 3/8" ps front and back. The rear coils are wider and have 6.5 turns versus 8 turns on the front starting from the end of the base and moving up. I am certain of this because I checked it twice before telling the guy and then he came out and verified. The ones in your photo are rear coils. The one on the left in your photo has 6.5 turns but the one on the right is more like 5 3/4. I do not remember ANY difference between turns on the ps and ds coils and the difference in height between ds and ps looks greater on your coils.

 

[semlin]

Also, if it helps I calculated that my stock coils compressed were 12" front and 11 1/4" rear (although I didn't directly measure this so I had to do this by extrapolation based on measurements I took between axle and follow shock before and after the lift and measuring the ome coils compressed). My truck is 5200lbs

 

[robinhood4x4]

Interesting that he used the front coils as everybody I know have used the rear, I don't think I've ever heard of anybody using the fronts.

Unfortunately, I would need to know the exact weight distribution to use your truck weight to calculate the spring rate.

If anybody wants to do the leg work, all you need to do to calculate the spring rate is put a big weight on the back and measure the amount the back sags. Then, measure the wheelbase and the horizontal distance from the center of the front wheel to the middle of the weight.

The force the springs see will be = weight x distance from front tire to weight / wheelbase.

To make it easy, measure the deflection at the wheelwell (centerline of the springs). This is the height change, so it'll probably be only 1 inch or so.

Spring rate will be ForceAtSprings/DeflectionAtSprings. Divide that number by 2 and you have the spring rate for each spring.

Hints: make the load as concentrated as possible, like a person standing up and as far from the rear wheels as possible.

 

[medtro]

https://forum.ih8mud.com/showpost.php?p=359549&postcount=3

 

[Beowulf]

Based on Dan's part number post above, I conclude that 96-97 FZJ80's and LXs have a softer spring, while the FJ80s and FZJ80s before 96 have stiffer ones. This contradicts some posts in the link in the 80 series FAQ.

And I believe you have reached an incorrect conclusion.

-B-