LX570 AHC Rear Coil Spring Experiment (1 Viewer)

[medtro]

Regrettably, I'm going to have to shelve these springs for now. Surprisingly, to me at least, these coils are apparently waaay stronger than I excepted them to be. I don't have the time to fiddle f*** around with this if I don't see the possibility for positive results. I think @medtro has summed it up. I'll need steel bumper type weight to take advantage of these and I do not see that in my future.

An option to have less "spring" from the LX570 set is to create hybrid springs. Use shorter spring from the LX570 set, and longer spring from the LX470 set. Vehicle will go down to L mode easier with this combo. Maximum height in H mode is shorter compare to when both LX570 springs are used. Negative sensor lift is also needed with hybrid springs.

 

[medtro]

Measured spring rate for used LX570 springs with 218k mile is 105 lbs/in.

k (spring rate) = L (load) / T (travel)

= 202.7 lbs / 1.938 inch
k = 105 lbs/inch

This agrees favorably against known data and allows us to finally fill in the blank:
LX470 AHC - 95 lbs/in
LX570 AHC - 105 lbs/in
King Springs AHC KTRS-79 - 130 lbs/in
LC80 - 150 lbs/in
LC100 - 170 lbs/in
LC200 - 170 lbs/in

Thanks for taking the time to measure that!

Understandable. My best guess from some 570 forum digging is that the OEM 570 AHC springs fall somewhere between Kings (130lb/in) and OEM non-AHC 100-series springs (170 lb/in). That will be too much spring for a lot of builds.

 

[GTV]

That's much less than I was expecting. That doesn't leave much room in-between for the supposedly stronger 2006-07 LC AHC coils.

I've recently settled down and unloaded the awning, RTT and bikes + rack off my truck plus a lot of the extras I was hauling around. It feels like it is riding firmer than it previously was, I'm thinking the Kings might be a bit too much for my truck in "light" street trim (although I may just need new globes which are on order). Now that I've got a garage I just might have to try out the take off 2021 LX coils I've got in stock. I do like that they are much longer than the Kings and of unequal length, although I'm sure some fine tuning (shims) will still be necessary to level it out perfectly.

 

[thibaut]

Did you consider simply adding a spacer.
That is the very cheap mod to increase the weight your stock springs can carry

 

[GTV]

Did you consider simply adding a spacer.
That is the very cheap mod to increase the weight your stock springs can carry

Spacers are only really good enough for restoring pressures on stock coils when you're at near stock weight/lift. If you sensor lift and/or add weight the spacers on old original coils aren't enough to get the pressures back in spec.

 

[chriscosta416]

With my Gamiviti rack coming soon and an expected weight increase to follow I’ve been thinking about coil springs. I’ve decided to test out some LX570 coils to see if this is a viable alternative to Kings as they aren’t exactly cheap and there is often a wait to get your hands on a pair. I’m also the type that prefers OEM Toyota stuff as much as possible.

Some rudimentary googling shows my 2007 LC weighs in at 5425lbs and the front/rear weight distribution is 51/49. I have my third row removed and drawers installed so I’m fairly confident that my actual weight isn’t too far off from that figure. I’ve been able to travel pretty light so far.
By comparison a 2021 LX tips the scales at 6000lbs with the same f/r weight distribution.
The only thing I don’t know for sure is exactly how much weight is supported by the springs and how much is on the AHC for the 100 vs 200 series.

I found this pair on eBay for $120 shipped. They claim to be off of a 2021 LX and look virtually brand new.
View attachment 2972713

The drivers side (left) spring has a blue marking, comes in at about 19” tall and has 5 1/4 wraps.
The passenger side (right) spring has a white marking, comes in at about 17” tall and also has 5 1/4 wraps.
I’ll see if I can get my mitts on a dial indicator to measure wire diameter.

I currently don’t have access to a proper garage and tools right now so I apologize that this won’t be the most scientific experiment mud has seen. I will run Techstream before and after the swap as well as take height measurements. I currently have 35mm of spacers on my original AHC LC rear coils and I will transfer them over to these springs to have an apples to apples comparison, at least to start.

Hoping to get these installed this coming weekend. I’m wide open to any other suggestions the mud brain trust has.

I have an LX570, willing to sell me your like new 570 coils? Ill send you my old ones

 

[GTV]

I have an LX570, willing to sell me your like new 570 coils? Ill send you my old ones

Potentially… I want to take some measurements and compare them to my original 06-07 coils first.