Longer term coil conversion observations; field tests side by side with an EAS truck
Apologies in advance for the length of this, figured more is good.
Purpose: admittedly much of this is in response to quixotic adventure of arguing on facebook, so take that for what it is. What I mean is, generally, when people post up asking for ‘opinions on coil conversions’ there is a lot of commentary but I get the distinct sense that very little of it is based on actual firsthand experience. ExpO is better than many places and we have some folks that have had both platforms who offer very good advice. Facebook and other forums, however, are a different world. Specifically, I’ve gotten into several discussions where people have said:
“The ride will be ruined” and “You will lose all of your suspension travel!” While both are maximalist comments, they are illustrative-and ironically they are verbatim even if not necessary representative of the entire dialogue.
So given that my buddy John has an HSE with EAS, and happens to have his own offroad park with a very controllable/repeatable situation ‘playground’ we could use to test the latter contention, in context-we decided to use a beautiful fall day to see just that. I also let a few frequent EAS LR3 drivers take my truck for a spin to see what their anecdotal observations on the former aspect would be. Keep in mind this isn’t an effort to say that EAS is bad, coil is better or what have you-each has their place and everyone has to weigh the pros/cons in their specific context. The purpose of this is to add a bit more information to the discussion beyond internet conjecture.
Bottomline:
-Coil springs do not ruin the ride of the truck, at least not in the opinion of anyone I’ve had drive or ride in my truck over a protracted period of time. In fact, the EAS owner(s) noted the ride was smoother, less ‘jarring’, and felt tighter, for what that’s worth.
-Coil springs (OME +2 specifically) will reduce your rear suspension down travel approx 2.5”. An EAS truck exhibited approx. 8” of downtravel (wheel totally off the ground, i.e. the max amount of possible ‘cross-linking’ that could have been provided). This is compared to approx. 5.5” of rear wheel downtravel on my coil sprung truck.
Test subjects:
08 HSE with EAS, HD package (locking dif*), 160k on the truck, AMK compressor. 285/60/18 Nitto Terra Grapplers**
06 SE w/OME +2 coil conversion, 100k on the truck. 285/60/18 Nitto Terra Grapplers**
*When we tried to get both stuck it was apparent the locking dif made a significant difference, as one would expect, in the truck’s abilities. While I still don’t think a locking dif is critical for most wheeling and most D3/D4 owners it is clear that the additional traction provided is substantial.
**Identical tires, albeit with some difference in mileage
Test Environment:
Twin Mountain Offroad Adventure (link in sig line) has several hundred acres of mountainous terrain in WV near Moorefield, WV. To assist in instruction, demonstration, and provide a more controlled environment for offroaders of all skill levels the park has a (relatively) flat clearing that includes obstacles to demonstrate approach angle, breakover, departure angle, cross-axleing, side slopes, a practice bridge crossing, a mud pit/trench of sorts, etc. During our testing we ran both trucks throughout this offroad playground with the specific intent of replicating conditions to see what the differences were in terms of suspension travel and response. Each truck was in low range, typically in either mud & ruts or rock crawling mode, with HDC engaged and DSC turned off.
Ride Quality Observations
-My opinion, since the swap, remains unchanged. The coil conversion ride is different but not inherently in a negative way. I found my EAS to feel like it wallowed around, the coils feel tighter and more responsive.
-My significant other had similar observations when she drove the truck after conversion, and since after having driven EAS truck(s) at various times.
-The past few weekends we’ve been in WV the owner of Twin Mountain and the EAS HSE LR3 (and an EAS LR4 for that matter, along with an EAS P38…and some air RRCs…nevermind) rode and drove in the coil D3 several times both at speed on mountain roads, highways, as well as offroad. His observation was the ride was actually nicer than the EAS in his LR3-it felt smoother and more controlled.
-His sig other also drove the truck and she made the exact same comments.
Is this definitive? Of course not. However, it tends to counter the popular narrative that switching to coils will ruin the superb EAS ride
Suspension travel tests
TMORA D3 went first, finding various obstacles to get both front and back wheels off the ground-in some places we managed to get both a front wheel free and a back wheel free at the same time. Coil D3 went second with the wife driving and TMORA owner in passenger seat (he’d been the driver of the EAS truck), having her replicate the obstacles as best as possible to facilitate the same dynamics. Measurements are based off a static distance of approx. 4” from tire to fender flare (i.e. you can see where the EAS rear wheel is 12” from the fender at full droop, thus 8” of downward motion)
Front suspension downtravel appears to be approx. 9.5” (5.5” travel) on the EAS and 9 (5” travel) on the coil truck, i.e. nearly identical and given other suspension geometry elements at play of very little substantive difference for most. Tires, at this size, stuff equally well for both trucks
Rear suspension downtravel appears to be approx. 12” (8” of travel) on the EAS and 9.5” (5.5” of travel) on the coil truck; this is likely the most substantive real difference we could glean from our time putting the trucks through the paces. Of course it also depends on how you look at it, the 2.5” delta between EAS and coils is a decent amount of droop-on the other hand I think my internet war with someone who heard from a friend about coils and thus said I had no down travel at all may be a little off base. Tires, at this size, stuff equally well in the back on both trucks. As the next picture illustrates, in many ways both trucks are structurally inhibited-particularly on the front, and slightly less so on the rear, by their independent suspension setups. You are only going to extract but so much from these trucks regardless of EAS or coil.
Observation: I would note that, in my limited offroading experience with Toyota Tacomas, Discovery 1’s, Range Rover Classics, and now D3’s (i.e. the past 20 years or so) the D3 likes to get wheels off the ground the most regardless of suspension-and the computers do an excellent job of compensating for that. This is particularly true when there is a locking dif in the back, but regardless the truck tends to have a wheel off the ground at times-and that’s ok.
Observation: the cross linking feature in the terrain response may be integral to the D3’s offroading ability, we just couldn’t find much evidence of that. This may be a facet that my D3 retains the terrain response even without the EAS, or a facet that we just didn’t find the right obstacle where that oft touted feature made that much of a difference. I’m open to comments from those that wheel these things a lot more, or a lot harder, on that since it wasn’t evident in our field testing. This ties back to my previous comment about having experienced, and seen, a lot of D3’s (and D4’s) put a wheel off the ground as part of how they deal with obstacles far moreso than I ever have in a traditional LR coil sprung platform like a D1.
Follow on observation: My D1 feels a lot more tippy than my D3, or the EAS D3 for that matter. What I can’t determine is how much that feeling correlates to true instability. The discussion John and I had was it is difficult to see where the threshold for a D3 is in terms of rollover and such, given that we don’t have one that we want to attempt it with we’re not keen on finding out. What I mean is from a seat of the pants feeling doing a 20 degree sideslope like the one pictured is not uncomfortable at all in the D3, in the D1 it is considerable more pucker. The gut feeling we have is the D3, in no small part due to weight and wide stance, is more stable-right up till she isn’t. Then you have a very heavy problem.
Concluding thoughts: Far from the definitive word on the subject, I felt this was all worth sharing for those considering coils-and for those running EAS too for that matter-to further the dialogue about these trucks. It is definitely subjective and likely biased to a degree but at the same time is at least representative of what we saw on that day, with those trucks. It is not an indictment of the excellent and rather robust EAS of the D3/D4 platform; there is a multitude of reasons for retaining that aspect. Towing in particular comes immediately to mind. Heavy loads in the truck; the desire to get into lower garages; access mode for kids, pets, the elderly; offroad height only when needed; crosslinking of airbags (I guess), and a myriad of other things I am likely missing. The superiority in terms of the rear suspension droop for EAS over coils does point to that being desireable if you intend to wheel this truck hard and need every bit of performance. As discussed on these pages and in my D1 thread; I’ll stick to my older (lighter, field repairable) platform for that but for many that is neither desirable nor the point. The counterpoint for those considering the D3/D4 as an overlanding platform for long journeys and such is that the coils may not be the performance and ride ruining detraction that corners of the internet espouse. Removing a variable from the equation and retaining a comfortable and very reliable platform in terms of drivetrain may well make sense, particularly as the truck’s age. Food for thought at least!