Hello everyone,
Been lurking for years. Great site with lots of good info.
I've been thinking about a Locost for years. Used to live in NE Ohio in the city - back then I didn't have the garage space.
Now I have plenty of garage space, but am in very rural West Virginia. I drive a lot these days with around a 45 minute commute.
Probably 75% of my driving is on 55mph rural routes. Paved, curved, heckuva lot of fun. Problem is, the other 25% is on one-lane dirt/gravel, including our road that also has some pretty steep hills, mud, ruts and, in the winter, ice. We have a '13 Escape with AWD and wide tires, and a good part of the winter and spring, we can't get it down our road both due to the wide tires and the lack of ground clearance. Other two vehicles are an 00 Sierra 4wd and my DD which is an 01 Cherokee (also 4wd). I didn't have the Cherokee last winter - the truck was able to get up and down the road, although sometimes tire chains were required. I have some more aggressive tires for the Cherokee and am hoping they will get me by (but I will have tire chains in back just in case)
Despite both of the 4wd vehicles having essentially the same type of drivetrain, the Cherokee is far more competent. I attribute this to the lack of weight compared to the truck - the truck really gets stuck easily. That's what had me looking into a lightweight platform. The jeep has straight live axles. I have put urethane bushings on the Cherokee, and for what it is, it handles pretty well on the twisty roads, but I'd like to build something a little more competent on the pavement that I can still get to and from home. It also rides pretty hard. Looking for lightweight plus independent suspension also brought me back to the Locost idea.
My first thought was to build a typical Locost, and then add some sort of suspension lift (hydraulic/air) to get the clearance i'd need. But you can imagine what that does to the camber with a typical setup, especially going from, say 4" ride height to 8" ride height. Not to mention the CV joint angles, which over time, are going to end up in that raised position quite a bit of time.
Then I started thinking about how much I could accomplish simply with wheels and tires. The Cherokee has 235/75r15s on it, which are pretty tall, narrow and are available in pavement-friendly, all-terrain, and mud-terrain versions. It's also a very common size in the area since we have a lot of Cherokees running around and this is the largest size that will fit without a lift. Having two cars with the same size tires/wheels also has some benefit, especially if I was able to match the bolt pattern.
Been playing with vsusp with some of the suspension configs I found on the web, especially the car9, and found just putting those wheels/tires on the various models gets me a pretty respectable ride height - about 7" to get the camber close to the original setting at 3.6 ride height. That keeps the CVs within their normal range, keeps all the suspension out of the weeds for the most part.
The Cherokee has about 9" to the bottom of the differential and suspension brackets - about 12" to the bottom of the axle tube. I haven't measured the truck yet. Neither has ever bottomed out on our road. I'm thinking 7-8" might be good enough with a belly pan/skid plate as insurance. Maybe some sort of mild lift system that would add an inch or two would be worth adding for the worst times.
Suspension design is not my forte, but I'm a pretty decent googler. There's not a lot of info out there on setting up suspension for a high-clearance, vehicle with tall/narrow tires other than for fully offroad. For example, should I manipulate the control arm mounting points and lengths to get the roll center back down closer to the ground? How much camber change should I be shooting for during compression? Or is just raising the existing suspension with taller tires pretty sufficient for a road-going vehicle? Should I build it with the clearance I need, or try to design a suspension that keeps reasonable camber throughout a long travel and lift it when I need and then lower when I don't? It seems there are plenty of SUVs out there with pretty high clearance and they're not rolling off the side of the road (for the most part) due to terrible geometry. Seems something more sporty with the same clearance should be attainable? Not that they handled all that well, but the early cars had some pretty good ground clearance for the same reasons I need it.
This isn't something I want to race. The goal is for something that's fun to drive and does better on-road than our other 4wd vehicles, which, just with lower CG alone, seems like it should be doable. That's kind of a low bar and I'd like to do better if possible. It doesn't make sense to invest the time in a car build if I can't at least drive it most of the year, nor if it isn't safe. If I have the clearance, drivetrain and tires, I don't think traction will be a problem off the pavement. It's getting that setup to work on pavement reasonably well that is perplexing me.
I know this way off the beaten path but I was hoping maybe someone had some thoughts on if this is doable and where I might head next in terms of research and design. Maybe someone's thought along the same lines before? Any thoughts/ideas/suggestions appreciated.
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