Just like choosing wheels and tires, the decision to lift a Jeep is not a light decision. The wrong lift can dramatically affect the way a Jeep handles. Because everyone is different, first consider this one important question: What do you want to do in your Jeep?
Will it be a commuting vehicle, spending a lot of time on the freeway? Or will the weekends occupy its primary usage? Or, will it be a dual-purpose vehicle, driving both off-road and on-road? Over half new Jeep owners are most likely in the dual-purpose crowd, and a small lift would do the trick. This allows a weekly commute, while on the weekend we can go air down the tires, lock it in, and take the kids fishing.
At TeraFlex there is a butt for every seat, tire size, and lift.
TeraFlex Vice President Jeff Mock states, “Most people think the higher they go, the better the lift. That they need higher ground clearance to clear bigger tires and four-wheel better. I’ve always thought the opposite. The lower you go, the lower you stay, and the more stable your Jeep. I usually get [33's with] a 2.5 – 3 inch lift.”
Joe Thompson of TeraFlex International Sales, however, loves to go big. “In the past I liked the 3 inch kits with 35 inch tires combination. But after I saw a JK that TeraFlex built with a 4 inch kit and 37’s, I knew that's what I wanted.” Love at first sight.
AJ Swenson of TeraFlex National Sales goes even bigger. “I think I will always have 40 inch tires. Clearing that 40 inches is going to take a 6 inch lift, our Long Arm Kit. That’s what I did.”
Basically the tire size and lift kit go hand in hand. First, choose which tire to run, and then base the lift height off that tire size. Most Jeepers probably aren’t driving ten out of every thousand miles on the trail, and will want a Jeep they can drive around town. Something that can run those daily errands, go on vacation, that’s stable on the road, and can still go to Moab for a good time off-road. For many, these Jeeps are a second car, and for some a primary. Especially for those with families constantly climbing in and out, which is becoming more common, a lift height that maintains ease of access is often ideal.
TeraFlex Engineer Bryce Calvin says,
“The big advantage of the Budget Boost (see JK 2.5 Budget Boost) is that you’re able to get a larger tire without the expense. Because the Budget Boost is just a spring spacer, you still use your factory springs. Luckily with a JK, we have bigger openings. Meaning that with a 2.5 inch Budget Boost, we’re able to run up to a 35 inch tire. But, it all depends on what type of trail you like to run.
“If you start running slightly harder trails,” Calvin explains, “you’re going to have a hard time with some obstacles. You’ll have less ground clearance, less breakover angle, less approach angle and departure angle. You want to be sure you’re tall enough for clearance. Otherwise you’ll drag.
“Although, it does depend. Because maybe you’ve got heavy duty rockers and skid plates, and yes that will keep you from getting body damage. But you can still get hung up.”
The JK 2.5” Lift Kit however, has its advantages and benefits. The Budget Boost means adding a spacer block, but the 2.5” Lift Kit means adding active coils, providing more suspension and spring travel. The springs help with additions such as a winch in the front or a heavier spare tire in the back, causing overall weight to become less problematic. This lift also includes a beneficial lift in the front to improve the low-nose factory rake.
So for the weekend warrior out to do some fishing and maybe some light trail use, and still needs to get the kids to football, the 2.5” Budget Boost or 2.5” Lift Kit is probably all you need.
“That’s going to get you where you want to go,” says Calvin. “It’s going to allow you to run a bigger tire, and give you a great ride.”
However, those who decide to go big will need a lift with some adjustability to correct geometry and to save their driveline from an otherwise short and painful life. If we want to be rough and tough, we have to pay to play. Bigger lifts require more components and added costs.
For example, TeraFlex has a kit that includes only four arms, the JK 3” Suspension System With 4 FlexArms. This includes front lowers, which allow the front lowers to lengthen, helping to regain the caster angle. There are two things to pay attention to in this setup: the caster angle, and the pinion angle. Because of a solid axle, the angle between the pinion and the caster is fixed, so there must be a compromise between the two. Taking a look at the driveline angle, specifically at the axle housing during a lift installment, the angle is becoming steeper. Making sure that the driveline is pointed directly at the transfer case is important in order to reduce driveline vibration and strain on the U-joint. The rear is doing the same thing, but because there is no caster in the rear, only the driveline is being adjusted.
As the vehicle is lifted, wheelbase decreases due to the arc of the arms. So if someone buys a kit that includes all eight arms, such as the JK 3” Suspension System With 8 FlexArms, they can move the axle back into position and regain the factory wheelbase.
For this 3” lift, the 35” tire is still recommended. A 0.5” upgrade from the 2.5” kit is a small difference but it does provide more ground clearance. Another advantage of the FlexArms is that TeraFlex has included a flexible joint on one end, which allows more articulation than just a rubber bushing.
Swenson approaches a large obstacle in his coworker’s 2010 JK with a 2.5" lift kit and 35's. The approach angle clears as he drives the front tires up the wall of the obstacle. “I hear the hitch dragging, but that’s it,” Swenson comments. The front tires reach the top of the obstacle, and as he attempts to continue climbing, the jeep remains put.
He explains, “What’s happening underneath is that the breakover angle is too great on this obstacle to get this Jeep up and over, because of the wheelbase.” A 2-door JK with the same 2.5” spring lift would have easily cleared that obstacle, because of the wheelbase difference. Meaning the smaller distance between the front and back tires of a two door would increase breakover angle, and decrease chances of the belly hitting the edge.
Wheelbase length can work for us, as well as against us. A 2-door build will not need as much lift as a 4-door, to clear the same obstacle’s breakover angle. However, that longer 4-door wheelbase will shine on a steep incline and approach angle. That’s the nature of wheelbase – one must take the good with the bad.
Swenson explains, “Really the way you want to build your rig is you want to figure out, What is it that I want to be able to do, the trails I want to do, and the ease that I want to do it with? And that’s how you outfit your vehicle.”
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TeraFlex asked Hank, a brand new Jeep owner, about which lift he's considering. He states, “I’ve done a ton of research, and there are a couple of looks that I like. I like the big burley look. But with my budget I’m thinking a 35 inch tire. But I don’t actually want a 35, I want at least a 37. I’m just not sure what that entails.”
TeraFlex professional Dennis Wood offers guidance, “You can run a 37 tire on a 3 inch lift. With a 37 tire we need to be able to move that tire back and forth in the fender well. The tire needs to go in the center of the fender well, so it can go up and down as you ride without rubbing.”
Hank replies, “And you’re saying with a 3 inch lift, I can actually adjust that?”
“As long as you’ve got the eight adjustable arms,” Wood replies. He then suggests, “There’s one more option we could do that would work a little easier, and that’s to throw in a 1 inch body lift.”
“Wait a minute,” Hank hesitates, “a body lift? Now I don’t want it looking like a Suzuki Samurai.”
Wood responds, “I understand, but I’m only talking 1 inch. That way if you did a 3” lift kit, we can run these stock drive shafts. That’s going to save you maybe $1,000.”
The 1” body lift helps keep the center of gravity lower by keeping the frame and power train that much lower. However, manual transmission equipped Jeeps need to consider the feasibility due to additional modifications that will need to be made. That being said, a body lift will not improve frame clearance or breakover angles.
Hank lights up, “So basically, I can take the money I would invest in a drive shaft and put it toward the tires. That will keep the wife happy.”
Wood confirms, “You’ll save some money on the lift, you still get the bigger tires, it will look good, and you will love the difference.”
* * *
Meanwhile Joe Thompson expounds on his “big” perspective. “I think you can do a lot of things with the small lifts, it’s just that those don’t fit my personality or what I want out of a JK. The small lifts have a lot of advantages, you know like better gas mileage, easier to get into, but the problem with those is that, in my opinion, they’re more plain looking. They get more lost in the crowd. I like a vehicle that stands out, that’s got some personality to it.”
Jeff Mock chuckles, “Well there’s a lot to be said about ego, and there’s nothing wrong with that. If you like the stance of a Jeep with a taller lift, hey it’s your Jeep. Do what you want with it. But there are a lot more geometry issues when you go taller.”
Referring to Mock, Engineer Calvin says, “If he wants it to be quicker, if he wants to run the smaller tire, there’s no reason for him to go with a bigger lift. If you start running a large 37 tire, it’s going to rob you of horsepower.” Calvin explains that one of the advantages of keeping it low when pre-running is keeping your center of gravity down. By running a shorter and smaller tire, acceleration will be much quicker. “On the other hand,” Calvin continues, “as you look at it on the trail, a 37 inch tire offers a more capable rig. But someone like Jeff Mock, he’s not interested in running that type of trail.” Jeff Mock will not only be happiest with a smaller lift and tire, he’ll also have an actual advantage according to his preference of Jeep use and lifestyle.
Swenson, owner of the 40” tire, comments, “To me, a bigger tire is better. If you can manage to stay low, and clear a bigger tire, I think that’s going to benefit you more.”
Calvin comments on the JK 4” Suspension System with 8 Flexarms, “When you run a 4 inch kit, you’ve got two choices. You can do our Short Arm Kit, or our Long Arm Kit. The advantage of our Short Arm Kit, is it’s probably the most cost effective way to get that 37 tire under there, because you’re just mounting to the factory mounts on the frame.”
Calvin explains that once the Long Arm Kit is chosen, for example the JK 4” Elite LCG Long FlexArm Suspension System, the geometry changes so much from the factory geometry, that a more drastic correction is needed. This is done by cutting off the factory control arm mount brackets, and welding on new mounts which will shallow up the angle of the control arm. “That’s going to put the geometry where we want it so you’ll get a better ride on the road, and off the road.”
Thompson, whose JK runs a 37” tire and 4” kit, says, “All the advantages of the taller kit over the lower kit are about the ground clearance. This is my tallest Jeep I’ve ever owned. I’ve had it since 2012. I like the looks. I like the clearance.”
Further commenting on the 4” Long Arm Kit, Calvin says, “It’s a big jump up in performance from the Short Arm Kit, especially when we’re talking 4 inches of lift. You really need to do some correction to the suspension dynamics.”
Mock reaffirms the engineer’s words, stating, “Anything around 37 or 40 inch tires, you’re really getting into axle issues, gearing issues, drivetrain strain, engine power issues, and you can’t really do that many more trails. And the trails that you do run, chances are you’re going to get some body-damage.”
Swensen states, “Obviously, it’s big. You have to build it to withstand the abuse it’s going to take.”
Thompson describes his Jeep build which sustains his large tires and lift.
“I have a 4 inch Long Arm Kit running a TeraFlex Tera44 Front Axle, with 5.38 gears and an E-locker. I have a TeraFlex CRD60, also with an E-locker. There are 4 speed bumps, in the front and in the rear. I like all the compression range with 4 speed bumps.
Driving his Jeep, Thompson approaches the same obstacle which Swenson failed earlier in a 2.5" lift. Thompson comments as he drives, “I’m going to come up to this obstacle slow. I don’t want to ram it. I want to make sure my bumper clears it.” His tires reach the approach angle. “Looks good. I’ll give it a little gas.” He crawls to the top with ease.
Calvin continues to describe the dynamics of yet a larger kit, for example the JK 6” Elite LCG Long FlexArm Suspension System. He explains, “You’re going to be running a bigger tire if you’re running a 6 inch lift. You’re going to be running a 38 or 40.” With 37"-40" tires, the gearing must be modified. “You’ve got to gear it down in order to compensate for that bigger tire.”
Calvin also explains that the stock axle can be used with new gearing, but the problem is that a larger tire in diameter allows more leverage to break that axle. Another problem with a taller lift is the abundance of air passing underneath the vehicle. Objects are hanging down, obstructing a smooth passage for the air. This will result in increased turbulence, drag, and decreased fuel efficiency.
This may be perfectly fine if you’re like AJ Swenson who runs the 6” lift. “I didn’t buy a Jeep for gas mileage,” he states, “but with this new Jeep I’m actually getting 16.8 miles to the gallon. With CRD60 axles, of course I have a manual transmission, and that helps a little bit. But still, I have no complaints with gas mileage. Obviously you won’t get the stock 20 mpg, but I think that anyone who is lifting their vehicle will realize, hey, bigger tires, heavier tires, thicker gears, it takes a lot more to turn those.” Obviously, Swenson is more interested and concerned with his experience off-road.
The practical reasons for a bigger lift are all found on the trails. The approach angle will be steeper and better. Tires will hit a rock ledge first instead of the Jeep, and the bigger tires will provide more leverage, moving the Jeep up the face of that rock. On a departure angle, coming off a ledge or down a boulder, body damage will be avoided. Larger rocks passing underneath can be straddled with ease. Driving can be handled less carefully, and things can be done off-road that other vehicles can’t.
Mock says, “I’ve had Jeeps with the hemi’s, 5 inches of lift, the 60 axles, and they’re good. They’re a lot of fun. But for the actual utility and being a grocery getter at the same time, and being able to take it around town all day, the 2.5 inch to 3 inch lift on a JK is much more everyday user friendly.”
Thompson states, “I like to go fast in between obstacles and be able to choose if I want to go slow or if I want to fly up. To me the 4 inch kit is the best mid-range kit there is.”
Swenson concludes, “It is very smooth, no bumps, no death wobble. I am extremely happy with the setup that I have."
There are some great companies out there that make great lifts. Some drive well on the road. Others drive well off the road. The trick is finding one that will drive well on and off-road, which is where the TeraFlex advantage comes in.
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