General Information About Lifting Your Jeep Wrangler JK

Chris

Administrator
Staff Member
Joined
Sep 28, 2015
Messages
31,345
Location
Florence, AZ
The JK uses a complex combination of arms, braces, and rods to make a reliable and effective steering and suspension platform both on the road and off. This makes it an easy vehicle to build upon for off-road use. A lot of questions may come up when you decide to add a lift, such as, "What problems might I face when lifting my JK?" or "What type is best for my goals?" After determining the answers to your questions, you will know how to combat common problems associated with lifts for a reliable, trouble-free Jeep JK.

Component Breakdown
Adjustable Upper and Lower Control Arms
Adjustable upper and lower control arms allow you to adjust castor. The factory control arms are non-adjustable. After installing a lift (generally over 3") the front caster angles may become more negative, creating a "flighty" feeling. This is countered by increasing the castor in the positive direction to increase vehicle stability.

wrangleradjustablecontrolarmcorrect-119188.jpg

Figure 1. An adjustable control arm.

Adjustable Trackbar
When you install a suspension lift on your JK in excess of three inches, a lot of the suspension geometry changes. One of these is the horizontal position of the axle. An adjustable trackbar is needed because the factory trackbar is too short to keep the axle centered. Instead, it moves the axle to the side to keep the distance between the axle and track bar equal.

wrangleradjustabletrackbarcorrect-119417.jpg

Figure 2. A front adjustable track bar.

Rear Track Bar Mount
Instead of installing an adjustable track bar for the rear, some companies provide a new track bar mount. This relocates the rear track bar to maintain factory position of the rear axle.

wranglerreartrackbarmountcorrect-119421.jpg

Figure 3. An aftermarket rear track bar mount.

Driveshaft
Once your JK exceeds four inches of suspension lift, you may need a modified driveshaft to maintain factory-like universal joint angles. Although a modified driveshaft is usually not required or included with a suspension lift installation kit, damage to the factory driveshaft and differentials can occur once the universal joints reach their maximum working angle.

wranglerdriveshaftcorrect-119423.jpg

Figure 4. An aftermarket driveshaft.

Exhaust Spacers
Once your lift exceeds 2.5 inches to 3 inches, you may need exhaust spacers. These move the exhaust crossover pipe further back, creating more clearance between the exhaust and front drive shaft/crossmember.

wranglerexhaustspacercorrect-119610.jpg

Figure 5. An installed exhaust spacer.


Common Questions

What are some different types of lifts?
There are many ways to lift your JK depending on the height desired and the components you'd like to change. These range from body lifts and leveling kits to coil spring lifts and coil spring spacers.

What size lift do I need to fit 35" tires, 37" tires, etc.?
You do not need a lift to fit 33" tires that are less than 10" wide when using stock wheels. If you have aftermarket wheels, the backspacing must be 4.5" to clear a 33" tire. 35" tires will require a 2" to 3" lift while 37"-40" tires will require a 4" lift. Aftermarket fender flares will help increase the fender-to-tire clearance.

What are some companies with lift kits for the JK?
Teraflex, RK, and Metalcloak are some commonly used lift kit companies.

What size tire can I fit on the stock tire carrier?
A 35" tire can fit the dimensions, but the weight may damage the tailgate and carrier. Owners install reinforced hinges and extended tailgate bumpstops to counter the problem.

Will my JK's handling suffer with a lift kit?
This comes down to several factors such as alignment, type of tires, and type of lift. If you decide not to purchase adjustable track bars and control arms, then your alignment may be off and not correctable after the lift. This will affect your JK's handling. Larger 35"+ tires will create more rolling resistance, increasing the steering effort required to make a turn, although with power steering this is not a large concern. Some lift types simply modify the stock components rather than replace them with modified versions. This can create wear and make the components work outside of the designed operating range, reducing their effectiveness on road.

How will larger tires affect my JK's drivability?
Larger tires will make your engine rotate faster to cover the same amount of distance in any gear. Those with final drives lower than 3:73 and tires larger than 35" will notice the increased engine revolutions at highway speeds.

How will a lift effect the Electronic Stability Program?
Your lift kit may alter the way the E.S.P. functions. You may be required to shut the program off or re-calibrate it to restore proper operation.
 

Jeepguy1

Member
Joined
Jan 22, 2020
Messages
77
Location
Manitoba
ow will larger tires affect my JK's drivability?
Larger tires will make your engine rotate faster to cover the same amount of distance in any gear. Those with final drives lower than 3:73 and tires larger than 35" will notice the increased engine revolutions at highway speeds.



THIS STATEMENT IS COMPLETEY OPPOSITE OF TRUTH !!!

big tires increase your ratios, and reduce your RPMs
 

UKNOWME

New Member
Joined
Feb 9, 2020
Messages
20
Location
Albuquerque NM
ow will larger tires affect my JK's drivability?
Larger tires will make your engine rotate faster to cover the same amount of distance in any gear. Those with final drives lower than 3:73 and tires larger than 35" will notice the increased engine revolutions at highway speeds.



THIS STATEMENT IS COMPLETEY OPPOSITE OF TRUTH !!!

big tires increase your ratios, and reduce your RPMs
Not true! Before I regeared my RPMs we’re higher than when I had the stock tires on
 

Jeepguy1

Member
Joined
Jan 22, 2020
Messages
77
Location
Manitoba
Not true! Before I regeared my RPMs we’re higher than when I had the stock tires on
You are saying 2 things here.
“regear” ... from what to what ??
“Stock tires” from what to what ?

if all you do is put larger tires on, your rpms will be less than they were with smaller tires. Do the math.
This is why we regear, to a deeper ratio. We want those rpms back, plus a few more to compensate the extra wind, weight and rolling resistance.