So you want to lift your Jeep..
You've been out to the trail and had a blast, even though high centering on that log really was embarassing! So you decide it's time for some bigger tires to get some more clearance. What all do you need to take into consideration before you plop down your hard earned $$ for new tires...
How much lift do I want/need?
So you've made the choice, time to get bigger. Just how high do you want to go is just that...How high do you want to go? It's all a matter of personal tastes. Some things to consider:
What size tires do I want?
First thing to decide is the size tire you want to run. Do you want to keep your Jeep the way it is and only go with the biggest tire you can stuff in the wheelwells right now? Can you live with a bit of rub on teh springpack or fenderwell? If you don't want to hassle with anything, you can bolt on a set of 30x9.50's. If you can live with a bit of rubbing, then go on up to 31x10.50's, though you will have to adjust the steering stops will get some scrubbing on the fenderwells when the suspension flexs. If you want more than 31's then a lift will become a necessity.
Okay I decided what tires to use, now how much lift do I need?
You decided on the tire size, now just how much lift do you need? A quick and dirty guide would look like this:
30x9.50 - No lift required
31x10.50 - a 1" body lift, or a 2" suspension lift
32x11.50 - a 1" body lift and a 2" suspension lift; or a 2" body lift; or a 2-1/2" suspension lift
33x12.50 - a 1"-2" body lift and a 2-1/2" suspension lift; or a 3"-4" suspension lift.
35x12.50 - a 2" body lift and a 3"-4" suspension lift
What else do I need to consider?
Okay, wheels and tires are picked out, you've decided how much lift you are going to need, what else is there to consider? Plenty! Are you going to need longer brake lines? Will my shocks work or do they need replaced? Do I need longer brake lines? Am I going to have to replace my r&p gears? Do I need any other drivetrain modification?
Drivetrain
Gear Ratios
Many things to conser int he drivetrain area when you move up to bigger tires and wheels. If you've got a stone stock 6 cylinder, chances are that you have 3.07 gears from the factory. If you go to 33x12.50's you will notice a significant loss of power on the highway. Offroad you might be okay if all you do is play in mud where wheel speed is important, but if you do any sort of slow speed crawling, you will have to re-gear. Most people receommend going to 4.11's or 4.56's when switching to 33's. Be sure to replace front and rear otherwise you will have a catastrophic failure of a transfer case the first time you throw it into 4-drive!
Differential
While you are getting the gearsets swapped (a job definitely not for most of us to do in the garage), it's a perfect time to have the differential swapped out and add in some sort of a locking differential. Be it an LSD (limited slip), locker or an ARB air locker. This saves you from paying twice for labor since the gearset is already out!
Driveshafts
Jeeps have a notoriously short wheelbase (but then that's part of the reason we love them so much). Almost any lift causes binding in the drivetrain. Rotating the axle will relieve some stress from the driveshaft U-joints, but will not cure the problem. Most suspension lifts of over 2" come with spacers to drop the transfer case to help. There are also many aftermarket SYE (slip yoke eliminator) kits on the market, that shorten the rear shaft coming out of the transfer case which serves two purposes. (1) It increases the length of the rear shaft (which decreases the stress placed on the U-joints) and also allows you to run a cv-type rear shaft which is normally a bit more forgiving than traditional U-joints. Up front the main concern is ensuring that the shaft is long enough to not slip out of the transfer case when the suspension is at full extension.
Speedometer
With larger tires, you are going to have to get your speedometer recalibrated (it gets hold real quick trying to remember what rpm was 55!!). It's a simple procedure to swap in the right gear that can be done at any competent shop for around 25.00.
Okay, I know how much lift I need, so now what are my options?
There are a couple of ways to go about getting extra lift. Body lifts, suspension lifts and shackle lifts.
Body Lifts
Body lifts generally come in two sizes. 1" and 2", though you can find larger if you really want to go that route. Body lifts work by raising the body tub of your Jeep from the frame rails. You'll need to address radiator mounting, brake lines and any other lines that attaches to the frame rails and the body if you go this route. Generally, with a 1" body lift, there is ample play in the lines that nothing needs be done. With a 2" body lift, you need to start considering lengthening lines, relocating mounting brackets, as well as cosmetic cleanup (hiding that large opening between the tub and the frame rails). Body lifts will give you the extra clearance to stuff the tires you want underneath, however they do nothing to address the handling or flexibility of the suspension. You have now increased your COG (center of gravity) but done nothing to address your "roll stability". They do not affect ride quality since you are not changing your springs or shocks. A 1" body lift can be purchased for around $100.00
Suspension Lifts
Everybody has their own opinion on how much is enough (and for some there is never enough!) and who has the best product on the market. A quick rundown on some of the major players in the field would include Rancho, Superlift, Skyjacker, Explorer ProComp, Old Man Emu, Rubicon Express, TeraFlex and Warn. There are many more out there, but many companies are offering rebadged components from one of these companies.
The following breakdowns are merely my opinions on the suspensions I've helped installed, rode in and those gathered from the Rec.Autos.Makers.Jeep+Willys newsgroup.
Old Man Emu (OME) has what is considered by many to be the best YJ suspension on the market. Their springs offer a 2-1/2" lift and their complete system offers a 1" body lift, springs, shocks, extended brake lines to allow you to run 33x12.50 tires on your YJ. They are imported from Australia (the reason the company only offers springs with a 2-1/2" lift). For an OME kit be prepared to plunk down some duckets, it doesn;t come cheap. You can purchase the springs separately as well. If you have a 6 cylinder and decide to go with OME, be sure to order a kit with back springs for the front (part #J1R) as the normal front springs will be way too soft. My own belief is that any spring that is as compliant as these are reputed to be, will be worn out long before anything else does especially if you are running a winch/heavy duty bumper or anything else adding weight.
Superlift offers a 2" and a 3-1/2" lift for YJ's. Their springs are not overly soft, but due allow for good articulation with the right shock package. I've ridden in a 3-1/2" lifted UYJ and the ride was suprisingly solid on road with a good amount of flex offroad even with the front swar bar still connected. For a Superlift 3-1/2" kit (minus shocks) look to spend around $500.00
Explorer ProComp provides what many will tell you is the stiffest suspension for a CJ/YJ. I have ridden in a CJ with a 4" kit and yes it was stiff, though I wouldn't call it unbearable. The big drawing card for ProComp is their affordability. You can get a complete kit (springs, shocks, sway bay extension (not disconnects), extended brake lines) (everything you need except for a drop pitman arm for the steering) for under $500.00. ProComp recently released a "bolt-on" coil over kit for YJ's that uses a unique 3-link suspension. The only info I have is from what is written in the magazines, but no real world knowledge.
Warn upped the ante for everybody when they became the first company to unveil a coil over suspension for the YJ, but it is not a "do-it-yourself" system at all. The system totally replaces the entire factory set-up and once you switch, their is no going back to your old leaf springs. The system is not cheap, running around $1500.00, installation will probably run another 1000.00, add to that that you need to replace the exhaust system (because of the new mounting point for the control arms) and replacing front and rear driveshafts, it really is a cost prohibitive kit for most of us who use our Jeep as a daily driver as well as a weekend play toy.
Rancho offers a 2-1/2" suspension for both CJ's an YJ's. I had installed a Rancho suspension on my old CJ in less than half a day and loved it using RS5000 shocks. It allowed me to run 33x12.50 and the ride improved dramatically over the original springs and shocks.
Rubicon Express offers several different kits. Their normal duty kits are merely rebadged ProComp springs, with whatever shocks they have a special on (normally Doetsch Tech 3000's). Their extreme duty kits use custom springs (I have heard that they are National Springs, but don;t know that first hand).
You can also purchase springs separately from other sources nationally and locally to assemble your own custom setup. National Sping comes highly recommended and sells custom CJ&YJ springs for around $130.00 a spring. National Springs uses a lower spring rate with a multiple leaf pack to allow more controllability and flex than stock.
One final type of suspension lift is the Spring-Over. What this does is relocates your spring pack from mounting underneath the axle housing to the top of the housing. Effectively you giving you as much lift as your axle housing is thick Normally this is around 5-1/2" of total lift. By using a Spring-over you retain stock handling characteristics since you retain the stock springs.
Shackle lifts
Shackle lifts lift your Jeep by replacing the spring shackle with a longer shackle. To gain an extra 1/2" of ride heighth, you would have to use a shackle 1" longer than stock. Most people do not recommend trying to gain extra height by longer shackles.
What else do I need to address?
Shocks
Did your kit come with shocks or do you have to order them separately? To determine the length of shock you will need to accurately measure your extended length and your compressed length. Otherwise you will find your shock limiting your amount of travel. If you dont get one that will compress to allow full compression you will find yourself replacing shocks the first time you hit a bump hard and the shock totally bottoms out before the suspension does. To measure, make sure the Jeep is securely mounted on a set of stands and then use a jack to compress the springs fully, then measure from shock mount eye to shock mount eye. Then do the same measurement with the suspension at full droop.
Bump stops/Limiting straps
Just as the names imply these two things serve purposes. Bump stops are there to keep the suspension from overcompressing and binding which of course leads to breakage (usually at a very inopportune time!) Limiting straps are there to keep the suspension from drooping too far which on a CJ/YJ is not as much of a concern as it is on TJ.
Swaybar extensions/Quick disconnects
Swaybar extensions/quick disconnects will be a necessity if you lift your Jeep. You will need one or the other! Quick disconnects allow you to quickly disconnect the front sway bar to allow the front suspension to work easier while you are offroad. Extensions can be disconnected as well, though it does take a bit more work, but if you keep the mounting points clean, you will find that with practice you can disconnec them in a couple of minutes with normal hand tools :)
Well I hope this helps some and if you have any questions or want to add anything just drop me a line.