|Home||Forums||Reader's Rigs||Tech Library||Trail Stories||FSJ-List|
Rear Spring Replacement
Contributed By: Mark Wallace
A problem that seems to be inherent in our Full Size Jeeps is that the rear ends tend to start sagging with time. Be it a pickup, Cherokee, or Wagoneer there are a couple of ways to deal this problem, some being better than others. Probably the best way is to just replace the rear springs and be done with it.
1.) Before you attempt to replace front or rear springs on your Jeep it'd be a really good idea to go to the pressure wash and wash the underside of the Jeep very thoroughly. Chances are it's a lot dirtier that you think.
2.) If you are getting springs out of a salvage yard or a spring shop count your leaves before hand. There were several different factory spring combinations going from a two leaf (very thick) to a seven leaf, with everything in between. For all the 74 to 91 vehicles all the different springs have the the same eyelet to eyelet dimensions as well as having the centering pin in the same place so they are all interchangeable, which is a good thing in the event that you want to soften or stiffen up your ride. The 63 to 73 trucks have different spring dimensions, but the method of operation is more or less the same.
3.) If you are getting springs from a salvage yard get the pivot bolts too (usually the yard will just cut the spring hangers off) because chances are you will have to cut some of your old pivot bolts.
Okay, Now onto the Job.
1.) Support the truck with the rear tires just touching the ground on solid jack stands.
2.) The first thing that you need to do is get the rear axle off the springs that you are replacing. There are a couple of methods for doing this. For safety reasons I'd suggest replacing the U-bolts at the same time as u-bolts stretch over time. This means that you can destroy the old u-bolts getting them off. Sawzall, torch, cutting wheel, die grinder, etc are all valid ways of getting off old u-bolts. If you don't have these tools than you'll have to do it the old fashioned way, by removing the nuts from the u-bolts. If you can wrestle an impact wrench in there, than do so, if not you'll need a long breaker bar and probably a cheater pipe. The nuts are above the axle (along with the spring) so access isn't great.
3.) With the axle clear of the springs comes the fun part. Dealing with the next six bolts could take the better part of a day, every tool you own, and the better part of your sanity. It's probably easier to start at the shackle end (rear). It's a tension (upside-down) shackle unless someone in the past has flipped it. On the 74-91 frame the pivot is supported on both sides by a box structure, on the earlier frame it is only supported on one side. Take the nut off the bolt on either rear pivot bolt, either the shackle to frame bolt or the shackle to spring bolt. This is a lot harder than it sounds as the bolts can get extremely stuck in worn spring bushings. Ways to get an intact bolt out include, but are not limited to pounding them out with a big hammer or using a pickle fork. On the passenger side there may be a stock exhaust hanger attached to the spring pivot. It can be removed from the exhaust system, at which point it's pretty flexible and you can wrestle it out of the way.
4.) The spring may just drop to the ground or you may have to pry it free. Either way it's really heavy, and it probably wants to hurt you so it's a good idea to clear it's path.
5.) Here comes the fun of the front pivot. On the passenger side it's not that bad because you can get to the nut from the inside. On the driver's side the nut is welded to a piece of spring steel which has an extreme tendency to bend or break. This would not be such a huge deal except for the problem that the gas tank is in the way, and the gas tank is not trivial to remove.
5.) Removing the gas tank is for another how-to at a later date, but it's a good idea to know how the gas tank is held on. On the later frame there is a sheet metal skid plate (the one that's always dented) bolted along the driver's side frame rail, and to a couple of brackets up above the rear drive shaft. The gas tank is held to the skid plate with metal straps and as far as I remember the straps do not need to be removed. The drive shaft probably will need to be dropped at least on the differential end. You don't deed to drop the gas tank all the way to the ground to access the bolt.
Note: the area behind the gas tank is a collecting spot for mud and is a breeding ground for rust. Now might me a good time to clean that area up, and paint it.
6.) When I did this job (along with my front springs) I had some of the pivot bolts that absolutely would not move from out of the shackle. If you have a Sawzall (on my want list) you can probably get between the hanger and the bushing and get at it that way, or you can do what I did. I ground the bolt's head off with a die grinder (time consuming) and put a nut on the other side and tightened it until I ran out of thread, at which point I would remove the nut, place some shims on the bolt and go through the whole process over again until I had pulled the bolt through the other side. For the less stubborn bolts a chipping hammer was usually very useful in getting the bolt out, and would give you a usable bolt.
7.) Put everything back together in reverse order, by the time you get to this point it will probably be three in the morning.
8.) MILLER TIME
IFSJA.org hosting provided by Golden Computer Service.
© 2000-2006 IFSJA Site Staff. Jeep® is a registerd trademark of DaimlerChrysler.