The penguin's motorcycling and Jeep blog

Sunday, June 19, 2011

Springity sproing

So yesterday I finished the next step in project Put Bigger Tars On Teh Tuxjeep: I changed out the *rear* springs and put on a trackbar relocation bracket.

Note that I'd already changed out the front springs, so I had a spring mismatch between front and back. The Jeep was level when I was unloaded, but load it up and the back end was dragging like a cat in heat. It wasn't a spring height issue, but, rather, a spring rate issue -- the rear springs were the original factory springs with spacers on top of them to make them taller, and simply weren't up to the same standard as the front springs, they compressed under load more than the front springs. The front springs are some Old Man Emu 933 springs that I scored off a club member, so I decided to put the matching Old Man Emu 949 onto the back. At the same time I was also going to install an Old Man Emu trackbar relocation bracket, which accomplishes two things: 1) the original bracket has a "roof" on it and will get bent up if your suspension sags too much and the trackbar "tops out" in the bracket (as will happen if you lift the Jeep and put longer springs and shocks on it) and 2) helps relocate the axle back to under the center of the Jeep, which in turn helps the Jeep track better (duh!).

So, anyhow, here's how I dunnit:

  1. Approximately 2 hours before starting any of this, blast the bolts you're going to unbolt with PB Blaster, Liquid Wrench, or other penetrating oil of choice. (For list of bolts, see the things we're going to unbolt below)
  2. Put the Jeep into 1st gear (or Park if automatic), 4-Lo, and put on the emergency brake
  3. Chock the front wheels front and back. (Yes, making *sure* the Jeep doesn't roll while I'm under there!)
  4. Remove spare tire from back of Jeep (so there's room to use the Hi-Lift there)
  5. Get axle jack from beneath passenger seat of Jeep, and its assorted rods and such
  6. Get Hi-Lift jack out of Jeep
  7. Line up your new parts behind the Jeep -- the springs, the bump stop extensions (if you don't have bump stop extensions already on there, necessary to keep the springs from overcompressing), a short piece of fuel line and two couplers (to extend the breather hose for the axle, which otherwise tends to top out against the trackbar at full droop) and the trackbar relocation bracket. (Sorry, I don't have specs on the fuel line and couplers, they were already in my junk box).
  8. Line up tools behind Jeep, including: Tall jack stand (do *nothing* under a Jeep supported by a Hi-Lift jack, they are inherently unstable, which is good if you're on the trail trying to move your Jeep around off a rock it's grounded out on, bad if you expect your Jeep to *stay* on the Hi-Lift), lug wrench, and hand tools.
  9. Disconnect rear sway bar at both ends
  10. Disconnect rear track bar at both ends (because we're going to need it out of the way to install the bracket, and it's easier this way)
  11. Disconnect both shocks at the bottom.
  12. Jack up the DRIVER's side with the Hi-Lift from the bumper until the spring starts to get loose in its seat, then put the jack stand under the frame just in front of the rear control arm mount and lower the Jeep onto it. Move Hi-Lift out of the way.
  13. Place the axle jack under the spring mount, jack up the axle until the tire is off the ground, and remove the tire.
  14. Lower the axle with the axle jack until the spring is loose in its seat. The spring should then be easily removed by lifting it and removing it to the rear.
  15. Remove the rubber bump stop at the top by simply grabbing it and wiggling and yanking downwards until it pops out of its seat.
  16. Remove the bump stop seat via unbolting the bolt in its middle. If you previously had a spacer lift, this will allow you to remove the spacer. But note that even without a previous spacer lift this makes installing the new spring *much* easier since you won't have to work it around the bump stop, and the bump stop will go through the coils of the spring. You'll also be installing bump stop extensions at the same time if you didn't already have them on there.
  17. You'll notice that the breather hose for your axle is basically taut with your axle at full droop. Extend the breather hose by cutting it above the fuel tank (easier if you have a body lift on your Jeep) and patching in a few inches of fuel line so that you'll have some slack at full droop.
  18. You already removed the trackbar above. Install the trackbar relocation bracket using the directions in the OME packet, including all the drilling and stuff (the real reason why we bothered lifting the Jeep so high in the air in the first place was to give clearance to the drill under the floorpan of the Jeep). Don't bother trying to put the trackbar into it right now, it won't go because the bracket is twisted by the axle droop, we'll put it back on after the Jeep is back on the ground.
  19. Install the *SHORTER* Old Man Emu 949 spring here, on the driver's side. It should just pop right in. Jeeps tend to sag at their passenger rear due to the weight of the spare tire carrier and the torque of their engine, so the taller spring goes on the passenger side.
  20. Work the bump stop extension, bump stop seat, and bump stop bolt through the coils of the new spring, and bolt them into place. You can't get a torque wrench up here so it's probably a good idea to use blue (medium strength) threadlocker on the bolt too, to keep it from going anywhere.
  21. Work the rubber bump stop through the coils of the new spring, and push it into place. A prybar prying against a coil of the springs can help get that last little bit of oomph to get it seated.
  22. Jack up the axle enough to match the bottom of the shock with its crossbolt, and install the rear shock again. This is easier than compressing the shock by hand to install it after the tire is back on.
  23. This also jacked up the axle enough to put your tire back on. Do so. Torque your lug nuts in criss-cross pattern to 100 ft/lbs of torque. (This is *IMPORTANT* -- use an actual lug wrench here, if you overtorque your lug nuts, you *will* stretch your axle studs and cause them to fail on the trail, and of course undertorquing them is equally a bad idea since wheels that come off while you're driving down the road are unwanted).
  24. Lower your axle jack and remove it. Note that this will be using your shock as a limiting strap holding the tire off the ground (usually it's the trackbar that limits downtravel here), but this won't hurt it here.
  25. Jack up the Jeep from the rear bumper with the Hi-Lift enough to drop the axle stand and pull it out of the way, then lower the driver's side to the ground.
  26. Repeat the process to remove/install the spring on the passenger side (remember, the TALLER spring goes on the passenger side), with the exception that on the passenger side you don't have to install a track bar bracket (doh!).
  27. Now, with the Jeep back on the ground on its own four wheels with the new springs and no jacks or jack stands under it, reinstall the track bar. It *should* match up hole-wise on both ends, because the geometry of the control arms naturally wants to center the axle (though not strongly enough to do without the track bar) and the new location of the axle end of the trackbar is in the proper place where, with these springs, the trackbar should match up. If not, you may need to get a piece of 2x4 and pry between the tire and frame until the axle is centered and you can bolt the trackbar into place.
  28. Reconnect the rear sway bar.
  29. Put the spare tire back on the Jeep (duh!) and replace all the jacks and the lug wrench into their proper nooks and cranny in case you have a flat.
And done! Note that when you reinstall bolts, you should torque them to factory spec if at all possible. If you can't get a torque wrench on them, at least use blue threadlocker on them to keep them from coming loose and sending you into a ditch (your suspension falling apart on the highway is *not* recommended as a recipe for health and happiness!).

In my case, the process was made more difficult by the fact that my original trackbar bracket was bent up from the trackbar topping out against it due to the extra sag allowed by disconnecting my sway bars up front, the longer Old Man Emu shocks, and the spacer lift. The lesson there is that if you install *any* lift, even a 2" spacer lift, you need to relocate the trackbar bracket at that time rather than at some later time because the trackbar bracket becomes the limit on downtravel at that point. So I had to sort of hammer and bend and press things into shape again. But it's all together now.

So how does it work? Well, the rear end of the Jeep is now about 1 1/4" higher off the ground than the front end of the Jeep. On the passenger side, from rocker to ground is 22" immediately behind the front wheel, and 23 1/4" immediately in front of the rear wheel. So when I put a full trail load into the Jeep (tools and water are *heavy*), the rear should sag to the point of basically being level.

But does it make it too harsh on the pavement? Well, remember, I'm using the Old Man Emu shocks that are basically matched to these springs. I decided to put things to the test and, uhm, I can't notice any difference from previous. The ride is firm, but not jittery or harsh. It helps the handling a bit, it seems, but not by much. Probably just psychological on my part.

So anyhow, I'm done with getting clearance. I may add some bump stop extensions up front to put 33" tires under here, but it appears that I only need 1/2" of additional bump stop up there to clear 33" tires under my fenders. While bouncing me Jeep up and down to test for things that go "clunk" when they shouldn't, I also noticed that one of my front sway bar links has gone bust and has movement in it that it shouldn't have, I'm sure that replacing that will help the handling a bit, luckily I have a spare in my junk box. So anyhow, that's that... the next step is going to be the expensive one, re-gearing to 4.56 front and rear, installing lockers, and actually purchasing 33" offroad tires to put on the thing. The re-gearing and lockers will be over $2,000 (eep!), the tires and wheels (to replace the bent-up ones) will be over $1,000 (gulp!). Oh well, it's still cheaper than buying a new Jeep!

-- Badtux the Wrenchin' Penguin