Eagle

That's another point. I assume the ZJ bar was swapped in because it's larger in diameter. Which bushings did you use? If you used the original MJ bushings with a fatter ZJ sway bar, the bar can't rotate like it's supposed to and that could explain why the suspension feels bumpier.

There is no reason in the world why 3/4" lift spacers, which on an old truck probably barely returned it to stock height, should require 2-inch or even 1-inch longer sway bar links. More likely, the sway bar is rusty and is binding up in the bushings. I would remove the sway bar, clean and sand it smooth where it rides in the bushings, paint it, spray silicone on the bushings, and reinstall.

Flint54's explanation of how it works is pretty good. The reason for it is that a pickup without a load has very little weight over the rear axle, so it's easy to have the rear brakes lock up before the fronts. The height-sensing valve is intended to alleviate this, while adjusting the rear brakes to provide more braking when the bed is loaded. And, if properly adjusted, it does that very well. I am only partially in flint's group A. I don't regard the height-sensing valve as absolutely necessary, but I do regard it as a good thing. I am, however, in flint's group B. I have personally experienced a potentially catastrophic failure of a rear height-sensing valve. I had to make a panic stop, and the valve simply exploded. The result, of course, was NO rear brakes. So I don't trust them. If they were available (and not overly expensive) I would replace it. But they have not been available for many years. Personally, I am comfortable driving without one. It must be recognized that, under some conditions, the rear wheels WILL lock up prematurely with no proportioning to the rear wheels. I grew up long before such devices were offered, so this doesn't bother me. For those who aren't accustomed to dealing with rear brakes that lock up before the fronts (which can cause oversteer and spin-outs), I recommend removing the height sensing valve and installing a Wilwood (or Mopar, which is probably the same thing) adjustable proportioning valve in the rear brake circuit. It can be set to properly limit the rear brake force when empty, and then allow more rear brake force when loaded. The downside is that it's not automatic -- you have to experiment, find the right settings for your truck, and remember to turn the knob when you load or unload your truck.

They all did when they left the factory. I know of one 1988 red Chief that doesn't have one now ... and I know of two others that won't have it when they get running and registered.

You can use an OEM electric fan, but regardless of whether you use the old style (which I think is no longer available) or the new style, it is NOT plug-and-play if your truck was not originally equipped with one. The sensor screws into a bung in the driver's side radiator tank, so you'll need that sensor. That sensor, in turn, feeds a relay that mounts to the driver's side inner fender, near the air box. And then the relay sends power to the fan. If your truck doesn't have the fan, I'm 98.7% certain the wiring isn't there.

Maybe less. They were about $12 per PAIR when I bought them, but I'm sure they've gone up. But that's per pair. When I ordered mine, after seeing 4x4 vendors getting $40 and up for so-so perches, I heard "$12" from the parts guru and I had to ask, "That's for one, right?" He said, "I don't know, that's the price for the part number you gave me." (I had the number from the printed Mopar Performance catalog, but the catalog didn't specify if it was one or a pair.) So I had him order two. When they came in, the boxes clanked. So we opened one box -- and out came two perches. Best deal in history, beyond a doubt.

You still have to open a front caliper and blow the pressure off the front circuit so the shuttle valve will open the by-pass circuit to the rear. Otherwise, the pressure bleeder can't push fluid through the second line.

Buy the Mopar perches. They are HEAVY duty, and you can't possibly justify wasting the time to make your own given how cheap the Mopar parts are.

If you look at the photo of the cut-away front distribution block, the bypass port is blocked by the shuttle. You can open rear lines and let it drain by gravity for a week, but there won't be anything flowing (or dripping) through the bypass circuit. That be the problem.

Well, here's the thing about that -- I don't know how the height-sensing valve relates to the bypass circuit under normal conditions, so it's possible that your brakes work fine normally, but if you were to lose the fronts you might not have any rears. What's supposed to happen is that normal operation routes brake fluid from the master cylinder to/through the rear proportioning valve. But if you're running with no load so the valve is allowing very little force to the rears, if you lose pressure to the front circuit you're then stuck with maybe 10 percent braking power. So, those clever engineers engineered a bypass circuit that's activated by the shuttle valve in the master cylinder. If you lose pressure to the front circuit, the shuttle valve (in addition to triggering the "You got no brakes, Dummy!" light) opens the port to the bypass port. That sends brake fluid past the rear height sensing valve and directly to the rear axle, so you get the full benefit of however much braking your rear wheels can produce. However -- if there's air trapped in the bypass circuit, activating will NOT send full force to the rear wheels, because the air will compress and negate the bypass circuit. As I said, I'm not 100 percent certain just what the rear valve does internally, but I am of the opinion that good rear brakes under normal conditions does not provide any evidence that the bypass will function as advertised if there's a problem.

1989? Overflow? You don't have an antifreeze overflow. That plastic bottle on the firewall is NOT an overflow, it's an integral part of the cooling system, it's pressurized, and that cap is your pressure cap. You do NOT remove that cap unless the system is cold. (Unless you enjoy third degree scald injuries, of course.) Get (or borrow) a compression gauge and check the compression on all cylinders.

10-4. I know Hornbrod disagrees with me, but I try to learn from experience. The height-sensing valve in my '88 MJ was functional, too ... right up to the day the old man in the Buick cut me off and I had to make a panic stop. The height-sensing valve exploded. Considering that 1992 was the last year for the MJ, that means the NEWEST of those gilhoolies is now a minimum of 19 years old. I don't trust them. I'm a bit funny about brakes -- when I stomp on the peddle, I sort of prefer that the system not blow up. I grew up in the era before they had proportioning valves -- I can deal with too much brakes a lot better than I can deal with standing on the peddle with both feet and not even slowing down very much.

Yeah, and we had ONE guy in the original Javelin/AMX Sports car Club of Connecticut who single-handedly destroyed FIVE of them. Moron. Then there was my brother. When we got into speed events a bit more serious than Sunday autocrosses I bought a cheap, base model Javelin and built that up as my budget racer. My brother gave me a load of [bleep] about what a dope I was for wasting all that money when I had a perfectly good AMX (three, actually), while he raced his pristine '69 AMX and saved all that money. Pristine, that is, until a hill climb at Okemo in Vermont, when he went straight where the road went left. Did I mention that Okemo is a mountain? And that when you fall off the road it's a loooooooong way down? Moron x2

:agree:

Or just call Crutchfield. The speakers are 4" x 6", not 4-1/2" x 6" http://www.crutchfield.com/S-OTggjUtNpM ... tp=105&l=J The 4" version mounts on a 4" x 6" plate. There was a Mercedes model a few years ago that took the same speaker.

They are 4" round speakers on a 4" x 6" plate. http://www.crutchfield.com/g_400/All-Ca ... tp=105&l=J

I wasn't trying to be insulting, just inject some humor. But the search only works when you type in the right word. There won't be many discussions of MJ brake systems if you search this site for "porpoise."

You plug the BOTTOM front outlet on the front metering block. The thread is 1/2" fine thread. The shortest bolt I was able to find in a 1/2" fine was 1-inch -- I cut it to the length that allowed it to just seat with an O-ring under the head, then I put a glob of RTV on the end before I installed it. Discussed in this thread, toward the end: viewtopic.php?f=2&t=22773&p=235043&hilit=bolt+proportioning+block#p235043 And, Brandon -- it's "proportioning" valve, not "porpoising." No aquatic mammals were harmed in the manufacture of the MJs.

You plug the BOTTOM front outlet on the front metering block. The thread is 1/2" fine thread. The shortest bolt I was able to find in a 1/2" fine was 1-inch -- I cut it to the length that allowed it to just seat with an O-ring under the head, then I put a glob of RTV on the end before I installed it. Discussed in this thread, toward the end: viewtopic.php?f=2&t=22773&p=235043&hilit=bolt+proportioning+block#p235043

I was afraid you were going to say that. So you haven't read any of the threads about how to remove or eliminate the rear height-sensing valve, I take it? What you DON'T want to do is plug it back at the valve itself. If you do that, you still have two lines running the full length of the chassis, which doubles the probability of a leak or rupture. Why keep two lines if you're not going to use the height-sensing valve? And how are you going to close off the line you remove from the rear height-sensing valve? The right way to do it is to remove the bypass line completely, starting at the master cylinder, and then run ONE new line directly from the master cylinder to the upper end of the flex hose at the rear axle.

Why do you need the thread size if you're getting rid of it?

I have a couple of AW-4s with transfer cases. I don't have a 4WD BA 10/5 or AX-15.

Truck's originally a 4 speed. It should have 3.55. And it does. I have 3.73 axles available to swap in, but not 4.10s. And it ain't gettin' a lift. This is going to be a daily driver.

Wire brush ==> Epoxy

I have a 1988 MJ SWB with a 2.5L engine and 4-speed manual tranny, in 2WD. The internal slave ruptured, so it has not been driven for a couple of years, and the engine has 208,000 miles on it. I would like to get it back on the road this summer, but with a change to 4WD. I have some options -- enough to have me unable to decide which route to go. 1. I could rebuild the 2.5L, keep it as a Renix, and swap in a 5-speed AX-5 with transfer case to make it 4WD. 2. I also have the parts to convert the 2.5L to an AW-4 automatic in 4WD. 3. I have a 100,000 mile 1987 4.0L AW-4 4WD drive train I can swap in from a complete XJ donor vehicle. 4. I have a '95 YJ 2.5L engine and 3-speed auto with the MPFI parts on the engine, but no wiring harness or computer. I could get the missing stuff from a junk yard and upgrade to the newer 2.5L setup. I'm not looking for a heavy-duty off-road beast (I have an old XJ for that), and I'm not looking for a street rocket. Gasoline will top $4/gallon by the end of this week (a couple of local stations are already above $4). I'm looking for a reliable and economical MJ to replace my '88 XJ as a daily driver. What would you lads do?