1stDeuce

Just becasue I used them and they worked very well, I'll also add that there is now an easy way to change camber on our solid front axles. I got shims from O'Reilly that go between the hub and knuckle, just like the old "cosmo" shims that we used to use on spindle axles from the 70's. I put a 0.5° shim on the right, and a 1.0° shim on the left of my TJ to fix a cross camber issue. That fixed a left drift that always existed on my TJ, and got me just slightly positive camber on both sides. Positive camber helps do the same thing that caster does, but without making the steering feel heavy in turns. That way I can run a bit less caster for better front u-joint angle, and still get good return to center. I'm at about 5 degrees of caster now, and it drives pretty well. :) P/N's for the shims are 26012 and 26014. (~$10, and half an hour to install if your hub isn't seized in the knuckle.) They're from SPC, who also make the better option in offset balljoints, but those require a bit more effort to install... Chris

He didn't mention checking, but he just "refreshed" the front end, which I took to mean replaced ball joints. If not, it's time to check them also. Careful your terms... You say camber, but you're talking about adjusting caster with shims... And yes, it will affect setback (which is what you mean by offset I think..) It will NOT change cross caster, as you can't "twist" the axle tube differently left vs. right. There is a slight amount of cross caster built into our axles, so you'll normally have ~0.25° more caster on the right side than the left. This was done to help compensate for driving on crowned roads. (It's not common practice anymore, as crowning is now much less than it used to be, particularly now that we drive lots of miles on highways...) It's not really enough to do hardly anything really... And the OP has a right pull, which would be opposite what the cross caster would do. Barring tire and brake influences, that takes us to camber, which can be affected by worn ball joints and "smiling" axles. Both would be pretty common and believeable in a 30 year old truck... To check cross camber, air the front tires up to their max, then find a very level surface to park on. (Check it with a level, don't just "eyeball" it...) Place a bubble level against the bottom of of the tire sidewall and level it vertically. Measure or estimate the distance between the level and the top of the tire sidewall. (Our axles always have slightly negative camber, which is top-in.) Compare that measurement side to side. A difference of more than 1/8" or so would indicate opportunity for a pull from cross camber. For a right pull, the distance on the left side would be larger. (More negative camber on the left than on the right) I'm curious to hear from the OP if a tire swap helped... All else being OK, it usually does. If he did a bunch of needed parts replacing on the front, it's rather likely he has a "coned" front tire which is causing the pull, and it'll follow the tire when he swaps them, and it'll go away with new tires if that's the case. :)

Hornbrod, I say the same thing over and over. If people get it in their head that they need adjustable control arms or track bar, telling them they don't doesn't do any good... OP, if swapping tires doesn't change the drift, find a nice level place to use a bubble level to compare camber side to side. And check (feel for temp) the brakes to make sure you don't have a dragging caliper.

Yup. Check tire pressure and swap them side to side before round do anything else. You can't change cross caster on a solid axle without offset balljoints, so none of the adjustments you have made should have caused a pull.

I have a plow on my tj, and before that on an older Chevy. I'd recommend putting the controls on the left side so you can shift and run the plow at the same time. It makes plowing much easier!! I had the joystick mounted on the left bottom if the dash on the Chevy, which was OK, but on the tj, its on the top of the dash on the left. Great spot because it's inches from where my left hand is normally gripping the steering wheel.

Actually, on the 94 HVAC that I put in my comanche, it only shuts off the coolant when you slide the selector to the off position. I want it off in vent too, but it doesn't do that. I'd agree there's no reason not to remove it.

Love your MJ!! I'm working on bringing one back that was quite a bit more neglected... I was reading your thread last night, and I see something I'm surprised nobody else has piped up about... I'm going to help you fix your somewhat lacking rear brakes... Your proportioning valve lever and relay rod are not oriented correctly... I noticed it in a much older post, but I see from this one you still haven't fixed it... The lever that comes out of the valve should be horizonal, pointing to the passenger side, and the round relay rod that goes from the diff cover bracket to the lever should be vertical. Oriented the way yours is, it isn't doing anything as you load or unload the bed, and it's got your rear brakes pretty much shut off I think. Here's how it's supposed to go: http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/0a/a1/05/medium/0900c152800aa105.gif If you fix this, you'll probably find out that the dual diaphram booster isn't even necessary. You're welcome. I think... :)

The dash pad is indeed molded to the entire plastic dash assembly. My ugly red pad was cracked, with no good way to fix it. I found a gray one at the JY with only a tiny crack in it that I didn't think would show if I painted it... I used Dupli Color vinyl and fabric paint, which in Charcoal is an almost perfect match to the factory gray color. The tiny crack still shows. :doh: But at least it's only a tiny crack, vs. the cracked mess that was there before.

Thanks for the great pictures Eagle!! It looks like the XJ prop valve isn't a pressure reducing valve after all... It looks to be a pressure limiting valve... Unless that spring loaded piston is more than one piece, it basically only allows pressure to build to a point, then no more. (I'll take one apart and confirm as soon as I get one...) It will allow full pressure to pass up to a "knee" or cutoff, after which you'll get no additional pressure to the rear brakes. On a pressure reducing valve, the rear pressure output is at the end of the screw-in part, instead of below it, and there is a multi-piece/multi spring piston assembly inside that actually allows pressure in the in the rear circuit to continue to rise after the "knee" is reached, but at a reduced rate. That's the better style valve for performance use, but for a Jeep, evidently limiting the pressure was felt to be enough. (Which means the prop valve function is probably only having an effect at REALLY high pressures in an XJ, where weight transfer off the rear axle is significant...) I still can't find anything that says how the Wilwood single in/single out adjustable valve works, but because of the design, I do believe it's a pressure limiting valve instead of pressure reducing. Note that even on the OE valve, you can raise the knee point by shimming the spring, or using a stiffer spring. The knob on the Wilwood unit simply adjusts the preload on the spring, thus raising or lowering the knee point. Here's a quickly drawin graph showing the difference between pressure limiting and pressure reducing prop valves, and how they relate to the ideal pressure distribution that they're trying to approximate. I'll update after I dissect an XJ valve... And I should also add that the OE load sensing prop valve on our trucks is the best thing for them if the load is varying... Unfortunately, the complexity of the 30yo system is less than ideal at this point, and usually a standard prop valve will do the job well enough.

I put 98 doors on my 86. Used the 86 hinges. Drilled out the spot welds holding the latch plate to the b-pillar. Welded up all the holes. Drilled holes for the new striker and used a tapped 1/4" plate on the back side. The xj doors with manual windows fit fine with the older dash. Figured out the wiring for the power mirrors my self, since there are differences year to year. Not that hard...

I put an xj sender in my Comanche. I think it was for an '88. (Important so the gage reads correctly iirc.). I re- bent it just a bit so it would reach the bottom. I have an 86 long box with the bigger tank, and no pan in the tank because it was a carbed 2.8l. Works great so far...

Thanks Eagle... I'd look online and find a diagram, but I really need to get back to work on my MJ bed. I'm pretty confident that you'll find that the XJ prop valve works like I've explained it... (I was a brake system enginerd for TRW for 7 years before I got the heck outta Detroit. And I've stayed at a Holiday Inn Express a LOT!) :) As I said before, the usual problem with drum brake XJ's and TJ's is that the self-adjusters don't work for crap, and that leads to the rear brakes not working for crap... Either that or the axle seals leak 90wt onto the brakes and render them useless. But all prop valves work to slow pressure rise at the rear above a set pressure level. If I get some time, I'll find a diagram and post it up. Actually, forget me doing it, here's a link to an excellent explanation on Grassroots Motorsports forum of how a factory prop valve works: https://grassrootsmotorsports.com/forum/grm/learn-me-adjustable-proportioning-valves/63619/page1/ The 4th post, by Warren, is the one that shows proper function. The first graph shows how the knee point (Labeled Change-over pressure) tries to approximate the curve that's needed due to weight transfer. The second chart shows how the SSBC and Jegs adjustable distribution valves above work. The dial allows you to choose which knee point or change-over pressure you want. Note that this is NOT how the one inlet/one outlet "prop valve" that many people install works. For that valve, the knee goes flat, meaning up to a certain pressure, rear pressure is unchanged from what's coming out of the master cylinder, but once you hit a set pressure, no more pressure will go to the rear no matter how hard you stomp on the pedal. You can see why I'm NOT a fan of this kind of "prop valve", which is really just a pressure regulator. (Most people do NOT understand this, and it certainly isn't advertised... Aren't brakes fun?? :)

This one would be my first choice if I was spending someone else's money: P/N 63025 There's also a SSBC version that's P/N 884-A0730. Both willallow you to adjust the "knee" point at which it begins reducing (Not stopping!) the pressure rise rate. If you're converting to discs at the same time, then use the WJ prop valve too. But with drums, it'll probably be sending too much pressure to the rear in a panic stop... Might be OK if you run loaded mostly, or on a long box if you're not afraid to "drive" when the rear starts coming around... With very little experimentation, it would be possible to "tune" an XJ (or any) prop valve to have the knee at a desireable place, but my guess is that for a light to no-load condition, the XJ valve is probably in the ball park. You just need to make sure your rear brakes are "tuned up" so they actually work. The "self" adjusters rarely self adjust, unless you use the parking brake a LOT, or back up and stab the brakes a LOT. :) Unless you're only driving the truck for one load condition, and one road condition, this valve with one "IN" and one "OUT" is NOT the valve you want, nor is anything like it: P/N 884-A0707 This valve only blocks pressure to the rear from going higher than a set point, which means if you tune it with an empty truck, and then load your truck, you got WAY less rear brake than you need... As a former brake system engineer, I do NOT recommend this route. A regular proportioning valve would be much better for almost all of us! :)

Eagle, I'll have to take a look myself, but having the prop valve function like that would be completely negligent, and XJ's would be spinning out of control in panic stops everywhere. Either your inspection was in error, or someone really messed up that prop valve. As you say, a valve that functioned like that would kill people, and to the best of my knowledge, XJ's don't have issues locking the rear in a panic stop, which would result in a spin. Quite the opposite, actually. (Not enough rear brake in panic stops.) ?? Well, I'll take a look at the one I get before I put it in I guess... If it's that messed up, I certainly don't want it in my truck!! Any idea what year XJ yours was?

Not to be critical, but with the measuring method you're using, I could see you getting a 5/8" difference on a perfectly square truck... :) It's really only possible to do that measurement on an alignment machine. And quite often, the rear axle is NOT square to the rest of the truck anyway. If I'm reading correctly, with the tires pointed straight ahead, there is less room between the tire and the rear of the fender opening on the passenger's side by ~1/2" or so? If that's the case, you've got something wrong with the front, and it isn't track bar centering related. XJ's and Comanche's have caster adjustment on the lower control arm pocket at the frame, and that adjustment can slightly affect the wheel centering (fore-aft) in the fender opening. You may just have the driver's side full forward and the pass side all the way back. It is common for alignment shops to do that in an effort to "correct" cross caster. It doesn't work at all (Can you say SOLID axle??) but they sometimes do it anyway... Check the lower control arm pocket for some small shims, where the two little bolts go facing rearward. You should probably have ~1/4" of shims on both sides. Adding more to the pass side will move that tire forward a little. If you have a crapload of shims in the driver's side, but none in the passenger's side, your fore/aft wheel offset will match what you're seeing. If so, loosen the big bolt, then the two little nuts and take half the shims out of the driver's side and put them on the passenger's side. That'll at least even it up, and take the bind off the bushings. More shims = more caster, which is almost always good, and generally needed on lifted XJ/MJ's anyway. You can also just loosen the two small nuts all the way up, pry the control arm as far forward as you can, and then tighten the big bolt. Don't bother with the shims or small nuts after that. :) Chris

I should clarify, you can't leave the resistor powered full time, just do that to run the truck and verify that it solves the problem. :) I remember tracing that wiring on my '92 Cherokee, but I don't recall where it went. And I recommend you bypass the resistor anyway, so it can't ever leave you stranded. The fuel pump will appreciate it as well. :) Chris

If I read correctly, you already said that there was no power to the ballast resistor in "run". That's your problem, not the resistor itself. I gather you've tried bypassing the resistor, but have you tried giving it 12v directly? If the resistor is good, applying 12v to either side should get your pump powered up full time, and my guess is that your engine will run fine then. If so, then you'll need to figure out why the resistor isn't getting power in "run". There is a fuse, but I don't recall where it's at... Chris

Reviving a older thread that I find Interesting. I was planning to do a XJ or TJ prop valve swap on my Comanche since the prop valve is unhooked and fairly crusty anyway... Since this truck will be my wife's daily driver, I don't want to just sending full pressure to the rear, since she'll be driving it unloaded most ot the time. Eagle, you recommend against a prop valve, but your understanding of how a prop valve works is completely upside down... Prop valves work off pressure, not flow. It should allow full pressure UP TO a set point, at which it knees off at a percentage of the input pressure. The idea is that under low to moderate braking, it's fine to use full braking at the rear, but as you stop faster, weight transfer lightens the back of the vehicle, requiring less pressure to the rear to prevent lockup. The prop valve is supposed to make sure the rear always locks AFTER the front. (Fronts always get full MC pressure) It's also important to note that drums take LESS pressure to lock than discs normally, so a prop valve from a drum brake vehile will be under-braking the rear on a disc vehicle. Shorter wheelbase vehicles also tend to knee at a lower point, since they are more prone to weight transfer than longer wheelbases. The Wilwood adjustable pressure regulator that has only one inlet and outlet is often referred to as a prop valve, but it is NOT. It only functions to limit pressure to an adjustable set point, meaning it'll allow full pressure up to a certain point, then limit it to that pressure no matter how high input pressure goes. Exactly like a pressure regulator used on an air comprssor output line. That's great if all your stops are under the same condition, but not so good for loaded vs unloaded, or wet or slick roads vs. dry ones... SSBC and Jegs both offer adjustable proportioning/distribution valves that offer a true knee point, with continued rising pressure after the knee point. This prop/distribution valve functions exactly like the factory prop valve, but offers an adjusable knee point. This is a much better solution for a daily driver!! Additionally, the distribution valve has the ability to throw the brake light if one circuit fails, and keeps the two circuits separate so failure of one does not mean failure of all. As to the lack of wear in the XJ rear brakes, it may be true that the XJ is under-utilizing the rear brakes, but it probably has a lot more to do with adjustment of the drum unit than pressure. If the self-adjuster seizes, or one never uses the park brake to adjust it, then you can get to the point of needing more volume than the master can supply, and if that happens, your rear brakes become fairly ineffective. Unless your wife was a real hard braker, I would expect the rear drums to last quite a bit longer than the front discs anyway... Disc brakes have much higher pad clamp force than drums for the same amount of stopping torque, and usually less pad area, so they wear out faster. I guess I should put a build thread on here... I've been doing it over at Expedition Portal, since that's where I was hanging out most of the time, and this truck is our weekend getaway ride! :) Chris