Eagle

I don't have any idea what #2 and #5 refer to, but you do NOT use the bypass line to run the rear brakes, because it's a bypass line that only functions when the front brakes have completely failed. Are you keeping the MJ front distribution block, or replacing it with one out of a ZJ, XJ, or YJ? That makes a difference.

Are you certain that it has 4.10 gears? If it's a 2.5L 4-speed, it should have 3.55 gears. The 4.10s were used with the 5-speed 2.5L MJs. To be honest, since it's a 2WD and you don't have to worry about matching ratios between front and rear, it would be much less expensive to just buy a Chrysler 8.25 rear axle out of a 92 or newer 4.0L Cherokee with automatic. That will be the correct 3.55 ratio for your engine and transmission setup, it's a stronger axle that the Dana 35 that is probably what you have now, and you can buy a junkyard axle for a lot less than the cost of a set of gears, bearings, and setup. You will need to relocate the spring perches, but the existing ones can be cut off and welded into the correct location using your old axle as a setup template. The best cheap axle swap is a 97 or newer XJ Chrysler 8.25, but for a 2.5L even the older 8.25 will be better than the Dana 35.

If you want to use the 96 engine and ignition/injection system, you need everything from the '96. The XJ (Cherokee) and MJ (Comanche) underwent a total revision from 1990 to 1991. Up to 1990 they used the AMC/Renault/Bendix ("Renix") injection and ignition system. Starting in model year 1991, they switched over to a completely different, Chrysler-engineered ignition and injection system. There's an old saying, "In for a penny, in for a pound." Once you say you want to update, you have to update everything. So you will have to strip out the entire wiring harness, in the engine room and under the dashboard, and swap in the harness from the '96 donor vehicle. The brake and taillights on XJs work differently from the way they work on the MJ, so you'll need to retain the MJ taillight wiring and make an adapter splice somewhere near the back of the cab.

The XJs with 4 cyl and 4.56 were using the 904 3-speed tranny, not the AW4 with overdrive. Now that I think about it, I have no idea what ratio the factory used with the 2.5L and AW4 combinatuion.

So what's left if you unscrew the quick disconnect -- a conventional flare fitting?

I don't remember which is which, anode or cathode, either, but it seems to me that both of the videos have it wrong. They both refer to the submerged rebar as the "sacrificial" element, but it's not sacrificing anything. It's being "plated" with ... rust. It's attracting the iron oxide from the rusty parts. In your case, if you used powdered zinc sulphate, how did you make your electrical connections? And what was the purpose of the Karo syrup and vinegar?

The water is dirty, but the sludge is just iron. Dumping it on the ground isn't really any different than taking a rusty part outside and chipping/scraping/brushing the rust off. (I think).

Somewhere on Youtube there is (or was) a series of videos by a guy who came into possession of a VERY old Colt 1911 pistol that had been buried for about fifty years. He used electrolysis to de-rust it and get it back to where he was actually able to shoot it. It wasn't a thing of beauty, but from what it looked like when it wsas dug up you would never have thought it would function again -- ever. In fact -- it looks like there are two series on such projects: https://youtu.be/B28_VN8Q6YE https://www.youtube.com/watch?v=bDM69iNaI_8

But he can't engage cruise, and the SET button is on the left. Is it possible that the brake switch isn't adjusted correctly, and you can't engage cruise because the "brain" thinks the brakes are on?

As my signature indicates (I think), one of the MJs I currently own is a 1988 2WD SporTruck 2.5L 4-speed. It has been off the road for a long time because it blew the clutch slave cylinder and had too much else on my plate to repair it. The body seems to be basically sound -- haven't crawled underneath to fully assess the condition underneath, but I expect it to be salvageable. I'd like to put it back on the road and do some upgrades, but I'm severely conflicted over what direction to take regarding power train. Which way would you go ... and why? My options are: Replace the clutch and slave cylinder and keep it as a 2WD 4-speed. I have a complete AX-5 and transfer case from an '88 2.5L, so I could replace the clutch, and swap the tranny and transfer case to make it 4WD. I have all the parts, including the bell housing, to convert the 2.5L to an AW4. That would go 4WD. I also have a complete '87 XJ 4.0L 4WD AW4 drive train, so I could convert to a complete 4.0L automatic setup. It's currently sitting on a 3.54 rear axle. I have a couple of 3.54 front axles, I have front and rear MJ axles in 3.73, and I have an '86 XJ 2.5L sitting on 4.10 axles. What would you do?

My friend did his outside in the driveway. Let's face it -- you're not building a NASCAR Grand National. Clean is good, but it doesn't have to be operating room sterile to run. I did one many years ago in my brother's hay field.

I need to start unloading "stuff." I came across the factory service manual for my 1993 Honda Accord. The car was sold almost 20 years ago, but the buyer was an effete intellectual snob, prep school teacher type so I didn't mention that I had a FSM. I'm going to put it up on Craig's List -- what's a fair price for it? It's in like-new condition.

A friend and cross-town neighbor just blew a piston in his 2.5L Wrangler. He bought a set of new Sealed Power pistons and rings, dropped the pan, and just replaced all the pistons. He didn't even hone the cylinders, just used a ridge reamer to clean away the carbon ridge at the top. You could do the same job, but in your case I think a light hone in the cylinders after cutting the ridge might be in order. Not trying to remove material, just to clean up the bores and leave a very fire tooth pattern to help the new rings seal.

The factory service manual shows the height to the top of the roof as 63.7" for 2WD and 64.7" for 4WD. The track is specified at 57" with 6" wheels and 58" with 7" wheels. If you go with the 8" Wrangler wheels you should pick up another half inch (not a full inch, because they have more backspacing), or 1" with 1/4" spacers. So let's say we can get your track to 59". You need to lower the roofline by 4.7" ... call it 5" to be safe. Setting aside whatever you can gain by installing 2WD 2.5L springs, what can you get from the tires alone. You can't go by the numbers calculated from the size, because when a tire is installed on a vehicle, the vehicle weight squashes the side that's in contact with the road. Most of the tire companies used to quote a number for that in their specs, called either "static radius" or "rolling radius." It's less than the theoretical radius, but there's no way to calculate it, because it's a function of weight and tire pressure. The spreadsheet I made up for NAXJA many years ago includes the static radius for representative tires in as many sizes as I could find data for, but I wasn't looking at anything smaller than a stock XJ/MJ tire. But, to give you an idea what the order of magnitude difference might be, let's look at a common XJ/MJ tire size: 225/75R15. The theoretical tire diameter is 28.3", so the theoretical radius is 14.15". But the number I have for actual static radius is 12.8" -- so that particular tire loses 1.35" due to sidewall squat. As you get into the lower profile tire series, there's just not as much sidewall there, so you won't have as big a difference between the theoretical radius and the actual, static radius. Just going by theoretical (calculated) dimensions, if you're starting with a 14" radius, and 7.5" of that is the wheel, that leaves you with 6.5" of sidewall. To get 5 inches out of that, you're down to a 1.5" sidewall. I don't think that's going to happen, so it's time to start looking at your springs.

According to JeepForum.com, the TJ Canyon wheels are: Canyon * 15x8 aluminum * 5 on 4.5" bolt pattern * Backspacing = 5.5" * Optional wheel with 30" tire package * Offset = +25 mm Be careful, because the ZJ Grand Cherokees had a wheel that looks almost identical, but it's only 15x7. Here's the 8" Wrangler version:

Can you use wheels from another vehicle if the backspacing matches? Wheels for the TJ Wrangler (at least some of them) are 15x8, so that would gain an inch for you compared to what you have now.

Check out springs for TJ Wranglers. They are the same diameter and will fit an MJ, but my understanding (subject to verification) is that they are shorter. Or don't your rules allow using springs out of a different vehicle?

Nope. Those are not super basic wheels. Those are the 15x7 factory wagon wheels. The base wheels are 15x6 and have nine rectangular slots around the periphery of the web where it meets the rim. As I mentioned above, there are NO aftermarket rims that provide 5-1/4" backspacing like the factory rims. That means you can buy the cheapest steel aftermarket wagon wheels and increase your track by at least two inches, maybe more -- without spacers. Do the rules require that you run factory wheels?

The only way the ECU knows what flywheel is there is from the signal sent by the CPS. If the CPS doesn't match the flywheel, you don't get a signal (or you don't gat a signal that the ECU can understand). Actually, all three have to match up. What often happens is that someone with a Renix vehicle throws in an "new" engine out of an HO. They use the Renix CPS, but they forget about the flywheel. No go.

8-inch cross-section width, or 8-inch tread width? 8-inch cross section works out to 203.2mm, so a 205 x anything is an 8-inch tire ... but the tread width is never the same as the cross section width. What are you running now for wheels? The factory 195/75-15s and 205/75-15s came on 6-inch rims, and everything else came on 7-inch rims. I can't imagine that you can't fit 195s on Jeep rims. Correct. Tires are centered on the wheels. To increase track, either go to a wider wheel with the same backspacing, or go to a wheel with less backspacing. Changing tire size in the same wheels does not change the track dimension.

AMC cars from the 60s and 70 used 14-inch wheels with the same bolt pattern that the Cherokee and Comanche use, but I'm not sure a 14-inch AMC rim will clear the disk brakes on the front. The factory rims on the XJ and MJ are 5-1/4" backspacing. It's not hard to find wheels that widen that track -- there are (AFAIK) NO aftermarket rims that provide the factory backspacing, most are in the 40" to 4-1/2" range. Be careful about going too small in combination with wide rims to increase the track. The first number in a metric tire size (the 195 or 225 part) is the cross-section width at the sidewall, in millimeters. Pete mentioned a 195/45-15. 195mm divided by 25.4 mm/inch works out to a tire width (not tread width) of 7.68 inches. Jeep mounted the 195/75-15 base model tires on 6-inch rims. The 45 series have much less sidewall to play with than 75 series. If you try to mount those little tires on very wide rims, you may have other problems. 7-inch rims will probably work, but I think 8-inch might be pushing the envelope. Most tires list the acceptable wheel width range, so be sure to check that.

I think there was. Unfortunately, the Renix CPS operates on a completely different principle than the HO CPS, which is why the flywheel and CPS have to match. And why there aren't any factory CPSs any more. The Renix models have been out of production for 28 years, so the factory doesn't have to service replacement parts any longer.

The cooling system doesn't matter, but the temperature does. The coolant temperature sensor in the block is what tells the Renix ECU when to switch from open loop (pre-mapped fuel curve, set rich for warm-up) to closed loop (computer/sensors control air/fuel mix). I don't remember what the temperature required for the switch-over to take place is, but I think it's around 175 or so. So you need to be sure that the system is functioning correctly and keeping the temperature up. Most people don't understand the role of the thermostat. The cooling system is to keep the temperature down, but the thermostat is to keep the temperature UP. If it's too cold, or if it sticks open, you're stuck in open loop mode and the fuel economy goes out the tailpipe.

Okay, good. When was the oxygen sensor last replaced? What temperature thermostat are you running?

I believe you are correct. But the dashboard voltmeter still "dips" when he turns on accessories, headlights, or even turn signals. That shouldn't happen. Your suggestion to retest at the battery while having a helper turn lights and accessories on and off is spot on. That's what I suggested in post #4 ... so of course I think it's spot on.