Eagle

No, Jeepman clearly stated that the relationship between engine speed and road speed changes in wind or when the engine is working harder going uphill. And that's simply not possible unless the clutch or the automatic transmission is slipping. Here's what he wrote, if you missed it: Followed by:

Remove the tach from the cluster. On the back, there's a potentiometer with a plastic head that has a "+" shaped recess in it. Turning that adjusts the tach. Hook that up along with a known-good idle tach and calibrate away.

^^^ This. Tranny mounts can be expensive, though. Inspect visually. If you don't see chunks of rubber missing, it might be worthwhile just shimming with a washer or two on each of the bolts to create enough clearance to stop the rattling.

Okay, you win. In the United States, there is a fixed relationship between the engine speed and the wheel speed. In Canada the laws of Physics and Mechanics do not apply. Now we can both be right.

But, as Jeepcoma tried to explain, and as I tried to explain, unless you have an automatic and the torque converter lock isn't working, the engine is mechanically connected to the rear wheels through the transmission, transfer case and drive shaft. The road speed simply cannot change without a matching change in engine speed, and the engine speed cannot change without the road speed changing. The Speed-to-RPM relationship is fixed. Yes, the vehicle may slow down on long or steep upgrades, and a 4-banger may even slow down when buffeted by a headwind -- but both the engine speed and the wheel speed will slow down in direct proportion to the gear ratios involved. Or, again as Jeepcoma stated, you may need to give it more gas to maintain speed (which is proof that the engine is working harder), but if the road speed doesn't change, the engine speed doesn't change. It just uses more gas to maintain that same speed. Unless you shift gears.

Wind and hills have exactly zero effect on the relationship between engine speed and road speed. Unless you have an automatic that's slipping very badly, the same engine RPM will always push the vehicle down the road at the exact same speed. I realize that -- and for comparison purposes it's a better calculator than any other on-line calculator I've found. But, unfortunately, it isn't suitable for helping figure out if your speedometer is correct after a gear swap and/or tire size change, and that's something we all should be aware of, too.

Three or four years ago I replaced the rear bumper on the '88 Cherokee. I bought from the dealer, and I thought I was buying a new bumper but I'm pretty sure it must be a rechrome, because the original lasted 20 years, and the replacement is already showing rust. I'm wondering how it would work if I were to wipe down the rusty areas (which are mostly on the top, horizontal surface) with rust killer, and then apply a layer of that shiny silver tape that HVAC guys use to seal joints in ductwork. Does anyone know if that stuff would hold up outdoors? Is it stainless steel or aluminum? TIA

That's a very nice calculator, except for the fact it's wrong. Aside from the fact that they show the 5th gear ratio for the BA 10/5 as 0.79:1 and the factory manual shows it as 0.72:1, even checking their fourth gear speeds to RPMs they're off. I think their calculations (like every other on-line calculator I've seen) use mathematical formulas based on tire dimensions. What these don't take into account is that sidewall "squat" results in a real-world rolling radius that's less than half the static tire diameter. When I made up my spreadsheet, I researched tire manufacturers' data and used published numbers for revolutions-per-mile as the basis for my formulas. The result is that, for the final section of this calculator, they show lower RPMs for each speed than they should. For 225/75-15 tires and 3.07 gears, 65 MPH in fourth gear should be 2395 RPM. They came up with 2370. For 30" tires and 3.73 gears (and I used a tire diameter of 29.5 in their calculator, not the nominal 30) the actual RPM in fourth gear at 65 MPH should be 2849. They came up with 2761. The differences aren't horrible, and since they're wrong across the board the calculatpor is still useful for predicting how much change you'll get from regearing or swapping tires. But the numbers aren't accurate.

3.54s will be "okay" with 30" tires, but 3.73 would be better. And if 31s are on the horizon, you really want 4.10s. When I picked up my '88 MJ I regeared with a set of 3.73s I had bought for my Cherokee, with the intention of running them with 30" tires.The MJ came to me with a 4" lift so I threw on a set of used 31" tires and the 3.73 gears. The overall final drive ratio, as indicated by MPH per 1000 RPM, came out to be exactly the same as a stock XJ or MJ with 3.54 gears. I have now removed the lift and the MJ is on 225/75-15 tires, and the 3.73 gears with the 5-speed are still a good combination. In mountain terrain, I think 4.10s would be better for you with either 30s or 31s, and it's a lot easier to find a 4-banger XJ donor vehicle with 4.10s than it will be to find 3.73s.

The gasket is only trim. Either way, the glass is sealed to the windshield frame with a heavy bead of sealant. It used to be a Butyl based sealant, but I believe now they use a type of polyurethane.

It sounds like you just have some "slop" (excuse my use of such highly technical terminology) in the steering. That can sneak up on you, and then it may be easy or difficult to pinpoint the cause. It may or may not be one thing. In the XJ/MJ front suspension, there are four ball joints, each of which is subject to wear -- especially if not lubed regularly. There are also five tie rod end type joints, plus a bushing. All of those are also subject to wear and can cause slop. After about 175,000 miles, my '88 XJ (which I bought new) finally got to where I had at least a quarter turn of free play in the steering wheel before the road wheels began to respond. In my case, the culprit was the upper end of the track bar -- which is the fifth tie rod end in the XJ/MJ front suspension. On the early XJs and MJs, the track bar upper end didn't have a grease fitting. The replacements DO have a grease fitting. A new track bar fixed my problem. The way I inspect for which joint (or joints) is/are causing slop is by feel. You can feel flex in tie rod ends that you can't see by looking. To do it, you need a helper to turn the steering wheel. The procedure is to unlock the steering wheel. I don't start the engine, but you can. The problem is that power steering makes it too easy for the assistant to turn the wheel too far. The helper should stand OUTSIDE the vehicle and reach in through the driver's window to turn the steering wheel back and forth. The helper should watch the front tire, and turn the steering wheel only to a point in each direction where the tire sidewall starts to flex, but the tire doesn't quite turn on the ground. What you want to do is load the joints to the max in each direction. Once the tire starts to actually turn, the load in the TREs is released. While your helper is turning the steering wheel back and forth, you get to crawl under the vehicle and grab each TRE to feel for how much flex there is. It should be about zero -- they should be free to rotate, but not to flex or have any lateral movement. While you're under there, you can also watch the pitman arm and see if the steering box has free play across the center (in other words, the input shaft connected to the steering wheel turns, but the pitman arm DOESN'T move).

How old is the oxygen sensor? If it's old, it doesn't respond as quickly as it should to changes in the fuel/air mixture. When you let off the throttle, it allows too much gas to keep flowing, the engine doesn't burn it, so it does down the exhaust and burns in the catalytic converter. Backfire.

"Steer ahead"? You mean the steering wheel isn't centered when driving straight? That's not in the steering box, that's a simple adjustment of the drag link. That's tire balance. The steering box can't cause shimmy. It's a 20+ year old truck. It can't feel like a new car with rack-and-pinion steering, and should not be expected to. If that's what you are looking for, you're doomed to disappointment regardless of how much money you throw at it.

You will need a speedometer cable for an 88-90 XJ or MJ. If the cluster came from a vehicle with a different engine than yours, you may also have to calibrate the tachometer. If i swap the Speed-o-meter with the current will that be good. You can do that, but the up-scale clusters have speedos with a trip odometer. If you swap in your old speedo, you won't have the trip odometer. It certainly isn't a necessity, but it's nice to have on occasion.

You will need a speedometer cable for an 88-90 XJ or MJ. If the cluster came from a vehicle with a different engine than yours, you may also have to calibrate the tachometer.

That's the 12.7:1 ratio. It's also available from Borgerson if you decide to go that route. Stock XJ/MJ steering is usually 14:1, although I believe the very early (AMC) XJs and MJs used an 18:1 box if you bought the off-road suspension package. I would definitely go with the 12.7:1 for an MJ that's used as a daily driver.

Brand? Borgerson http://www.borgeson.com/xcart/catalog/J ... c-111.html Before you lay out big bucks for a new (or rebuilt) box, have you adjusted the over-center screw?

The MJ carburetor was computer controlled, plus you still need the ECU to control the ignition so a carburetor (even an old-school, non-computerized carb) won't allow you to get rid of the ECU.

The entire wheel arch opening on the MJ is both longer and taller than the XJ. For something that might look close to the shape/profile of the 97+ front flares, try YJ Wrangler flares.

It will also wear out faster without the friction modifier.

That's what it is -- unbalanced tires. If it were death wobble, you would have to slow down almost to a stop -- or stop completely -- before it would stop its gyrations. That photo looks like there's a lot of mud caked on the rims. That can affect balance ...

As you posted above. Thanks to your heads up, I decided to get mine while I could. If there were 126 on the 23rd and 100 on the 28th, with a holiday in the interim, that tells us they won't last long. If you want/need one, act now.

I called my dealer and ordered this morning (November 28). As of late morning today there were 100 in the system -- that was BEFORE my order.

On the firewall, in the engine bay, ABOVE the brake booster. There's a major wiring harness that runs parellel to the bottom of the windshield in that area. The C101 connector is the junction where the two sections of that big, fat bunch of wires snap together. There was a TSB out on removing it, so there is a remote possibility that an '87 or '88 won't have it. If you look under the hood of my '88 XJ, for example, you won't find the C101 connector. (Of course, paying $500 to have it removed didn't accomplish any of the things that dealer's service manager told me it would fix. And when I mentioned that to him later he denied ever having said it would help anything. One more stealership crossed off my list.)

What are you asking? There is no C101 "bolt." The C101 connector sits much higher than the brake booster. All '88s had it -- the change to delete it was a mid-year change in the 1989 model year. What "prob" are you referring to? If you mean the C101 connector, it was removed on my '88 XJ and my '88 MJ still has it. I don't see any difference/improvement in the XJ for the $500 I paid a stealership to remove it.