Eagle

If shopping for new shafts for a Dana 35 axle, don't forget that from '84 (XJ only) through '89 they did not use a c-clip retainer, they were retained by a flange at the outer end. From 1990 through 2001 they used a c-clip retainer. They are not interchangeable.

An 'L' stamped on a stud indicates a left-hand thread ... which was never used on the XJ or MJ.

No, the ratio will be stamped into the edge of the ring gear. It is unusual not to find a ratio tag on a front axle. I've looked at old XJs and MJs that were sunk right up to the pumpkin in muddy fields behind old barns and still found the tag intact.

A ZJ rear will be another D35, or a "Dana 44" with the crappy aluminum case -- the only axle in the universe that's WORSE than a Dana 35. And there are no late model XJs with 3.73s. From the factory, all 5-speed 4.0Ls had 3.07, all 4.0L automatics had 3.55s, and all 4-cylinders had 4.10s.

alright good but is there anyway that i can recalibrate or something like that? Yes, it can be calibrated ... but you don't know if it's wrong. If it ain't broke, don't fix it.

Put the rear axle up on jack stands, start the engine, and let it idle in first gear. See if the wheel wobbles. It could be just a bent rim. If the wheel wobbles, take off the wheel and repeat with only the brake drum in place -- see if the brake drum wobbles. If the drum wobbles, remove the drum and check just the flange. You look for a new axle only if the flange wobbles.

That first tick above the zero IS 500 RPM. Your needle is pointing slightly above the 500 mark. Idle spec IIRC is 650, so you're close.

Correct. The ZJ was offered with a 5-speed only in 1993 and VERY few were sold, so for all practical purposes there are no 3.07 ZJ axles. A ZJ axle is probably 3.55 or 3.73. As noted, it will be a low pinion, and it will use the horrible composite rotors that like to warp every other week. If the ratio matched it would be better than nothing if it's free, but regearing it will cost $$$ so it's probably better to keep looking for an XJ or MJ Dana 30 with the ratio you need. Unless, of course, your plans include changing the rear axle ratio.

You are reading the tachometer incorrectly. The photo shows it reading approximately 550 RPM. The first mark above the bottom is 500 RPM.

I'm confused. What's this about splices and extra wires? The cluster swap is (or should be ) 100 percent plug-and-play at the dashboard. Take the old one out, put the new one in. The ONLY changes necessary are to replace the temperature sender in the head and the oil pressure sender next to the oil filter with the senders for use with gauges. Did you cut and splice wires under the dashboard?

The light on an '89 doesn't mean much. It is activated by a mechanical timer and it's nothing but a reminder to replace the oxygen sensor. Most of us have unplugged the light. The O2 sensor should be replaced about every 75,000 miles.

The seal is on the inner end of the tube. To replace it you have to remove the differential. Big job. If the axle is going to get replaced, just keep an eye on your fluid level.

:doh: First thing to check. ALWAYS. My bad ...

I REALLY disagree with this. Just "dropping in" a 258 (4.2L) crank and rods creates all kinds of problems. It is not a simple plug-n-play swap. The two engines had slight differences in deck height, which translates to a high compression issue with the "budget" stroker. If you are not prepared to deal with that, don't even start.

Oil pressure is lower at low engine RPMs. Your problem could be the sender, could be the poil pump, but most likely is the rod bearings being excessively worn. What year, what engine, and how many miles?

Probably anything is "traditional" somewhere. I grew up knowing about New England clam chowder and Manhattan clam chowder. The first time I was served Rhode Island clam chowder in a restaurant I thought I'd been cheated. Now I prefer it over the other two. Didja know in Rhode Island they eat French fries with vinegar, not ketchup? Yyyuucchh!

I would not do the head gasket. I WOULD do the rear main seal, because it's SOOOO much easier with the engine out and upside-down on a stand than when you're lying on your back under the truck. Once the pan is off to do the rear main seal, it sort of doesn't make sense not to replace the bearings. I wouldn't even bother to plasti-gage them ... just do a preemptive strike.

Your speedometer may be off a little. With 31" tires and 4.56 gears, 75 MPH should be 2906 RPM. I guess that's "about" 3000 RPM, but it's lower than, not higher than. Secondly, for a 1991 the torque peak of the engine is around 4,000 RPM. 3,000 RPM cruise is below the torque peak. That RPM isn't going to harm the engine. You have to remember that the 4.0L engine is an evolution of AMC's older 232 (3.8L) engine that came out in 1964. Back then, nobody had overdrive, and most cars were still manual transmission with "three on the tree." My family owned a number of AMCs from that vintage. They were typically geared with 3.08 axles and small-ish tires, such that the speed to RPM came out to 24 MPH per 1000 RPM. 3000 RPM produced a 72 MPH cruise speed. They ran forever like that. The one we tracked the longest was a 1970 Gremlin that my brother and his wife rallied, autocrossed, and used as a daily driver for four years. When they bought a new '74 Gremlin, he sold it to a local auto parts store to use as a parts delivery runner. Last he heard, it had gone over 375,000 miles and they never had the head off it. My view is that 4.10 gears are the optimum for 31" tires, but if I bought one with 4.56s I certainly would NOT spend the money to change to 4.10s. There would be very little to gain for the expense and trouble. Your 75 MPH cruise would drop to 2614 RPM.

How high and how long?

'86 thru '90 had TBI, '91 and '92 had MPFI. The 4-cylinder was carbureted in the '84 and '85 XJ, never in the MJ.

Does NOT sound like fun, but get it fixed and get well soon.

I didn't say they are the only safe hooks. It is absolutely unsafe to bolt hooks directly to the unibody -- reinforced mounting brackets are a must. I think the C4x4 kit is the best. The one you linked to also looks decent but I haven't seen it "up close and personal." There are others out there, as well -- including (last I knew) as individual parts from Keystone (the Chinese fender vendor). Take your pick -- just DON'T bolt tow hooks (or D-rings) directly to the unibody.

:agree: OBD-XYZ is here to stay. The scanners that Harbor Freight now sells for $29 or $39 are infinitely better than the brain-dead unit they sold for $49 (on sale) just three or four years ago. But ... don't buy the cheapest one they have. Spend a few extra $$$ and get one of the ones with CAN [something], so you'll have more flexibility to use it on newer cars -- whether your own, your family's, or your friends'.

You have the right idea, but using tire circumference isn't very accurate. Most of the tire manufacturers include in their specs a figure for revolutions per mile, which takes into account the amount of sidewall flex under a normal load as well as tread squirm. In making up my spreadsheet for comparing gear ratios and tire sizes, I used manufacturers' revolutions per mile for the calculations. Even within one (nominal) tire size there's variation between/among brands. In fact, at one Time Cooper had a P235/75R15 and the same tire as a 235/75R15 LT. The LT had stiffer sidewalls and, even though ALL dimensions of the two tires were identical, the revs per mile were different. Back to the bottom line. In round numbers, going from a stock 215/75R15 to a 30x9.50 is a difference of approximately 6%. Going from the same 215 to a 31x10.50R15 the difference is 11%. If you start with a 225/75, the difference will be slightly less. In VERY round numbers, and for most practical purposes, I think it's valid to generalize and say that going from "stock" to 30s is about a 5% change, and going from "stock" to 31s is about a 10% change. If you're running 31s and the gas mileage calculated from the odometer is only 12 MPG, then correcting by adding 10% only brings it up to 13.2 MPG. That's not very good for a 4.0L MJ.

Thanks for the tip. The driver's door speaker in my wife's 2K XJ is out and I was planning to dig into it while she's visiting her kids.