1995 Jeep Grand Cherokee - Life Support for My Car

The smaller tire on the one corner had to spin significantly faster at any given speed. As a result, the drive axle had to spin faster to make up this difference. Thus, you ended up with one axle, driveshaft, etc, turning a fair bit faster than the other. And yes, this would have made your transfer case very unhappy.

As far as what to do about it, it sounds like you need to replace your transfer case. Which really isn't a big deal, as the thing weighs a less than a hundred pounds. You can find one at a local wrecking yard for probably a few hundred dollars. The actual job is almost pathetically easy. Take loose the two drive shafts, disconnect the linkage and speedo cable, and then pull the four bolts that secure the case to the tranny.

As far as turning it into a 2wd, you wouldn't have to anything inside the transfer case. Really, all you'd need to do is remove the front drive shaft. Of course living in Wyoming, that's not something I personally would want to have to face.

The problem I have right now is with the 'few' hundred dollars... $50 is a bit of a stretch just at the moment. My plans for the not too distant future include off-loading the jeep (my wife doesn't want me lugging my project car around the country and we're planning to move from AZ to NH (don't ask) in the next 6-18 months) so I'm not terribly concerned about anything more than keeping it functioning in the meantime.

My friend, if you're planning to move to New Hampshire, you are seriously going to want 4wd, and you can replace that transfer case a lot cheaper than buying a new truck or SUV. I suggest that you start by calling your local wrecking yards and seeing if they have the transfer case and how much they need for it.

As for $50 being a stretch, I can relate. I've been unemployed for more than a year, living on my Navy pension. But even so, you need that truck for now, and you're going to need it even more when you move.

Of course, if it needs a lot more than the transfer case, I suppose it might not be worth fixing. That is something you're going to have to weigh before you make that call. Good luck and don't hesitate to ask for help. There are a lot of very talented engineers and techs in this community.

For New Hampshire I figure to get a smaller 4WD of some sort, I don't do much hauling and figure I'd probably be ok with a newer Subaru or similar matchbox type car to get us started with and then I can buy an old beater with some power once we're settled. There is just enough wrong with the Jeep for me to not argue with my wife about taking it with us... Needs a new fuel pump, eats a water pump about every 18 months, the insert that runs down the turn signal switch to activate the windshield wipers shot out the window, it's been hit by a beer truck, the ac system needs to be rebuilt.... It's time to pass the poor old gal off to someone who has the time to care for her properly or to just do the decent thing and put her down... well, almost time... I still need a few more months...

If the trouble is in the transfer case, and I yank the drive shaft so that I'm running 2WD, will the wheel rotation possibly continue to wear whatever the problem is and possibly lead to the transfer case locking up or otherwise being a major nuisance?

And while i'm thinking about it... since I'd be converting to a 2WD would my gas mileage improve? If so could you explain that... I've never understood how moving the same amount of mass with a different number of drive points would increase the power consumption beyond the inherent friction in the system; which I can't imagine is THAT significant...

Wow. I had no idea that the thing was in such rough shape. I would have to agree with you that it's just about time to let it rust in peace.

As for keeping it going for just a bit longer, it's hard to say. Obviously, you have serious transfer case issues. However, if you do disconnect the front shaft and run it in rear wheel drive only, this might extend it's life a little by unloading that part of the system.

And yes, you might realize a slight improvement in fuel economy. It has to do with mechanical friction throughout the entire system. By removing nearly half of said system, you are no longer driving it directly... On the other hand, you're still pushing the bloody thing... Hard to say. But let me give you a for-instance.

I have had two Toyota 4Runners, an 86 and a 91. Both had the same injected 4cyl and 4spd automatic tranny. The only real difference between the two is that the 86 had manual locking hubs and the 91 has an auto-disconnecting differential with fixed hubs. The 86 got 18/25mpg consistently, the 91 gets maybe 14/21mpg. And the only real, functional difference between them was that the 86's hubs could be unlocked so that they could turn freely without spinning the rest of the front drive axle components. I still have the 91, BTW. It has 223K miles on it and is as dependable as a galvanized bucket.

"with one axle, driveshaft, etc, turning a fair bit faster than the other"

I have to disagree with this statement.

The differential spider gears are there to allow you to turn corners without skidding a tire, but also allow you to run two different size tires without tearing anything up. The spiders allow the axles to turn at different rates.

I think both drive shafts are turning at the same rate and any noise is more likely to have come from the differential.

It seems reasonable that you could pull some gears out of the transfer case, if that's the problem. But, I drove my old Chevy with the drive shaft removed from the rear and with front drive only, it was not fun to drive.

Good Luck

Lyn my friend. Do the math. If one tire is turning faster, then simple mathematics tells us that the total rpms of the system is going to have to increase. Those extra rpms don't come from nowhere. Trust me on this one. Especially when the mismatch is a 20 inch tall doughnut spare and the rest are 29 inch tall SUV tires

Also, didn't Jeep put limited slip differentials into the full-time 4wd of the Grand Cherokee transfer cases?

In any event, we know already that his transfer case is having issues, whereas he doesn't seem to be having any problems with the drive axles. And the first rule of troubleshooting is to look for the obvious. This is not to say that there may not be axle issues, I find that driveshaft play somewhat disturbing. However, I have seen worse.

If it was up to me, I would replace the transfer case with a part-time 4wd unit and put a set of manual hubs up front. Of course if it were up to me and be looking at it in a lot more detail before I made any pronouncements. Long distance troubleshooting is always difficult, no matter how long you've been doing it.

Sorry DrMoose,

differential gear: Definition from Answers.com

The smaller tire will mean the the spiders are really turning, but they allow for mismatched axle shaft speeds.

Of course, I could be wrong.

The limited slip function is another story. The only one I'm familiar with, GM factory locker, had a centrifugal clutch that disengaged the locking feature at about 10MPH.

Don't know if the speed differential between the two axles is enough to engage a normal limited slip, but I'll bet someone has an opinion.

Cheers!

I drove my old Chevy with the drive shaft removed from the rear and with front drive only, it was not fun to drive.

could you elaborate? Was it just not Fahrvergnügen or was it in some way actually bothersome?

I had a manual transmission and when I accelerated away from a stop, the drive train would jerk as the drive shaft slip joint caught and slipped. Also, since the front drive shafts are different lengths, turning short radius turns was jerky.

I got it fixed the next day.

Your Jeep may be more tame.

Thanks for that. If I do move toward yanking the drive shaft I'll make sure I can put it right back together if it's not copacetic.

I am concerned abut the speed difference from l to r of the same axle, which as you say the spiders make up for in an open spool differential. The limited slip will not like the speed difference and will cause problems.

I am more concerned about whatever is used to make up the speed difference of the front drive shaft compared to the rear drive shaft. Putting the original sized tire back on may have solved the problem. -- JHF

Most of the large high schools teach auto workshops. Some of them will

use your problems to TEACH the young guys and they will fix your car

for free. Call the big schools.... this will "sometimes" work wonderful!

If it doesn't solve your problems... Try the "tech" schools....

dcl

That's a good idea... I'll give it a shot...

A strong possibility for the noise that was heard is the fact that jeeps had limited slip differentials and with the two different size tires then the clutches in the differential would have to continually slip which will cause a chattering type of sound that could travel through the drive shafts and make the sound more difficult to isolate as to where it was coming from. As for the backlash in the transfer case it sounds as if one of the bearings is starting to wear out are it may be low on fluid. Since it is full time 4 wheel drive the noise could have come from the transfer case which should be a model 249 transfer case with the different size tires on the front and the rear then the Viscous Coupling could have caused the noise because the two drive shafts would have been turning at two different RPMs and would have caused the coupling to have slipped. The first thing I would do is drain the oil from the transfer case and strain it through a cotton cloth such as an old t-shirt and see if you find any metal are friction material in the oil. The friction material will look like a dark gray pasty material in the oil. If you find a small amount you may be able to get it to live for a while with fresh oil of a high grade as this is not a place to skimp on $5.00 for the better lube. the clunking could also be slack in the Viscous Coupling which if goes out it will make the transfer case useless and therefore you will have no drive to the wheels. The coupling will also make it hard to shift the transfer case between high and low because the drive shafts will have different loads on them and will therefore cause a lot of tension which will make the fork slider in the transfer case hard to slide. The full time four wheel drive uses the same fluid as the transmission which if your not sure if your transmission used dextron IV or ATF +4 I would recommend using the later as it has a higher flash point that will let it live for a longer life.

Good Luck I hope I have helped you to understand the problems that you may be having and some inexpensive patches that may get you a little more life from your Jeep and not break the bank just getting it to survive.

In my previous life I used to be dirt poor and used worn out tires to drive on. I noticed all different types of sounds when I would put on different tires. I'd say the funny sound they heard may have just been the unique sound the donut was making. Tire sound period! That being said it sounds like there may be other things going on with the jeep but if I read the post correctly the sound has gone away now that they have the tire properly replaced. If it were me. I'd completely ignore that fact that there ever was a problem and "hope" that it kept going for the next however many months I needed to get out of it. I bet it runs just fine without any more tampering for the next 6 months. Some of the ideas of messing around with the transfer case seem extreme to me. Just my humble opinion. I also think as long as they get a "Front Wheel" drive they will be fine in New Hampshire with just two wheel drive.

Dump it somewhere and buy an old Cherokee with a 6 cyl there are parts for them everywhere and they are excessively easy to work on.

Take into consideration that New Hampshire has an annual vehicle inspection that costs around $45. After you register your car, you have 10 days to get it inspected. Since Jeeps have a reputation for self-recycling into iron oxide, this could hinder successful passage of your inspection. Don't do what I did and patch a hole in the floor with a coffee can lid, thereby earning my vehicle the moniker of the Juan Valdez car. Lights, horn, tires, front end, brakes, exhaust, wipers, uncracked glass, and no engine codes are the current inspection items.

I (along with 50K others) had the same problem with my '95 Grand. There is a viscous converter clutch in the front half of the transfer case that is prone to failure. It is what lets your vehicle move from 2wd to 4wd without you doing anything. Your ZJ isn't full time 4wd, the front axle engages as needed, dictated by the VCC in the t-case. When the VCC unit starts going bad it also tends to tear up the shifter fork in the t-case, which will make the t-case slip in and out of gear. The VCC unit alone cost about $500, it is relatively easy to replace if you have decent mechanical skills.

Pulling out the front drive shaft would be a last resort only in my opinion. Not having the load on the front half of the t-case may promote the transfer case failing sooner rather than helping your already bad situation.

No, you cannot strip the guts out of the transfer case and run it two wheels. The noise was probably a result of differential wheel circumference because the spiders were being over worked, or possibly because you transfer case oil han't been changed in eons. You should have a full size spare for that vehicle, especially now that you've had a noise warning. You're better off to drive it (not very far) until it breaks, then swap a junkyard version of whatever breaks until you can afford to replace the vehicle. Good luck...

The jeep has a limited slip differential to allow you to drive around corners with each wheel covering a different distance, and still be able to apply traction to both drive-shafts when needed for traction. In addition to this there should also be another limited slip differential in the rear axle. Again to allow turning and still apply power to the both back tires.

When the limited slip differentials are made to slip on a continued basis, as when there are two dramatically different tire circumferences on the same axle, The clutch plates, or whatever friction controlling device Jeep uses are going to be wearing more than normal. This additional slipping is going to produce some terrible noises. Where I work, we ordered a F350 in 1987 with a limited slip differential in it. (Dana 80HD) When the truck would drive too long without any sharp turns to allow the clutch plates to work locking and then releasing, the plates would loose the lube between them. When driven on a turn, the back pair of tires on either side would try to skid around a corner. The solution was to do a series of figure 8s, to lock then unlock the differential. This would allow lubricant to get between the clutch plates and they would operate quietly again for another six months.

If your noise went away after the tire sizes went back to normal, I would check the fluid levels in the front and rear axles as well as the transfer case. If they are low, splurge and drain and refill. If they are full still, just ride it out and keep a tow company card with you.

My first rule is the last guy that touched it screwed it up. The second is if it ain't broke, don't fix it. Good luck.

If you remove the front driveshaft you will no longer have park. So unless your parking brake still works, carry blocks to place behind your tires when you park. =)