Hello,

I'm not new to 4WD or trucks, but this is my first quadra-trac transfer case, and I'm wondered if the problem I'm having is normal age and wear, or if I may have something more intense going on.

One of my front tire sidewalls came apart today at 70mph, and I was able to get my 94 Jeep Grand Cherokee stopped in about 1/4 mile. I changed the tire, putting the donut spare on it, and it seemed fine for a mile or so, but then started pulling (felt like wobbling) to the side the donut was on, and then making a popping/ clunking noise every 2-3 seconds once a speed of 30mph was reached. It would be fine if I stopped and put it in park, and then resumed, for another mile or so. I finally had it towed so I can get the new tire on it, hoping the problem would resolve itself.

I'm running stock 225/ 75R15's, and my Jeep has about 240K miles on her. The tire is on tight, and was lug nuts were installed and tightened in cross pattern.

Has anyone else had an issue with the donut causing these noises, or with a blowout at high speed causing transfer case issues?

Thanks in advance for the input!

 

Don't use a donut spare, I do believe there is an open recall for a full sized spare tire.

 

Thanks, Mike. I wasn't aware of the open recall, so that is great information!

 

I just wanted to let anyone hoping for a full-size spare that there is no open recall on 94 Grand Cherokee for the spare.

 

Shoot, i'm sorry! Could have swore I read there was a recall because of the AWD reaquiring all four tires being the same size.

 

My '97 has Quadra-Trac and came with a matching full size spare.
Dan

 

Hmm... apparently Jeep figured out the full-sized spare was a better idea.

 

What was happening is the viscous coupler inside your NP 249 transfer case was locking up... The difference in tires sizes was causing it to bind and cause the popping noise and jerking feeling.

I have the same T-case in my ZJ.. and I got a full-sized spare for exactly the reason you are talking about here. Take some figure 8 turns in a parking lot or somewhere paved where you have good traction.. Do it when the T-case is cold... if you feeling binding or hear the popping noise.. the viscous coupler is bad or on its way there. Eventually you will be stuck in full-time 4wd all the time.

 

Did you mean to type eventually it would be "stuck in 4wd all the time?"

QuadraTrac transfer cases only have 4wd, 4 high and 4 low.

??

I'm going to check the stop adjustments on my tie rod ends, which I think were the cause of the clicking/ popping noise in cold, tight turn conditions last year.

But I think the viscous coupler may be the problem when it's hot, though. After sustained 65-70mph for an hour, I definitely get some popping when turning into park. Thanks for the info!

 

Yeah Whowey, Quadra-Trac is full Time 4WD. I think the issue happened when using a donut spare. I may be wrong though.
Dan

 

I have a question about the viscous coupler. Would it be related to switching the transfer case from 4HI to 4LO , and some noise in 4LO?

 

Honestly.. I don't pay attention to the idiotic revived marketing names that Chrysler used for the different T-case options in the ZJs. Quadratrac was also used in the FSJ line and is a maintence hog for them also. So I will post the info regarding the NP 249. Eva's 94 could have had a 231, 249 or a 242 installed originally. From the description here, I am fairly sure its not a 231.. so its one of the 2 other T-cases... but the 242 could be taken out of 4wd.. its settings are 2wd, 4-full,4-hi, neutral, 4-lo. I have had them in the XJ.. but not the ZJ. I think I have a shift bezel in the tool box, I will have to go pull it to check the actually name of the settings...

I have the 249 in my ZJ... and I have recently had the final failure of the viscous coupler. The settings on a 249 are 4wd full-time(not High) neutral and 4wd Low. There is a difference between a 4wd High and a 4wd full-time.

The viscous coupler when operating correctly, just basically sits there and doesn't do anything as long as both axles are turning at the same speed. When it detects that the axles are not..It will lock-up and put the transfer case into 4wd. The smaller donut spare was causing a speed differential.. causing the coupler to want to lock up.

But... The coupler is a known bad spot on this transfer case. As it starts to wear out, the fluid inside of it will expand as the transfer case gets hot and cause the coupler to lock-up even when you don't have different axle speeds and put your truck into 4wd when you don't want it.

Eventually the coupler fails completely.. and permanently sticks the truck in 4wd. Hence the reason I posted that way originally.

Now shifting from 4wd full-time to 4 low... The 4 low setting on an NP 249 is an old fashioned locked 4 low setting. It operates the same as the 231 or 242. There is no axle differentiation in the speeds they operate at. So the viscous coupler would have no effect on the T-case in 4-low.

 

Good info.

 

Just as FYI... my ZJ is *stock*, truly stock. I bought it from family, and I know its history. It is the original transfer case.

That was a nicely detailed explanation of the viscous coupler and Quadratrac/ 249, and what was happening. I appreciate it, because, though I owned a commercial fleet shop for 10 years, and have built several Ford 4wd rigs, this is my first Jeep. So thanks for taking the time to be thorough.

 

check CV shafts.