I have a 1999 Jeep Cherokee Sport with the 4.0 engine & auto trans. It has 145K on her, but runs like it has 45K. I had the trans fluid changed and a new filter installed a few months ago. It shifts great with no issues other than once in a while in reverse it shifts hard. Its like the shifting in reverse at 1200 rpm's. Doesn't happen all the time, but its annoying none the less. Vacuum issue? Any thoughts? Thanks in advance as you guys always have the right answers.

 

Check the drive shaft U-joints for play.

 

Uh oh. The AW4 transmission requires the use of DexronIII Mercon only. First find out what they used.
Some have used ATF4, it works for some and others develop shifting issues.
Hopefully the shop only did a `drain & fill`, and did not use a machine that flushes the fluid. The machine flush can actually contaminate the internals.

 

OP, what is the issue? Is it hard to shift into reverse, or is there a clunk when shifted into reverse?
Other gears ok?

 

Excellent question. What the OP said is, " once in a while in reverse it shifts hard. Its like the shifting in reverse at 1200 rpm's."

I suspect what he meant is, " once in a while when shifting into reverse it shifts hard. Its like the shifting into reverse at 1200 rpm's."

"In" and "into" are two different words, and they mean two different things.

The original statement says that he's already in reverse, and driving fast enough to cause the gears to shift (which isn't possible, AFAIK). It would also mean he's a blithering idiot, unless he's a trained stunt driver on a closed course.)

So, LWechterPA, which is it? Are you getting that clunk when shifting INTO reverse? Or are you having problems once you are in reverse?

 

The Chief of Grammar Police has spoken!! LOL.

 

What is the engine RPM when the problem happens? Normal?

 

Sometimes this is a tough place to ask a question.!

 

The transmission (2WD) shifts normally cold or hot. Just once in awhile when shifting "into" reverse it shifts hard like the rpm's suddenly jumped. RPM's are normal at all times.

 

Confusion benefits only an enemy.