Hey everyone. So I'm not mechanic, especially when it comes to things like engine function and transmission. I can do basic maintenance procedures at best. Lol. In any event, I have a 2019 Jeep Compass Latitude with a 6-speed automatic transmission. The issue I'm having is that when I am accelerating from a stopped position and am in a situation where I need to slow down while accelerating, I'll let off the accelerator (I'm guessing by this point it's usually around 3rd or 4th gear) and once I let off the accelerator it seems the transmission is trying to downshift but when it does it makes a clunking sound and jerks the vehicle for a brief moment. Keep in mind this issue does not happen if I continue to accelerate to higher speeds such as merging on an interstate highway, etc. In addition it doesn't seem this issue is present when I'm slowing down to a stop from higher speeds. Mainly it's when in stop and go type traffic where I'm able to accelerate to anywhere between 25-35 mph then had to stop suddenly. That's when I hear the clunking noise and feel the slight jolt as the vehicle downshifts and I slow down. Any insights on this would be greatly appreciated. I'm not even sure if this is directly a transmission issue or something else. Just wanted to get some feedback if possible before I run to 4 different mechanic shops. Thank you in advance!!!
PatrickRyan33
Welcome to the site! Like you, I'm not a mechanic. However, I own a 2019 Compass. You said a 6-speed automatic? I presume you meant the 9-speed automatic. Yes, there are a log of gears in there and I think it is reasonable to expect some gear hunting, especially when you confuse it by letting off the gas after accelerating, and particularly when hitting the gas again real quick. Stop-n-go is rough on any car, and it sounds like that's where your problem is.
What I know is that the ZF-9HP is a sort of 2-tiered arrangement -- gears 1-4 get used again for speeds 5-9. There is some dog clutches that switch between 4 and 5. It works smoothly when accelerating, but there is a gap between 5 and 4 when decelerating. I live in a hilly area and if I'm using the gears when descending a hill, I feel a 1 second pause between 5 and 4. I suspect that is where you're feeling the clunk -- the tranny is confused as to what range it want to be -- if you're continuing to accelerate it wants to get into the higher range, if it thinks you're slowing down, it wants to get to the lower range. If you're at that gap between 4 and 5, the poor thing doesn't know what's coming next, and the dog clutches can't react fast enough.
This video explains it way better than I can. The guy is a college professor of automotive technology. He seems fairly positive about it. This is the first of two video, and he is very thorough, but understandable.
I don't know how many miles on your Compass, but I had my transmission fluid changed around 120,000 miles. The manual says you don't have to, but I don't believe that. Not at all. The owners manual gave inadequate serivice intervals for the CVT in the 1st generation Compass and many failed even before the first scheduled service. If you're in the 100,000 mile range, I strongly suggest it.
What I know is that the ZF-9HP is a sort of 2-tiered arrangement -- gears 1-4 get used again for speeds 5-9. There is some dog clutches that switch between 4 and 5. It works smoothly when accelerating, but there is a gap between 5 and 4 when decelerating. I live in a hilly area and if I'm using the gears when descending a hill, I feel a 1 second pause between 5 and 4. I suspect that is where you're feeling the clunk -- the tranny is confused as to what range it want to be -- if you're continuing to accelerate it wants to get into the higher range, if it thinks you're slowing down, it wants to get to the lower range. If you're at that gap between 4 and 5, the poor thing doesn't know what's coming next, and the dog clutches can't react fast enough.
This video explains it way better than I can. The guy is a college professor of automotive technology. He seems fairly positive about it. This is the first of two video, and he is very thorough, but understandable.
I don't know how many miles on your Compass, but I had my transmission fluid changed around 120,000 miles. The manual says you don't have to, but I don't believe that. Not at all. The owners manual gave inadequate serivice intervals for the CVT in the 1st generation Compass and many failed even before the first scheduled service. If you're in the 100,000 mile range, I strongly suggest it.
These transmissions have everything but hamsters on treadmills!
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