What's my transmission doing?

[HawkeyeScott]

2000 Durango, 4.7. 124,000 miles. Had it for year and a half (14,000 miles).

Trying to diagnose what I'd call a weak shift. Not crisp, takes a half second longer to shift compared it its "best" shifts. It's more noticeable if I accelerate more slowly. For instance, the shift from first to second is crisp at 2000 or 2100 RPMs. If it shifts at 1700 RPMs, though, there's a bit of a lull. I'd call it a sluggish feeling. A hesitation.

I try and avoid it by accelerating faster than I otherwise might to let it shift at the slightly higher RPMs.

Fluid is good. Maintenance records from previous owner shows it's gotten fluid changed at various times. I serviced the ATF and installed new filters when I got it.

Shifted this way as long as I've had it...just trying to figure out why.

 

[Robenstein]

Sounds like a bit of clutch slip going on. Did you use the proper Mopar fluid(ATF+4), or did you use one of the universal ATF fluids?

 

[HawkeyeScott]

Used the SuperTech ATF+4. Previous owners had taken it to dealerships, so it all should be ATF+4.

 

[WobblyElvis]

If the filter were partially plugged it might cause low fluid pressure and slow/weak shifting. Has the filter been changed recently?

Sorry ...just read your first post completely...daaa

 

[Koz1]

I had the same problem with a 2000 Caravan Tranny.
A small bottle of zMAX 6oz Transmission Formula cleared that up believe it or not. Thats just me though.
Then 20,000 later the input speed sensor went on the tranny so I replaced both the input and output speed sensors, they were cheap for me 25-30 each. Never had a problem after that with the tranny.
I changed the fluid and filter every 32,000 miles.

I always used ATF+4. Didnt need to be the the Mopar type either.
Mobil and Valvoline.

 

[901Memphis]

Supertech ATF+4 is the correct fluid, if everything else was ATF+4 also it would be something other than the fluid.

Also verify proper fluid level through the specific procedures in the owners manual, probably checking while fully hot.

 

[The_Eric]

Would be worth scanning for codes. Also investigate the TPS and MAP sensors.

 

[Doog]

Originally Posted By: Koz1
I had the same problem with a 2000 Caravan Tranny.
A small bottle of zMAX 6oz Transmission Formula cleared that up believe it or not. Thats just me though.
Then 20,000 later the input speed sensor went on the tranny so I replaced both the input and output speed sensors, they were cheap for me 25-30 each. Never had a problem after that with the tranny.
I changed the fluid and filter every 32,000 miles.

I always used ATF+4. Didnt need to be the the Mopar type either.
Mobil and Valvoline.


This ^^^ I had 3 of those back in the 1990's absolutely loved them but the drive line needs constant tlc. I thought they were hands down the best SUV made for my wife to drive. I might be inclined to add a bottle of lubeguard red at the next service.

 

[Mud]

Clutch pack and/or band engagements are typically controlled by internal pistons also called accumulators or servos. Some clutch packs also have their own internal Pistons. All of these devices have rubber seals that can deteriorate over time heat and miles. Fluid is routed into the accumulator which in turn causes the clutch pack to engage. At the same time fluid is exhausted from another accumulator causing another clutch pack (previous gear) to disengage, that's what you feel as shifts. The time for one pack to engage while another disengages is shift overlap.
Slow overlaps can be caused by worn accumulator seals but usually seen as more specific to a particular shift like 2-3 for example. For overall slow shifts I would drop the valve body and thoroughly clean it. You cannot clean a valve body without removing it. Fluid changes cannot move debris out through the check balls and "back flushes" are a joke. Plus if the VB is removed that also allows replacement of the gaskets at the VB and separator plate (if provided). Slight leaks at these thin gaskets also can cause slow shifts.
Summary if it was me, drop and clean out the VB, new gaskets, replace filter, fresh fluid with Lubeguard additive.

 

[HawkeyeScott]

Just to close the loop on this in case someone is using it for research in the future.

Soon after posting the original message, I tried the Lubegard route. Drained 6ish quarts from the pan (and the drain plug I installed two years ago) and refilled with more fluid and additive. I waited several months, but it didn't change anything.

So this week I got a wild hare and decided to go the TPS route. I spent $44 on the BWD at O'Reilly's. I figured it was worth a guess and I'd at least have a new TPS sensor, as I'm sure the one on there was OE.

Sure enough, it worked. It immediately changed the way the thing drove AND shifted, especially on acceleration. It was poochy before and is much less so now. Trouble is, it must have had a bad TPS sensor when I got it two years ago and i just assumed this is how underpowered these Durangos were.

Anyway, guessed and it worked out. Pretty happy, but wished I'd tried it sooner.

Another lesson to start with the easy stuff.

 

[Silverado12]

I had a 2003 Durango 4.7 4WD and can tell you it would run like a scalded dog. Could pass anything but a gas station LOL. Glad you got it fixed.