Weak acceleration after tranny rebuild

[derekinairdrie]

Hello!
I have a 1994 Ford Ranger 4.0 L 4X4 with the A4LD automatic transmission. I recently have a full tranny rebuild done at a local shop, and ever since I've had some strange symptoms.
When I go to accelerate, I need to bring the rpm up to 2700+ just to keep up with normal traffic. If I floor the gas I can still make the tires squeak, but the acceleration seems quite a bit weaker than what I remember before I had the rebuild done.

I performed a stall speed test by holding down the brake and stepping on the gas, and the rpm ran up to 3100. Is that in the normal range for the stock torque converter? I've found a ton of different numbers online for stall speed ranging from 1800 up to 3200, and I'm not sure which is correct.

I also have a slight shudder around 1800 rpm in first gear, basically as I am getting going off of a light. In addition, I noticed that the rpm doesn't seem to drop on the tach at all when the gears change. Is that even possible? I hear the gears changing, but the rpm will stay constant before, during and after the change.

I brought the truck back to the shop and they don't feel anything is wrong in relation to the transmission. After some discussion, they said they are willing to replace the torque converter under warranty and if that doesn't resolve the acceleration problem, then "it is not transmission related".

Any advice or ideas would be much appreciated!

 

[Denisefwd93]

I feel for you, This why I rag on about auto transmissions. I Can't believe the bad luck people have with auto transmissions being rebuilt!

 

[enjr44]

My first thought is that they installed a torque converter with a different stall speed than your original. FIRC, the stall speed on the newer years was higher.

 

[Denisefwd93]

Derek...how about a follow up?

 

[derekinairdrie]

I dropped my truck off at the tranny shop this morning. They are going to replace the torque converter. I will let you know if it resolves any of the issues.

 

[derekinairdrie]

Got the truck back from the shop yesterday. They replaced the torque converter and now the acceleration problems are completely resolved! My truck now accelerates the way it used to.

 

[enjr44]

Got the truck back from the shop yesterday. They replaced the torque converter and now the acceleration problems are completely resolved! My truck now accelerates the way it used to.

Did they tell you what was wrong?

 

[Denisefwd93]

Got the truck back from the shop yesterday. They replaced the torque converter and now the acceleration problems are completely resolved! My truck now accelerates the way it used to.

which means dropping the whole thing again.. did they charge you for this? Glad it's fixed! I'm not quite so confident in auto transmissions and those that rebuild them. I get some hate for that sorry guys

 

[derekinairdrie]

The shop said they cut open the torque converter and some of the fins were slightly bent, preventing proper fluid flow.

 

[Denisefwd93]

The shop said they cut open the torque converter and some of the fins were slightly bent, preventing proper fluid flow.

If they didn't show you... it's just words. Mine has a shudder or shake around 45-65 mph. but not all the time which has me wondering.. But we are doing a swap to 5 speed on it in the spring so another A4LD boat anchor will be available to anyone that wants it.

 

[enjr44]

Either it was defective or they put the wrong one in there. Either way, glad they stood up and fixed it.