Transmission problems

[Hkp7]

Looking for some ideas on what to check. I know very little about the inner workings of automatic transmissions. I have an 84 which is lacking power and has a shutter while driving coming from rear of vehicle. Engine runs smooth but I feel like the car is towing a trailer. It seems to shift just fine, fluid is at proper level. Upon chasing this problem by doing things that could be hit or miss, I changed the fluid and filter, as well as the vacuum modulator. The fluid I changed out did not appear abnormal or burnt. It also lugs the engine while making turns from a stop.
Any suggestions that can help me get started would be appreciated. If it gets too costly, I will just replace it with a good used one.

[Maleficio]

Replacing the fluid has always fixed those kind of problems for me. You've already changed your fluid, so I'd say your tranny is probably shot.

I'm not an expert, though.

[dtool242]

Sounds like a problem with the differential.

And I'm not an expert either.

[Danglerb]

All that stuff sounds "weird", not like any failure I am familiar with.

Did you properly check the level, engine running etc?

How is the vacuum line and bowden cable?

Before you get much deeper I would have a 928 expert look at it.

[924CarreraGTP]

My '83 kind of feels strange when it accelerates cold. It warms up and drives fine. It kinda feels like a torque converter problem.

[Hkp7]

I did correctly check the fluid level. I will admit that I havent yet checked for good vacuum to the modulator yet. Also, when the car has been sitting for a while cold, it almost feels like im starting off in third gear just to illustrate the engine lugging.
After driving a couple hundred feet, it starts to smooth out but the problem described earlier is still there. I am using dextron 2. Not sure if thats the correct fluid or if it would even make a difference.

[dtool242]

Originally Posted by Hkp7

It also lugs the engine while making turns from a stop.

That sentence is what is making me think differential. Ever try to drive an ATV w/o a differential on pavement and try make any sort of sharp turn?

[harborman]

Originally Posted by dtool242

That sentence is what is making me think differential. Ever try to drive an ATV w/o a differential on pavement and try make any sort of sharp turn?

Why not jack the car up and check rear wheels by hand.

[Maleficio]

If you had a vacuum problem, you'd feel hard, abrupt shifting, not really loss of performance, .......save for the effect a vacuum leak has on air/fuel control.

Before you do anything else, I'd replace the fluid yet again with a quality synthetic, like from Amsoil.

I'm running Castrol ATF, and I don't like it. Also, I had no good way to flush out the old fluid from the cooler and lines, so I have a mix of old with new/cheap fluid. But I did drain the torque converter.

[MPDano]

Originally Posted by Hkp7

I did correctly check the fluid level. I will admit that I havent yet checked for good vacuum to the modulator yet. Also, when the car has been sitting for a while cold, it almost feels like im starting off in third gear just to illustrate the engine lugging.
After driving a couple hundred feet, it starts to smooth out but the problem described earlier is still there. I am using dextron 2. Not sure if thats the correct fluid or if it would even make a difference.

I know what you mean. My Euro (3 speed) in Reverse felt that way, like it was dragging something. Doesn't matter now since I toasted it the other day.