Tranny Jerks

[2.5GT]

alright, its a '98 BD with an auto.

its gotten a little bit worse now. but whenever i accelerate up to 10-15mph slowly or hard, the tranny jerks the car forward (kinda like when you're driving a stick)

so..any comments, suggestions, add ons? and i just change the fluid not long ago.

[Wiscon_Mark]

How much have you done for a tuneup lately? Have you reset the ECU recently?

[2.5GT]

nothing big. and i havent reset the ecu yet.

but i still dont see how a tuneup effects the jerkin of the tranny?

[Manarius]

Does the jerk come with a tranny shift? Or does it just do it randomly?

[2.5GT]

it does that when it shifts yes. but only when it hits almost 10 mph then it shifts smoothly after that.

[shazapple]

My car has always shifted hard into 2nd when Im going slowly. It doesn do it when Im accelerating quickly though. Have you tried some of that Lucas stuff Huffer recommends?

[Huffer]

Normal operation for a transmission that has done a few miles.

If you want to smooth things out a little - replace as much of the fluid as you can, and drop in a bottle of LubeGard ATF protectant - it helps lower the overall temp of the AT

It works. My transmission bucks 1-2 randomly, but much much less than before.

185k on same auto.

[2.5GT]

alright, ill see if it improves or not with that lubegaurd fluid.

it bucks so hard that people thinks its a stick :roll:

[SlowLeg]

...185k on same auto.
Thats good to hear, im hoping to see similar life on mine im sitting at 140K. I also experiance this, maybe i'll give that fluid a shot.

[2.5GT]

but i still want to find out what it is that cause the "jerkin"

[Perdue]

I think this is pretty normal for a transmission that's got that many miles on it, or has been driven hard. Mine seems to act up, but it comes and goes. I may try changing the fluid and adding a bottle of that stuff Huffer recommended.

I never really have problems going slow though. I was running a call in my car last month and when I got up in speed and the tranny shifted, it seemed like it was slipping before it went in gear. Ran a call the next week and didn't have a problem.

[Huffer]

but i still want to find out what it is that cause the "jerkin"

It's a TCU issue - and basically means the TCU is attempting to shift at a point where it used to shift fine, but I believe there's just 'wear and tear' that prevents it from happening all the time.

I do get smoother shifts once the ATF is warm, but even still, I can make it buck if I drop some throttle off at a certain speed/rpm point.

If it's any consolation, I did an ATF change (plus added the LubeGard) to a 2004 Outback (35k), which had similarly rough shifting. We used no-name Coastal ATF (owner's a bit cheap) and the results were outstanding. The snappy 1-2 shift had smoothed out, it was still a quick shift but wasn't as noticeable. Getting onto the freeway from a stop light was also smoother.

AT's that shift "like butta" are probably generating a fair amount of residual friction, because of the way the gears are synching up. Heat causes degradation of the transmission, so lowering the overall peak temp is a good thing.

LubeGard ATF Protectant is basically a friction modifier.

[Perdue]

LubeGard ATF Protectant is basically a friction modifier. :smt107 OH NOES!!1! He broke out the big technical words on us! :smt042

Anyways, where can you get the ATF Protectant, and how many quarts of ATF do you need to refill the transmission after emptying the pan? I need to change my drivetrain fluids and hopefully make this tranny last until I can get a 5 speed swapped in.

[Huffer]

:P

You can get it at Autozone, Murray's etc. Most autoparts places should carry a couple of bottles. The kids that run the places have no idea what it is though. It's usually found in the ATF section.

On my auto, I drain around 6 quarts, and a full fluid replacement is about 12 qts. You never get the full monty though. I drained mine twice in a week (after plenty of city/freeway running).

I have heard of some people who do a drain while the car is running, leaving the AT in N, and slowly refilling. When the draining liquid becomes the same as the input liquid, that's when you've cleared the majority. Same procedure I guess as a "flush" machine, but less aggressive?

[PetterFan]

My car has always shifted hard into 2nd when Im going slowly. It doesn do it when Im accelerating quickly though.

I read a review about the 1997 GT from 1997 (written by a guy driving a brand new car) and he commented on the "bucking" of the transmission between 1 and 2 gear.
My car does the same thing too. As to why it does it...?

[Wiscon_Mark]

boxer engine...

:shrug:

Subarus are usually a little hesitant under 3000 rpms, honestly.

Although I haven't really had that problem, or I don't notice it.

[Huffer]

boxer engine...

:shrug:

Subarus are usually a little hesitant under 3000 rpms, honestly.

Although I haven't really had that problem, or I don't notice it.

You don't have an auto...

And the mid-90s Legacies are well-documented for suffering from hesitancy. It's something the Euro Impreza's suffer from constantly. My Legacy had an alternator recall early in it's life for the problem. I don't notice it, because I accept that my car is older, and suffers from a detuned auto and a worn engine. So I don't hammer it. :)

But the autos are more "hesitant" than the manuals. With the 5MT, you can tickle the rpms more.

The 4EAT TCU is definitely a weak point on the BD series.
The 1-2 buck is real.

[Wiscon_Mark]

so? That doesn't change the fact that the boxer engine really doesn't wake up until 3k rpms :razz:

Although I realize that I have a much better transmission :D

[Huffer]

so? That doesn't change the fact that the boxer engine really doesn't wake up until 3k rpms :razz:

Although I realize that I have a much better transmission :D

The only reason your MT would have a 1-2 buck is if you're crap at shifting. :P

[Wiscon_Mark]

or if the engine is cold and it's suffering from cold starts (I'm switching back to 5W-30)...