4L60E 94 Impala

[92TAWS6]

Friend of mine has a 94 Impala with some high mileage.

It runs great and the trans shift well driving through town. If you drive aggressively it's another story. It takes a looooong time to make the shift from 1st to 2nd. Not as in it holds 1st for a long time, Rather you feel it coming out of 1st and going to 2nd but it's very mushy. Like it is slipping but the RPMs don't really change like it's slipping. Sluggish I suppose. I'm transmissionaly stupid so I told him I would ask here.

We are pretty sure of the obvious answer (trans needs redone) but I told him I would ask :)

He has had a PCM tune done to firm the shift points but they are anything but.

[WS6 VERT]

It could be that the band is worn and cannot hold under load, or it could be that perhaps the accumulator piston is cracked or the Accumulator valve is sticking.

Best thing to try, is instal a TransGo kit. It will come with a larger boost valve, modified 1-2 shift valve, updated spring for the accumulator valve and many other updates. This will also give you a chance to inspect the accumulator pistons (if plastic may be cracked, if aluminum, the center hole may be worn out). This can all be done without pulling the trans.

If that don't fix it, then you may be putting a band/drum in it.

[92TAWS6]

Cool, thanks.

This old, tired Imp needs quite alot of attention.

[92TAWS6]

If that don't fix it, then you may be putting a band/drum in it.

I'm assuming that would require special tools. Expensive special tools that I don't have :(

Looks like we are both getting the TransGo kit. Plenty of good comments, etc on it at the ISSF. I saw a site that explained the install and it doesn't seem all that bad. I figure my trans works great, so why not upgrade it :)

If something bad happens I have spare trans in the garage. It's from a 95 though and requires slight modifying to put in my 94.

[WS6 VERT]

To rebuild the trans requires special tools. If you remove the transmission just to replace a band, no special tools required.

[92TAWS6]

Really? Cool.

The article I read on installing this kit thanks YOU actually, so I know it must be good :)

[WS6 VERT]

Yeah, I used to do a TON of stuff of the B-body community. A great bunch really, but at that stage of my life I had alot going on and had to pull the plug on my transmission shop.

[GeoffP]

Hey, I thought the 95 trans didn't have to be modified to put in a 94? The 95 just has a PWM torque convertor clutch engagement circuit (if I remember right). Since the 94 PCM code doesn't utilize it, it just goes unused. Bernard would have to confirm this though. Regardless, my brother put a 95 4L60E in his 94 years ago and has never had a bit of trouble out of it.

BTW, I sure wish you could start back up rebuilding transmissions on the side! Not that I need it right now, but I'm sure I will eventually.

[92TAWS6]

According to the numerous posts at the ISSF, the PWM solenoid valve needs to be staked open. The TransGo kit eliminates the need for this though.

http://www.impalassforum.com/vBulletin/showthread.php?t=227225&highlight=valve+body

[WS6 VERT]

I didn't see where a '95 was mentioned in this post :confused0033:

But Bill is right, the TransGo eliminates the PWM feature, so its OK if your putting in a '94.

[92TAWS6]

lol

I mentioned having a spare trans from a 95 in case I muck something up on mine or my friends.

[GeoffP]

I hated the way the PWM made the torque converter in my 95 Z work. I'm glad the 4L60E in my IROC is from a 94, no PWM.

What's the general consensus on the TransGo kit over say using the performance trans shifting table in the PCM? I copied the performance table values into the standard table so I get the performance option shifting all the time. I'm fairly pleased with it considering it shifts firm but not harsh like some "kits" do.

[WS6 VERT]

Programming via the PCM can only do so much. Typically, at WOT, the tables have the Pressure solenoid maxed out anyway, so the only thing you can "really" tune is part throttle shifts anyway. Going into the transmission with the TransGo kit can fix some of the "hardware" issues with the transmisison and extend the range of what the pressure solenoid can do.

[92TAWS6]

Yup, the TransGo kit is wayyyyy more than just a "shift" kit. It improves on quite a bit and can extend the life of the trans quite a bit.