Jb1123

new here, just picked up a 1998 silverado 5.7 vortec with the 4L60E

it slips a little around 25 mph, wont shift into 3rd unless i go WOT and let off, then it wont shift into 4th at all.

previous owner said its the second tranny, speedo sensor fell out and he put it back in

RacerX

sounds like a valve body solenoid issue, in the later years the PCM uses the VSS to determine upshifts points. He says the VSS fell out? Weird, crawl under there and look for yourself.

dhoff024

I just bought an 01 4.3l and mine has tranny problems as well mine shifts very hard from 1st to 2nd and reverse is pretty bad sometimes it works and sometimes it doesnt. It will go into reverse but its hit or miss if it works right sometimes the whole truck will shake pretty bad backing up and then finally pick up but I know the frustration with the tranny issues I would love to help but I dont even know whats wrong with mine so I dont think I would be of much help.

Jb1123

Like the shift solenoids?

What I was gonna check first were the tps and vss, where is the vss sensor located on the tranny?

Jb1123

I've never really had tranny issues with any other vehicle so this is a first, I got a good deal on the truck though, of worst come to worse ill just pick up a tranny from the junkyard. Hopefully it's just a sensor or something small.

It only has 140,000 miles, I think this is the second tranny though idk

Allan In NE

You have an issue with the band not clamping the reverse input drum.

You can rule out the solenoids because they are in different states in 1st, 2nd, 3rd and in 4th. Neutral works and 1st, 2nd and 3rd will engage so odds of a bad solenoid are very slim.

Could be a forward sprague, BUT since this transmission uses a stacked shift from 1 to 2 and 3 to 4, that's really a 'reach' of faith.

Since the band uses two different servos in 2nd and in 4th, you can also rule out the hydraulics as well. That leaves us with just the band/drum.

The 'key' thing here is that it is "slipping in 2nd" and won't even pull with the higher ratio of 4th.

She's gotta come down outta there.

Allan

Jb1123

That's another thing I was thinking when I read about the common problems with these trannies. Is it hard to replace? Where can I order the band? Is there a how to with pictures? I've pulled transmissions but never opened one up.


Also another thing I've noticed is the lever stops when I get to 3rd, it won't manually go down to 2nd or 1st.

RacerX

I m not so sure, because the Reverse band is applied using the 1st Gear solenoid. The band is applied to the Manual Low Drum. If there is confusion in this solenoid signal, R wont apply(sometimes). Another thing is the 2nd Gear solenoid can override the 1st(Manual 2nd) but they cant both be applied at the same time. If they are then it feels like the gear is slipping. So what if the 1st doesnt detach for the 1-2 upshift when the 2nd is energized?
If the band doesnt apply then the servo, spring or piston could be bad, but in this case R should Never work. He says it works sometimes, so I am thinking Valve Body Solenoids, Slackness in the Manual Lever or Low Fluid Pressure in the system. And since Overdrive is gear reduction through the Direct Drive Drum, the solenoids may be gummed up preventing upshift into OD or that 1st solenoid could be energized(fully or partially) parasitically sucking current from another circuit to prevent upshift. In most hydraulic instances you lose 3rd and 4th together which indicates low system pressure or worn clutches in the direct drum.
If this was a Cadillac you could test all of this using the Climate Control Cluster.

If your lever stops at 3 and doesnt move lower you have to crawl under there and see if there is a restriction in movement. These things sound funny because the previous owner obviously did something wrong here. Disconnect the Manual Lever and work it manually from under the car and see if all the gear ranges are there on the side of the case. P-R-N-OD-D-2-L, there should be 7 detents. If you dont have 7 detents something is wrong internally. If you do then there is problem with the length of the linkage in the steering column.

The VSS should be in the tailshaft on the left side of the transmission.

If you want to rebuild this thing, ATRA makes the manual and sells it on Ebay for $28. It isnt hard to remove if you have the 2wd, the 4wd requires a little more effort and time