Will the 4L80E shudder at highway speed

[96GMC7.4l/454]

You can pick up vcxdiag on amazon for around $110 last I checked and it will give you full oem scanner ability through your laptop. Otherwise you could try something like the torque app with a bluetooth to obd2 dongle. The TCC lockup valve is a known problem area in the 4l80e. Sonnax and transgo both make a lockup valve with a scarf cut seal to correct the oem lockup valve. When you look at the scanner data watching tcc apply, it should ramp up to 96% in 1-2 seconds and hold around 96-98%, so don't be alarmed if you don't see 100% apply as pwm solenoids have max duty cycles under 100%. If your tcc slippage is under 40 rpm's, it will normally not code for a pwm apply tcc(the 4l60e for 98+ is a 150 rpm before it codes).

Very knowledgeable thank you for sharing this information

 

[dbrannon79]

@THEFERMANATOR I was unaware of this issue! Please do share more info on this. I remember seeing mine on GMTDscan only showing about 50-60% while in lockup. my slippage would show upwards around 100+rpm under light acceleration and would go 500+ when heavy footing it. I always thought my converter clutches were gone. could this be an issue. only ever got the PCM code that one time a while back. I will have to reconnect the laptop and verify the numbers I mentioned.

@96GMC7.4l/454 I apoligize if I sound like I'm hijacking your thread. I'm just reading and learning on these tranny's myself

 

[96GMC7.4l/454]

@THEFERMANATOR I was unaware of this issue! Please do share more info on this. I remember seeing mine on GMTDscan only showing about 50-60% while in lockup. my slippage would show upwards around 100+rpm under light acceleration and would go 500+ when heavy footing it. I always thought my converter clutches were gone. could this be an issue. only ever got the PCM code that one time a while back. I will have to reconnect the laptop and verify the numbers I mentioned.

@96GMC7.4l/454 I apoligize if I sound like I'm hijacking your thread. I'm just reading and learning on these tranny's myself

Hey we are all here for information no issues from me

 

[Will L.]

I agree with you that normally I do most everything I can myself for lack of $,
I agree with WW that verify transmission first before use of parts cannon.
But in ujoints- yup do them all at once. Make sure to mark timing of shafts on 2 piece, but you said you have 1 piece (no carrier). Do front shaft same time on 4wd.

Definitely after you put in ujoints run it to driveline shop for balance. It makes a big difference on seals, pinion bearings, trans, etc. many driveline shops sell best ujoints for less money and do install free when balancing. My hummer getting both shafts done with carrier was only $20 more for them to do it all!

 

[snarl95]

I know this might seem obvious but did you check the fluid?

 

[MrMarty51]

Oh yeah. On abbreviations.
PWM = Pulse Width Modulation.
I dont have a good way of explaining it or how it works. It is a on and off system, so many times a second.

 

[96GMC7.4l/454]

I agree with you that normally I do most everything I can myself for lack of $,
I agree with WW that verify transmission first before use of parts cannon.
But in ujoints- yup do them all at once. Make sure to mark timing of shafts on 2 piece, but you said you have 1 piece (no carrier). Do front shaft same time on 4wd.

Definitely after you put in ujoints run it to driveline shop for balance. It makes a big difference on seals, pinion bearings, trans, etc. many driveline shops sell best ujoints for less money and do install free when balancing. My hummer getting both shafts done with carrier was only $20 more for them to do it all!

Hey I appreciate you sharing this with me. I never would’ve imagined that it was only another $20 there about to have them do it. I’ll definitely check into that. I’m going to see if I can find someone local that has this reader and will spend an hour or so in my truck one day for a little bit of $$ but I can’t buy that set up unfortunately. At least not right now. I’ll also see what it would cost to have a shop hook it up and see what they find but I have trust issues especially when it comes to someone else turning a wrench on my truck. Also the mechanics around here like to charge whatever they think they can get out of you.

 

[WarWagon]

In thinking of a quick and dirty way to check if the Torque Converter Clutch is the problem: Ride The Brakes. Just pressing them a little causes the ECM to unlock the torque converter. Anyway this reminded me that this era ate brakes switches for breakfast. Possible the brake switch is causing you problems.

The bad thing about the TCC unlocking is it "unloads" the engine some. (A badly running engine will cause the ECM to unlock the TCC as well.) Possible you have an engine problem causing the shudder.

I suggest if the u-joints and/or driveshaft is a problem it would show up on jackstands wound up to freeway speed. The TCC would not have enough load to act up. Neither would a engine problem.

 

[96GMC7.4l/454]

In thinking of a quick and dirty way to check if the Torque Converter Clutch is the problem: Ride The Brakes. Just pressing them a little causes the ECM to unlock the torque converter. Anyway this reminded me that this era ate brakes switches for breakfast. Possible the brake switch is causing you problems.

The bad thing about the TCC unlocking is it "unloads" the engine some. (A badly running engine will cause the ECM to unlock the TCC as well.) Possible you have an engine problem causing the shudder.

I suggest if the u-joints and/or driveshaft is a problem it would show up on jackstands wound up to freeway speed. The TCC would not have enough load to act up. Neither would a engine problem.

I do my best to keep it running tip top since it is a big block and gas is expensive. It eats rotor bug and distributor caps aswell. I replace them every six months like clock work or I pay at the pump. I do appreciate your input and thoughtfulness greatly

 

[Stoney]

@THEFERFENATOR mentioned getting the torque app. It works good..also dash command and car scanner are good ones...
You can get a OBD2 Bluetooth plug- in at Walmart called "micro mechanic" for 20 bucks or so...plug it in to your OBD2 plug and Bluetooth it to your laptop or a tablet and you can see everything the truck is doing in real time while driving so you may be able to tell what changes when the problem starts happening

 

[96GMC7.4l/454]

@THEFERFENATOR mentioned getting the torque app. It works good..also dash command and car scanner are good ones...
You can get a OBD2 Bluetooth plug- in at Walmart called "micro mechanic" for 20 bucks or so...plug it in to your OBD2 plug and Bluetooth it to your laptop or a tablet and you can see everything the truck is doing in real time while driving so you may be able to tell what changes when the problem starts happening

I can afford that one thank you

 

[Will L.]

If the problem is the tcc being commanded to lock/unlock/lockunoock etc- the. Yes the brake switch test would show it. Simply unplugging the brake swith- you don’t have to try riding brakes and smoking pads/rotors.
But it it is something internal causing it- brakes applied it won’t stop it. So your still at the point of seeing it on a scanner.

It would be astonishing if the $20 thing from wally world shows it. I would wager against it- but hopefully am wrong. Just make sure you can get it returned if it doesn’t.

 

[dbrannon79]

I have the micro mechanic from wally world and an app called car code that will show data. I have not tried it on a obd2 chevy to see if it shows the tcc data though. the app was 2.99 on the iphone app store. they don't make torque app for iphone unfortunately.

I have never done it, but have been told that you can get an obd2 to 1 adaptor from amazon and use it on older vehicles. I would love to see it in action but I have my doubts.

 

[Stoney]

The piece from Wally world is basically just the transmitter.. it's the apps that do the scanning. Micro mechanic has there own app too but it's crap.

 

[MrMarty51]

I for some reason was thinking this truck is a 6.5, but itiz not.
Some of those cheaper dongles might work okay on this truck.
I tried many of those different OBD2 apps and they would not show timing and timing off set on the 6.5, the would probably show the other functions of the gas engine okey.

 

[96GMC7.4l/454]

If the problem is the tcc being commanded to lock/unlock/lockunoock etc- the. Yes the brake switch test would show it. Simply unplugging the brake swith- you don’t have to try riding brakes and smoking pads/rotors.
But it it is something internal causing it- brakes applied it won’t stop it. So your still at the point of seeing it on a scanner.

It would be astonishing if the $20 thing from wally world shows it. I would wager against it- but hopefully am wrong. Just make sure you can get it returned if it doesn’t.

I looked in store and online and didn’t find anything that would read that much info from the OBD-II though there are a lot of other options throughout the internet so now I have homework. I’ll try the brake switch being disconnected though. I still in the back of my head think it’s the front passenger wheel area. I just can’t seem to get it right. I have some old phones I’m planning to zip tie to the frame and record all the movement I can.

 

[96GMC7.4l/454]

I for some reason was thinking this truck is a 6.5, but itiz not.
Some of those cheaper dongles might work okay on this truck.
I tried many of those different OBD2 apps and they would not show timing and timing off set on the 6.5, the would probably show the other functions of the gas engine okey.

Im not looking for gas engine information I’m looking for transmission information I don’t think it will make any difference what motor is in front of it

 

[96GMC7.4l/454]

I have the micro mechanic from wally world and an app called car code that will show data. I have not tried it on a obd2 chevy to see if it shows the tcc data though. the app was 2.99 on the iphone app store. they don't make torque app for iphone unfortunately.

I have never done it, but have been told that you can get an obd2 to 1 adaptor from amazon and use it on older vehicles. I would love to see it in action but I have my doubts.

OBD-II isn’t old it’s current ECU connection for codes and scanners

 

[Will L.]

I looked in store and online and didn’t find anything that would read that much info from the OBD-II though there are a lot of other options throughout the internet so now I have homework. I’ll try the brake switch being disconnected though. I still in the back of my head think it’s the front passenger wheel area. I just can’t seem to get it right. I have some old phones I’m planning to zip tie to the frame and record all the movement I can.

WHOOAAA HORSEY! “...think it’s the front passenger wheel area”
This thread started with the assumption you were feeling it from transmission actions. Kinda how you titled the thread.

Absolutely wheel/ suspension/ steering components can create high speed shudder.
Have you tried rotating tires front to back to see if the feel changes (moves location)?
Out of balance tire, tire separation, bent rim, is highly possible and normally occurs at specific speeds.

Bad shock absorber will have one wheel going down the road like dribbling a basketball while the rest of the truck is stable. That is a unique sensation I found most people couldn’t identify other than “something is different than usual”.
One wheel knocked out of alignment caster, camber, toe can be an issue, especially a wiled out ball joint in the beginning stages of getting a “death wobble” can all send a shutter through the truck.
4wd? I have seen cv joints without grease from torn boot binding create an oddball feeling at high speed.

I’m gonna go back to WarWagon’s suggestion- get it up on jackstands. Start by dojng a drive and noting what speed and exactly how it feels with a helper. Then onto the stands, Make sure if it comes off it can’t crash into anything. Have someone “drive” it up to the speed where you notice the issue the worst and you go around the outside of it -SAFELY AWAY FROM IT- and watch wheels, drivlines, etc.
If you see nothing, swap front and rear tire positions and drive it again, same road same speed and see if anything changed.

Having someone drive along side of you and signal them when to start video recording focusing on tires one at a time, driveshaft, and if they can get good angle from small car, from front end also. Zooming in and out to study it. Post the video on YouTube, bitchute, whatever and put a link here.

You might get an old phone, go-pro, etc. and mount it underneath for same thing. This is a legit way to find problems that otherwise never get found until the crash investigation or the one bad part has destroyed multiple other items and it all gets swapped.

 

[THEFERMANATOR]

OBD-II isn’t old it’s current ECU connection for codes and scanners

Im not looking for gas engine information I’m looking for transmission information I don’t think it will make any difference what motor is in front of it

Yes, which engine is in it will effect which scanner you need. And obd2 only dictates that a universal plug is used and that a generic scanner can read the codes, beyond that there is DOZENS of different data protocols used, pwm, voltage based, high speed, low speed, can bus, lan, and so on. For diesels GM used a modified form of there j1850 pwm data protocol adapted over the OBD1 infrastructure, hence why finding scanners to do the diesels is so difficult. The data network used in your 96 died in 05 with the last s10 based blazer, but it largely stopped in 00 when the gmt400 suv line ended.