2001 1500 suburban with 6.0 and 4l80e swap. Computer has been flashed and all wiring done accordingly at oval plug at trans and at computer.

Used transmission out of and 2004 1500HD Stock TQ converter/reman from advance auto looked to me.

When i tore it down nothing jumped out looking bad other than the Pump to converter bushing was worn. All other bushings though out looked to be in decent shape.

HD2 kit (but did NOT install pressure relief plate and drilled VB for that mod.
Used Transgo separator plate and drilled holes to .096
Dual feed mod
Drilled pump for pressure relief
rollerized the rear of the case.
Replaced pump bushing and seal

Problem#1
1st to 2nd shift 1/4 throttle SHUDDER shift and sometimes will throw P0757
No throttle extremely soft shift into second
Problem#2
1st to 2nd shift 1/2 throttle major shudder shift and squealing Drum brake sound. P0757 right away
I replaced SOL A and B since i got the code. I did however check all the solenoids before reinstall and all Ohms checked out. I checked the reading again right after a drive outside the case using a pigtale the only one that came back with a high Ohms reading was EPC Solenoid. recommended is 4 to 5 and I was at 11.

While replacing A and B Sol i physical removed and inspected the valves and springs and saw no signs of wear or damage
Problem#3
3 and 4th feel good but doesn't seem like the the TQ isn't locking??? 3000rpm at 60mph isn't right.

Brake switch checks out ok for TQ not wanting to lock.

only code i keep getting is P0757 no matter how long or far i drive. Trans temp has never seen over 185Deg. while driving i will have to erase the code for it will drive normal. Like every 3rd time i have to start from first gear again and a stop light or sign i will have to erase the code

Pressure check while warm
P/N 70PSI idle revving 100PSI
R 80 psi idle stall 165psi
1,2,3,D idle 70PSI stall 150psi

I did as much research as i could and feel my googling and youtube skills are exhausted and i only come up with i have a bad VB, solenoids, internal wiring.
Any advice would help before i start to throw money away for a possible easy fix.

 

I bet the AFL is wiped.
Sprag probably pretty worn out too.

 

I could see the AFL being bad/loosing pressure. Sonnax sells a resleeve repair kit but also got to buy the reamer kit. Is it worth it?
The Sprag, is that what is making that noise on hard shift. It's just not holding? Are there any bands that are active when its shifting from 1st to 2nd.

 

AFL bore/ valve are commonly bad...
I purchase these in bulk.

Only when the transmission is in reverse, manual first and in manual second, are there any over-run bands in use.

Reverse uses the low-reverse band.
Manual First also uses the low-reverse band (over-run).
Manual Second uses the intermediate band (over-run).
Manual Third uses the over-run clutch pack.

The over-run clutch pack is used for all of the manual gear ranges...
However the over-run bands are only used in manual first and manual second as I typed above.

 

So buy the sonnax AFL kit or the Sure Cure Kit even though I've done the HD2 kit? Will this solve these issues? what about the sound and lazy shift?

 

Buy the transgo AFL kit.

do 3rd and 4th work?

 

Ok WOW after looking just the Jig/Tool for fixing the AFL is $230-$280 depending where you look. Spend $100 and get a complete ACDELCO VB with warranty..
Any other options or opinions?

 

transgo afl tool/jig/5 valves is less than $100

Link to ACdelco vb for $100 brand new.
I might buy a handful at that price

 

I forgot to look back at TransGo and what I was saying is for all the Sonnax jig and valve replacement almost adds up to a new VB. That's what I meant by spend $100 more with the price of the sonnax stuff it worth it to just by the complete VB.
$276 reamer kit only ebay
$34 AFL valve kit only ebay

VB ACdelco from napa $370

Found the trans go version for $137. Still will this fix the issue i am having?

 

Yes 3rd and 4 work Well my cheapy scanner shows command 3rd and 4th and i feel it shift but that may be converter locking 3rd but not 4th. I really cant tell for sure. RPM to high for speed im going.

 

Transgo kit with tool and 6 valves is less than $100
Can't say for 100% certainty that will be your issue...because I'm on the internet 100's of miles away.

Have you tried adding a quart or two of fluid?
The 1-2 shift is usually the first to experience symptoms of low fluid. Its a cheap and easy thing to try.

Pressures seem normal...If it were in my shop I'd be dropping the valve body to vacuum test it and see what is leaking

 

I understand your taking a guess at it. It's hard to tell if you don't physically have it in front of you to figure it out. I guess I was more asking in your experience and it seems you have some does this normally solve the issues Im having?

The fluid has been checked several times and it always dead on the money. I guess i could add more fluid what could it hurt right..lol
I guess I'll try one more time with this TG valve repair. If that doesn't work than a complete rebuild and a new/used VB is in order.
Though I could get lucky with a junkyard 80E. It was pretty clean for the most part outside and inside but that's how stuff is sometimes.
Thanks for the info.

 

Even if the AFL valve-train repair is not the solution to your problem...

You will be either improving the operating consistency/ making the transmission act as if it has less miles on it...

Or you will be fixing another problem that you didn't even know you had.

 

You do make a good point. Theres is no telling how many miles this bad boy really had on it or how hard they really beat it. Maybe they were chasing the same problem i am right now, hince the new/re-man converter and still decent color trans fluid and filter looked new.

 

If you're going to pull the valve body...vacuum test it!

If you have $75 to spare and some free time, you can build one. I have a thread with a "how-to"
https://ls1tech.com/forums/automatic...alve-body.html

 

Nice write up. I'm an HVAC guy so I can rig something up. So I will definitely be Vac test it. Repair kit from TG already came in so this weekend is do or die for this thing.

 

So I finally got everything back together. I built a little vacuum test manifold as suggested. Didn't run a vac test prior but I completely removed every valve,spring,check ball's and o-ring. Bought the AFL transgo kit, Took a nylon bottle brushes to every bore cleaned till it looked brand new. Stoned blocked the valve body to make sure it was flat and no burs changed every O-ring and reassembled. Also bought a new internal wiring harness and new seperator plate. Got rid of the Transgo one. Vac checked everything I could from the sonnax web sight. Numbers were between -19 and -21.
On the test drive it shifted in second better.... but still stuttered a bit and a drum break sound again but not every time. Drove it for 30mins lots of stop and go with no issue other than the shutter shift to second but no code. After a quick blast down the hwy, still 60-70Mph at 3000RPM??? Notice the trans temp 185-188 pulled off the hwy to a stop light. Started from first then second then Bam code P0757 every stop light back to the shop...