Trans recommendations

[555hp]

2003 Suburban Z71, 4WD 5 3L, 155K miles. Interesting in towing 6k lbs, and need advice on the 4L60e trans. It's fine now, though see a few bit the dust at this age.

I'm thinking that a 4L60e trans rebuild in the minimum, though it seems that the a rebuilt 4L80e is not that much more expensive and mostly bulletproof (though harsher shifts).

Anyone personal experience/advice on the better choice? I'm really trying to avoid a trans nightmare while towing.

 

[Scottydoggs]

be a lot easier to just use a 60 vs a 80. 4l80's dont shift harsh either, unless its broken. quicker shifts tho, they help the trans last longer due to way less slip when shifting. you can make the 4l60 shift quicker/firmer too. aka shift kit.

 

[OR VietVet]

There is a 4L65 as well, if I am right. I would reach out to @NickTransmissions and see what he recommends.

 

[NickTransmissions]

There is a 4L65 as well, if I am right. I would reach out to @NickTransmissions and see what he recommends.

Thanks! He and i have conversed on it.

There's a couple 4L60e family variants:

* 4L65E ('01-'06) - vettes, gtos and high end trucks/suvs
- upgrades: 5 pinion planetaries, induction hardened input shaft, 7 clutch 3/4 pack, vette servo, better shift calibration (spacer plate and valve body)
- RPO: M32

* 4L70e ('07-13) - same vehicles as the '65; same parts as above plus induction hardened reaction shaft
- RPO: M70

* 4L75E (non prod) - sold otc by GM as an alternative to a 4L80e for project cars; rated to 650HP/Torque
- billet servo
- 8 clutch 3-4 pack
- aggressive mechanical shift calibration
- maybe other parts
-RPO: none

 

[SnowDrifter]

While I have no input on the 80

I do have a couple theories on failure modes on the 60s. Nothing I can prove, but, observations of failures and maintenance habits from reading pages of threads

- Old fluid: Gets acidic. Acid = high affinity to give hydrogen atoms up. Or to phrase it differently, push hydrogen atoms where they shouldn't be. Hydrogen embrittlement of steel / alloys is pretty well documented. See: sunshell failure. It breaks riiiight around where it would either be work hardened, or explicitly tempered.

5.4.4 Hydrogen Embrittlement [Aeroengine Safety]

aeroenginesafety.tugraz.at

- High temps: The temperature sensor on these is located in the pan. The trans cooler returns to the pan. This means that what the temp sensor sees is effectively the 'coolest' fluid in the unit - before it's been subjected to work. Actually it might be after it goes through the pump but regardless.... The thing's dunked in pan fluid. Couple that with the kind of anemic stock cooler and the transmission warmer in the radiator..... Well, I've seen mine hit 220-230 in traffic before I threw an aftermarket cooler on. It's probable that local hotspots in the unit were warmer than that.

- Temps pt2: I put a trucool40k on mine. Also have my efans mapped to turn on at a lower temperature. My fluid generally runs around 90-110 degrees in the winter, and like, <135 in the summer unless we have a flaming hot 110 degree day. Then it's in the mid 140s. But regardless, way lower than stock. And also well below documented embrittlement temps in the article I posted above.

- Corvette servo. More grip pressure, less slip. It's like a 15 minute install. Just... Put the seals on, assemble the thing, THEN put it back in. Don't try to slide the cup over the seals on install or you'll pinch them. Oh, and check no less than 6 times that it's actually seated all the way. It's real easy to feel like it's situated all the way in. But only halfway on. If it conks out sideways under pressure, that's casing-cracking territory.

- External filter. The stock pickup-tube-filter-thing is a rock catcher. Not an actual filter. I use magnefine on mine, located on the 'hot' side before the cooler so it catches the fluid while it's thinner/warmer. Has a bypass valve inside so there's minimal (not none, but minimal) obstruction to flow. Can snag some pics of location/orientation if you'd like

- Tune it. No, seriously. Crisp up the shifts, raise the shift points up a hair. Pull timing during shifts (reduce torque). Firmer shifts - less slip. Higher shift points - trading torque for RPM and keeping some load off. Pull timing during shifts - why make a shift with full engine torque? Just un-needed wear and tear.

- Extra magnet in the pan as per TSB # 08-07-30-040B. https://ls1tech.com/forums/attachme...350568544-new-turbo-gxp-service-bulletin-.pdf

- Keep the fluid changed. I drain/fill mine once a year through the dipstick. Mityvac or similar makes it easy. ~3qts. I use amsoil signature atf (black bottle, red label). I skipped on the 'fuel saver' which is a bit thinner (black bottle / blue label).


And... well... Like I said, I can't prove any of this. But I just ticked over 175k on mine this morning and it still shifts around better than the dude selling pocket watches behind the movie theater dumpster. Hopefully my ramblings were at least useful on care and feeding of these things

 

[Marky Dissod]

'03 Suburban Z71, 4WD 5.3L, 155K miles. Interesting in towing 6000lb, need 4L60E advice.
... really trying to avoid a trans nightmare while towing.

Besides upgrading the 4L60E rebuild to 4L70 standards, and tuning the pcm specifically with foreknowledge of the rebuild and its purpose (especially the Tow / Haul mode shift table), my only question would be:
Does your Suburban have 4.10 or 4.30 axles? 4.10 would be enough, 4.30 would be better.
If the axles are 3.73, I'd not tow without the tune, but if you do, keep it out of 4th unless the 4L60E was rebuilt specifically with that in mind.

 

[NickTransmissions]

You guys pretty much captured the key cosiderations and approaches when towing/hauling/working with the 4L60e.

If in for overhaul i usually install high energy clutches, super-hold servo assemblies and a kevlar band if the the towing is particularly intensive.

 

[Alex_M]

6k # isn't too bad. Not sure what Nick has recommended, but he seems very knowledgeable so I'd go with what he says. My key recommendations would be:

Upgraded trans cooler *
Hardened shell
Block off PWM Solenoid *
.500 boost valve *
Corvette servo *
Zpak 3-4 clutch pack or similar
Wide 2-4 band
HD valve body separator plate *
Torlon Check Balls - probably a bit overkill to have both, but ain't no kill like overkill. Won't hurt anything to have both. *
Block off the 3-4 accumulator in the case *

Again, 6000# isn't too bad as long as you drive reasonably. As long as your tranny is acting right, you could do several of these upgrades without pulling the trans if you wanted to. Actually, I'll go back and put an asterisk beside those. You do start seeing some '60s falling off around 150k, but some go much longer depending on how they've been used and cared for.

 

[NickTransmissions]

6k # isn't too bad. Not sure what Nick has recommended, but he seems very knowledgeable so I'd go with what he says. My key recommendations would be:

Upgraded trans cooler *
Hardened shell
Block off PWM Solenoid *
.500 boost valve *
Corvette servo *
Zpak 3-4 clutch pack or similar
Wide 2-4 band
HD valve body separator plate *
Torlon Check Balls - probably a bit overkill to have both, but ain't no kill like overkill. Won't hurt anything to have both. *
Block off the 3-4 accumulator in the case *

Again, 6000# isn't too bad as long as you drive reasonably. As long as your tranny is acting right, you could do several of these upgrades without pulling the trans if you wanted to. Actually, I'll go back and put an asterisk beside those. You do start seeing some '60s falling off around 150k, but some go much longer depending on how they've been used and cared for.

Good list - I recommended the Sonnax Smart Shell for more serious towing.

For additional mods to the above * while trans still is in the vehicle:

Block off the 3-2 downshift valve from moving. Shortens up the "dwell" time from shift command to completion.

Leave the 3-4 accumulator (acc) piston bore empty and remove the 3-4 acc check ball if blocking off the 3-4 acc circuit in the case. Folks can also run two pistons in that bore, an old one with legs up and no sealing ring and a new one with legs down and a sealing ring. Mesh the legs (you will need to grind about 1/4-1/3rd off the legs of the old one and sand the bumps off the top).

Sonnax pinless accumulator piston kit in the 1-2 accumulator

Drop in upgrades AFL valve or ream the AFL bore and install the Sonnax oversized valve. Take the spring from the 3-2 downshift valve (blocked off) and put it inside the AFL valve spring.

Do NOT drill the AFL balance or TCC signal holes in the plate unless you're running a Transgo shift kit with instructions to do so.

Drill the 2-3 feed, 3-2 exhaust and 3-4 shift orifaces to .093; drill the 1-2 feed oriface as follows:
- vette servo: .086-.093
- Sonnax super hold or similar servo: .076-.080

Early pre-PWM plate shown but hole locations are the same for all years.

 

[Rocket Man]

You could go with a Performabuilt 60, they build them with their own proprietary upgrades to handle up to 1000 hp. I’m running their level 3 in my blown 02 Denali. They make a black edition that’s never been broken by anybody even racing on them for years but that’s an overkill unless you’re racing with a lot of powah.
www.Performabuilt.com