lxcoupe

iTrader: (9)

I know the 8.1L trans is the same as the 6.0L but I wasn't sure about the Duramax 4L80's that came in Express vans. Anyone know if it will work?

ILuvJDM

iTrader: (4)

Yes, those are actually the 4L85e

lxcoupe

iTrader: (9)

Thanks. I had a 4L85e in my last build and it was quiet and flawless. But now I'm reading that the 4L85's are noisier? I guess every trans is different and no one knows until they get it installed and turn off the torque management. I know I've read that eliminating tm can eliminate the 4l85e straight cut plentary gear noise, apparently.

03sierraslt

iTrader: (22)

It does not. Not sure where that came from. But if you can get a 85e then do it.

ILuvJDM

iTrader: (4)

I've heard the same thing, that the first gear whines. I have a 4L85e sitting in the garage ready to go in, hoping my exhaust is louder than any possible whines

lxcoupe

iTrader: (9)

I had a 4L85e in my turbo truck and I remember with the 5.3 and stock 4L80e transmission tune (ie. full torque management enabled), it whined in 1st gear under load. But then I did the basic trans tune edits to remove TM and it got a lot quieter, if not completely quiet. I don't remember it making any noise because I would have done something about it since I've always been obsessive about perfection no matter the cost. That being said, there is a TSB out for 4L80e/4L85e trucks/ vans about noise in 1st and how it's normal. Obviously, those trucks had TM fully enabled.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
The 4L80E/4L85E automatic transmission may experience a condition of planetary gear whine noise in first and second gear.

The planetary gear noise is typically louder in first gear as compared to second.

Recommendation/Instructions

This planetary gear whine noise can be characteristic of the 4L80E/4L85E.

The vehicle should be compared to an identically built vehicle (same GVWR) for comparison before attempting any repairs.

If it is determined that a vehicle has an abnormal amount of noise and the transmission was built after 9-01-03, perform the Rear Unit End Play Check (SI Document ID # 52027).

The correct end play is between 0.127-0.508 mm (0.005-0.020 in).

If end play is out of specification, inspect and replace the output planetary gear set (661 - Output Carrier Assembly and 650 - Sun Gear) as necessary.

Set rear end play between .005" - .020" using correct selective thrust washer (674). Target between .010"-.015".

If end play is within specification, replace the transmission assembly. Refer to bulletin 02-07-30-029A before ordering the transmission assembly.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

03sierraslt

iTrader: (22)

I’ve never ran one that made noise, but the ones I’ve been in were built, not stock.

Would someone like to explain how torque management is changing planetary whine?

smokeshow

iTrader: (16)

Disabling torque management won't change the whine. Torque is only reduced or 'managed' during shifts. That's why they detune engines (not rely on transmission to request steady state torque reduction) in front of weaker transmissions, which is the case with the Duramax in front of the 4L85e in vans.