09- GM trans, not Allison

[seasonedsole]

Our 09 W-16 with the 8.1 has the GM transmission. Is it any good? Does the Overdrive switch on the dash do anything, or is it for applications with the larger W series?

[DriVer]

Quote:

Originally Posted by seasonedsole Our 09 W-16 with the 8.1 has the GM transmission. Is it any good?

The 4L85e transmission is a very good unit and you should not have any trouble with it.

Quote:

Does the Overdrive switch on the dash do anything, or is it for applications with the larger W series?

I'm sure that one of the 4L85e owners here will reply to that question shortly.

[KJINTF]

I too have an '09 W/16 with the 8.1L and GM 4L85E transmission
It's been good to us we now have about 10,000 miles on it
Just today picked up a new filter for the tranny
Looks like the same as the 4L80e tranny filter
Plan to change it real soon

As Driver says it's a good transmission

I do not have the dash mounted overdrive switch you mentioned so can not say what it does

Looking forward to hearing from others with more experience about the tranny

[seasonedsole]

After checking the overdrive switch, there were no wires attached. Thanks for the replies. Happy trails.

[DriVer]

From My Blog:

During the course of the day I wanted to stop by real quick and see what was going on at the GM exhibit. I spoke with one of the gentlemen from the commercial side of the business just to find out what was new at GM. The cut away van chassis for use on Class C motorhomes is still alive and well and has a GVW of 14,200 pounds however plans are in the works to lengthen the wheelbase and increase the GVW at that time. I also found out that the Class Cs van cutaway chassis are equipped with 6-Speed Hydra-Matic automatic transmissions. The reason for the use of a Hydro-Matic is because GM could not fit an Allison on the cut away chassis without redesigning the floor pan. A CNG and LP option for some commercial applications was discussed which would affect the commercial side more than the RV side of the business.

I expect that when the W16-W18s come back to the market that they will be using a 6-Speed GM Hydra-Matic transmission.

More about that:

• Second-generation longitudinal (Rear Wheel drive)
• 2006– 6L80/6L90 — 6-speed heavy-duty (used in GM trucks and performance cars)

The 6L80 (and similar 6L90) is a 6-speed automatic transmission built by General Motors at their Willow Run Transmission plant, in Ypsilanti, MI. It was introduced in late 2005, and is very similar in design to the smaller 6L45/6L50, produced at GM Powertrain in Strasbourg, France. It features clutch to clutch shifting, eliminating the one-way clutches used on older transmission designs. In February 2006, GM announced that they would invest $500 million to expand the Toledo Transmission plant in Toledo, Ohio to produce the 6L80 in 2008. (From Wikepediia)

[pkmesser]

Seasonedsole, I put about 90,000 miles on an 08 Silverado HD before I retired, it had the GM 6 speed, the transmission performed extremely well. That 90,000 miles included probably 20,000 in 4WD, and probably half of that in low range. (I would wear the markings off the 4WD shift buttons way before the seat showed any wear). So even though it was in a pickup, it was tough service. I would bet you have a paddleswitch on your shift lever, for making manual shifts, if so, that OD switch on the dash is a leftover from a previouse generations nightmare, In this case, the new generation. is definately better!
If this is what you have, forget about any of the mods discussed here, you have the best solution already! BE HAPPY.

[seasonedsole]

Quote:

Originally Posted by pkmesser Seasonedsole, I put about 90,000 miles on an 08 Silverado HD before I retired, it had the GM 6 speed, the transmission performed extremely well. That 90,000 miles included probably 20,000 in 4WD, and probably half of that in low range. (I would wear the markings off the 4WD shift buttons way before the seat showed any wear). So even though it was in a pickup, it was tough service. I would bet you have a paddleswitch on your shift lever, for making manual shifts, if so, that OD switch on the dash is a leftover from a previouse generations nightmare, In this case, the new generation. is definately better! If this is what you have, forget about any of the mods discussed here, you have the best solution already! BE HAPPY.

The GM transmission in my W16 is a 4 speed. No paddle shift or tow-haul mode.