2011 Tahoe LT 4X4 - 3.08 gears??

[jbenoit28]

Is this a misprint or is this normal for a Tahoe to have such low gears AND a tow package? It also has factory 20" rims. The truck seems to drop two gears any time we are on a grade. Trailer is an 18' Hybrid and 4000lbs max. 3.08 gears just seem too low even with a six speed tranny. 5th and 6th are overdrives anyway. May have to look for another TV. Plan was to use this in the NC mountains, seems that if it has issues in relatively flat Florida, the mountains will be a major issue. Expected 3.55 or 3.73 rear gears with a Tow Package and especially with 20" Factory rims.

Any thoughts?

Joe

[Skip426]

You, would hope that the tow package, would give you a towing gear but , trying to meat fuel economy requirement made the factories do funny things. Should be a ratio tag on the diff. if you want to check but with the performance issues, you mention I'd say that's what you've got.

[jbenoit28]

Skip, we ran the VIN to be sure. Crazy thing to do to a truck with those gears. Looks like we will be shopping for one with the proper ratios. Thanks.

[jbenoit28]

Would you think if we could find the same truck, but with 3.73 gears it would be fine towing 4000lbs in the smokey mountains?

[SmokeyWren]

No need to trade trucks just to get a more suitable gear ratio. Buy a new ring gear and pinion set and have it installed by a local rear end shop. Randy's Ring and Pinion is a good discount source for the ring gear and pinion:
Diff Wizard

Assuming an 8.6" rear diff, they have ratios anywhere from 2.76 to 5.57, including 3.73 and 4.10 (4.11) that are good towing ratios for a V8 Tahoe. Note you have to change out both the front and rear ring gear and pinion on a 4x4. Cost probably about $1,000 total, if you can find a reliable shop that will do it for $400 plus you provide the $600 in parts. That's probably a lot less expensive than trading SUVs.

As to the 20" wheels, it depends on the "low profile" numbers. Stock or optional tires on that Tahoe were 275/55R20 with 655 tire revs/mile. That's the same revs/mile as the LT235/85R16 tires that were stock on my '99 F-250. So even though the wheel diameter is 20", the tires are the same diameter as my 16" tires way back then. So they're fine for towing.

As to the "trailer package", that means only that the vehicle has a trailer hitch receiver and wiring/plug to plug in a trailer. You have to get the "heavy duty trailering pkg" to get axle ratio and tranny cooling and bigger radiator suitable for serious towing.

[Skip426]

Originally Posted by jbenoit28

Would you think if we could find the same truck, but with 3.73 gears it would be fine towing 4000lbs in the smokey mountains?

A few posts about the , towing ability, with regard to handling , of the short wheel base Tahoe, and before you spend money on 2 gear sets, or trading for a similar unit, might be an idea to get your loaded weights.
Part of the performance issue , may be actual weight , compared to vehicle , GCWR. Posts on that as well.
JMHO. 4,000 lbs. for an 18' trailer loaded for travel seems low.

[jbenoit28]

Skip, I will have a chance to drive this combo on Saturday. It belongs to my in-laws. The unit is a Travel Star Expandable 186RD. Shows a gross weight of 4475#. They just bought it new and went straight to storage so I know there is nothing inside it. It says the overall length is 20'7". One mechanic suggested checking to see if the trailer brakes were dragging. Also the rims are 17", not 20" per the VIN decoder I used. I will check the brakes and also look at the actual tag on the rearend to see what ratio it has. I'm hoping that a few adjustments and it's fixed.

[jamesrxx951]

Originally Posted by SmokeyWren

No need to trade trucks just to get a more suitable gear ratio. Buy a new ring gear and pinion set and have it installed by a local rear end shop. Randy's Ring and Pinion is a good discount source for the ring gear and pinion:
Diff Wizard

Assuming an 8.6" rear diff, they have ratios anywhere from 2.76 to 5.57, including 3.73 and 4.10 (4.11) that are good towing ratios for a V8 Tahoe. Note you have to change out both the front and rear ring gear and pinion on a 4x4. Cost probably about $1,000 total, if you can find a reliable shop that will do it for $400 plus you provide the $600 in parts. That's probably a lot less expensive than trading SUVs.

As to the 20" wheels, it depends on the "low profile" numbers. Stock or optional tires on that Tahoe were 275/55R20 with 655 tire revs/mile. That's the same revs/mile as the LT235/85R16 tires that were stock on my '99 F-250. So even though the wheel diameter is 20", the tires are the same diameter as my 16" tires way back then. So they're fine for towing.

As to the "trailer package", that means only that the vehicle has a trailer hitch receiver and wiring/plug to plug in a trailer. You have to get the "heavy duty trailering pkg" to get axle ratio and tranny cooling and bigger radiator suitable for serious towing.

The only possible issue with changing the gears is the PCM and speedometer calibration. Due to how the vehicle was emissions certified, the gear ratio change may not be able to be programmed in through a GM dealer. An aftermarket programmer may be needed to perform that calibration change. This is a big thing with the Mustang guys that change the rear gears.

[JIMNLIN]

The 3.08 gears will work fine for that size trailer. The 3.08 with the new 6L80E is nothing like 3.08 gears with the old 4L60E.
The old 4L60 had a 3rd 1:1 direct gear with a OD gear.

I ran some numbers just for a comparo only..
The 6L80E has gear splits on both side of 4L60 trannys 1:1.

..The 6L80E with 3.08 axle ratio in 3rd gear = 3166 rpm at 60 mph/30" tires.
.................................................. . 4th gear = 2380 rpm.
.................................................. ..5th gear = 1750 rpm.
.................................................. ..6th gear = 1380 rpm.

The only other gear available is the 3.42
The 6L80E with 3.42 axle ratio in 3rd gear = 3500 rpm at 60 mph/30" tires.
.................................................. 4th gear = 2642 rpm.
.................................................. 5th gear = 1900 rpm.
.................................................. 6th gear = 1500 rpm.

And the 4L60E/4.10 axle ratio in 2nd gear = 4500 rpm same speed and tire dia;
.................................................. 3rd gear = 2755 rpm.
.................................................. 4th gear = 2000 rpm.


I see the Tahoe has a 5500 lb tow rating for the 4x4.
The 20" tires are the P275/55-20 at 31.9" diameter.
ve the P265/70-17 at 31.7". Tire diameters are a wash.

[jbenoit28]

Great information! I feel much better about it now. I will pass the info along. We will still check for any brake dragging etc. Thanks again for the info.

[jbenoit28]

I took the Tahoe and camper for a test drove and we also turned off the traction control. Totally different towing experience. Much better. Much more comfortable. No trailer brakes. Now I must assume the truck only had the tow package and not the HD tow package. I will confirm that it also has no transmission coolers. The transmission temp got up to 207° driving around town for about 25 minutes.

I think we can install a transmission cooler, and electric brake control and they will be good to go.

[TXiceman]

You also need a good weight distributing hitch with sway control.

Ken

[jbenoit28]

He already has a reese with sway. Not sure what version it is, but it works well and has the truck and trailer level.

[FamFun]

My 2011 Tahoe has the same gear ratio with the 18" tires. Had the same issues with high temps and searching for correct gear. Tried to go the gear ratio change route and was told by Chevy that the PCM couldn't be reprogrammed except for at the factory. They told me I was out of luck unless I wanted to buy new with the correct setup. Sold the TT and bought the C we now have, to solve that issue. Much better now