[04crewcabz71]

My truck is pretty much babied. It has all synthetics and fluid changes, and all plugs, wires, and belts, hoses, maintenance has been addressed with ac delco parts. It's a 2004 CC Z71 and it has the GT4 axle (3.73's), a k&n cai, and a flow master exhaust. I then purchased a Black Bear tradional tune. I recently added a six inch lift, and 33X12.5 inch Toyo MT's on 20X12 Moto Metal 962's and going to work, I encounter a slight grade on the roadway and it downshifts to third gear more frequently than it used to compared to no lift and tires. I know that the tires, lift (drag), and wheels all create more weight and rotating weight, but I never turn on the tow haul mode (performance) mode while going uphill because I don't want to overwork the transmission. Granted the transmission works fine and all. Do any of you drive with the tow haul mode on frequently, or going up grades, or off a start at the stoplight? I don't have the funds to get gears yet, but I know it's the stock gearing that's causing the transmission to downshift. The corvette servo helps though.

 

[NuckenFuts]

Only time I use it is when Im racing as shift points are higher and TQ management is 100% removed. Its also set up for all out performance drag class. If your asking if you will hurt anything using it I would think it all depends how its set up. If its set up for a performance class other then TOW class then you might not want to drive it all the time as shift points might be different ect. I guess try it and your right foot will determine how hard its on your tranny. Maybe it will be better for your situation.

You need gears as you said and don't think there is a band aid fix for your issue.

 

[04crewcabz71]

Thanks Jim. I think I will use it just for going up a the slight incline on my way to work. I used to use it to blow the doors off many cars and trucks off the line or for passing. BlackBear performance is the best bolt on performance I ever felt and experienced.

 

[bighead38]

I know the majority will say otherwise but gears aren't neccesary when you have 3.73's and 33's. Yes I know it would help but it's not a necessity for your situation IMO.

In before the gmfs gear lovers come in saying you need 4.56 or 4.88 gear ratios installed.

 

[darnie1987]

33's with 4.11-4.30 gears would put you at or just alittle better than 3.73's with stock tires.

 

[00silvyON]

Only time I use it is when Im racing as shift points are higher and TQ management is 100% removed. Its also set up for all out performance drag class. If your asking if you will hurt anything using it I would think it all depends how its set up. If its set up for a performance class other then TOW class then you might not want to drive it all the time as shift points might be different ect. I guess try it and your right foot will determine how hard its on your tranny. Maybe it will be better for your situation.

You need gears as you said and don't think there is a band aid fix for your issue.

TQ management is 100% removed when in tow/haul, even from factory? Or you had a tune to achieve this?

 

[04crewcabz71]

I think with my traditional tune, I have 75% percent removed and elected for firm shiftness.

 

[04crewcabz71]

Driving around on flat roads, it feels fine and even on highway and passing with the 3.73's. I think optimally, 4.30's would be perfect overall. I wish tax return was sooner.

 

[NuckenFuts]

TQ management is 100% removed when in tow/haul, even from factory? Or you had a tune to achieve this?

Was tuned that way from black bear.

 

[IMI4tth3w]

33's with 4.11-4.30 gears would put you at or just alittle better than 3.73's with stock tires.

just fyi, the 20x12's and 33 1250 20's are a bit larger and heavier than most 33" tall tires.

also, the 305 55 20 trail grappler is a bit heavier than the toyo 33 1250 20 (76lbs vs 72lbs). also the nittos run slightly larger. not really relevant but just stating some facts.

IMO i'd say 4.30 is a perfect gear for 20x12's and 33's with the 5.3 4l60e combo in there. 4.56 if you want a bit more pep off the line and don't do too much highway driving. 4.10 if your on the highway at lot and want a good cruising rpm. but going form 3.73 to 4.10 really isn't worth that much so i'd say at least 4.30.

wish i could speak from experience. still waiting on funds to upgrade my 3.73's to 4.30's on the tahoe (20x12 moto metals 305 55 20 trail graps 5.3 4l60e)

 

[04crewcabz71]

Thanks Matt for the great information. I totally agree with 4.30's. I had 4.56's on my Gmt 400 with a 33x12.5 and 15x10 welds and a 6 inch lift and doing 55-60 on the freeway made it feel like it was running to high of engine rpms. Going with a 4.30 for sure and a true trac possibly in the back.