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3.42 gears

20K views 29 replies 19 participants last post by  Jason m 
#1 ·
Found a great deal for an 07 ext cab 4x4 1500 5.3. Only problem is it has GU6 code, which is 3.42 gears. I've been looking for 3.73s because I live in the Mountains (little mountains:). Anybody have them? What do you think of them? What rpms' are you turning at 70 mph? Does it shift in an out of OD alot when you're in the 50-60 mph range?
Thanks, Gabriel
 
#2 ·
Should do fine unless you tow/haul a lot.
 
#3 ·
The dealer here orders all new trucks with 3.42 with V-8, other dealer orders 3.08 with V-8 engine. Mine shows over 9500 lbs towing with the package I have. I run 285 75r tires also. No problems nor no problems with my 07 NBS crew 4x4 with 3.08 4.8 V-8. We don't live in the mountains, but go up into some every once in a while. Mine have all had the hd trailering package too. Hook it up and pull with it and see if you like it.
 
#4 ·
Another +1 for the 3.42 gears. Perfect combination. Remember, the new trucks have a 6 speed tranny, which changes the ratios enought to make the 3.42 a very strong towing truck.
 
#5 ·
Ok fellas, now I need some numbers. I test drove two trucks today, both 04s. One had 4.10s (GT5) and hit 2k rpms at about 63 mph. The other had 3.73s (GT4) and hit 2k rpms at about 71. My 01 Tahoe also has 3.73s.
What rpms are you guys with 3.42s running at 70 mph? Or what mph do you hit 2k rpms at?
Seems like it must be 78-ish mph at 2k, which would put the rpms way down by 1,200-1,300 at 55-60 mph. Seems really low.
Talked to a guy with an 06-ish Z71 with (he thought) 3.42s. He regularly gets 18-19 mpg around here, and has gotten more based on his computer readout. Stock truck. Impressive. Now I need to verify his gear ratio...
Oh, and all this is for an 02-07 truck. Regular old 4 speed auto, I wish I was in the market for a 6 speed, but not yet.

Thanks
 
#6 ·
Cruising @ 70mph engine is @ about 1900 - 2000rpm and @ 60mph engine is @ 1850rpm. I drive in hilly areas and rarely feel it shift out of Od. All around it is pretty good combo
 
#7 ·
You all probably already know this but when comparing speed and RPMs you have to take into account the tire size, are they the same or different. Even a little change in size will change the other. Also, when I bought my O7 I remember all to the ext. cabs having the 3.43 gears...was it standard?
 
#8 ·
05 Z71 with 3.42 and 265/70/17 tires. At 70 I'm around 1800. I think it takes 75 or above to hit 2k. 55-60 is 15-1600 if I remember right. There is math to figure all this. I'll see if I can get it.

With a decent hill, my truck torque converter will unlock, on a pretty steep hill, like going through the Ozarks last summer it would kick down to 3rd to hold cruising speed.

Found some calculators. My #'s are pretty close here. http://www.ringpinion.com/Calc_RPM.aspx
 
#9 ·
Up to dealers to order what package, gears, engine or combo they like. Guess every dealer is different to what they sell. Around here most trucks are loaded you would have to have a WT version brought in from another dealer as these don't seem to order any.
 
#10 ·
Again, I'm talking about 4 speed auto trucks, 02-07. You fellas with 6 speed autos are going to have completely different numbers.
And yes, tire size makes all the difference in the world. You can compensate for 4.10s by putting on larger tires, but then you have more wind drag and rolling resistance.
 
#11 ·
I have a 2011 1500 crew cab with 3.42 gears with 5.3L. SO far I have had no issues with shifting in and out excessively but I have heard of that complaint in other forums; I have the 6 speed transmission. I have been trying to stay at 65 mph to see if I can achieve the 17 mpg's as advertised (so far I have not been able to) but I am turning 1700 rpm at 65. Good luck!
 
#15 ·
I am at about 1950 at 70mph and have the 5.3 4sp with 3.42 gears. Being new with the truck I was concerned that the converter was not locking. I do not see any change in rpm when cruising to indicate lockup or "overdrive" as some refer to it. Not to hijack but what are we supposed to see. Is there a way to check?
 
#16 ·
I have 3.42's and a 4.8 with the 4L60E and last summer I drove to KC Missouri when I still had my stock tires. It would downshift going up almost every hill. Got so irritating (mainly because of my Flowmaster and the drone in the cab) I turned off the CC and I got into a rhythm of gaining some extra speed going down the hills so I would have enough momentum to get back up without downshifting. I would definitely regear if I lived in a hilly area..
 
#17 ·
:lol: Just realized this thread is 2 years old...
 
#18 ·
Glad to have it resurrected...
I bought an 06 with the 5.3 HO and 3.42s. I've had it almost 2 years now. Having had a 96 with 3.73s and an 02 with 3.73s, I don't care for the 3.42s. They bug me every time I drive it. I still love the truck, but the 5.3 doesn't have excess torque around 1,500 rpms, which is where you hit 55-65 mph, so it seems like poor engineering on GM's part. I'm sure they did it to achieve mpg ratings, but that's all flat-track stuff. I live in the hills (Blue Ridge Mtns) and I rarely drive over a mile without coming out of overdrive.
Seems like that's gonna wear out the tranny quicker than a lower gear would as well. And towing, man I wouldn't want to tow much with this setup. I've pulled about 800 lb and I could feel it. Shoot, I put 500-1,00 lbs in the bed fairly often, and I can feel THAT. That WITH a Blackbear tune.
If re-gearing weren't $1,400 (got a quote from a shop), I'd put 4.10s in it. 4.10s with 285s would put me back at 3.73s overall. I love these trucks, but 3.42s for anything but highway is a bad idea.
With stock tires I average 17.5 mpgs, hand-calculated (Truck computer LIES!) and averaged over 15 months (12/11=2/13, so more winter gas in there than if I did a 2 year average). I got that out of my 96, and my 02.

By the way, ZEEGMC4ME, your rpms sound like you have 3.73s. Check your glove box codes. 4.10s = 2k rpm @ 62-ish, 3.73s = 2k rpm @ 70-ish, and 3.42s = 2k rpm @ 78-ish.
 
#21 ·
I had an 05 Avy with 4.10's that ran like a raped ape truck would jump every time you punched the throttle. Only bad part was the MPG's, running 70-75 the truck would turn about 2300 rpms, average MPG was 16-17. There is always a trade off either HP and pep or MPG. Had a 2010 with 3.08's got really good MPG's but even on small hills it was constantly shifting.
 
#23 ·
I don't know why everyone is complaining about the 3.42s haha... I had to pull my boss's covered trailer because his Ford went for a dump and it pulled fine! I have a 2012 Silverado 1500 CCSB 4.8 with 3.42 gears and it pulled 4000lbs just fine
 
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