What Rear End?

[phildaug]

Looking around at the info and it seem the 5.3 has some nice advantages for fuel economy. How much impact will the gear play here? I a vacume the 4.10 would seem to get worse than the 3.73 but this is not always the case.

 

Any info?

[superbee]

Depends on where you drive, here in the hills/mtns of western Pa, 4.10s are great (think of it as towing all of the time).

[gmcjoe]

Generally, the 3.73 is a great all around gear including minor towing.

 

not a huge diff in MPG between that and the 4.10, it depends on how you use your truck

[Dans Denali]

4:10s suck! My 2002 SD gets 2mpg less than my wifes 2003 YD and weighs #500 less! The only difference is the gear ratio, with the 4:10s the rpm is up around 2200 on the freeway in the pickup and this seems th really hurt economy. When towing a light trailer either is fine but for a really heavy load I like the 3:73s because I can tow in drive instead of OD and have a more reasonable rpm, 65mph in drive with 4:10s is too much rpm. The transmission runs much cooler in drive with a heavy load than it does in OD.

 

Dan

[mmmikkke]

If you're going to put 285's on the truck, then the 4.10 starts to make some sense.

[flatlander]

Wish I had the 3.73 instead of the 4.10's. There seems to be about 200rpm difference between the two at 70mph. You can search the internet for gear ratios and find a calculator, I found one at www.4lo.com/4localc.htm

 

Tire size makes a difference, for example there is a 52rpm difference between the 265/75x17 and 265/70x17 tires. At 70mph with my 4.10's and 265/70x17 tires the rpm at 70mph is real close to 2200 according to the tach.

Looking around at the info and it seem the 5.3 has some nice advantages for fuel economy.  How much impact will the gear play here?  I a vacume the 4.10 would seem to get worse than the 3.73 but this is not always the case.

 

Any info?

 

<{POST_SNAPBACK}>

 

 

[OFF-RD]

I've had everything from 3.42s (now) to 4.11s in trucks...and I can tell you that my experience is the 3.42s are definitely better. The gas mileage you save with 3.42s is awesome, and 4.11s just aren't worth it unless you are towing and hauling every single day with your truck. So my vote is...the numerically lower, the better with gears.

[ZZebes]

Numerically lower is nice but i have 3.23's and that is to freakin low

[camshaft]

3.42's are completely useless in a truck IMO. Not many people ever change their gear ratio's from a 4.10 to a lower gear, but there is always someone wishing the truck had 4.10's.

 

Dans Denali: "4.10's suck. 65mph in drive with 4:10s is too much rpm"

 

What???. Too much rpm at 65mph....if thats the case, u must have 12 inch tires on ur truck.

 

As for mileage, my 05 crew 4x4 is getting 18mpg in the city during summer, and at least 21 unloaded on the highway w/ 4.10's. Throw any decent size trailer behind that w/o 4.10's and u will soon start to hate life.

 

If u never pull anything then 3.73's are likely a good gear choice, but believe me, the difference in gas mileage over the useability of the truck w/ 4.10's will never be noticed. Plus when it comes time to sell, it will be easier to sell a tuck w/ 4.10's compared to any other gear choice.

[C & A s Dad]

I bought a 02 Yukon XL with 4.10s and almost did not buy it due the the gears. I thought I wanted 3.73's. I bought the truck with the inetention of changing the gears to 3.73s and even had discussed this with my dealer. But after towing my 6,500lb camper with it, I would not change to 3.73s or any other gear even if someone offered me a new rear end free. I love the 4.10s. I am getting an avg of 18.7MPG (not towing) (12 MPG towing) and can get over 20 MPG if my driving is hwy only. When towing I like to run about 55 to 60 for safety reasons and do this in 3rd gear and not OD. The Revs run about 2400 at 55 which is right in the 5.3's sweet spot. It pulls like a tank as long I keep the revs above 2200 and I do not have to worry about the hills.

 

If I was not towing at all or only towing 2,000 to 3,000 lbs and the trailer did not have a lot of wind drag, then 3.73's would be my choice. However, if you plan to tow a load similiar to mine, you will like the 4.10s.

 

As stated by many already, it depends a lot on what you plan to use your truck for and the geography where you will be driving.

[Frank Sub]

Hi Dans Denali--I have a 2001 1/2 ton Suburban 5.3 ltr with a 4.10 rear, which I use to tow a 6400 lb Airstream. With or without the A/S, at 65mph I run 3000 rpm in 3rd gear, and 2000 rpm in 4th gear. I don't think that's too fast, but rather just right, as I'm in the sweet spot of the torque curve, particularly in 3rd gear, which is where I tow.--Frank Sub

[Frank Sub]

Hi C & A s Dad--I see you have Air Lift Air Springs on your Yukon XL. Why did you get them, and how do you like them?--Frank Sub

[C & A s Dad]

Frank, the Airlifts may have been the best $75.00 that I have spent on my Yuk. The fit inside the coils and I run them at 10 to 12 PSI when not towing and you never know they are there. When towing, I run them at 25 PSI and they make a world of difference in the stabliltiy without making the ride too harsh.

 

I bought them from Southwest Trailer which I believe is in TX. I otdered them at the same time I bought the Putnam XDR and they were having a sale which made them about $75.00.

 

If you are towing anything of any significance with your Suburban, you will like the Airlifts.

 

If you do buy them, PM me so I can offer a pointer or two that can reduce your install time and frustration. It was not difficult once I figured it out.

[pwall]

Do they affect the auto-levelling on the YukonXL ?

[C & A s Dad]

Patrcik, my Yuk is not equipped with AutoRide so I am not real sure how the two would mesh. I do not think there would be any issue at all since Airlift's instructions tell you to air them up to 35PSI before hitching your load and then let them down to the desired PSI, which in my case is 20 to 25 PSI. However, I would think the AutoRide would do almost the same thing on a truck equiped with it.

 

Hey, I like the chrome handles on your truck. Where did you find just the handle cover and not the entire chome sheild kit?