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Rear-End Gear Changing Quote

fastdrvr23

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fastdrvr23 Enthusiast

fastdrvr23

Posted
Posted

Well, I went down to the local drivetrain shop on Saturday and finally got a quote for my truck to either be swapped to 4.10's or 3.73's or maybe even 3.92 (what a guy at the shop suggested). The prices were the same for all 3. Anyways, while they were in there, I told them I wanted to get some sort of streetable locker or limited slip unit. For an Eaton unit with richmond gears it was going to be $700 installed with tax, for an Auburn unit and richmond gears it was going to be $615, and for a Powertrax No-slip locker and richmond gears, it would be $575.

 

The prices didn't seem too bad to me, as the LSDs are pretty expensive on their own.

 

He said they'd have a truck in on Wednesday that was getting a Eaton LSD and that I should come by and check it out.

 

I have a sheet with all the model #'s for the different parts, but I left it at home... Doh!

 

For you guys who have swapped, does this sound ok price wise?

snoman Senior Enthusiast

snoman

Posted
Posted

Got with the eaton as it is study and fully rebuildable by end user (Auburn is not) and still a true diff as well. A power trac unit has no spider gears and it either 1 wheel drive in turns (with one wheel coasting under very light or no power) or 2 wd and they can really suck if you ever tow because they may not unlock in a turn towing if enough power is applied. Also I would go at least 4.10 to and no waste money on a 3.73. Forgetget about the gas mileage concern because OD will knock it way down when engaged and yeild a 60 MPH rpm of about 1850 with stock tires.

fastdrvr23 Enthusiast

fastdrvr23

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Got with the eaton as it is study and fully rebuildable by end user (Auburn is not) and still a true diff as well. A power trac unit has no spider gears and it either 1 wheel drive in turns (with one wheel coasting under very light or no power) or 2 wd and they can really suck if you ever tow because they may not unlock in a turn towing if enough power is applied. Also I would go at least 4.10 to and no waste money on a 3.73. Forgetget about the gas mileage concern because OD will knock it way down when engaged and yeild a 60 MPH rpm of about 1850 with stock tires.

I was wondering about that... My tires are stock sizes and will stay that way... With that in mind, how many RPM's should I be turning at ~75MPH (where I drive a whole lot commuting every day). I've tried keeping the Rpm's at ~2500 in 3rd a few times on the highway, and my gas mileage doesn't seem to get any worse, although I do romp on it more that way as it is quicker to respond without downshifting and all. hahaha

 

I don't really tow that much, maybe two or three times a year, and mainly just 2 atv's or my motorcycle on a small 5X10.. so that isn't really a concern. I mainly want stronger acceleration, and the insurance to tow more if I decide to.

 

4.8L, 3.42 and 4L60E for the drivetrain now.

 

With the 4.10, would it hurt anything to tow in OD? 3rd would probably limit me to 60MPH at 3000 RPM's, hahaha.

snoman Senior Enthusiast

snoman

Posted
Posted

3rd should do about 2600 at 60mph with 4.10's. I would have no resevations at all about towing a heavy load at 3000 to 3300 all day if need be. It will not hurt a thing. I would not tow in OD with 4.10's as RPM would be kinda low for towing (maybe a trailer less than 2000lbs) and load tranny a lot too. As you have discovered, lower RPM do not always mean better MPG in a big heavy vehical. Somethin you "might" consider but I am not pushing is installing a 4.56 as that would give you about 2100 RPM at 60 in OD and make it more usable towing too. Remember that 4.8 is a good engine but it does make its best power above 3000 RPM and the closer you are to it at your normal cruise speed, the better the truck will run and when a engine is in or near its "sweet spot" it will use less gas per HP hour produced.

fastdrvr23 Enthusiast

fastdrvr23

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3rd should do about 2600 at 60mph with 4.10's. I would have no resevations at all about towing a heavy load at 3000 to 3300 all day if need be. It will not hurt a thing. I would not tow in OD with 4.10's as RPM would be kinda low for towing (maybe a trailer less than 2000lbs) and load tranny a lot too. As you have discovered, lower RPM do not always mean better MPG in a big heavy vehical. Somethin you "might" consider but I am not pushing is installing a 4.56 as that would give you about 2100 RPM at 60 in OD and make it more usable towing too. Remember that 4.8 is a good engine but it does make its best power above 3000 RPM and the closer you are to it at your normal cruise speed, the better the truck will run and when a engine is in or near its "sweet spot" it will use less gas per HP hour produced.

Thanks man!

 

I'll go by tonight and see about when the shop can get around to me...

03Bowtie Enthusiast

03Bowtie

Posted
Posted

Snoman, I know we've been round and round with this gear thing, but I have to ask this. Who drives on the highway at 60mph anymore? Heck down here in FL and in most other states, the interstate speed limit is 70mph. So say if I have 4:10 gears and my highway speeds are usually around 78 to 80 mph, what kind of rpms will I be pushing w/ 4:10's?? They just seem a little too low to be doing this on the highway AND getting reasonable mpg's.

I know you can't have your cake and eat it too. (sorry guys) So let's throw this out there for everyone considering going to 4:10's. You can't expect your truck to perform at the track and get good mileage on the highway. Something's gotta give. Am I right?

snoman Senior Enthusiast

snoman

Posted
Posted
Snoman, I know we've been round and round with this gear thing, but I have to ask this. Who drives on the highway at 60mph anymore? Heck down here in FL and in most other states, the interstate speed limit is 70mph. So say if I have 4:10 gears and my highway speeds are usually around 78 to 80 mph, what kind of rpms will I be pushing w/ 4:10's?? They just seem a little too low to be doing this on the highway AND getting reasonable mpg's.

I know you can't have your cake and eat it too. (sorry guys) So let's throw this out there for everyone considering going to 4:10's. You can't expect your truck to perform at the track and get good mileage on the highway. Something's gotta give. Am I right?

Another one with a chip on the shoulders I see. 60mph is a standard that if you know math you can easily adjust from unless that is too hard to do then I can give you 55,60,65,70,75 and so on. Why be a "pill" about this? Besides, most state the limit is 65 in highways so if you cruise at 75 you are "speeding" as well as wasting a bit extra fuel too.

03Bowtie Enthusiast

03Bowtie

Posted
Posted
Snoman, I know we've been round and round with this gear thing, but I have to ask this.  Who drives on the highway at 60mph anymore?  Heck down here in FL and in most other states, the interstate speed limit is 70mph.  So say if I have 4:10 gears and my highway speeds are usually around 78 to 80 mph, what kind of rpms will I be pushing w/ 4:10's??  They just seem a little too low to be doing this on the highway AND getting reasonable mpg's. 

I know you can't have your cake and eat it too.  (sorry guys)  So let's throw this out there for everyone considering going to 4:10's.  You can't expect your truck to perform at the track and get good mileage on the highway.  Something's gotta give.  Am I right?

Another one with a chip on the shoulders I see. 60mph is a standard that if you know math you can easily adjust from unless that is too hard to do then I can give you 55,60,65,70,75 and so on. Why be a "pill" about this? Besides, most state the limit is 65 in highways so if you cruise at 75 you are "speeding" as well as wasting a bit extra fuel too.

Here's one for you.......Instead of acting like a 2-yr old and saying I'm speeding, why don't you try reading the entire post for a change and making an educated response to my post. I can do the math, I just chose not to hoping you would and seeing how you're wrong about going to 4.56 gears. I should really do a poll too while I'm at it.......Cuz who the heck drives 55-60 on the highway anymore??? NOBODY GRAMPA!!!! maybe you do, truckin those 4.56's gettin passed by schoolbusses on Sundays...... :):sigh:

snoman Senior Enthusiast

snoman

Posted
Posted
Snoman, I know we've been round and round with this gear thing, but I have to ask this.  Who drives on the highway at 60mph anymore?  Heck down here in FL and in most other states, the interstate speed limit is 70mph.  So say if I have 4:10 gears and my highway speeds are usually around 78 to 80 mph, what kind of rpms will I be pushing w/ 4:10's??  They just seem a little too low to be doing this on the highway AND getting reasonable mpg's. 

I know you can't have your cake and eat it too.  (sorry guys)  So let's throw this out there for everyone considering going to 4:10's.  You can't expect your truck to perform at the track and get good mileage on the highway.  Something's gotta give.  Am I right?

Another one with a chip on the shoulders I see. 60mph is a standard that if you know math you can easily adjust from unless that is too hard to do then I can give you 55,60,65,70,75 and so on. Why be a "pill" about this? Besides, most state the limit is 65 in highways so if you cruise at 75 you are "speeding" as well as wasting a bit extra fuel too.

Here's one for you.......Instead of acting like a 2-yr old and saying I'm speeding, why don't you try reading the entire post for a change and making an educated response to my post. I can do the math, I just chose not to hoping you would and seeing how you're wrong about going to 4.56 gears. I should really do a poll too while I'm at it.......Cuz who the heck drives 55-60 on the highway anymore??? NOBODY GRAMPA!!!! maybe you do, truckin those 4.56's gettin passed by schoolbusses on Sundays...... :):sigh:

Actually I mostly do the speed limit these days and have for years and it is not because of my "gears" either. I did not know that 2100RPM at 60 or 2400RPM at 70 was "excessive" RPM. I guess my Wife 2000 Cherokee with 4.10 and a .86 OD and a 4cy and tiny 28.5 inch tires that cruises easily at 70 at about 2900 to 3000RPM and handles hills well is doomed to blow up even though it gets about 28 MPG doing it huh.

GlennRMK Enthusiast

GlennRMK

Posted
Posted

I'm not sure what size tires come on a 2wd, but say 30" as a guess.

 

Your going to be just short of 2600 RPM @ 80 MPH in OD.

 

2750 RPM @ 60 MPH in 3rd.

 

Those kind of RPMs are not going to get you good mileage. My 5.3, with 31.7"(265s) is right at about 2200 RPM in OD @ 80 MPH.

 

Montana speed limit is 75 MPH. So I usually do 80-85 MPH. With 4.10s, I'd be at around 2450 RPM @ 80 MPH, which would hurt my mileage.

 

I got 20.1 MPG on a highway trip on my first tank of gas.

 

So far I am getting great mileage.

 

If I lived back east, were the speed limit was 65 MPH, and you usually do 70 MPH. 4.10s would be the way to go.

 

I like the 3.92 ratio. I would go for that. Or 4.10s if you don't do much high speed highway driving.

Frank S Senior Enthusiast

Frank S

Posted
Posted

Sorry to interupt in the discussion here but I once again feel it necessary to remind everyone that personal attacks are not going to fly around here.

 

Difference of opinions will fly around any time mechanical questions are being asked but please remain civil in discussions and leave it at that.If you see something that you don't agree with,give your opinion on the matter,preferably backed up with facts,and leave those who are seeking advice to draw the most sensible conclusion.The whole point of message boards is to spread knowledge but name calling kind of takes away from that aspect.

 

Thank you

fastdrvr23 Enthusiast

fastdrvr23

Posted
  • Author
Posted
Sorry to interupt in the discussion here but I once again feel it necessary to remind everyone that personal attacks are not going to fly around here.

 

Difference of opinions will fly around any time mechanical questions are being asked but please remain civil in discussions and leave it at that.If you see something that you don't agree with,give your opinion on the matter,preferably backed up with facts,and leave those who are seeking advice to draw the most sensible conclusion.The whole point of message boards is to spread knowledge but name calling kind of takes away from that aspect.

 

Thank you

Yeah, I didn't mean to get everybody all fired up. :sigh:

Chris97K1500 Enthusiast

Chris97K1500

Posted
Posted

Price doesn't sound too bad. A couple quotes I got was $700-$1000 an axle depending on what I wanted. If you are going to keep stock size tires, I'd probably go 4.10's. IF you ever think you might go up a bit on tire size, I'd go up to a 4.56's. How you drive is going to determine whether or not your mpg is going to suffer. If you do lots of stop and go traffic, the numerically higher gears will probably help mpg, but if you are constantly running around 70-75mph, it might suffer a bit. If you drive at those speeds going up and down hills, the numerically higher gears may benefit you because you won't be downshifting all the time to a lower gear. You'll actually be able to hold your speed and rpm's in OD. Whatever you do don't forget to get some sort of programmer/custom tune to get full benefit from your new gears. I should be getting my 4.56's within the next couple weeks. I've got 4.10's now, but they just won't cut it with 35's and towing a little. Good luck with whatever you decide to do. Just keep in mind, if there is any chance you may go up just a bit it size of tire, or a heavier rim/tire combo, the 4.56's would probably give you more performance vs. mpg, while 4.10 or less will give you better mpg vs. performance. Just some food for thought. :sigh: Chris

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