View Full Version : Change Diff Gears
corvettemick
03-11-2007, 11:10 AM
Has anyone looked into or changed the rear end gears? Something like 3.43s, there seems to be enough low end torque to handle the change with minimal impact and it could affect gas mileage enough to pay for the change after 10,000 miles.
TIA,
Mick
85vette
03-11-2007, 11:35 AM
What do you have now?
TrailBlazer LS
03-11-2007, 11:36 AM
All SS's have 4.10's.
Mark.
trailblazingold
03-11-2007, 11:46 AM
I'm pretty sure they come with 3.42's and the 4.10's are an option.
85vette
03-11-2007, 11:46 AM
Sorry, I failed to recognize he had an SS. (blame it on daylight savings) I'm sure you could improve mileage by maybe 4 mpg by doing this. But are you willing to give up the performance? A rear gear change could cost upwards of $600.00 unless you are capable of doing it yourself, and if you are disatisfied with it......
TrailBlazer LS
03-11-2007, 11:58 AM
I'm pretty sure they come with 3.42's and the 4.10's are an option.
They come stock with 4.10's. There are no options for gearing for the SS's.
Mark.
corvettemick
03-11-2007, 01:21 PM
What do you have now?
Mine has the 4.10s, I'm curious if anyones done it and how much bottom end performance they lost. My Vette has 3.43s and still plenty of bottom end, but it's also a 6 speed and I don't know how much that affects it. I would think with the torque multiplication of the converter it wouldn't be that bad. I'm just hoping someone else has blazed this trail first.
Thanks,
Mick
85vette
03-11-2007, 01:57 PM
Your Vette also weighs about 1K lbs less than a TB.....Big difference.
pcoxe
03-11-2007, 04:36 PM
My TBSS with 4:10 gears turns less than 2000 rpm at 60 mph. My Z28 Camaro with 3:73 gears is turning over 2250 rpm at 60mph. It's not just in the gears, tire size has a major impact also (20" wheels vs 15" wheels). 4:10 is probably the optimum gearing for this vehicle with regards to both economy and performance. If you want to give up a lot of performance to gain a little more fuel economy, why not just get the 6 cylinder engine in the first place? Something else to consider, the LS2 has a longer duration cam which may not operate as efficiently at lower rpms. You might actually lose fuel economy by going to a lower ratio gear. My engine doesn't start making any significant power until it gets over 3000 rpm. All in all, I think the current factory gearing is the best balance of economy and performance.
Patrick
85vette
03-11-2007, 05:14 PM
Get with the folks at pcm4less and see if a tune would help you out, they can probably get you a couple miles per gallon AND boost your performance....If you can keep your foot out of it!
ScarabEpic22
03-11-2007, 05:43 PM
I'm pretty sure they come with 3.42's and the 4.10's are an option.
They come stock with 4.10's. There are no options for gearing for the SS's.
Mark.
Exactly, the 3.42 option on the GM website last year was a programming fluke, you cant order an SS with anything but 4.10s and a G86 LSD.
And, yes, the 4.10s were chosen because they can get the heavy SS off the line much better that the other options GM has used on the GMT360 (3.42, 3.73s). So it doesnt get the best mileage, what do you expect from a 4600lbs truck with a LS2 in it? The 16-18mpg on the hwy is pretty good looking to me, plus a tune gives you about 1-2 more easily, especially on the hwy if you set cruise.
corvettemick
03-11-2007, 07:01 PM
Exactly, the 3.42 option on the GM website last year was a programming fluke, you cant order an SS with anything but 4.10s and a G86 LSD.
And, yes, the 4.10s were chosen because they can get the heavy SS off the line much better that the other options GM has used on the GMT360 (3.42, 3.73s). So it doesnt get the best mileage, what do you expect from a 4600lbs truck with a LS2 in it? The 16-18mpg on the hwy is pretty good looking to me, plus a tune gives you about 1-2 more easily, especially on the hwy if you set cruise.
I knew it wasn't an economy car when I bought it. And since it's still new to me I'm having a hard time staying out of the gas. Is a 1 to 2 mpg increase real with just a tune?
TAI,
Mick
ScarabEpic22
03-11-2007, 07:14 PM
I knew it wasn't an economy car when I bought it. And since it's still new to me I'm having a hard time staying out of the gas. Is a 1 to 2 mpg increase real with just a tune?
TAI,
Mick
Yes, it is real with a tune, as long as you drive it like you do now. If you go from babying it now to romping on it a lot with a tune (I know I sure did), then it wont change at all or maybe go down.
If you can drive it the same way, then yes you will get better mileage.
corvettemick
03-12-2007, 08:38 PM
OK, thanks for the info. Here's a newbie question; are all mail order tunes equal, or is there one tha stands out?
TIA,
Mick
85vette
03-12-2007, 09:11 PM
I don't have one in my TB yet, but from what I have observed, pcm4less offers great customer service and I have not heard any complaints from people that have theirs installed. I'm sure others will confirm this. When I do get one, it will be from them. Search tunes and draw your own opinion though.
ScarabEpic22
03-12-2007, 09:26 PM
OK, thanks for the info. Here's a newbie question; are all mail order tunes equal, or is there one tha stands out?
TIA,
Mick
Well, first I would look to see if there is a tuner pretty local to you. I know PCM4Less is near you, but I have no idea how close Bryan or Alvin/Kelly are to you. Also, TuneTime Performance is in NJ.
If you cant find a local tuner either, then its tough to say as each vendor on here is AWESOME and delivers top notch results. Check out the vendors websites and check to see what packages they offer and the individual services, etc. Each and every one will make you happy with your ride, it kinda comes down to individual choice. TuneTime Performance uses tunes by Lyndon Wester, Vector and ADM both do in house tuning.