Rear End Gears- Discuss

[Dr Jkel]

I have been looking into a few things about the drive train, specifically rear end gearing lately. I did a search and found a few things on this subject but was wanting to kind of get a thread with all the inforamtion in one area.

What do 4.10/4.11 gears really do for your car? Or far that matter what does any gear change do for your car?

Does having a bigger cam in your car make any difference in the gears you select?

Does increasing or decreasing the gear ratio in the rear end add added stress on the rear end resulting in other additions? Basically if you add gears should you change other things when you do this?


Does a gear change affect drivability, fuel mileage, longevity etc.....



I have seen a few threads about problems with gear swaps and a variety of opinion for the failures, so when doing a gear swap what should be looked at when doing this, what should you be aware of when considering this mod...i.e. Pro's and Con's


Vendors, Experts, all general opinions welcomed. Do not really want this to turn into Vendor A is better than Vendor B type or Product A is better than Product B.

[v6sonoma]

Originally Posted by Dr Jkel

I have been looking into a few things about the drive train, specifically rear end gearing lately. I did a search and found a few things on this subject but was wanting to kind of get a thread with all the inforamtion in one area.

What do 4.10/4.11 gears really do for your car? Or far that matter what does any gear change do for your car?

They increase the mechanical advantage so basically the engine rev's more to move the car less but since it's easier to do, it moves quick. Think changing gears on a 10 speed except that your engine can pedal faster.

Does having a bigger cam in your car make any difference in the gears you select?

Possibly. Depending on the cam you choose and you purposes it will move the power band. If you have a cam that brings it in the top end you'll run out of gear when the powers coming on. On the lower end with large amounts of power (HP) you'll roast the tires without trying and have no grip.


Does increasing or decreasing the gear ratio in the rear end add added stress on the rear end resulting in other additions? Basically if you add gears should you change other things when you do this?

Since switching to a lower gear ratio INCREASES the amount of power that is applied to the wheels then yes. Beefing things up does help, but mostly if it's a manual just make sure you don't abuse it.

Does a gear change affect drivability, fuel mileage, longevity etc.....

If set up correctly longevity shouldn't be much of a problem. Fuel mileage will be affected since it takes more rev's to move the same distance, however depending on your habits since you can drive in a taller gear some have seen improvements. Highway mileage will definitely take a small hit. Some gear noise might be heard.


I have seen a few threads about problems with gear swaps and a variety of opinion for the failures, so when doing a gear swap what should be looked at when doing this, what should you be aware of when considering this mod...i.e. Pro's and Con's

It's best to think what you want to get to in the end. If it's a 1000hp screamer 4.10's might be a bad idea. Make sure you take it to a place that has done it before and had good results. JRE has done quite a few as well as some other good shops on here. LPE offers a 3.91 gear that while pricey seems to be beefier than the 4.10's out there while offering similar gains.


Vendors, Experts, all general opinions welcomed. Do not really want this to turn into Vendor A is better than Vendor B type or Product A is better than Product B.

Also be aware that any gear change will require a tune.

Hope this helps.

(also if anyone else has something to add or finds me to be inaccurate feel free to correct/add)

[Dr Jkel]

I appreciate it......My cam is a stage II and I absolutely love it. It seems to come alive around 2500 to 2800 rpms, especially when you mash it. The issue is when not mashing it and putting around it seems that it feels sluggish at real low rpms so you have to rev it up.

I was told by lowering the gear that it would help on take offs and just crusing around type stuff in town and with the tall 6th gear that it would not affect fuel, drivability etc...too much.

[pensphan87]

So if I want a quicker car (faster 0-60 and 0-100) what gears would you choose?
Looking at 2012 2SS VERT

[steeleshark2]

For the SS an A6 go with 3.73s. For a M6 go with 3.91-4.11. These gears make a big difference with a cam. No sluggishness at all from stop to wherever you let off. Even everyday driving becomes a lot easier with gears. With my cam and gears, the PZeros sometimes start breaking loose before shifting into 2nd gear. Here is a video I made a while ago.

[v6sonoma]

Originally Posted by Dr Jkel

I appreciate it......My cam is a stage II and I absolutely love it. It seems to come alive around 2500 to 2800 rpms, especially when you mash it. The issue is when not mashing it and putting around it seems that it feels sluggish at real low rpms so you have to rev it up.

I was told by lowering the gear that it would help on take offs and just crusing around type stuff in town and with the tall 6th gear that it would not affect fuel, drivability etc...too much.

Correct. Your cam probably gives up some low end power to get more high rpm power so switching to a lower gear in the rear will give it some help off the line.

Originally Posted by pensphan87

So if I want a quicker car (faster 0-60 and 0-100) what gears would you choose?
Looking at 2012 2SS VERT

I would go with 3.73's for an auto or the LPE 3.91's or 4.10's if they are to costly for a stick.

[B-Rex]

now if you get a cam that has a ton of high end power, but you still use 4.11/3.91 on a M6, are you going to be wasting power from the cam because the gears are so steep?

[v6sonoma]

Originally Posted by B-Rex

now if you get a cam that has a ton of high end power, but you still use 4.11/3.91 on a M6, are you going to be wasting power from the cam because the gears are so steep?

No you'll just have to change gears sooner which if drag racing might add another shift to your 1/4 mile run and might hurt you time, but it all depends on your individual goals.

[B-Rex]

1/4 mile time would be my end goals, but i was just wondering in general. a 3>4 shift is pretty easy to do, and 4.11/3.91s would hopefully make up for it (and then some) in the 60'.

this is my train of thought anyways, i don't know because i haven't done it yet

[SSE 4 2SS]

There is a science to selecting gears for your car... And there are calculators to help you with the process...

There are lots of people that select a gear that sounds like a race gear... 4.10, 4.11, 3.93's etc... But, this is a WAG at best... ( wild ass guess )

Proper gear selection involves the specific hp/Tq range and goals for the car...

For the quarter mile, you want to select a gear that has you trapping at the peK of your power band in the given gear. With the six speed transmissions, is usually equates to third or fourth gear...

my Camaro when stock was crossing the finish line red lining in 3rd or I had just shifted to 4th... now I'm going into 4th at the 1/8th mile, same speed as I used to trap at the quarter...

What this translates to is, 4.11s would be stupid crazy for me... I would be in fifth gear in the quarter... No thanks....fewer shifts for me...

I am going with 3.07 gears when I upgrade to a nine inch differential... The calculators say this will allow me to go 219 mph in 5th gear... For the standing mile runs, and I should be close to topping 4th gear in the 1/4 mile... so, I'm in strong areas of the power band for the entire runs...

Finding the gear you need involves either a calculator, or some seat time at the track... Make some passes and determine where you are at the end of the pass... GM got it about perfect on the stock LS-3... redlining third...at the quarter.. Next make a choice if you have the power to run out of 4th in the quarter,,,,then a taller gear may be in order... But don't go too far or you end up in 5th in the quarter...

any power adders will put you into 4th in the quarter, so gear appropriate to redline or close to it, or go with a taller gear and try to keep it in 3rd....

4th gear can be a long pull if underpowered...

I've been to 5800 - 6000 rpm or thereabouts in 4th gear in the quarter, and this was with a very easy launch... 2.55 60 ft... On purpose... Car was at 131 mph... With a hard launch and shifting sooner, I'll run out of 4th gear so I'm going with a taller gear set... More importantly, I plan on going over 200 in the mile and I don't want to go into 6th trying to do so....

[steeleshark2]

Yeah, with the 4.11s 4th will get you into the 120s mph range. Thats why I recommend 3.73 or stay stock if you are going supercharged for an LS3. Why go less then stock? 3.45 gives you a 161mph 4th gear.

[SSE 4 2SS]

Originally Posted by steeleshark2

Yeah, with the 4.11s 4th will get you into the 120s mph range. Thats why I recommend 3.73 or stay stock if you are going supercharged for an LS3. Why go less then stock? 3.45 gives you a 161mph 4th gear.

Good point, but as mentioned, my goal is to run over 200 in the standing mile...

3.45's allow me to go 196 in 5th gear or therabouts, 3.07's allow me to go 219 in 5th...

Shifting into 6th would pretty much assure no chance of hitting 200... so... My car will still pull in 6th gear rather than falling on her face, but... to break 200, I need to stay in 5th... and thats a long pull... The computer programs say my car is power limited in 6th gear at 236 as it currently sits, but it would take a long run to get there... I will go to the Texas Mile with substantially more power than I have right now...

[SSE 4 2SS]

Steeleshark2, I went and watched the video you posted above, very nice comparo...

[Dr Jkel]

Hey Robert... In my case since I do not really track my car, or race I am mainly looking to increase low end take off without sacrificing top end power.

The fasterest I have ever had my car was 132 mph on a controlled roadway, but I would never want to change a gear and run around town and it sound like I am going 300 mph because the rpms are so high.

What do you think about that? Remember I have only 463 rwhp.