3.08 to 3.42? Worth it?

[dgreet77]

Ok I know this has been beat to death but I'm gonna ask again...

I found a T/a rear end locally with 3.42's with an Lsd, although I don't know what kind. I asked the guy for some more info on how good of shape the rear end was in and what not, but was just curious if the jump from 3.08 to 3.42 is worth it?

I have an Auburn in with the 3.08's so the gain of an Lsd really isn't that big of a deal to me. I know I'll run at higher rpm's and mileage on the highway will drop...but how much?

The rear does have disc brakes which would be nice, but I really don't have an issue with my drums and just replaced the shoes about 4k miles ago.

The car is a DD for now, but after I graduate college the plan is to buy a truck and retire the bird to a weekend cruiser/race car.

So will I be happy with the 3.42's after I retire the bird or should I hold out and go to something higher like 3.73's?

Sorry for beating a dead horse; but I'd like to see some new opinions.

[venom3300]

Re: 3.08 to 3.42? Worth it?

your rpms wont be all that high... you will have plenty left. i get 28 on the interstate with mine running almost 80.

if u can pick it up for cheap/do it yourself i would say go for it.... if not, just wait

[pace2006]

Re: 3.08 to 3.42? Worth it?

Definitely worth it. I went from 3.08s and an open diff to 3.42s and a limited slip. I too was concerned with highway rpms, but only noticed a very small increase. With my automatic, rpms were originally around 2100 @ 75mph, and only jumped to 2300 rpms @ 75mph with the 3.42s.

[Mark42]

Re: 3.08 to 3.42? Worth it?

I went from 3.08 to 3.73. RPM at 65 went from about 1900 to 2400. Plenty of rpm left for high speed driving if thats what you do. Nice part about the 3.73 is how well the car responds to throttle because it's always at a rpm where horse power is available.

3.42 is going to make a nice improvement in overall performance too, just not as dramatic as 3.73. But the fuel economy will be better by a mile or so per gallon.

Just something to think about.

[BallerMaro13]

Re: 3.08 to 3.42? Worth it?

3.73's or nothin' :D

go big or go home!

[dgreet77]

Re: 3.08 to 3.42? Worth it?

Yeah, I can pull 30 mpg pretty easy with these 3.08's even after all the stuff I've thrown on my car. :D. And since I'm in college and this is a DD that counts for a lot.

So I can expect about a 200-300 rpm jump at cruising and a 1-3 mpg drop? Sound right?

[venom3300]

Re: 3.08 to 3.42? Worth it?

Yeah, I can pull 30 mpg pretty easy with these 3.08's even after all the stuff I've thrown on my car. :D. And since I'm in college and this is a DD that counts for a lot.

So I can expect about a 200-300 rpm jump at cruising and a 1-3 mpg drop? Sound right?

largely depends if u can keep ur foot out of it ;)

but about right

[dgreet77]

Re: 3.08 to 3.42? Worth it?

largely depends if u can keep ur foot out of it ;)

but about right

Lol. Good point. And I do tend to cruise at somewhat above the speed limit. :D

So will I regret going to 3.42's by having to spend money later on by going to more gear? Or will I be happy enough with 3.42's if I turn this into a race car?

[crazytrain65]

Re: 3.08 to 3.42? Worth it?

i have 3.42 and want to upgrade to better gears. i also have an open differential. check out my sig for times and mods with these gears

[pace2006]

Re: 3.08 to 3.42? Worth it?

Lol. Good point. And I do tend to cruise at somewhat above the speed limit. :D

So will I regret going to 3.42's by having to spend money later on by going to more gear? Or will I be happy enough with 3.42's if I turn this into a race car?

If you can handle the few extra rpm's, definitely go with the 3.73s. 3.42s aren't enough and I'm already looking at upgrading to 3.73s (also partly due to my Torsen prematurely giving up the ghost). Gas mileage will be down a little, but I haven't noticed a huge difference overall. If anything, the fun outweighs the mileage difference.

[venom3300]

Re: 3.08 to 3.42? Worth it?

Lol. Good point. And I do tend to cruise at somewhat above the speed limit. :D

So will I regret going to 3.42's by having to spend money later on by going to more gear? Or will I be happy enough with 3.42's if I turn this into a race car?

if ur looking for a race car then 3.42s are a no go

if ur looking for more pep then yes

[dgreet77]

Re: 3.08 to 3.42? Worth it?

Alright. I gotcha on all of this.

Now for a slightly different question...

Is it better to buy the 3.42 and have the series 3 carrier OR better to skip the 3.42's and just buy series 2 thick gears if I deicide to make the jump to 3.73's? Is there any downfall to the series 2 thick gears vs. normal series 3 gears?

[venom3300]

Re: 3.08 to 3.42? Worth it?

Alright. I gotcha on all of this.

Now for a slightly different question...

Is it better to buy the 3.42 and have the series 3 carrier OR better to skip the 3.42's and just buy series 2 thick gears if I deicide to make the jump to 3.73's? Is there any downfall to the series 2 thick gears vs. normal series 3 gears?

that sir, is over my head.... im sure someone else can help though

[Mark42]

Re: 3.08 to 3.42? Worth it?

If you keep your foot off the throttle, and keep speeds at 65 or under, there should only be about 1-1.5 mpg loss. At least that is what I have measured so far.

BTW, earlier I wrote that I was cruising at 1900 rpm doing 65 mph. I checked my notes, and 1900 was 60 with the 3.08's. Now 60 mph is at 2300 rpm with the 3.73's.

The dyno graph below shows why this 400 rpm change makes such a difference.



http://www.hypertech-inc.com/media/d...rd_-_38l_1.pdf


At 1900 rpm the 3800 V6 is making 60 hp and 170 lbs torque. By bumping the RPM up 400, the engine is now making 80 hp and 180 lbs torque. Thats a 33.3% increase in HP! And 10 more fl/lbs torque.

What other bolt on is going to give an instant and permanent 33.3% boost in HP for the same cost? Plus there is no additional stress on the motor, no No2 bottles to fill, no worries about blowing head gaskets, throwing a rod, burning holes in pistons, etc because the motor has not been modified at all.

[Pewter02Camaro]

Re: 3.08 to 3.42? Worth it?

If you keep your foot off the throttle, and keep speeds at 65 or under, there should only be about 1-1.5 mpg loss. At least that is what I have measured so far.

BTW, earlier I wrote that I was cruising at 1900 rpm doing 65 mph. I checked my notes, and 1900 was 60 with the 3.08's. Now 60 mph is at 2300 rpm with the 3.73's.

The dyno graph below shows why this 400 rpm change makes such a difference.



http://www.hypertech-inc.com/media/d...rd_-_38l_1.pdf


At 1900 rpm the 3800 V6 is making 60 hp and 170 lbs torque. By bumping the RPM up 400, the engine is now making 80 hp and 180 lbs torque. Thats a 33.3% increase in HP! And 10 more fl/lbs torque.

What other bolt on is going to give an instant and permanent 33.3% boost in HP for the same cost? Plus there is no additional stress on the motor, no No2 bottles to fill, no worries about blowing head gaskets, throwing a rod, burning holes in pistons, etc because the motor has not been modified at all.

That is an incorrect statement, the car is not making any more horsepower than before. You have simply shifted the where the powerband is for a certain speed. you have not gained any power at all.