I was thinking that if i need to rebuild my rearend i might put in 3.42 gears. If i did what can i expect as far as milage, performance, and wether or not it will effect my speedo. Any opinions?

 

I can't possibly imagine that would have any effect on performance--very small jump and not worth the cash outlay.

 

There really won't be that big of a difference between the two. If you are HAVING to rebuild the rearend I would recommend the 3.42's but I wouldn't recommend anyone making the change just to be making it. You will be pulling a little higher RPM. At 70MPH I pull about 2400 RPM.

 

Well i would only do it if my rearend had to be rebuilt and also depending on how much extra it would cost. So there woulnt be much difference in milage or 1/4 mile times?

 

You realize that 3.27s are 9 bolt and 3.42s are 10 bolt, right?

Maybe you mean 3.23--3.42s or 327s to 3.45s??

Might be a small--and I mean small difference--but if your gonna change it and pay--may as well make it worth your while and get a more profiund difference.

 

ok i guess ill stick with 3.27's. Thanks for the info everyone!

 

I would def. say change it. I had 3.23s in my car, 350tpi/700r4 and rebuilt my rear and added 3.42's while i was at it. I drive alot of highway and cruise at 80 usually. The difference was so much more than i expected. The car really gets out of the hole so much better now, and all around its much improved. It just seemed to put the car in its power band. I'm being honest when I say it made a bigger difference then when I did headers and full 3" exhaust on my car. I wish I had done it a year ago.

 

It depends on your power level too...I am keeping my 3.27 gears because going numerically higher will not help my wheelspin...in your case though it may help with a stockish 350.