strange 12bolt
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1) With a 6spd, the whining you will get after a few hard launches on a 12 bolt will likely not be determined by the manufacturer of your 12 bolt. It doesn't seem to matter whose 12 bolt it is. The shock on the drivetrain from a 6spd doesn't mix with the 12 bolt well on a torque arm setup. Almost everyone complains of whining after a few trips to the strip. Some have theorized the location of the torque arm mount on the 12 bolts causes the torque arm to distort the housing after repeated high rpm launches. Most 6spd guys shy away from the 12 bolt for this reason. Autos run them and don't seem to have any problem, but the transfer of energy launching the car is different with an auto. It's not as severe.
2) You can't compare a 4spd nova with 14 inch wheels to a 6spd camaro with 16 or 17 inch wheels and look at the same rear end ratios. I believe the Muncie's first gear is similar to the T56's (2.66), but the tire size is different between your two cars. You will need a deeper set of gears to get the same final drive ratio with your car that your friend has. Best thing you could do here is measure his tire size and yours, find a final drive calculator online and punch the information in (tire size, first gear ratios, and rear axle ratios) for each car to compare what the final drive would be. Most guys seem to like 4.10s with a 6spd. You shouldn't lose too much MPG because you still have the double overdrive.
Regarding your choice of axle (12 bolt), here's some good info from one of our sponsors: http://shop.brutespeed.com/Brute-Spe...nformation.htm
Last edited by 01ssreda4; May 26, 2012 at 04:10 AM.
As far as gears go, If you seriously wanna use every bit of power you have, I'd go with no less than a 3.73 in a 6 speed. With 4.11's my car is running 2080rpms at 79mph and has plenty of pull from thst speed in 6th and still gets 27mpg's avg on interstate. Mixed driving (city/hwy) is about 19mpg's. It pulls good everywhere and also allows me to shift less around town without having to rev high to skip gears. Start in 1st or 2nd then shift to 4th at about 20mph and that gear will pretty much run any in town speed limit with ease. Seat of the pants power is deceiving, but not entirely. What I mean is it will feel like its a full second faster when in all actuality its maybe .3 tenths faster in the 1/4. Definitely one of my favorite mods on my car.
OP, if you don't want to take it to the track, then a 12 bolt will probably be fine. If you are like me, however, to pay 2K+ for a rear and get gear whine after a couple trips to the track would make me mad. I would love to put a GM based rear in my car, but the possibility of shelling out the money then picking up a lot of annoying gear whine keeps me from doing it.
OP, if you don't want to take it to the track, then a 12 bolt will probably be fine. If you are like me, however, to pay 2K+ for a rear and get gear whine after a couple trips to the track would make me mad. I would love to put a GM based rear in my car, but the possibility of shelling out the money then picking up a lot of annoying gear whine keeps me from doing it.
I would have went with a 9" but at that time there were various install issues and modifications that I didn't want to deal with. It seems that nowadays they've become much more user friendly to install. So I'm pretty sure that if I was buying a new rear today it would be a 9", but that's not saying that I'm unhappy at all with my 12-bolt. FWIW.






