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BRAND NEW 3:09 REAR DIFF

1672 Views 15 Replies 7 Participants Last post by  Cheapokitty
Hey guys, I was going to make the switch to a 3:09 diff so I ordered it new from Steve White Motors but I decided not to.
My loss is your gain, $900 and it's yours located in Queens NY.
I would prefer a local pick up but if you want to pay for shipping, I'll drop it off at a ups store and you can arrange shipping with them.

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I have a few 3.70鈥檚 in my shop if your looking for any of those let me know. Can meet you with them instead of shipping.
That's good to know brother, so far my 3:70 is holding up but I'm sure once I start drag racing and launching the car I'll need a new one soon, lol.

I was going to try the 3:09 to extend my time in boost but after further calculations and thought I realized it may put too much strain on the transmission.
For those who don't know I own a 1200hp twin Turbo hellcat with a 6 speed manual.
The 3:09 is the perfect upgrade for you auto guys 馃憤馃徑
You are worried about the strain from a 3:09 but not from a Twin Turbo :)
Lol, I'm worried about asking the transmission to stand up to both. I'm on transmission number 4 in this year alone. Every pull is a prayer because I haven't found a builder who can keep a 6 speed in a hellcat with big power. I'm working on another build now, hopefully 5th time is the charm.
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Have you looked up rpm transmissions. The 6 speed is the tr6060 right? If so they have different builds and they are usually the go to guys for corvettes.
They don't hold up even using their highest level rebuild
the lower gear ratio rear end would be easier on your transmission btw
Less shifts maybe but the lower multiple would absolutely put more strain on each gear.

The real solution for my setup is a Turbo 400 but I enjoy fun drives on curvey back roads, rallies with friends and even some track work. A Turbo 400 is a terrible driving experience for those things.
no, you have it backwards...the lower the gear ratio, the less strain on the drivetrain as it takes less power to move them. And your overall RPM's for a given speed would be higher at the same speed of a higher gear ratio resulting in more frequent shifts not less. Think of a bicycle, in the lower gears its easier to peddle (less strain) especially from a dig, and in the high gears (more strain) its harder to peddle but nets you higher top speed.


better yet think of your M6 transmission, is it easier to start from a dead stop in first gear (lower ratio) or 5th gear (high ratio)? Lower ratios have a greater mechanical advantage and require substantially less force to move them
I just realized we are saying the same thing:

Currently I run a stock 3:70 ratio at 3k rpm in 4th (1:1 gear) gear I am doing approx 70mph.
With a 3:09 ratio at 3k RPM in 4th gear I would be doing approx 83mph.

PPG, gforce and other transmission builders all offer gearsets with shorter ratios than stock to help with acceleration and strength in the lower and overdrive gears.
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Sorry man I think I am to keep it and try if out. I was talking to my trans builder about it and he said hold on to it. Thanks
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