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Odd gearing


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Posted

My car hits ~44 when I am WOT in 1st, but I run 5K at just over 60. That is about 12 MPH / 1K RPMs, running only to 79 MPH in 2nd gear before shifting. What do the other 3.4's run and why is mine different? I know that my tranny has been replaced or worked on at some point. Do you think I have some different gearing for some reason?

Posted

on another look, If I am holding steady, I run about 4700 RPMs and this changes quite a bit when I get on the gas or let off. When I am at WOT though the RPMs are higher and in that case, I can't hit 80 in 2nd. Going 70 in 3rd gear I run about 3200 I believe. Maybe BIGBULS can shed some light on this for me. And yes FFP does change the shift points but that shouldn't affect the gearing.

Posted

Your 1-2 shift (44mph/6250-6300rpm) seems dead on the money.

 

You 2-3 shift DOES seem a *little* short, but not much...............if yours is going off at 79mph, it's only 2-3mph lower than most other stock cars (most shift at 81-82mph/6150-6200rpm). I expect your torque convertor just isn't locking up all the way.

 

I should also point out, the main reason you rev so high at ~60mph is because the TC doesn't lock back up (of the 1-2 shift) until ~75mph...........it takes THAT long. This lack of lockup is also why you have so many rpm off of the 1-2 shift (~4200rpm, which is about 800rpm worth of slip when you consider that 1st gear is a 2.921 and 2nd a 1.568).

 

 

The other possibility is that your speedometer is a little pesimistic..............you may very well be AT 81mph even though the speedo says 79............got a GPS or a radar trailer handy? :wink:

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