changing gear ratio from 3.23 to ? Street & Strip Experiences?

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Buschi340

Buschi340

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hm, currently I'm asking myself to what gears I should swap in my 8 3/4.
1 have 27" tires, 3.23 behind a stock carurated 6.1 Hemi/5speed (Toyota).

Gear Ratios
First 3.251
Second 1.955
Third 1.310
Fourth 1.000
Fifth 0.753

This is great for long distances (Autobahn High speed). But on the track I stick in second gear, 7.5rpm, 95 ml/h. wanna go shorter to be faster than 15seconds on the track but don't wanna lose highway comfort. :)

in the moment i'm undecided between 3.55 and 3.91. Is it a big difference to go straight to 3.91?
 
If you are going racing a 3.91 would make a good set of gears and yes you will notice a heck of a difference between 3.23 and 3.91. Now here is the beauty of the 8.75 rear. Drive to the track, jack the rear up, swap the center sections, add fluid, go racing! When you are done for the day, repeat the process and drive the car home. If you do it that way, you'll get to the point of swapping gears in about 30-40 mins.
 
For the type of driving you want to do, 3.55's would be the logical choice. It would be the best compromise between dragstrip and autobahn driving. If you went with the 3.91's you risk making first gear useless due to much higher torque multiplication. First gear would be very short (3.25), and imo, would affect normal driveability in a negative way. As for autobahn driving, according to my calculations, at 4000 rpm (reasonable sustainable rpm) the 3.91 gear would be running ~110 mph. With the 3.55's the car would run ~122 mph at the same rpm, so there is quite a difference. I don't know if you looked at it this way, but these are the reasons I would personally choose the 3.55's over the 3.91 gears.
 
Don't forget, 3.73 gears are available for the 8 3/4 now.
 
Always wondered why mopar never made 3.73 an option from the factory.
Also if its the autobahn, why not drop a set of 2.76 gears in and findout the top speed of the car, you might be surprised (or poop your pants).
 
He has a trans with a .75 overdrive ratio, so that definetely helps.
 
Would they consider your car safe for High speeds? We didn't have any trouble when we were on the autobahn but I have heard of people being stopped in older cars because the authorities didnt think it was safe.
 
Buschi340 said:
hm, currently I'm asking myself to what gears I should swap in my 8 3/4.
1 have 27" tires, 3.23 behind a stock carurated 6.1 Hemi/5speed (Toyota).

Gear Ratios
First 3.251
Second 1.955
Third 1.310
Fourth 1.000
Fifth 0.753

This is great for long distances (Autobahn High speed). But on the track I stick in second gear, 7.5rpm, 95 ml/h. wanna go shorter to be faster than 15seconds on the track but don't wanna lose highway comfort. :)

in the moment i'm undecided between 3.55 and 3.91. Is it a big difference to go straight to 3.91?
Click to expand...

3.73 WITH 27" TIRE . 6.1 Hemi and you turn 15 sec , must be the tall tires , 1 have 25" tires with 3.23 and a little 340 , Hemi in a light car should be smoking . Don't want to think what the top end is on the highway , yeehah
 
1970Duster said:
Always wondered why mopar never made 3.73 an option from the factory.
They did for years, got a factory 3:73 gearset in the dart right now. With that out of the way, 3:55 would be a nice improvement for what your doing...
Click to expand...
 
with a 27 inch tall tire and 3.91 gear 70 mph at 2500 with .73 overdrive
 
yes, a spare 3rd member would be cool.
Toyota had on the Turbo Supra a 4.10 rear. But those engines are living in the high end of the rpm band.
So 3.55 is the allrounder and you are guessing 3.91 is too short?
I never drove above 230 km/h. The engine has still potential above that. A lot I felt. But it's simply too dangerous. And Police doesn't stop because of all our old Porsches etc :)

5th gear, 5000 rpm, 230 km/h with my tires is the 3.55 (theory). At 5500 it is the 3.91.
currently it is at 4500.

Is the change from 3.23 to 3.55 noticable?
 
Blew up my 430's and bought a set of 355's (was really looking for 391's). I have to say that the 355's make the drive on the highway a much more pleasant experience but I really miss my 430's, talk about neck snapping acceleration. I'm going to get them rebuilt I think.
 
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