gearing

Randy V

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#2
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Thank you
 
#5
Nick,
The gearing alone doesn't really mean anything. People run different tire diameters and transmissions with different drive ratios etc. What rpm are you cruising at on the freeway? For example I am running a 29" tire in 5th on a g50 trans, 2800rpm at 80mph in florida.

What are you doing with your car, track, race, or cruising around? S
 
#6
And what kind of gearbox do you have? Knuckle-dragger front engined car guys discuss rear end gearing as an absolute because the premise is that their transmissions are running a 1:1 ratio in top gear. However transaxles rarely have a 1:1 top gear, so comparisons become next to meaningless.

In a GT40 with a standard ZF transaxle, top gear is .70 and the ring and pinion ratio is 4.22. But there are .655 and .642 top gears available, along with 3.77 and other R&P ratios. I don’t have any idea about the various other transaxles commonly used but I presume they are just as varied.

So, what is your real question?
 

NickF

Newbie
Lifetime Supporter
#7
I want it to pull like a monster in all 5 gears. I am spending 15k on a trans and assuming I need to get nice half axles to handle the 600+hp.
 
#8
Nick, I’m sure with 600hp it will pull like a beast no matter what gears are in it. The cars only weigh 2100-2500lbs. The reason I stated rpm/tire diameter/speed is that you may not be able to drive it anywhere if you gear it wrong and are taching 3500 rpm at 60mph...... With a 70mph speed limit...... S
 

NickF

Newbie
Lifetime Supporter
#9
my hwy speed limits are 70mph, and I usually drive 85. so would I need to be in 5th gear at 85mph around 2500 rpm?
 
#10
Nick,
A 2500 cruise rpm is reasonable for cruising at 85mph. (I would probably want the rpm to be a little lower going any long trips) Even with a low (.6 something over-drive top gear) and 26" tall tires and a 4.11 r&p you will hit 2500 rpm around 70-74mph........

Which tranny have you chosen that will hold up to 600hp blasts??????? S
 

NickF

Newbie
Lifetime Supporter
#12
I am going with mendeola trans and some nice half axles. Found a 27in Avon by 12.5in wide with 15.25in bulge 411 gear
 
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