gearing

Big-Foot

Randy V

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C

Scott

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
 
5

Mike Drew

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?
 
F

NickF

Lifetime Supporter
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.
 
C

Scott

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
 
F

NickF

Lifetime Supporter
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?
 
C

Scott

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
 
F

NickF

Lifetime Supporter
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
 
T

TurboTerry

I know this thread is not exactly hopping, but I think I can contribute something helpful to it, can make this much less work, unless of course, no one is interested. If there is a response, then I will move forward, might take me a day or two, but if others are interested in the topic, it will be worth my effort.
 
Big-Foot

Randy V

Staff member
Admin
Lifetime Supporter
TerryF said:
I know this thread is not exactly hopping, but I think I can contribute something helpful to it, can make this much less work, unless of course, no one is interested. If there is a response, then I will move forward, might take me a day or two, but if others are interested in the topic, it will be worth my effort.
Click to expand...
What sort of response are you looking for Terry?
If you have a contribution that you think would be valuable to our community, please feel free to share it.
 
T

TurboTerry

Big-Foot said:
What sort of response are you looking for Terry?
If you have a contribution that you think would be valuable to our community, please feel free to share it.
Click to expand...
Well, what I was thinking, was that I might build an online calculator, that let's one input transmission gear ratios, and differential ratio, and tire sizes, plus engine RPM and then it would display speeds in gear, that sort of thing, probably also calculate the tire diameter and circumferance, based on the tire size (like 315 40 19), if that would help.

The response that I was/am, looking for, is wanting to know IF that is valuable to the community. If no one is interested, then it might not be valuable enough for me to want to invest the time. No sense making it, if no one would use it, right?
 
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