Your thoughts on my Drive-line requested

Transmission to Rear-end

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predator
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Your thoughts on my Drive-line requested

Post by predator » Sun Oct 04, 2015 12:01 am

I'm thinking about running a manual six-speed Transmission in my Car. My Car has in it right now a Torque-flight transmission. It also has a Gear-Vendors over-Drive. Currently I have 4.88 Gears in the Car.

Well my thoughts are like this: I think to have my car to be capable of a broad speed range. I am thinking that I might want to install a lower gear-ratio in the Rear-end. Then I could put the needed gear in the Transmission. For a short time. I thought of adding a second G-V Over-Drive, But the mere thought of spitting my hypersonic lly spinning Drive-shaft out of my Car while I am moving along the road at 200 miles an hour, this thought freaked me out!

So, Guys do you have any thoughts on my cars drive-line set-Up? i'M THINKING THAT IF i RUN A sIX-Speed. I will be able to run my Car up at an event such as the Silver-State road race. While still be able to run pretty well down the Quarter mile.

So Guys, Do you have any thoughts regarding how I will set-Up my Cars Drive-Line?

Good By Chris McKeon

barnym17
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Re: Your thoughts on my Drive-line requested

Post by barnym17 » Sun Oct 04, 2015 6:25 am

I think I would figure driveshafts critical speed and work backwards,say the shaft is good at 8000rpm, then figure gear needed for the top speed you want and use it for a starting point. you do not want to get in the critical speed area bad stuff can happen.

autogear
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Re: Your thoughts on my Drive-line requested

Post by autogear » Tue Oct 06, 2015 9:25 am

I sell an awful lot of 5th speed gears for T56s. The higher helix angle they use to lower noise in the overdrive gears means a full power shift into 5th can peel the teeth off the gear.

Talk to the guys at RPM Transmissions in Indiana; they build a lot of this stuff. The above comment is correct, start at the back and work your way forward.

ChevyEFI
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Re: Your thoughts on my Drive-line requested

Post by ChevyEFI » Wed Oct 07, 2015 11:56 pm

Go for the full length T56 Magnum / Chrysler length mainshaft if you go T56 / TR6060. This would be a couple inches but would shorten your driveline a bit.

Don't go for 0.50 sixth; the gear ratio spread is poor if you're really upstairs using those gears for top end. Run taller rear gear and less OD if possible.

The Z51 Vette 5th is an example of taller is better; don't want to redline on the back stretch.
2.66 1st, 0.74 5th, 0.63 6th is buildable.
2.97 1st, 0.84 5th, 0.71 6th is buildable. Neither an off-the-shelf combo.

predator
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Re: Your thoughts on my Drive-line requested

Post by predator » Thu Oct 08, 2015 11:19 pm

Yes Chevy EFI, I am thinking that I might want to go with a Six Speed. A 6-Speed will allow me to run a taller rear-end gear, while at the same time the 6 speed will give me a good gear advantage when the CAR IS TRYING TO ACCELERATE DOWN THE qUARTER mILE. yes this is becomming interesting. A .63, or a .71 Sixth gear could work! THIS COULD VERY WELL END UP IN MMY car. BY 'this' i mean a 6-speed maunel.

guys, this project of mine: My 71 road-runner. This project is a work in progress. I feel like I will indeed reach my goals. One of which is to have my Car run up to 200 M-P-H. I want to do this with as safe of a Car as i can build.


Thanks for the GOOD impute.

Good By Chriis

pdq67
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Re: Your thoughts on my Drive-line requested

Post by pdq67 » Fri Oct 23, 2015 10:42 pm

Please consider hunting up the long write-up about "The Big Red 1" '69 Camaro that Ron and RJ Gotlieb own.

It won the Silver State Classic back about '89 and '90 if memory serves me right?

He, He!! I dream about my '67 growing up to be "The Big Blue 1"...

Also look through ALL the rear end gearing for all stock cars because I have read reference to 2.20 rear end gears or thereabouts... Some lower than Chevy's 2.48 or 2.56 or whatever it is...

Here is something else to think about that is almost brand new or at least to me.. The LGT700 stick transmission...

http://www.5speeds.com/legend/

pdq67

Brian P
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Re: Your thoughts on my Drive-line requested

Post by Brian P » Fri Oct 23, 2015 11:12 pm

Doing some math with what ChevyEFI posted.

If you want 200 mph at (say) 6000 rpm with (say) tires that are 28" outside diameter ...

Perimeter of tire = (28/12)*3.14159... = 7.33 ft
Wheel revs per mile = 5280 / 7.33 = 720.29

If you want 200 mph then the drive wheels will be going (200/60)*720.29 = 2400 rpm

So if you want that to happen at 6000 engine rpm then you need an overall drive ratio of (6000 / 2400) = 2.50 (close enough)

If your 6th ratio is 0.63 then the final drive has to be (2.50 / 0.63) = 3.967 and the driveshaft will be going 9523 rpm
If your 6th ratio is 0.71 then the final drive has to be (2.50 / 0.71) = 3.520 and the driveshaft will be going 8450 rpm. I like this one more.

These final drive ratios are in a pretty plausible range, so there should be no need of finding the super-tall '70's economy final drive ratios. Obviously you will have to pick an actually-available ratio instead of this theoretically-calculated one. It appears that, if you are using a Ford 9 inch, 3.50 is available. If you are using a Mopar 8 3/4 inch, 3.55 is available.

Obviously I guessed the RPM at which your engine makes peak power and I guessed the outside diameter of your tires. Feel free to plug in more accurate numbers and recalculate.

In 1st if you are using the Mopar 3.55:1 final and the quoted 2.97:1 first gear ratio, the overall drive ratio is 10.54:1. Right now, with your 4.88 and Torqueflite which has a 2.45:1 1st, it's 11.96 plus torque converter multiplication off the line, which obviously will not happen with the manual. So you'll lose something off the line compared to what you have now ...

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Re: Your thoughts on my Drive-line requested

Post by pdq67 » Sat Oct 24, 2015 7:13 pm

Here is the link to the "Big Red 1" story!

http://www.streetlegaltv.com/features/t ... hole-story.

I want to say that it used something like a 2.56 rear end gear?? And that it topped out at something like 7400 rpm to hit 220 or so???

My memory might be way off though??

pdq67

Brian P
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Re: Your thoughts on my Drive-line requested

Post by Brian P » Sun Oct 25, 2015 10:01 pm

Found it in the article - 2.64:1 which was a non-standard ratio. That was with a 4 speed transmission - no overdrive. Having a transmission with overdrive puts the required axle ratio into an easier-to-find range ...

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Re: Your thoughts on my Drive-line requested

Post by pdq67 » Tue Nov 17, 2015 4:34 pm

BTTT...

How is this thread progressing?

pdq67

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