Close vs. Wide

[My427stang]

The newest MT-82 and the new 10R80 have 4.24 and 4.69 first gears, respectively. With the Performance 3.73 gearset, that gives starting line ratios of 15.815 and 17.494. Underrated 460hp. Howzcum our steep first gears are useless, but them new cars ain't? 2018 Mustang weighs same as 1969 FE Torino.

So, I'd have to dig into all the parts of those cars, but overall

Drag racing - although not specifically built for drag racing, the engines pull 7500 rpm, so if the gears are steep, you don't have to pull the next one immediately, if you do, it's a 10 speed and has lots of intermediate shifts done by solenoid actuation not valve body, so happens pretty quick, and last, there is nothing loose about a modern converter.  My hunch is the converter has a very low stall speed and they make it up with gear

Street driving - lots of gears that shift a lot LOL, same tight converter and separate intake and exhaust cams that allow changing of the valve events significantly for load and RPM so you can have an engine tuned for a WAY tall top gear while still letting it rev for a short gear

My wife drives a Cherokee with an 8 or 10 speed, I forget, and it's pretty slick.  My daughter bought a new Wrangler (Jeep type Jeep) One year newer, same engine, 5 speed AT, it's a pig compared to the Cherokee.  30+ highway vs 19 highway, 24 mpg in town vs 16, and it'll eat it's junch in a drag race.  If that Jeep dropped to 3 gears, it'd be even worse

How come really fast drag cars sometimes use a two speed tranny with a 1.82 first gear?

Purpose built, loose converter, light car, lots of RPM, and very unique applications.  You won't see many big bodied girls hanging the hoops with Powerglides

But I see you answered yourself   I am not saying an always or never, but as a rule of thumb, the right ratios are right.  I just don't see a lot of right with the narrow boxes in big block applications.  AT, different story, but if you had more gears to choose, I'd likely change my mind because you could shift quickly and leave her screaming

[plovett]

As always a fair and measured response, Ross.  It all depends on the particulars.  I would say that in some instances I would rather have a close ratio toploader than a wide.  I think If I optimized my Cougar it would have a 4.22 or 4.30 rear gear.  It has 4.11's now and tops out at about 135 mph, but it does about 124 or so in the quarter.  So a lower rear gear would help.  With a 4.22 or 4.30 rear gear I think I would rather have a close ratio toploader.  This car uses sticky street tires, but not slicks.  I think I would be faster with the close ratio box. 

That said,  a wide ratio box will work good in a wider range of circumstances.   A narrow ratio box will work good in a narrower range of circumstances.   No doubt. 

JMO,

paulie

edit:  that is if I had a toploader, not a C6.

[BattlestarGalactic]

How come really fast drag cars sometimes use a two speed tranny with a 1.82 first gear?

Really light cars with big horse power and the lack of gear keeps the tires from spinning.  I know lots of dragsters that start in 2nd many times.  If not, they leave in 1st and have the noid shift it in like .2 seconds.  Again, keeps traction issues at bay.

Again, with a converter it is not an issue.   Most have a very loose converter anyway and heat is not an issue with a car that only runs for 8 seconds at a time.

[jayb]

How come really fast drag cars sometimes use a two speed tranny with a 1.82 first gear?

In my case, its all about the transmission's ability to take the power.  I'm confident that an ATI Powerglide backed by a Gear Vendors O/D can take anything I can throw at it.  I used a C-4 up to about 950 HP, but at the 950 HP level I had to have it gone through every year to make sure it would live.  The C-4 seems pretty bulletproof at 750-800 HP, but over 900, not so much.  And as far as I know there isn't a streetable trans with more gears out there that can take 1000+ HP, outside of a Lenco.  I've seen the power capacity claims from some of those overdrive transmissions but I don't believe them, based on others experience I've read about online. 

Here's another consideration - traction at the drag strip.  When I had the supercharged engine in my Mach 1, I was using a pretty small tire to fit the factory wheelwells.  Even with the 1.82 first in the Powerglide, I could not get the car to hook on the 10" Mickey Thompson slicks until I went all the way down to a 3.50 rear gear.  Just too much power at the wheels with a deeper gear, blew the tires off every time with 4.11s and 3.89s.  The picture of my Mach 1 in my signature was taken leaving the line at Cordova with 3.50 gears and the Powerglide.

And one other thing - I tried the "gear splitting" technique with the Gear Vendors overdrive on that car, and found absolutely no difference in ET.  So, first gear would have been an overall ratio of 6.37, first O/D was 4.97, second gear was 3.50, and second O/D was 2.73.  Of course I never got into second O/D on the track, trap speed was over 150 MPH in second gear.  But despite the fact that I had three gears on the track instead of two, there was no change in performance.  The converter compensated for the lack of the third gear, when just running two speeds.

This discussion drives home the point that the whole car and its use has to be a consideration.  The calculus is completely different for a 425 lb-ft, 550 HP small block street car, where an 8 or 10 speed transmission might be available, and might actually live.

[My427stang]

I am with you Jay, the best tranny is one that doesn't blow up...and if you have the rpm range and power to only shift once, that's the way to go. 

[FElony]

... the best tranny is one that doesn't blow

I'm quite sure Justin Trudy would not agree.

Anyway, watching videos of current cars I see lots of 8-second V8's going through 4 gears. I hear some mention 700r4's. Traction is key, yes. Years ago I asked Stan Weiss to figure, using a car that liked 4.11's in the traps, what would happen if an AOD was used with 6.20 gears, since 4th would be about the same trap ratio. He said it would be worth at least a tenth, maybe more.

I gotta think that racing a 2-speed automatic is one of life's most boring experiences. I also gotta think that shifting a 5-speed stick geared in the 7's was one the exact opposite. Gotta find middle ground.

[jayb]

Dude, 8 second passes are far from boring, no matter how many times you have to shift.

[Rory428]

Jay, it all depends on the car and setup. The quickest car I ever made a pass in , wasa buddys full tube chassis Super Gas 84 Thunderbird, low like a Pro Stocker of the day, in the late 80s. It had a 460 Ford based engine with a Powerglide, and it was a very boring car to drive. My best in the TBird was a 9.40 @ 146 MPH, and although it set you back in the seat pretty good, it just felt not very exciting, as it just kinda squited straight down the track, no more than an inch or 2 under the front tires,and like a few other 9  second Powerglide tube chassis cars that I have driven, once you put the Glide in high gear, not much going on. With a stock chassis, small tire car, you would probably have a bit more driving to do, so that would keep it intersting. By the way, the guy with the TBird made a couple of passes in my Fairmont the same day, even though it had the C6 at the time, and was only running mid 10s, he thought between the big wheelstands and having to shift it himself TWICE, it was a blast to drive. I have never driven a rear engine dragster (doubt I could ever find one I could fit into!), but talking to a few buddys that have tried them, they were fast but very dull to drive.

[FElony]

https://www.youtube.com/watch?v=cCFd2l_DPTo

The feel, the sound, the smell, is more important to me than actual ET.

https://www.youtube.com/watch?v=TrKJsP99pcQ

Although a Chev-fest back then, I can't help but wonder what the small Ford would be like in this form with today's heads and intake.

[FElony]

As usual, I'm feeling I have too many irons in the fire.