What gear to run

[Bigfoot]

3.89 Detroit is a dream

Sweet sweet dream

I also like my 3.91's.....

[shelbydoug]

I'm running 3.50's in my '68 with a Richmond (Doug Nash) 5 speed. 5th is 1:1. First gear multiplication is like running a 5.00:1 rear.

I'm going to drop that to a 3.25 rear. That will be like 4.88's with a 2.20 (GM) first gear. That's still plenty for the street.

Personally I think a lot of the reason GT350's are only 14.5 second 1/4 mile cars is that they don't have enough first gear multiplication with a 2.32 first gear and only a 3.89/3.91 rear. You won't even start to get serious until you get to a 4.33 like in the factory drag pack but who wants to cruise with that set up?

[kjspeed]

It all depends on what you want out of driving the car.

Theoretically you could run a 2.50:1 9" rear but as far as acceleration, forget about it.

The best combination of having your cake and eating it too would be to run something like a Richmond 5 speed with a 3.26 first gear and use a 3.25 rear ratio.

That would give you a reasonable cruising rpm, a first gear acceleration ratio of what you would put in a GM with a 2.20 first and a 4.88 rear for acceleration with the close spaced gearing of a T10.

If you want lower rpm cruising then that, then you need the 6 speed where 6th is in overdrive by about .7:1


These considerations were never possible back in the day and along with electronic fuel injection are the largest changes to the original packaging of a "current real high-performance vehicle" for the street.

I've got a Richmond 5 speed in mine with a 3.50 rear gear. It's similar to running a 4 speed with a 4.56 gear but with a 5th gear 3.5 final to bring down highway RPM. The gearing in my trans is; 3.27, 2.13, 1.57, 1.23, 1.00. In your application you could run a 3.00 final and the first four gears would be about what you have now. Of course this setup would require; a new rear gear, a $2900 transmission, fabricate a rear transmission mount, cut the driveshaft and get a new shifter. Plus my Richmond doesn't have a reverse switch so I have a toggle switch for that.

[Bigfoot]

Have a good Friend with a 5 speed in his 67.
Saw the car Monday. He said first gear is like 4.88's!

[shelbydoug]

Have a good Friend with a 5 speed in his 67.
Saw the car Monday. He said first gear is like 4.88's!

Yes...and then some!

A DN 5 speed with a 2.80 rear is about equal to a TL (2.32) and a 3.89.

I got my Richmond when it was called a Doug Nash and it cost $800. Now I did snap off the friction welded gear selectors and went to the billet versions. After that was fixed, I broke the shift handle off. I suppose it became the weak link.

Lots of folks have been running used T-5s out of the wrecking yards. There's even a turbo T-bird version of it with a 4.11 first gear. You don't have to go the high roller route. Then you could save some money and maybe use it to get a hair cut? I've been getting hair cuts lately.

It has mixed results. Lots  of people stare? 

[GT350Lad]

Have a good Friend with a 5 speed in his 67.
Saw the car Monday. He said first gear is like 4.88's!

4.88! Feels nice under foot when racing the 18 year old in the rice racer!

[shlby66]

 Just thought, I would add my 2 cents worth, to what has been mentioned. First, I'm more
of the "old school" type and have used, what is referred to, as the "poor mans" 5- speed.

For 30 years, or so, I've used the combination of: A wide ratio ( 2.78 first ) and a 3:25
rear gear.

The result is: You lose nothing in acceleration, because, the wide ratio transmission's gears,
times, the 3:25 rear gear, is mathematically, the same, as a close ratio ( 2.36 first ) and a
3:89 rear gear.

The wide ratio x 3:25's will give you right at 2900 RPM @ 70 mph in 4th gear ( 1:1).

The RPM may vary somewhat, depending on tire diameter. I've always used at least 26"
diameter ( tall ) tires, all of the time.

So, I end up with good acceleration, coming up thru the gears and decent RPM's, for
cruising on the InterState.  Works for me.

That's my story and I'm sticking to it.

Doug C.   


 

[zray]

"........Motor seems happiest at 2800 to 3000 rpm.

My my we are getting soft in our old age.  A HiPo 289 will run very happily at 4,000 to 4,500 rpm all day long, and get up the next day and do it again. Over and over. These cars were driven coast to coast like that without wearing out anything, without hurting anything, and lasting decades before needing any internal motor attention.

YOU may not be used to driving at these rpm levels hour after hour because modern cars have lulled today's drivers into thinking a motor should barely turn over at highway speeds (thanks to emmision / pollution constraints). And nothing wrong with that, I like to breathe as much as anyone. But don't think the motor in the Shelby's can't take a little exercise. The cars haven't gotten soft. You can drive it to the limit for the rest of your life and it will still be ready for more long after you are 6 feet under.

Z

PS. If you add a vintage Paxton, a 3.00:1 rear gearing , and a 2.90 1st gear works fine. But at stock horsepower levels, I would not go any higher than 3.25:1 , with  the 3.50:1 being a good all-round choice, and the same std. gear found in the stock 289 K code cars.

[gt350hr]

+1
     4,000 was "cruise" rpm on the highway with 3.89s and a 26" tall tire on my first GT350 ( 4 speed ) . Hiway 50 west out of Wichita was a blur at 4,500 but that was 43 years ago. LOL Oh the good old days when gas was cheap and full of lead.
   Randy

[GT350Lad]

Right on Randy, there is nothing like pulling up next to a electric car and knowing that what there car has done to help the environment you have just undone in 5 min of driving! Love it

Ps. Even though the environmental impact of mining the lithium and making the batteries is far more then people realise

[427heaven]

Hundreds of thousands of batteries litter the Nevada desert HAZ MAT site. This is waste that cant be undone for thousands of years. What impact it has on society wont be known for years... So much for progress.

[98SVT - was 06GT]

I built a 65 Fastback one time and all I had laying around was a 2.80 from an automatic. Ended up being a great highway gear. 28mpg @ 75mph.
I'd go the gear vendor or 5 speed route. That extra gear will not affect the "fun" factor but will drop the revs to acceptable levels at highway speeds.

[GT350Lad]

Hundreds of thousands of batteries litter the Nevada desert HAZ MAT site. This is waste that cant be undone for thousands of years. What impact it has on society wont be known for years... So much for progress.

So true mate

[shelbydoug]

"........Motor seems happiest at 2800 to 3000 rpm.

My my we are getting soft in our old age.  A HiPo 289 will run very happily at 4,000 to 4,500 rpm all day long, and get up the next day and do it again. Over and over. These cars were driven coast to coast like that without wearing out anything, without hurting anything, and lasting decades before needing any internal motor attention.

YOU may not be used to driving at these rpm levels hour after hour because modern cars have lulled today's drivers i Tom thinking a motor should barely turn over at highway speeds (thanks to emmision / pollution constraints). And nothing wrong with that, I like to breathe as much as anyone. But don't think the motor in the Shelby's can't take a little exercise. The cars haven't gotten soft. You can drive it to the limit for the rest of your life and it will still be ready for more long after you are 6 feet under.

Z

PS. If you add a vintage Paxton, a 3.00:1 rear gearing , and a 2.90 1st gear works fine. But at stock horsepower levels, I would not go any higher than 3.25:1 , with  the 3.50:1 being a good all-round choice, and the same std. gear found in the stock 289 K code cars.

Yup! All the noise too! And the bumps in the road? How can I stop it?

What was it that attracted people to these cars to begin with? They are "performance cars". Granted the definition has changed just a bit BUT if you look at the current Mustang GT packages, they are still based upon the original concept with some updates.

We are giving the formula for putting a 60's something criteria into a '18 data.

Next everyone is just going to complain that all the '60s did was make the Nauga extinct because we killed them for their skins?

I think those folks should all stay home and play their video games that show they are F1 champions of the Rec Room? Those thumbs should just be put in the Hall of Fame?

[Jimbc123]

When I bought my 4-speed GT350 I was surprised to find 3.00 gears in the rear. The date code on the axle tag was consistent with the build date, so I left it alone. I spent a lot of time on the highway so the 3.00 wasn't bad. I was always a little unhappy with the performance on the street. After retirement I went ahead and installed 3.89 gears. I couldn't be happier. It is a completely different driving experience and just what I needed after having the car as a driver 14 years.i would never go back to the 3.00, but I did save them. If I really needed to do more highway driving I'd try something in the 3.50 range, but not the 3.00.

Good luck,

Jim