I know this has been talked to death in prior years, but I need some advice regarding rear gears, rev limits and cruising speeds. My plan is to run a 16" wheels and radial tires. The rear tire is 31" tall. I have a WC T5 and the site I'm using allows me to input all this data and shows speed in each gear at various RPM using a sliding scale. https://www.blocklayer.com/rpm-geareng.aspx With 3.73 rear gears, in 5th gear, speed is 68 mph at 1867 RPM. The engine will have a stroker crank, aluminum heads and a hotter than stock cam. Three 97's with progressive linkage. So, will the engine have any pull in 5th gear at say, 1800 RPM, or would I be constantly shifting down to get some torque on hills or passing? Primarily this will be a cruising car that I want to drive every day all day if I want. Any constructive advice is appreciated.
it's a flathead, in a 39-40 sedan, is my guess from the clues given I wonder what the ratios are in all the gears of this particular T-5?
The '32 in my avatar has a 4:10 differential with 29.5" tall tires. The engine is a 392" Hemi with a WC/T-5, the Hemi has plenty of torque, but it will be lugging down if I shift into 5th at below 50 MPH. You may want to go with a 4:10 diff. KK
Trans. is a Ford 86.5-89 Mustang, Torque 265, Ratios 1st, 3.35, 2nd 1.93, 3rd 1.29, 4th 1, 5th 0.68, Rev 3.15, Speedo 7T
The best gears I have used with a T 5 and a mild to stock built small block have been 3:55 and 3:73 gears. the 3:55 was in my 64 Skylark with 255/60 15 tires on it, and the 3:73 in a 70 chevy pickup with a stock 307 in it. and 30.5 in tires on the rear. they would both cruise down the freeway at 70 at right around 2100 RPM
It would be nice if you could find a transmission with closer ratios. Or at least not quite so hefty 5th gear. Sent from my Trimline
I think you would be happier with a lower rear gear like a 4:11 unless you want a real freeway flyer.
Here is a little non relevant information just to help you think. In 1988 Chevrolet built an S-10 pickup. It was a 2800 LB vehicle with a T-5 5 speed and a computer controlled banger that made more zot than your flatty will on a good day (160 HP @ 4K and 230 pound feet @2800). 28" tall tires and 4.10 gears. 5th gear was about usless on anything but the flat. Not choosing gears for you that is up to you but just some food for thought.
I think your tall rear tires and the cam are going to be the deal breakers with the rear gear of choice, once you get into 5th. The tall tires could be just enough to lug you down in 5th gear when pulling long hills, or wanting to accelerate 10 mph quickly. The "hotter than stock cam" doesn't really give us much info. At what rpm is the additional power come in at? If its at the lower rpm, the whole combo may work very well, but if the extra power comes in at higher rpm, the thing is going to be a dog with the tall tires, the 3:73 gear, and the od at 1850 rpm. Installing the 4:11 gear might be the easiest option. Might drop the gas mileage a couple .10 per mile, but would be more fun to drive. I'm running a modern V6 (probably about the same CI and about the same HP as your flathead), 5 speed, a 3:55 gear, and 26" tires. If I'm accelerating (like coming out of a town) I can be in 5th gear at 45 mph and it works good, if I'm in traffic and can't choose my acceleration speed, I wait until I get closer to 55 to shift to 5th. My car pulls 5th gear really well above about 50, but if I'm close to 50 and pulling a hill, I will downshift or delay an up shift to OD. In the mountains, I will drop off 70 a little on the long uphill grades. We only put just under 10,000 miles on the coupe last summer. Gene
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