Hey fellas, i have a couple options for the rear end for my little hotrod project. Its a light little roadster pickup, will be running a 350 hp 327 and a t-10 4 speed. I have a 4.10 out of an s10 pickup, not really digging that, also have a 3.23 out of a 56 olds and what apears to be an early 50s ford rear, not sure on its ratio yet but most likely 3.73 or 4.10. I will also be running 31 inch tall tires in the rear. My question is, will running something as tall a a 3.23, with that tall of a tire, make it a snail off the start? Or being a light little truck, would she still have enough torque to stay al little peppy on the throttle? I did the rear ratio calulations per tiresize and it came out to roughly a 2 87:1 at final drive. I know in the past i have swapped gears for a better highway gear and have really noticed the difference in big heavy cars, juat wondering the difference in a really light car, is it livable? Thanks! Sent from my iPhone using H.A.M.B.
My roadster has a 3.00:1 rear gear and it's powered by a turbo'd 4-cyl backed by a T5. It smokes the 12" wide tires off the line and I rarely ever use 5th gear on the freeway. Car weighs 1500 lbs. I'll bet you'll be happy with 3.23's.
1800 lbs rod with 3;00 rear works find with 3 speed standard. Been driving with 65 Mustang rear near 20 years. The first rear I had in it was 49 Olds,was closer to 4/0. I like the Mustang rear better,First gear last longer.
I've got a '50 panel truck, stock-ish 350cid, that's on the hefty side, with a 2:80 open diff. The tires are shorter at 25" but like I said, "heavy". My neighborhood lets out onto a 70mph state highway and I have no problem merging and getting up to speed. The tires chirp and scratch a little. You'll be able to break 'em loose in that lightweight.
If you are going to drag race it in the 1/4 mile, the 4:10's are the way to go. For street driving, the 3.23's will be about perfect. Just make sure you have a flywheel in the 25 to 30 pound range. The inertia will overcome the tall gears when letting out the clutch from a stop.
Had a stock mid 70s maverick 8” with 2.79s and 28-29” rear tires under the fenders of a 32 ford. Basic sbc 350 with a Sag 4 speed, and it moved out ok. Wasn’t gonna set the world on fire but the car ran that way for almost 30 years (and ran down the highway really nice). I would think that the 3.23 with 31” tires would be fine.
31" tall tire - 4.10 gear - 3.23 gear 60MPH 2669 RPM 2102 RPM 70MPH 3114 RPM 2453 RPM I run 3:55 gear in my Coupe with 31 tall tires.
I think it would be fastest with the 3.23.. I don't remember a lot of hills when I was out your way a few decades ago...
You asked for opinions and you now have some very good workable ones, BUT, you must first determine what type of driver you are and what you will doing with the car MOSTLY. Lower gears are for around town and cruising. (remember, your engine will turn 6000 all day) Higher gears are for cruising the freeways in a car that handles well at 85 mph. (not too many home built cars will)
Have to agree with Pete1, where and how are you gonna drive it? My 36 has 2:75 gears, 330 horse 327, turbo 350, 2770 pounds, and its a hiway flier. Fast enough to be a good race for a 5 litre mustang, but awesome on the hiway, which is what I built it to do, and because I live in the middle of nowhere, its all hiway stuff here.
This is exactly where im at right now. I completley agree with the handling issues that would arrise at higher speeds. Just weighing out drivability of both ends of the spectrum. Thanks everyone for the great input. Sent from my iPhone using H.A.M.B.
Pretty sure its the single groove, early to mid 60s, i looked into the casting about 2 years ago, but need to refresh my memory. Sent from my iPhone using H.A.M.B.
Here is what I have in my Deuce highboy roadster. I was looking for decent mileage since we take long trips but didn't want a slug. I run a crate 350, 1406 Edelbrock 4 bbl, 700R4, 3.73 posi 8" Ford, and 30.5 tires. That roadster comes out of the hole just fine yet squeezes 22.5 on the Interstate at 70-75 mph at 2,000, 2,100 rpms. It weighs probably 2,200 lbs. I enjoy cruising at 2 grand while staying with most traffic.
Use the following formula to figure speed at said rpm. 70 ? (speed) x 336.13 x rearend gear divided by tire diameter. With OD trans, multiply sum by .70(usual OD drop).
The nice thing about the automatic is the torque converters stator, the ability to multiply torque. You want the converter to flash to 2500 or so then couple tight. .. For the street builds, I always stay under 3.23, I like over 450 cubes with the 2.73 or 3.08..
My 31"A" has a sorta radical for the street 355 SBC, a wide ratio Ford toploader 4 speed, 9" Ford rear with 3.70 ratio and 29" rear tire and weighs 2240#. It's fast for a street setup in the 1/8, and fun to drive around town and short trips up to 100 miles or so each way.Past that the loud roadster style side exhaust, wind buffeting, and 3100 rpm @70 mph can be tiring, but I suspect my being 83 has a little to do with that, LOL. Besides, it's a topless roadster and rain is always a possibility here in GA! Si, if I'm going over 100 miles one way, I either go in a DD or my '40 coupe with a mild 5.0 SBF, T5, 3.70 rear & 30" tires and 2000rpm @ 70mph! Quiet, smooth, AC if needed, and outta the wind and rain! Point of all this is the gear best for you depends not only on car weight, but engine build (especially cam), how you use it, and how much of your driving is in town and short trips vs highway long rides.
I went 12.03 @128 with a 3.08 gear in a SBC powered 4000 pound Chevy pickup. I like a 3.2 gear for a trade-off street gear. I got an idea you will be fine.
You need to factor in the engine cruise speed which is dictated by your cam. If you are making 350 hp out of a 327. you likely have a good bit of duration. That will dictate higher engine rpm at cruise speed if you want the engine to operate within it's powerband. I have a similar build: Model A coupe, 351 Cleveland, 4 speed, 3.89 gears and 31" tires. In fourth gear at 45 mph, it's turning under 2000 rpm. The cam doesn't "switch on" until 2500 rpm or so, so it's a bit flat. I need 4.11 gears or shorter. Or shorter tires.
I would look around for a rear out of a Ford Ranger pickup with a 4.0 v-6. It should be a 3.55 or 3.73 depending on transmission . should be the right width and have a Ford bolt pattern for wheels and be an 8.8 so it will take a lot of power.
My t-bucket with a 29 inch tall tire and a 350/th350 combo with 3.25's will still smoke them, I did have 4.11's for around 4 yrs but got tired of spinning 3 grand on the highway and still having to ride in the slow lane. Here's the 3.25's, did I mention it will still smoke 235/75/15's
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