Considering using a narrowed 9" rear that I have for my model A project. Worried that the gear ratio may be too high for use with a mild 302, C4, and tall 16" rubber (7.50's). The ratio checks out to be 2.75 (16/44 ring and pinion). I figure it will be a great highway cruiser but will it get out of it's own way at traffic lights? Car will be light, fenderless coupe. Opinions please.
I've had a 2.75:1 in two hot rods with similar power. I did switch to a 3.50:1 in my '40 because it was such a turd off the line with the tall tires(taller than yours). In that light car,you might like it fine. Will you be doing a lot of freeway driving?
I have a 276 8 inch in the coupe. 255 70 15's TPI 350 It will go quite well. But will not set the tires on fire. Ops turbo 350 trans.
If you already have it, I would surely try it. I think you would be ok since the Model A is probably pretty light. My experience with really tall gears is limited to my old Ranchero. It has a 2V 400 with a C6 and 2:75 rear gears. It will light the tires at will on take off and is fairly heavy. One thing I have noticed is that mileage seems to improve to run about 3000 rpms.( Which is speeding,lol) I am going to try rear tires that are a couple inches shorter and see what happens. You can always off set the high gears the same way, by using lower profile tires. Good luck.
I have a 2.78 in my '38 woodie. It's no drag racer, but it goes from 65 to 85 like a rocket out on the highway. What kind of driving will you be doing?
Yeah, I am interested in a good highway car. Was concerned about using a C4 due to lack of OD. Guess I don't have to worry. Not planning to need a tire scorcher but a decent pull from a light would be nice.
search online: project33.com - and click on calculators - easy way to figure out what results to expect with what you got
I'm running a 2.75 9" in a '32 Roadster highboy with a Richmond 5 speed 3.26 1st gear and 1 to 1 5th. 30" tire, it works perfectly for me and 70 mph is about 2200. I agree that you should try the 2.75 and change it if you need more acceleration, but you will increase highway rpm if you change to a 3.50. Check the speed and rpm formulas to help determine the best gear ratio for your application.
A 2.75:1 ratio is low...not "high". Because the final gear in a trans is sometimes referred to as "high gear", many make the common mistake of thinking that a highway-friendly gear is also a "high ratio". But it's a reference to the numbers. 2.75:1 is quite low, 3.55:1 is higher, and 4.11:1 is higher still.
I know what you mean Rickybop. Terminology may be wrong, but we are talking about the same thing. Thanks. All the other advice is also appreciated.
Mine: Ford 300 6 C4 trans 2.76 rear gears 7.50 17-- 32 inches tall Havent had it out on the highway yet, but it takes off easily.... no problem spinning the tires at all.
My Son is running 2.79 gears in his T bucket with a built 306 CI Ford and C4. When I am following him and he leaves a light I have to push my 27 hard to keep up and I am running a 331 stroker with 4.30 gears. I originally thought his gears would be too high but they have worked out perfect. I say try the ones you are thinking about and you might be pleasantly surprised. Don
If someone on here was complaining about the 3.23's in his heavy car, I would expect at least 90% of the folks on here would say they needed to go to a "lower" rear-end ratio, and we would all understand what they meant.
It's like when you're out drinking on a week night and its past midnight and you tell your buddies you gotta work tomorrow and the one douche bag says "But it's already tomorrow! Huyuk huyuk huyuk!" We know what you mean... Posted from the TJJ App for iPhone & iPad
90%? I doubt that, tubman. Douche bag?...lol..."thanks" deto. Wasn't nitpicking...just clarifying for those that truly don't know and might be mislead by the misuse of terms. I knew what he meant too. But it's still wrong.
All my life I have considered "lower" gears as being like 4.88's, and "higher" gears were like 3.00's. For example, if I had 3.00 gears and told my buddy I was going to put lower gears in it, those would be numerically higher, as in 4.88's . Same with saying you are going to put "deeper" gears in it, to me that means lower gears. "Steeper" gears would be higher gears like 3.00's. But it is all good, we interpret terms differently, but know what we all mean. Don
I ran 3.25:1 with a BBF(390) in my 66 Fairlane, best of both worlds when compared to the 3.9:1 I originally had. Great off the line but top end suffered as did economy.
What's the first gear ratio in a C4? I had a Suburban with about the same rear gear, but the 700R4 in it has a fairly deep first, it was never a problem, even did some towing with it. I have to think in a car that light you're still going to be able to spin the tires pretty easy if you want.
They'll call you sluggo from stoplight to stoplight, maybe, but on the open road, they'll be cryin'! I've got a 2:76 in my daily driver, a not-HAMB-friendly 1980 PLymouth Arrow pickup with a 360/904/8.75 combo driveline. The truck weighs 2,700 lbs with me in it. The motor is stock now, and yes, it's a bit light on bottom end acceleration, but like you, I knew it'd be on the highway a lot, and it cruises at 80 MPH at only 2,400 RPM. Sweet! If I do run it up through the gears, as soon as it gets over 3,000RPM, it really starts pulling as the engine gets into its torque curve. It'll run about 95 MPH in second, but I really haven't had it much above 115MPH in high yet. Even with a bone stock engine, its got lots to go on the big end.
WRONG, " Numerically " higher is a LOWER gear set when discussing rear end gear ratios. Always has been, always will be.
I had 4.11s behind my 401 and it wasn't a fast car anywhere. Now I have 2.70s and I usually just idle off at lights. Once it's rolling, I can plant it and burn as much rubber as I want. And I don't even need to change gears until I hit the edge of town.
I ran 3.08 for years, first in the muncie was good for 65 mph. Recently started w/a 2.79, then changed to a 3.43 w/overdrive. With an automatic and highway use planned sounds like you'll be OK.
I believe you are correct. Having taught Auto Shop over 40 years this was always a hard concept to grasp. Being this is a 'Traditional' forum we should use 'Traditional Terminology', not just what someone thinks it ought to be. Or as Rush Limbaugh says, "Words do matter!" Honestly, I don't really care but the OP was told he was wrong when, actually, he was right.
Thanks to all you guys for the input. I probably would have picked something closer to the 3's but since I got them with this narrowed rear, it looks like they should work okay. The project33 calculator was cool. It looks like I'll be around 1775 rpms at 60 mph with 31" rubber. In regards to the High-Low thing, it's all good.
crminal, that ge****t may not be ideal for acceleration from a stop, but it is what you have on hand. If it is a problem, it is easy enough to change to a LOWER gear ratio later. You may like it just fine, especially when filling the fuel tank. By the way the terminology you used is what I was taught and what had been the accepted term until relatively recently when some have tried to change it. When I was younger some oldtimers referred to it as a "lowspeed" rearend, or a "highspeed rearend, which makes some sense. ~Alden
2.85's in my fairly heavy '51 Pontiac wagon, 4.8L (that's 283 cid), 4L60. It'll light 'em up with a touch of power brake (posi), pulls hard, and goes from 60-80 like it's pants are on fire. We tow a 4500 lb trailer, and our enclosed car trailer, it's great. The travel trailer I can tow in 4th (OD), the car trailer, loaded, I hold it in third. I changed from 3.75's, it's MUCH better now. 55 mph is just a shade over 1500 rpm. It's loafing. Brian
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