I've been kicking around this idea for a while, could a person use a granny box 4 speed (out of a 60's chevy truck for example) and just use a rearend with really tall gears ( 2.73, etc ). It seems like it has been discussed on here before, but I can't recall, anyways just curious what everyone's thoughts were. Is there something I'm missing, sounded like a fine plan to me.
Thought about this myself. Can't see why it wouldn't work if your engine can pull the gear without bogging.
Why not just use a Vega Saginaw with the 3.11 low gear? as long as you do not beat on it or bang gears it should hold up for years.
For that matter, you could use any of several Borg Warner T-5 trannies that have a high 3 to low 4 first gear and never use 5th. 4th is straight through/direct. No real necessity to shift to 5th. The T-5 is much lighter and better shifting and is available with GM or Ford bolt patterns. And, they have becpme plentiful enough to afford, especially those with that really low 1st gear. On the other hand, that would make the most sense only if you already have the tall rear end gears. If you have to source a rear end anyway, well.................. Ray
Thats what i was thinking too, about the low 1st gear, it should'nt bog no matter the horsepower. I was sort of hoping that someone who has done it, would chime in, i know im not the 1st person to think of this.
The thing is, those transmissions are big and heavy, and if you want it for performance they're not designed for fast shifting.
if you're going for gas milage tall gears don't necessarly make it happen. best milage is a balance of factors. tires, gears, torque, you want your engine at it's sweet spot at cruising speed. a long stroke six might pull taller gears than a short stroke 8 at 55-60 mph. my 354 Hemi with 3.00 gears got it's best mpg at 80 mph. my 396 chev mpg went straight down after 60 mph I really don't care how much gas cost I'm not about to drive anything thats not fun dammit figure what RPM you engine torque peaks then figure what tires and gears will put you at that RPM at the speed you cruise. you'll be much happier than throwing the tallest gear you can find.
I agree with you NONAME about engine choice/ final drive characteristics. Part of the reason i was asking is because i already have these parts, i know right nobody saw that coming lol. I just love the feel of driving old stuff, ie the transmission, but also like my ride to have some longer legs if you get my meaning. Any of the overdrive 5 speeds just arent the same to me.
I've heard of guys using a second transmission to turn an old truck into a tractor, get lots of reduction and run tractor size wheels - not what you're thinking of?
Dont truck four speeds have a low first, granny low, and 2-4 are regular driving gears like a standard 3 speed? IE. regular driving is 2-4 and only use first when extra torque is needed. To me it would be pointless to use a truck 4 speed because even if you can take off in first with a high rear end gear once you hit second the gear split would negate any advantage.
How can you get any "overdrive" effect-different than your 3 speed, when that 4 speed has the same 1:1 high gear ratio? the "S"-5 speeds are your best option and shift a lot slicker than that old truck box.
^^^^^THIS^^^^^ how does the term overdrive come into a conversation about a 1:1 transmission? the only difference between the 3 and 4 speed is how you manage the rpm in between the 1st and last gear. i think you just misstated your intent. what has been stated above is spot on. there are plenty of 'calculators' that help you to figger the right combo. start there. play with tire sizes. i just bought a 57 chevy with a v8/4speed. the tires were too small. i put bigger shoes on it and its like a completely different car.
I'm looking at a New Process A-833 4-speed used mainly in MoPars and a few mid-eighty's Cheyy 1/2 (1500) trucks. Low is a 3.09, with 4th a .73 overdrive. 2nd is 1.79, 3rd is 1:1. My 2.20 Muncie isn't the best on take-offs with a 3.36 diff., 283 Fulie is thirsty spinning at 3k at 70. Input bearing collar needs to be cut down to fit the Chevy bell - unless you can get it with the tranny. Came STOCK with a HURST SHIFTER, from what I read. Located a couple around 'Dago for $350, in phone checking. The Fulie pulls really well down low - from 1k-1200 up, with a copy of the 097 Duntov cam, so it might be livable around town in 2nd and 3rd gears. The 3-speed-OD WAS NOT AVAILABLE with the Fulie engines - but the 4-speed (Borg T-10) became available (dealer-installed) around June - July of 1957 for the cars and Corvettes. Close enough to satisfy my quest for PERIOD CORRECT, while making the car better for longer trips. Do a search for the A-833-Overdrive, lots of info for being an odd-ball trans! - Tim
The perception of the major 1-2 bang shift with a "granny gear" trans is a false hope. The low range and 2nd (1st travel gear) are not synchronized. The granny gear, or what we called a "creeper gear" is for rough terrain or steep grades under load. At least all the trucks I drove were that way...
GM did exactly that. The M21 was offered with 3.55 gears and the M20 with 3.08 gears. I believe the 2.88 1st and 3.42 1st super T10's were used in conjunction with 2.73 and higher ratios
I think the answer to your question is that it could work, but we need more detail to determine if that specific combo would work very well... details like the specific trans gear ratios, rear tire diameter, etc. If you are dead-set on using that trans, then the rear ratio and tire diameter might need to be tweaked to make the car drive like you want. If you are locked into the trans AND rear, then expect to make changes to the rear tire size. I think most folks approach it the other way... decide on tire diameter first (usually not much variability here due to fitment or aesthetics), then trans and rear ratio are decided upon together, as a set, in order to make the car drive as expected. The rear ratio, in most cases, is the most flexible variable here.
GM truck four speeds have first gear ratios of about 6.5 in first gear and 3.50 in second gear.If your vehicle can't take off easily in second gear with a 2.73 rear axle is got a gutless engine,or it's very heavy or you're on a steep hill.
Years ago, I drove a '63 Chevy school bus with a 283 and granny gear 4 speed. I almost never used 1st gear. Even fully loaded, it could take off effortlessly in 2nd.
Why not just find a five speed? They are out there and easy to install. Save your cash and go this route. I for one love four speeds but gas is getting too expensive I want to keep some of my hard earned cash in my pocket. Jay
A good T5 can be found for $200, if you dig. The last 4 I purchased were under $275. Why go a harder route?
I 'get' what you mean by 'po' bo' o'erdrive, but this ain't the way. Mostly because the truck transmissions just aren't designed for a good 1-2 shift. Too long of a throw going in (or out) of first, and first is not syncronised. Sure you can double-clutch, but the gear spread is too much for any ease of use. You'd spin it out in first, only to drop 2500 rpm (at least)going to second. A no-go in my opinion. Cosmo
My trany guy has never been a fan of overdrives. Early styles were weak at best and he always told me if you use the right size tires and gears below the 3:00's you could gain the same results and gas millage. I'm trying that theory in my 62 Nova Convertible with a 305 TPI and 2:79 gears. It has plenty of low end torque with the tuned port and town driving power for me. Time to take it for a test trip.
They're still 1:1 in high gear, I don't see how using one would be any advantage at all, unless you want to pull stumps or really like grinding unsycnro'd gears... They weigh as much as 3 or 4 modern OD transmissions too. Brian
i think he's using first to take off then a high gear rearend for gas milage. like others have said there is more to gas milage than that. even if you could take off in a 1.1 geared rearend dose'nt mean you will get 40 mpg. find out what tire size you want and go from there . engine peak eff. rear gear and trans. have seen 4bbl v8 get better milage than 6cyl. it is about the total package working together.
Exactly. There is no (except in rare occasions) "one-part" solution. Everything has to be taken into account, and everything has to work well together. Both of my 2300lb. cars get 28MPG, and one of them has a V8, that is 2.43x the size of the other car's engine. How? Component selection, and ultra-tuning.
To expound on the idea of having a good combination, the overall weight of the car should also be considered. A lightweight car doesn't need as much gear (or flywheel) to get underway. Case in point, my '29 roadster uses a close-ratio Toploader Ford 4spd with a 2.32 first gear, a 283 Chevy with aluminum flywheel, and 2.99:1 rear gears in the quickchange. You'd think that the car would be sluggish off the line with that combo...but since the car is so light, I have to feather the throttle to keep from launching too hard when there is a car in front of me (or a cop watching). I haven't checked my mileage lately, but last I checked I was getting 17-18 mpg combined city and highway...and I have a notoriously heavy right foot. All that and the car will literally scare the bejesus out of you if you lay into too hard. My '29 coupe on the otherhand, with a healthy 331 Chrysler Hemi, Muncie M-20, billet steel flywheel, and 3.50 rear gears only gets about 13mpg on the highway...on a good day. Both cars have tall 7.50-16 Firestone rear tires. It's all about the combination.
I ran a saginaw with 3 rings, (3.50 first) and a 3.00 rear. great out of the hole and good cruising rpm. 4th gear was just for cruising. I think that is what your getting at. I got a chance to make a few passes at the track. ran first second and third,4th had no "legs"
The previous owner of my '64 Chevy C10 with a '70 250 6 cyl and granny 4 speed (SM420), 3.73 rear end, wanted a cheap/quick solution for over drive. So he mounted 265/75 x 15 tires on the stock rims. The tall street tires (31") lowered the rpm at 70 mph, from 3200 to 2800 rpm. On a 800 mile trip it only got 13 mpg. Yeah, it saved a little on wear and tear on the engine, but didn't amount to much in gas savings. Still, the tall tires allowed the truck to cruise at a higher speed. Going from second to third gear is very sluggish. If I keep the truck much longer, I will install a 5 speed or AOD.
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