So i know i have a Heavy Duty 3 speed out of a late 40s pickup. What speeds can i expect through the gears with this gearbox fitted to a stock & strong 8BA in a stripped down not so heavy model A roadster with a 1937 rear axle and 7.00 x 16 inch wheels. I,m familiar with the passenger car 3 speeds but not with the HD stuff. I have a feeling that 1st gear is for pulling out tree stumps, is this correct ? Not expecting racing speeds, just need a general idea.
Top gear (3rd) is the same 1:1 ratio as the car trans, so there is no difference. Not familiar with the ratios of the truck trans, but it is more likely a wide ratio that has a lower first gear. Someone will know more. I am not even sure if your trans is synchro or not. If non-synchro, it is time to learn double clutch shifting. That will be a pain in the**** for anytime you want fast acceleration. The non-synchro is also much harder to downshift without crunching gears. If the trans is a compound low, it will have a very low granny gear first ratio around 6-7:1. This is the stump pulling gear you refer to. The trans with compound low actually has four gears, but for normal driving you use 2-4. The 2nd gear ratio is more like a normal 1st gear. The extra low granny is for starting out with a heavy load on hills, not for normal driving.
34Gaz I had a 51 F-1 3-4 ton pick up v-8 flat head and the same trans. you have. it would top out in high gear about 60 m.p.h. I would recken the rear gear was 4.11 or more. the trans is a very good unit. good find!! Merry Christmas Don in Indiana
Final drive is still 1:1, so I suppose that it depends on how many revs you can get out of your flatty in top gear along with your tire outside diameter and your rear gear minus any slippage in the drive train.
I am not 100% I am sure I have the right trans identified in the bulletins, but I think I do. I'm not entirely familiar with later Ford bigger than 1/2 ton trans...the one I am looking at carries 8D prefix, which likely appears somewhere on your top cover. I think 8D corresponds to '48-up F series 1 ton or 3/4 ton or whatever it is. This is listed as 3 speed spur gear (pull that lid off and see if gears are straight cut teeth). This lump has 3.714 first, 1.871 second, and one to one top. This makes the lower gears significantly lower than the 29 tooth wide ratio early Ford trans, and even more lower than the generally preferred 28 tooth passenger car gears. I don't think this is a very good choice...you'll run out of gear at a very low speed in 1st and 2nd and then all the bicycles will pass you before the engine can get up to a good power level in top. It is made for getting a very heavy load moving in a truck that really should have had a four speed. Don't know and too lazy to research the ton truck rear axle, but if 4.11's were available that would be the very highest option! This thing is heavy and has bad ratios for a light car. If you have 3.78 rear ditch this for any flathead passenger trans and you'll be better off, and if you are using open drive and have a 4.11 rear use either of the '49 types of overdrive trans. Open drive also gives you the option of easily adapting a lot of different later 3 and 4 speeds or a late model 5 speed. That thing belongs in a dump truck, not a roadster.
I agree. Your rear end ratio plays a big part in this. Car*******s are the cheapest item in the driveline category. I'd find a good top loading car transmission. MacVP here on the Hamb can rebuild one for you for lump change.
first off your trans is 1to 1 final drive if you have the horsepower you can go to higher rear end some where around 3.78 or 3.53 and pickup some top end. being your from Europe you should be able to get a Volvo od unit and put that in the torque tube run a lower gear like 4.11 and still have a nice top end. get rid of the non syncro box though no fun double clutching.
The detachable front part of the trans case (bowl shaped) is often used to fabricate an adapter housing to mate a later transmission to flathead engines. There are threads here on the HAMB detailing that procedure. Unless you are building an off road stump puller, or know someone who is, that front housing is the most valuable part of the****embly. Ray
Don't scrap that heavy three transmission. The big truck guys want them to replace the no synchro four speeds in their trucks.
Scrap it......are you crazy?....advertise it on ford barn......someone could use it......make a few bucks on it.....scraping ANY old ford parts is bad carma! Posted using the Full Custom H.A.M.B. App!
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