I know I've made a lot of money selling T5 conversion kits and transmissions but for 25+ years there's been a nice 39 trans with open drive conversion sitting in my storage shed. I also have an early 93 world class T5. I have only had one car with a 39 box and that was 50 years ago and it always jumped out of 2nd gear. I have just had a nice FH built and this winter I'm starting on my retirement 32 roadster. I'm thinking about sending the 39 box to VanPelt for a freshening up and putting it behind the FH in the roadster which flies in the face of everything I've done for the past 25 years. I'm just wondering if I will regret my choice?
I was reluctant to install a t5 in my 37 coupe with a 430 Lincoln. I had installed one in my 65 mustang boss 302 Shelby clone. I really like the way they shut and with the 4.11 gears, the 5th gear was welcome.i think you will like it.
I agree. The '39 box it is! Driving a flathead with an original Ford trans is kinda a zen thing. You need to know the "rules", and usually follow them. It gives you a connection to real hot rodding, not modern hot rodding. Sure there are less gears to get you up to top speed, but once you are there the fun is the same. I bet you can choose the perfect gearset for the quickchange to cruise at 70 MPH.
Now if you're building a car with only original classic parts then go with the ford transmission, if not go with the t5.
I'm going to say it all depends on the driving plans for the car. I'd say that a lot of the feedback from your adapter comes from guys who rack up highway miles on their rods. The guys with the early boxes for the most part may not do as many long road trips. The overdrive lets you run a 3.7 or 4.11 rear gear and still be up around 3.0 final drive or under for the big long roads. With the three speed it is either run rear gears for poke around town or run gears for serious highway cruising with a bit of tricky clutch work around town.
I've had the old top loader 3 speed and a T5. They are both good but if a traditional build......gotta be the 39 box. Done right, it won't pop out of any gear.
So what if it doesn’t pop out of gear. It was designed for machines with lesser horsepower. A decently strong flathead can put the cluster gear in shambles. Yes, I have had a “heavy foot” for years and way back there in the 70’s when the “only “ adapter available was the Offenhauser to Chevy 3 spd or 4 spd labeled as 5272a,I purchased one and ran a Muncie close ratio 4 spd and a nine inch ford knowing my “stronger” flatmototors could not and would compromise my ability to run my flat motors hard..Ran a Muncie 4 spd for 25 years after destroying all the available weaker 39 style boxes from the local wrecking yard. I know I will hear from the traditional “believers” that the 39 is o.k. But I tend to disagree. My 39 cabriolet (street driven daily in s.Texas) has run 80 in the 1/8 mile and performed flawlessly time after time. I vote NO on the weaker 39 box.
I would do the T5 no questions asked. When I owned the Rocky33 that is the one thing that made that truck so fun to drive.
Gonna take my flathead powered sedan with its '39 box on a five hour (one way) road trip to Back to the Fifties next weekend. I've already done it over a dozen times.
Cruise about 70 at 2600 RPM. Gotta have some leg stretching breaks along the way. Still has the spoon pedal, and no cruise control.
I have one of each behind my hot bangers. The T-5 is the answer. BS on the “zen” of the ‘39. Mine has synchronized Zephyr gears.
Set your chassis up with a crossmember for each tranny. Put the '39 in for old times sake, if you decide you don't like it, you're all set to change it.
I've had a 39 transmission behind a flathead in my old black 4 door sedan, I loved it driving around town or on the interstate,but when I drove the car to North Carolina or Tennessee it was inadequate, I currently have a 5 speed in the wagon and it is the perfect transmission for town ,country or mountains. I had a top loader 4 speed in my old 3 window and it had the old school vibe, I still have another 4 speed and a flathead waiting for a future project. HRP
If you use the 39, wait till you can find a set of 25 tooth gears. They are much harder to break and being closer ratio will be a lot more fun to drive. Even with no synchro on first, you can still downshift at 60 with 4.11's if need be. If you use the T5, put the #212 gear set in it. You will enjoy it more behind the flathead due to the closer ratios. Oh, and if you use the 39, put the standard mods in the shift cover and it will shift as fast as a Lenco.
Funny.....maybe ask over on the Ford Barn with those guys running a 39 box behind their bangers - and how many smiles per miles they get ! Here - you always likely to get the non but happy not traditional reply.
The tower sticking up thru the floor and a swan neck shifter is way cool in a roadster, with the stock park brake handle. I run the 39 style box behind a 50 merc. Also run a quick change with 3.48 final. It runs down the freeway at 75. The small front tires, potholes and ruts are more of a problem than no o.d.
I have driven cars from the 30s, 40s and 50s ONLY for 52 years. No modern cars. I broke 39 transmissions and they had been rebuilt and driven carefully. Go ahead with the 39 if your car is a toy that is rarely driven. If it will be used as a driver, the modern transmission changes the car from a putt putt to a pleasure to drive. I have driven my avatar to 4 states since I installed the overdrive transmission. I use a Model A shift lever
As a side note here, any piece of machinery can be broken if abused. It is just knowing where the breaking point is. I won the Northwest Hot Rod Road Racing Championship in 1954 running a 300 hp flathead into a 25 tooth 39 transmission. That was a 6 race season. Did it on one transmission and one engine. Used first gear 4 times each lap with downshift at 60 mph. At the drags the next day I won my class at 116.58 in 11.34 sec. using second and high. The car was a 2300+ lb. 32 coupe.
The 39 box... It is what it is and what it is ain't bad. I think you would enjoy it. I had one in the F1 (the 1950 truck version). It was my favorite thing about the truck. Of course it was worn. It had been through at least one flathead and 2 302s. 2nd gear was an absolute blast behind a hopped up 302. That truck would freaking fly. Like I said, it was worn. It would not hold second in a coast. Under power or pulling it did fine. Personally I loved it, it was fun. Since you have/have had T 5 cars....been there done that, I think it would be nice for you to run a 39 again. If that unit is nice, I don't know if I would send it off. I would be tempted to try it if it looked good inside. Your results may vary. I had fun with mine and it was wore slap out. As long as you don't purposely try to tear it up, It should provide years of service.
Not to derail your thread, but have you considered a T-170 from a Ford pickup? 3 speed + OD. I have one for my 40 flathead coupe, but it’s still sitting on the floor. F-1 box in it works fine.
I love the 5 speeds behind flatheads and 4 bangers. I even loved the one I put behind my 291 Desoto hemi! You can so much more reep the fun of a flathead with the the added gear options. Just my opinion. I'm certain you can find an adaptor.
Could I ask what type of Q/C are you running ? And the gear set number in the rear - top gear number and bottom gear number ?
My answer is neither. Find a '49-51 Mercury overdrive transmission, install the overdrive guts in your toploader box and then you will have the best of both worlds; the oldschool toploader vibe plus overdrive when you need it.
Running an original Halibrand V8 center in a '34 rear. Using 4:11 ring and pinion # 4 gear set, 22 on top, 26 on bottom.