1936 Coupe ****** options ??

Al 29Tudor

Al 29Tudor

Well-known member
Good morning Gents,
I intended to post this question here yesterday but apparently posted it on the model "A" forum.
I've been on the model A forum for several years but I'm now considering buying a 36 coupe. Are there any transmissions you would recommend for highway use. I'd like to cruse at 70 mph without killing the engine.
Is the F-150 four speed an overdrive ******? If so, is it close to the 25% reduction of the Mitchell?
Thank you for your help.
Al Leach
 
Al, it's not the ****** that determines highway speed capability, it's the differential ratio. If the '36 has a 4.11, it can be changed out to a 3.78, which will allow 65~70 mph, or to a 3.54 for even higher speeds. The trade-off, of course, would be the low end, so you might consider a Mitchell, or better yet, a Columbia overdrive.
 
Alan, he's talking overdrive type trans, the F150 four speed is direct drive in third and overdrive in fourth, like fourth and fifth gears in a T5.
So I guess his question is about the ratio of the overdrive gear in different trans.
Will have to say this, you will not kill a flathead at 70 mph with a 4.11:1 rear gear. Sure it'll be buzzing some, but it'll live on fine. An overdrive will drop the rpm to what most would be more comfortable with. A Flathead V8 and a Model A engine are almost from different universes. A stock V8's valve springs will govern the high rpm (too about 5000-5500) at this rpm the engine won't eat its self, most folks won't go near that rpm. A stock model A engine can easily get to a rpm level that will shorten the life considerably. And that rpm is a lot lower.
Martin.
 
My bad. I was thinking this was a mostly stock forum, and I'm constantly reminded that it's evolving. :rolleyes:
 
Thank you Gents for your help and additional web site.
That's it - Marten. I want one more gear that's OD. Your other comments are reassuring also. Different universe - the "A" is fine up to about 45mph way too slow for the open road. Plus the brakes at speed just won't be enough.
Thanks again,
Al
 
scooder said:
Alan, he's talking overdrive type trans, the F150 four speed is direct drive in third and overdrive in fourth, like fourth and fifth gears in a T5.
So I guess his question is about the ratio of the overdrive gear in different trans.
Will have to say this, you will not kill a flathead at 70 mph with a 4.11:1 rear gear. Sure it'll be buzzing some, but it'll live on fine. An overdrive will drop the rpm to what most would be more comfortable with. A Flathead V8 and a Model A engine are almost from different universes. A stock V8's valve springs will govern the high rpm (too about 5000-5500) at this rpm the engine won't eat its self, most folks won't go near that rpm. A stock model A engine can easily get to a rpm level that will shorten the life considerably. And that rpm is a lot lower.
Martin.
Click to expand...
a Flathead running at 5000 to 5500 rpm for any length of time, in my opinion would eat its self, unless you plan lots of cross country trips were you need a overdrive ****** with lots of fab. work, adapters, open drive line, rear trans mt. ?? think about a Columbia, cool factor is way up thier
 
There are several different models of F150 trans. They come from different size engine packages, and the OD ratios are different. Regardless, the 84-87 is the one you want. It has the top shifter close to a stock early Ford position. I have one behind my '47 engine, and it's great. If you leave it stock, you are looking at converting the banjo to open drive (I used a '47 pickup banjo) and a system for locating the wishbones. However, over on the Model A forum there is a whole thread with pics on how to convert the tailshaft of the trans to a closed drive. I did this on a previous trans and it works fine. The only negative to that is needing to shorten the torque tube slightly. Whichever route you choose, it is a somewhat costly exercise, and not as easy as installing a Mitchell OD. The upside of the F150 trans is that your flathead will never destroy it, and it has synchro on 1st gear. here is a pic of the trans I modified to torque tube drive. I welded an early stick to the shifter stub.

 
There is a chart somewhere on the interweb of all the different models and all the ratios. I have it on my work computer, so will post it up tomorrow when back at work.
 
Gear Ratios

Truck
1st Gear 3.25:1
2nd Gear 1.92:1
3rd Gear 1.00:1
4th Gear 0.78:1
Reverse 3.25:1
Car
1st Gear 3.29:1
2nd Gear 1.84:1
3rd Gear 1.00:1
4th Gear 0.81:1
Reverse 3.25:1
 
34coupe said:
a Flathead running at 5000 to 5500 rpm for any length of time, in my opinion would eat its self, unless you plan lots of cross country trips were you need a overdrive ****** with lots of fab. work, adapters, open drive line, rear trans mt. ?? think about a Columbia, cool factor is way up thier
Click to expand...

Eat its self? That's your opinion and your entitled to it. Obviously if the valve springs limit the rpm you won't be using that rpm would you? The valves would be bouncing. And power drops off sharply at around 3600-3800. The oiling system and engine parts are perfectly within there capabilities at this speed.In top gear it won't get near 5000rpm, so it won't eat itself.
The fact is, a Flathead is a very good, very strong very well lubricated engine. Think of the life these things had in commercial operations, screaming there heads off in low dragging God knows what up God knows how steep a grade. I've said it before and I'll say it again, they aren't made out of chocolate and cheese! They can take an incredible amount of abuse, and still go on. If they are properly rebuilt. And won't be hurt at 70 mph even with the 4.11.
These engines deserve more respect than your giving them.
Not all overdrive trans swaps need open drive or lots of fab work. Sure a Columbia is cool, but the cost of a properly rebuilt one? Easiest has to be a Mitchell, Big Brown Box and wrenches, job done.

Martin.
 
sidevalve8ba said:
Gear Ratios

Truck
1st Gear 3.25:1
2nd Gear 1.92:1
3rd Gear 1.00:1
4th Gear 0.78:1!
Reverse 3.25:1
Car
1st Gear 3.29:1
2nd Gear 1.84:1
3rd Gear 1.00:1
4th Gear 0.81:1
Reverse 3.25:1
Click to expand...

Are these for the F150 trans?
Were they fitted in cars?
If so what cars?
Martin.
 
I think when they say cars they maybe mean the jeep. The 84-87 F150 RTS is the one to go for, they're all good, just variants in the ratios. My current one has 68% ratio in 4th, and I'm doing around 2000 revs at 60mph, with 4.11 diff gears and 31" tall tires. I can also slam it through the gears like a sports car without fear of it breaking, a feat I could never do with any of the couple of dozen flatheads I've owned over the years.
 
RPM examples at 70 MPH would be:

29" Tire - 4:11 gear would be 3333 RPM
32" Tire - 4:11 gear would be 3000 RPM
 
I did a little more digging around for the four-speed overdrive RTS Ford transmission and came up with this chart which shows available gear ratios in this particular transmission. As you can see they made them with different ratios depending on the application and the overdrive ratio varied somewhat.

https://www.fordbarn.com/attachments/67818/
 
Ted
That's a great chart.
It would appear that the 3rd trans in that chart would be best as far as the ratios are concerned. The other 2 are missing a gear (as opposed to a true toploader 4 speed).
Just my thoughts
Jim
 
Jim, I agree the third one has very similar ratios as a 29 tooth early Ford three speed plus am overdrive. So should drive real nice. The others have a deep first gear and are gappy, like you said "missing a gear"
I'd like to know if the ratios in the link above are for the four speed top loader with the shift levers on the side, where the overdrive forth is actually where the third gear usually sits in the trans. If you see a complete trans of this type, the third/fourth selector lever is upside down compared to a regular four speed top loader. Or are they for the late F150 trans with the shifter tower on top? And if the two types of fourth gear overdrive trans share guts?
Martin.
 
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