Overdrive in a B3B truck

[pflaming]

I have a nice '56 230 engine and a tyranny with OD that came out of a car. I intend to find a way to put that into my truck as it is , single carb, single exhaust pipe, etc.

There are differences between the truck and the car bellhousing to wit:

1. the car bell housing and tranny rest upon a cross member white the truck bellhousing rests on mounts attached to the frame rails.

2. the car brake and clutch pedals are mounted to the frame while the truck pedals are mounted to the clutch housing.

3. The front mounts are so similar so that that is not a concern, attach that mount then work in the back.

4. Fuel pedal linkages may work. . .

So now the QUESTION: What issues am I unaware of.

I really enjoyed driving this truck on the open road , i.e., freeways. All I wished for was another 7 mph and a quieter cab. The ride, tracking, handling were all to my liking. So now to figure out the OD. Suggestions encouraged.

[Don Coatney]

Suggest you simply find some taller tires for the rears. That is the easiest way to gain the 7MPH you are looking for.

[Desotodav]

Better diff ratio PP?... that would give you some more miles! I recall that you changed it, but I don't recall what you had in there.

[pflaming]

I have a 3:73, so an overdrive gives a 3:53 approx at the top. It's not just the higher top speed, it's all the choices availalbe between. An overdrive allows such convenient shifitng on rollng roads, passing, mountain driving, towing, ete. and that is Y I wnt 1. So sugesstions to install what I want, for whatever reasons, is the question.

[Don Coatney]

Have you ever actually driven an old Mopar with a overdrive transmission?

[pflaming]

No, but our '52 Ford and my '59 Nash American both had OD's. Ford a V8, American a flat head 6 and I learned to drive them and the benefits therewith. I have also driven a lot of 50's trucks with two speed axels and they work much the same. They just give a knowledgeable driver a lot of choices. So the difference to a Dodge has to be minimal.

[Don Coatney]

I have a 3:73, so an overdrive gives a 3:53 approx at the top.

 

Will you please explain how a 3.73 gives a 3.53 approx at the top? I tried all the mathematical tricks I have and I fully do not understand your statement.

[Don Coatney]

No, but our '52 Ford and my '59 Nash American both had OD's. Ford a V8, American a flat head 6 and I learned to drive them and the benefits therewith. I have also driven a lot of 50's trucks with two speed axels and they work much the same. They just give a knowledgeable driver a lot of choices. So the difference to a Dodge has to be minimal.

I suggest you quit talking with all this senseless gibberish and develop a sensible solution to your issues. It seems you want to maximize your torque and horsepower curves at all times irrelevant of the road topography. Below is the inner workings of a manual transmission. You will note all the moving parts that limit by design the maximum efficiency of maintaining engine torque and horsepower to suit the driving terrain.

 

 

One possible alternative to this system is a Continuously Variable Transmission as pictured below in elementary form. With this system the engine can always run at the most efficient RPM for maximum torque and horsepower utilizing both over and under drive. Transmissions using this design can be found in many cars built today. It may well be easier to find and install one of these transmissions than to do all the modifications required to install the antiquated overdrive in your proposal.

 

[pflaming]

Don, yes what you are showing is what was on heavy farm equipment in the '50's until the hydralic systems were designed.  Our self propelled combine (harvester) had such. There were several gears but the crop and terrain really determined what needed to be. Once that was determined then the dual variable pulleys took over. Always had to shine them up for the next season.

 

I don't want total flexibility. As a teenager I loved to haul wheat, that truck had a two speed rear axle and it was fun to keep the rmps stable over the rolling hills, deep valleys etc. on the way to town. I loved the shifting.  An overdrive in my truck is personal, "I like to shift"! Show what that flat six will do on an incline to the mountains by controlling the RPMS.

 

I'll figure it out and report back when done.  

 

Yet, thank you for your input, always appreciated.

 

PF

[Plymouthy Adams]

the CVT is out there..holding all opinions on longivity..they work great on a go-cart, snow mobile etc and some riding tractor and never without frequent belt changes..they tough on belts..

[Plymouthy Adams]

PP..in the hills..OD is virtually useless...unless you just like flying down hill without engine breaking and relying upon quickly fading brakes to slow your butt down...think theme park adventure ride here....OD is great at speed with little load and road variations that are generally less than +/- 200 RPM of sustained cruise..i.e, over passes and the like..ideally the OD needs to be 200 RPM less of max torque at lowest RPM this torque appears..as the flattie is very low RPM torque..you will always be out of socket for ideal torque and sustained cruise for max economy..you get a greatly increased mileage boost for sure..but imagine if you were able to speed about at the 1200 rpm and still be at 30% reduction..there is no balance for the flattie in this formula though you can achieve an acceptable value...ratio is still the very tool that gets you to top speed, engine speed..and when the torque runs out HP has to be developed to do the task that is why the higher RPM at a sacrifice of economy..again much improved with the OD but you still got a high trade off in the older set up.  I have never seen a torque/rpm chart for the flattie..but you can download that for other engines and see how it all inter  relates..principle is principle

[pflaming]

Tim, what you write is accurate, no help going down a hill. I grew up driving 50's vehicles. I loved to drive the trucks with their 2-speed axles and brownie trannies. There was so much a driver could do. I was hauling 300 bu ( 18,000 # ) in single axle trucks when I was 14 (Got a farm / school / church ) permit then. So I understand as much as most on what CAN be done with an OD.  

 

Thanks for the lesson, always nice to learn more, but my truck will have an OD! Case closed! 

[Don Coatney]

Will you please explain how a 3.73 gives a 3.53 approx at the top? I tried all the mathematical tricks I have and I fully do not understand your statement.

Still waiting on an answer???

[Dodgeb4ya]

the CVT is out there..holding all opinions on longivity..they work great on a go-cart, snow mobile etc and some riding tractor and never without frequent belt changes..they tough on belts..

Oh..and don't forget the reliable CVT trans in the early 90's Justy's!

[pflaming]

I haven't relocated where I got the information Don is requesting in post #13. First the 3:73 at the top is a 3:73, BUT when the OD is engaged, the OD ratio approximates a 3:53. I copied the following, edited as I copied so not the full article.

 

 

In 1953 and 1954, non overdrive cars used 3.73 and overdrive used 4.1. A car with 3.73 gears may not work too well with the over drive, you may never drive fast enough to avoid lugging the engine in overdrive. My ’49 with 3.9 gears seemed to be just fine.

 

 

    [personal note: I think this information came from an article in “Allpar” forum. Should have copied that] Note the effect of the 0.7 overdrive ratio on overall drive gearing:

Rear Axle Ratio Overall ratio in O.D.
3.54 -> 2.48
3.73 -> 2.61
3.9 -> 2.73
4.1 -> 2.87
4.3 -> 3.01 Wear and Tear

 

Plymouth engine design was quite advanced for the era. With full pressure lubrication to all bearings, a four bearing fully balanced crank, and aluminum pistons the engine was designed to withstand full power operation for long periods of time, that pertains for a Plymouth and other Chrysler products.

Edited September 25, 2014 by pflaming

[TodFitch]

Don't know where you got the first part, but the latter starting with "Plymouth engine design was quite advanced for the era. . . ." is from my website.

[Don Coatney]

I haven't relocated where I got the information Don is requesting in post #13. First the 3:73 at the top is a 3:73, BUT when the OD is engaged, the OD ratio approximates a 3:53. I copied the following, edited as I copied so not the full article.

 

 

In 1953 and 1954, non overdrive cars used 3.73 and overdrive used 4.1. A car with 3.73 gears may not work too well with the over drive, you may never drive fast enough to avoid lugging the engine in overdrive. My ’49 with 3.9 gears seemed to be just fine.

 

 

    [personal note: I think this information came from an article in “Allpar” forum. Should have copied that] Note the effect of the 0.7 overdrive ratio on overall drive gearing:

Rear Axle Ratio Overall ratio in O.D.

3.54 -> 2.48

3.73 -> 2.61

3.9 -> 2.73

4.1 -> 2.87

4.3 -> 3.01

Wear and Tear

Plymouth engine design was quite advanced for the era. With full pressure lubrication to all bearings, a four bearing fully balanced crank, aluminum pistons the engine was designed to withstand full power operation for long periods of time, that pertains for a Plymouth and other Chrysler products.

 

High revs on the engine can lead to premature wear.. So for continuous operations governors are used to limit the engine to speeds that can be maintained indefinitely. [Cannon 2002 14] Notes that over speeding an engine is defined as exceeding the RPM that maximum BHP is generated. [Cannon 2002 14] notes that “for long engine life, maximum engine RPM should be held a couple of hundred RPM's below the rated RPM at maximum rated brake HP”. Thus it is reasonable to assume 3200 to 3400 RPM, as a maximum sustained RPM for the engine. Production engines should give good service even when run below that RPM. (All Plymouth 6 cylinder engines of this era had maximum BHP at 3600 RPM.)

 

Interestingly people are no longer used to the sound of a high revving engine when cruising at highway speeds. So even though the engine and drive train is capable of sustained operation at above 3000 RPM, drivers younger than around 45 years old fear that they are beating the machine to death. There are lots of Internet posting and queries about changing the final drive ratio or installing overdrive transmissions to solve the non-existent issue of the engine turning over too fast. Many of those have not considered that the limit on high speed driving might not be the engine but rather safety issues with the brakes and suspension.

PP, The correct answer to the question I ask is included the gibberish you posted but I don't think you have a clue on what the answer is nor about what you are doing. I and others have directed you on where to go to figure out your engine RPM's at any given speed but it is apparent you have not followed the instructions. I hope you will be able to find tires tiny enough to make your overdrive work going up mountains with the current differential gearing you have in your truck.

[pflaming]

My apologies and regrets for asking the question. 

[Young Ed]

PP, The correct answer to the question I ask is included the gibberish you posted but I don't think you have a clue on what the answer is nor about what you are doing. I and others have directed you on where to go to figure out your engine RPM's at any given speed but it is apparent you have not followed the instructions. I hope you will be able to find tires tiny enough to make your overdrive work going up mountains with the current differential gearing you have in your truck.

I don't think gearing is his issue. I've got a 3.73 and overdrive in my 48 plymouth and its been great. His issue is trying to adapt a car transmission into a truck. The hole in the bellhousing for a truck is significantly bigger than one for a car. So you've got to figure out how to overcome that(adaptor) or figure out how to use the car bellhousing and reenginer the pedals and rear engine mounts.

[Jeff Balazs]

I looked at this very early on. For the truck application it seemed to be far more work than it's potential worth. 3.55 or perhaps even a 3.23 final ratio just made more sense. More bang for the buck and a simpler setup makes it a win/win in my book.

 

Jeff

[Dodgeb4ya]

I put an R-10 OD in a 51 dodge panel and the owner drove it for 2-3 years till he sold it. It operated perfectly and very smooth at 70 althought the panel was top heavy.
It was a bit of engineering work. The bell housing was re drilled a spacer ring made and the linkage was the biggest dificulty.

 

BTW 4.3 to 1 was the standard OD rear axle ratio for the plymouths.

Edited September 26, 2014 by Dodgeb4ya

[Plymouthy Adams]

per the book the OD for the long wheel base car Plymouth was 4.3 but for the 111 and 114 wheelbase the stock was 4.1..as the OD was made retro to dealer for 51 models still on the lot they were dealer installed and considered stock for judging, left with 3.9 as stock I assume as there is no mention that a hog head was included in the kit for axle ratio change..

[Dodgeb4ya]

My OD info is from the technical bulletins and of course now I cannot find that specific # bulletin.

 

A bulletin but not the correct one....

Edited September 26, 2014 by Dodgeb4ya

[Plymouthy Adams]

different sources..different specs is not uncommon it seems..the Plymouth Service Manual is my reference...(page 22..data and specification table)...for sure the 111 and 114 wheelbase cars did have different rear axle ratio as stock compared to the larger wheelbase car..these I have verified on numerous occasion and have proven out to be correct in my experience...the only thing I cannot get a verification on  is the dealer installed units..I am sure they did not change the axle ratio on install..inquiring minds want to know..thee is also a gear change for cars known to be shipped to hilly country...these cars could have a lower ratio as noted in the manual.  While the 54 is covered in the book the automatic tranny data is not..my automatic has a 3.73 rear gear same as the torque converter driven hy-drive units that debuted in 1953...the hy-drive due to the converters torque multiplying characteristics also had a higher first and second gear and also a higher reverse..the two speed automatic speaks for itself

[Dodgeb4ya]

Goofy production stuff like the P22 suburban and savoy rear axle ratio changed to a 3.9 in JAN of 1952.

Transmissions used 80W up till early 1951 then on to10W for easier shifting then back to 80W for quieter shifting in later 1952.