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3.54 rear?


Ward Duffield

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Often a greasy job as its all the #,s seem to hand stamped but are almost 1/4" high and fairly deep.(my experience on 4 only).

 

As Tim stated, Never  in one exact location- What fun! The #'s stamped are Most likely whats in the gears as it's just so much easier to change to whole third member as it is to just change the gears!. The factory would have the correct # even if optional ratio used.

 

The dealer may have done ?? if someone wanted a diff. ratio. Price?, replace the whole 3rd. member or replace the gears only.?.

 

Wrecking yard ratio change would almost guarantee a complete third member exchange as the price would dictate the 3rd. member vs. gears only change with labor and parts price to complete the change.

 

A stock 3.9 will work well for you in the 55-65 mph cruising range When you get used the the radiator fan noise!. Others have done it for Many miles!

 

Get it running and drive it some to see if whatever it has works for you,

Enjoy,

 

DJ

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A stock 3.9 will work well for you in the 55-65 mph cruising range When you get used the the radiator fan noise!. Others have done it for Many miles!

 

Get it running and drive it some to see if whatever it has works for you,

Enjoy,

 

DJ

 

This is good advice.  That's what I want to know anyway, before I change anything....  I need a basepoint before I start making changes.   Might put a tach on it temporarily, to keep an eye on engine speed.

 

When I had a 47 the first time around, in 1959, I didn't give any of this any consideration.  All I was interested in was getting there. Wish I could remember how it felt to drive it.  Maybe I'll find out when I get this one on the road.

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I might have a set of 3.54 in my suburban. That is if it's the same axle. I won't be using them since I'm running a double over drive transmission. So I'm putting in 4.10 gears behind my new hemi

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Should have looked it up before I asked.  I remember those, but they're kinda scarce now!

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station wagon

TRUE for 46-49-early series woody style wagon bodied Plymouths. Maybe, I don't know whether the all earlier  woody wagons  were 4 dr. style? So what you wrote was true, But--

 

49-up woody type 4 dr.  wagons were labeled wagons and 2 dr. all steel wagons were called Suburbans.

Edited by DJ194950
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Should have looked it up before I asked.  I remember those, but they're kinda scarce now!

 

 

TRUE for 46-49-early series woody style wagon bodied Plymouths. Maybe, I don't know whether the all earlier  woody wagons  were 4 dr. style? So what you wrote was true, But--

 

49-up woody type 4 dr.  wagons were labeled wagons and 2 dr. all steel wagons were called Suburbans.

 

Perhaps, but I'm pretty sure that the four door '63 Plymouth station wagon we had when I was a teenager was officially a Suburban. I believe that '63 was the last year that the Suburban term was used.

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Perhaps, but I'm pretty sure that the four door '63 Plymouth station wagon we had when I was a teenager was officially a Suburban. I believe that '63 was the last year that the Suburban term was used.

 

You likely were not wrong... the 1963 Plymouth Valiant v200 was referred to as both a "Station Wagon" and a "Suburban".   Here is the 1963 brochure. My Uncle Harry had the Red one and his Wife Joyce never let him forget that she wanted the Blue one.. lol

 

All I know is you could put about 87 kids, 5 dogs, 2 cats and a pot belly pig in the thing! lol

 

Ok..  It was really my Aunt and Uncle, their 7 kids (ranging from 2 to 17) their German Sheppard and her 4 puppies,  2 cats and yes, a pot belly pig in it, going from their house in Rockwood Ontario, to our Cottage in northern Ontario (near Dorset).. They had a homemade luggage carrier on top of the car with the luggage, that looked like about enough luggage for 87 kids and I remember Dad making about 5 trips from the Marina with the boat to haul everything in.   The easiest thing to move was the pig, who was about 20 pounds at the time and rode in a dog cage.

 

The point being that car had lots of room and lots of windows. Until you mentioned it Tod I had almost forgot about the old girl.

The other cute story.. it had a hemi........  emblem on the sides but seemed to be missing a pair of cylinders under the hood. Yep, the leaning tower of power, a slant 6.    I have no idea how that engine hauled everything it did, but it did and when it wasn't hauling the family, Uncle Harry who owned Toronto Pools used it for years to haul stuff for his business.

post-5630-0-39085800-1426470486_thumb.jpg

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What final ratio are you going to use?  I'm thinking around 3.01, but not sure how that will affect low gear from standing start.

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I would go no higher than a 3.55/1.

Don,  Help me understand this.  Why do you say that?  I've done various calculation on rpm ratings at highway speeds, 65, 70, etc.  and it seems to me that if I could keep engine rpms around the 2200 range it would be better for the engine. The car came originally with a 3.9.

 

For instance, at 3.9/1 the rpms would be close to 3400 at 70mph.  But with a 3.01/1 it would be 2600.  Assuming tire size at 27".

 

What I haven't considered and don't know the answer to, is what would it be like in first and second gear?  Slower than molasses?

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First with 3.9  is 10.023   with the 3.54 is 9.0978

Second with 3.9 is 7.137 with the  3.54 is 6.4782

Third 3.9 and 3.54 as it one 1.1

Thanks Plymouthy,

I appreciate the numbers.

What does this mean in actual application?  I'm sure many of you guys have already been down this road, and I don't want to experiment until I get it right.  

I know the lower the final ratio, the lower the 1st and 2nd gears, but I don't want to get run over pulling on to the highway.

 

So I guess what I need is a suitable compromise between the low gear and high gear??  Is this the right approach?

The only thing I know is the lower the final ratio the slower your engine runs.

This is all new territory to me and I'm trying to find out what others have done and what works best.  (For an unmodified engine.)

Edited by 46Ply
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you plug that all in with your tire size and get either your rpm at x speed or x speed at set rpm

 

the factors above is you multiplier of the engine RPM transmission through the tranny  and final drive..

I think maybe the light is beginning to come on.  I can use the calculator for low speed as well as high gear!   :D

 

Now for the other question.  What do most of you guys find is the best final ratio compromise?  I'm thinking it might be about 3.25.

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some argue that fact that 3.23 is too high...I am not so sure..they like to think there is too much feathering of the clutch on take of....I drove a 218 1952 Plymouth with stock 3.9 and stopped purposely at the foot of a very very steep driveway and pull off and up the drive in second without a single fault or feather..personally if you staying with the stock tranny and flattie you could move to higher final drive...IF you later thinking OD be it R10 or T5 and or other..you will want to rethink you entire gearing once again...you need the torque available to do the work for the ratio you will be in...else, it will cause you to up the rpm to tap into the HP reserve and that cost in fuel and some say shorter engine life...select your gear on the very terrain and speed you are going to operate in...keep in mind that tire circumference is a big part of the speed/rpm formula..

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Good info.  Most of the time, I have no hills to contend with on normal daily driving.  And, right now I have no intentions of an overdrive conversion.  

 

With what I know now, I'm thinking that something around 3.25 is where I need to be, or maybe just a little higher.  

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Good info.  Most of the time, I have no hills to contend with on normal daily driving.  And, right now I have no intentions of an overdrive conversion.  

 

With what I know now, I'm thinking that something around 3.25 is where I need to be, or maybe just a little higher.  

If I am following you correct your are talking about a stock 1946 Plymouth ?   If you are, the easiest conversion for you is to get a 3:54 gear set out of an older Chrysler, then you can just pull the axles, remove the gear set (pumpkin), but in the 3:54 gear set, shim them up, lock it down put on the drive shaft and away you go.

 

When you start to drop that number a stock 1946 motor is going to start to feel  like you don't have enough power/torque to drive the car.  So a stock engine 3:54 would be as far as I would go. Beyond that your over drive transmission your already travelling when you go into overdrive so you don't need the hp/torque to accelerate  like you do from the standing start.

 

If you want more than the 3:54 gear set will give you, then you best move to an overdrive transmission, or start making modification or getting a later model 230 ci motor and prepared to beef it up a bit. 

 

So I realize your looking at how many mph you will be going at a certain rpm,  but you missed the point that your stock engine in a 1946 is not going to yield you

decent performance getting  there.

 

Hope that helps.

 

Tim

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Just out of curiosity, why do you have "no intentions" of an od trans? You keep your stock ratios for starting off and have 33% over on your top end. I've ran mine at 80mph all day from Iowa to California with the od and a 3.73 rear. For bolt on speed it's about the easiest option in my opinion, you dont have to pay market value for one if your willing to put a little work into finding one

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Thanks guys,  Good information here.  Yes, this is a stock 47.   I'm just starting out here, so I didn't want to get too deep into this car until I'm sure it's going to be one I like to drive and then is worth further investment.

I want this car to be one that I like to drive daily and enjoy.  If it doesn't do that, I'll most likely cut my losses and move on to something else.

I've read so much about the overdrive complications of correct installation, I thought I'd try to stay away from it.  And, I'm not able or knowledgeable enough to do it myself.  

And, on top of that I already tried this on a 52 Ford F1 pickup.  It worked, (after a fashion), but was never correct.  Kept blowing fuses.  And I paid a guy good money to do the job.  So..., If I find the right guy to do a Plymouth OD, I'd go for it. 

So, initially, I thought I'd just try the rear axle change, (preferably just the center gear set, and not the whole axle), and see how that goes, and then maybe the OD down the road.

I'm just planning ahead and learning.  

Sounds like the 3.54 might be my best choice for now.

I'm sure this has been covered, but could you give me the specs and cars that have what I need?  Or, tell me where to find it?  ie:  What do I search for besides 3.54?

 

I do appreciate all the help.  I know this is old ground for most of you, but it's all new to me.

Edited by 46Ply
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