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P15 Overdrive transmission


Mazzdodgeboy

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They are around.

First offered in May of 1952, they can be installed in any year from 1940 till I think 1959, for sure till 1954.

Automatic Overdrive transmissions are highly desirable because of the 30% reduction in engine revs.

When installed at the factory they came with 4.1 to 1 rear axle ratios. Better to use 3.9, 3.73 or 3.54 ratios. (there were some 3.36 made too...very rare)

You can check your ratio by cleaning around the fill plug on the side of your differential carrier, it will be stamped there.

The Overdrive is best used as designed with a Throttle Kick Down Switch, Relay and the connection to the Ignition Coil. These offer automatic operation and they protect the Overdrive. Many folks operate them with a toggle switch and those same folks end up breaking parts eventually.

The automatic operation is so good it mystifies me why folks risk using toggle switches.

Overdrive Mopar Transmissions are worth $1000 to 1200. I would not pay more. The other brands such as Ford and Studebaker are coming up to the Mopar price (11 makes used the B-W Overdrive). Once you have driven a car with Automatic Overdrive (especially a Plymouth) that is installed properly you will always want one. Geared right a 55 mph car becomes a 65-70 mph car.

Drive shafts will be 6 1/4 inches shorter than original on 111 inch wheelbase cars. So if you're standing there looking at a donor car, take the carburetor (the throttle kick down switch needs the lever on the throttle and the bracket. Carburetor switches are smaller than the floor switches being reproduced now), the relay and the driveshaft.

Take the speedometer pinion gear out of your old transmission and put it in your new Overdrive...they fit and your speedo will read correctly. If you change the pumpkin in your rear axle to get a different ratio, remember to get the speedometer pinion from the donor car.

Keep looking is my advice. eBay, Craigslist and the Plymouth Bulletin are good sources. Be patient you will find one and do not over pay! There are two guys on eBay asking way too much money and during the time their transmissions have been listed I've counted 6 sold at $1,100 to 1,200.

If you find one and need a relay, kick down switch, cable or solenoid try Van Pelt Sales. They sell Ford transmission parts but are much cheaper than other sources and have both 6 and 12 volt versions.

PM me if you need more advice etc.

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I have also been thinking about an o/d for my 1941 Chrysler Windsor convertible ,but as its fluid drive I think it complicates matters.The fact that Im running a triple carb set up and 6 volt probably doesnt help either, along with being in ENGLAND!!

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3 hours ago, normanpitkin said:

I have also been thinking about an o/d for my 1941 Chrysler Windsor convertible ,but as its fluid drive I think it complicates matters.The fact that Im running a triple carb set up and 6 volt probably doesnt help either, along with being in ENGLAND!!

Just a matter of slapping the fluid drive input shaft from your transmission into the overdrive transmission. And then rigging up a kickdown switch on your throttle. Also need to make sure the overdrive is a pre 1955 as I believe it was '55 when they changed to the pin type syncros or you'll also have to swap your gears in the trans as well. Now the England part might make overdrives a little harder to find.

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I got my OD from George Ashe too.

He had no bank account and online connection available then, but his daughter- in- law had.

Best feature of my P23!

He sold it complete paired with a modified gearbox because of a hole needed for the shift rail,

preventing OD to be engaged in reverse or first.

The pair fitted my engine, hand brake and propeller shaft without any modifications.

 

I didn´t use the kick- down setup: I´m not so wild as I was 50 yrs ago and the setup seems to be to brutal to the equally old car.

 

Greetings from Düsseldorf!

Go

Edited by Go Fleiter
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12 hours ago, derbydad276 said:

I picked up a r10 from a 59 plymouth ... 

along with the bellhousing ... does anybody know if a A833 will fit the 59 bell ?

Assuming you have an A833 from a mopar, the front bearing retainer od will be much larger than the hole in the bell.  And the bolt pattern is taller than the machined surface of the bell.  The only bell that has the right size pilot hole is from 59-60 trucks.  Even that one needs modification to have a surface large enough to accept the bolt pattern.  And it will be a right side hyd clutch.  Here is a pic of one modified for my 56 pickup. We’ll. It’s too big.   I’ll resize and post later. 
edit here’s the pic.  Notice at the top and bottom there is added material, nickel rod. Provides a place to drill and tap.  Also a couple of holes were filled as the ne ones overlapped them.   
this housing requires different motor mounts and matching crossmember. That’s in addition to the hyd clutch mod.  

C9144961-97F7-455F-9CFD-D29EDC5AC3F1.jpeg

Edited by kencombs
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  • 5 weeks later...
On 9/6/2021 at 2:46 PM, Loren said:

They are around.

First offered in May of 1952, they can be installed in any year from 1940 till I think 1959, for sure till 1954.

Automatic Overdrive transmissions are highly desirable because of the 30% reduction in engine revs.

When installed at the factory they came with 4.1 to 1 rear axle ratios. Better to use 3.9, 3.73 or 3.54 ratios. (there were some 3.36 made too...very rare)

You can check your ratio by cleaning around the fill plug on the side of your differential carrier, it will be stamped there.

The Overdrive is best used as designed with a Throttle Kick Down Switch, Relay and the connection to the Ignition Coil. These offer automatic operation and they protect the Overdrive. Many folks operate them with a toggle switch and those same folks end up breaking parts eventually.

The automatic operation is so good it mystifies me why folks risk using toggle switches.

Overdrive Mopar Transmissions are worth $1000 to 1200. I would not pay more. The other brands such as Ford and Studebaker are coming up to the Mopar price (11 makes used the B-W Overdrive). Once you have driven a car with Automatic Overdrive (especially a Plymouth) that is installed properly you will always want one. Geared right a 55 mph car becomes a 65-70 mph car.

Drive shafts will be 6 1/4 inches shorter than original on 111 inch wheelbase cars. So if you're standing there looking at a donor car, take the carburetor (the throttle kick down switch needs the lever on the throttle and the bracket. Carburetor switches are smaller than the floor switches being reproduced now), the relay and the driveshaft.

Take the speedometer pinion gear out of your old transmission and put it in your new Overdrive...they fit and your speedo will read correctly. If you change the pumpkin in your rear axle to get a different ratio, remember to get the speedometer pinion from the donor car.

Keep looking is my advice. eBay, Craigslist and the Plymouth Bulletin are good sources. Be patient you will find one and do not over pay! There are two guys on eBay asking way too much money and during the time their transmissions have been listed I've counted 6 sold at $1,100 to 1,200.

If you find one and need a relay, kick down switch, cable or solenoid try Van Pelt Sales. They sell Ford transmission parts but are much cheaper than other sources and have both 6 and 12 volt versions.

PM me if you need more advice etc.

Hey there, I just picked up an overdrive transmission that I saw at a scrap metal yard, I know they are valuable and rare and I couldn't stand to see it go to waste. I do believe its a Mopar transmission but I am not sure, there are some markings on the outside of  the trans. It has the solenoid and the speedometer set up on it as well. The markings on the transmission are RIOG-1 and then below that it reads WG-DIV do these markings mean anything to anybody? thanks. As soon as I figure out how to post a pic I will

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Well I think I just figured it out, its an R10G-1 for a 49-56 Dodge/Plymouth. I have the 48 Plymouth I think it will go in it! Your right those guys on ebay want a lot of money for one. 

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I have a line on a 3 speed with an R11 from behind a desoto 291. Not sure if it will work but from what I understand, they're somewhat rare. Most of the hemi cars had autos. Can't say for sure though. Few hours drive north for you. 

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   48jumpdoors, a couple things to check are the length of the input shaft and the voltage of the solenoid. The pinion shaft should be 8.750” long from the face of the transmission. I believe 6 volt solenoids are stamped as such, I don’t know if a 12 volt is designated the same. If you have to open the transmission, you can get a 1064745 service package. You must use a battery to check the solenoid function, not a charger. Nice find.

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Thanks 9 foot box for the information, I just got off of Fifth Avenues site some good info on the OD is there. Does anyone have an exact location of the kick down switch under  the gas pedal? I have never seen one under a pedal before. 

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14 minutes ago, 48jumpdoors said:

Thanks 9 foot box for the information, I just got off of Fifth Avenues site some good info on the OD is there. Does anyone have an exact location of the kick down switch under  the gas pedal? I have never seen one under a pedal before. 

Never seen that. They were either on the carb or on the head- so either way the throttle linkage pushed the kickdown.

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3 hours ago, 48jumpdoors said:

Thanks 9 foot box for the information, I just got off of Fifth Avenues site some good info on the OD is there. Does anyone have an exact location of the kick down switch under  the gas pedal? I have never seen one under a pedal before. 

When I put the R10 in my 48 Plymouth coupe I had a dual carb setup so I just mounted the kickdown switch to the bottom lip of the dash. There was already a hole there on the left side below the starter button that appeared to be a factory hole and the kickdown switch fit perfectly. When I wanted to kick it out of OD I would just reach under the dash and push it with my finger. 

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Well shoot, I was assuming that it was under the gas pedal, my noobyness showing I reckon, my dad put a toggle on the gear shift! thats how he ran it on a 48 Plymouth coup he used to street race in the early 60's in south Seattle. He ran a Dodge motor with a Studebaker grind cam? Fenton Headers (which I still have) and an Edmunds dual intake with a Drag Fast brand strait shift floor shifter. Thanks guys for the info

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