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Hello all! I have a 1952 Plymouth Cranbrook that I recently finished restoring and have been driving around. After getting it on the road, I quickly realized the draw of an overdrive transmission, which my calculations show would give an estimated ~20 mph increase in range.(Which would be basically necessary where I live) I have had trouble finding an overdrive trans for a good price, it have recently found someone selling one nearby for $700. I was just interested if anyone was more knowledgeable about overdrives and could help give me some direction on exactly what needs to be changed, added, modified, etc. I know I will have to modify the electricals, but I’m not completely sure of “what” and “why” past what I found in my manual. Also wondering if the transmission is a complete swap in, or if I will need to modify things like driveshaft length and things like that. I am talking to the seller about looking at it and possibly purchasing it Saturday, so I would really appreciate any information, tips, and advice before then!!! Thanks!!!

A lot of us want to keep our trucks as original as possible and, at the same time, improve the safety and performance to drive comfortably on today's roads. Along with brake upgrades, wringing more horses out of our flatheads, adding seatbelts and tightening up our suspension components, many of us have asked--how can I cruise at 65 while keeping the RPMs in a decent range? The three "big" solutions that stand out are a- swap transmissions for something with an overdrive, like a T-5 or an A833, b- swap rear ends, or c- add an overdrive, such as a Laycock. The problem with a- is that the engine may need to be pulled, an adapter plate might be required, a new hole in the floor must be cut and then there is the clutch... and what about the parking brake? The second option, b- presents the problem of gearing that is too tall for the torque output of the engine, especially if the flathead is wimpy, such as a 201. So... c- was the option that I was most interested in. No modifications needed for the parking brake, transmission or engine. Gear Vendors sells a unit, or you can opt for the route I followed: find a Laycock J-type from a donor Volvo. Here are the modifications that I did: The old truck came with the factory optional, slightly more desirable 4.10 ratio rear end (as opposed to the 5.63 stock rear end), so it could putter happily at 45 MPH and, sounding like a manic sewing machine, hit 65 MPH. I wondered about switching out the rear end—and had picked up one that was a 2.80:1 ratio. After doing a few calculations, I realized that the rear end would make the underpowered engine even more so. Maybe an overdrive would be better? I began a search that led to a Laycock model J overdrive, about the size and shape of a small watermelon. It fit nicely in mid-frame. I installed two drive shafts, one from the to transmission to the overdrive, the second from the overdrive to the rear end. It is important to mount these with the correct angles to preserve the u-joints. I also had to move the gas tank over by about an inch to fit around the overdrive. That wasn’t such an issue—the tank needed to be replaced, anyway. The Laycock overdrive is common on older Volvos. These are often listed on ebay—without the front drive shaft. I found a complete one, cut off the end of the shaft, and had a local machinist weld a u-joint receiver onto the end to accept a short drive shaft connection to the transmission. I fitted an aluminum plate with an oil seal for the front end of the overdrive unit. Ran a 12 volt wire to a fuse and button mounted below the dash--and added a pilot light that shows when the overdrive is engaged--and that was it. Simple! (an aside: make sure that the overdrive isn't engaged when putting the truck in reverse) My biggest issue was with the speedometer output shaft. The truck cable housing wasn’t long enough to reach and the knurled connector didn’t fit. I am working on an alternative, though. A sensor connected to an Arduino, to read the speed and drive a little electric motor connected to the speedometer head… I’ll probably use a GPS to provide the speed signal. BTW, in the process of putting the overdrive in, I discovered that the parking brake drum had developed a number of fractures and was close to exploding into fragments, so I replaced the whole arrangement with a snowmobile mechanical disc brake. That set up works very well for my purposes. Another tip: I put Lucas transmission oil additive—the stuff that you see on the car parts counters—into the non-synchro transmission and it worked so well that, for most of the gears, I can shift as if the transmission is synchro. Very nice. So, does the new setup work? Oh, yeah--I say with a big smile on my face. Oh, yeah, it is very, very cool. My 201 has no problem running the overdrive, and as a side benefit, I get an extra gear in 2nd and 3rd that makes puttering around town a lot more fun. Plus, the overdrive makes it easy to downshift without double clutching. I can wave to people as go around corners! Here are the pictures:

First, thank you to those who have graciously answered my questions to date. You have saved me oodles of time and a bushel basket of twenties. I have a 1948 Plymouth special deluxe with the original flat six and column actuated three speed transmission. I plan on keeping the original engine as is. The column actuated three speed transmission works fine. The problem is that I want to drive the car long distances on the highway. At sixty-five it sounds like the engine is two seconds from blowing itself apart. (It would make a great sound effect for a single seat propeller fighter heading straight for the ground.) I have a manual transmission with overdrive for a 1948 Packard. Can I adapt it to the Mopar flat six? Does anyone make an adapter? Would the same clutch work? Does anybody have advice on the plusses and minuses? What are my other options? What would the other options cost and where can I acquire the parts? Is there a modern (less expensive?) four speed? What about the gearing for the flat six's presumably lower RPM's and horsepower? There is a shop in Tallahassee that will cut down the driveshaft if needed. Many thanks, Kind regards, Bern

Not sure if this pandemic is good for my wallet- I just couldn't pass up this '56 Suburban, listed as a parts car on Facebook Marketplace - pretty cheap and 3 hours from the house. What a great excuse for a road trip with the wife and granddaughter! An "adventure" as she called it. We have her 3 days a week since her school closed, so no social distancing needed ? The wagon was owned by a hoarder - after he passed away, it was sold during his estate sale. Local folks remember it sitting in the same spot in the northern California woods since the 1970's. It was so covered with pine needles that only the fins were showing, and everyone assumed it was a Handyman wagon. Moss is growing around the windows and doors. Crazy thing is, parts of the wagon are rusted completely away- floors, parts of the fins, tailgate hinges, etc and other parts are in good shape-frame, exhaust, stainless and some chrome. There were apparently 150 generations of mice living the dry life, as I am still vacuuming mountains of droppings out of every crevice and crack. The odometer says 49k miles, and that might be accurate. The motor is the one-year, 277 cu in "Semi-Hemi" Hy-Fire V8 - The PO pulled the plugs , shot lube in and got the motor to turn freely. It also has the standard transmission with the optional overdrive. I think I will be able to use the doors, bumpers, trim and other parts. Probably will sell the OD. Not ever having had a V8 (Mopar or otherwise) in any of my project cars, I'm not sure where the engine ID number is located. My Standard Catalog of Chrysler says "on flat surface, near front of block between two cylinder heads". It's pretty rusty, but I can't find it. Suggestions? Also I've read that the crankshafts aren't the most durable. Any personal experience with these motors?

In preparation for the impending overdrive installation, I spent this forenoon removing the center floor section. Aside from trashing the 72 year old rubber floor mat, the job was pretty easy even with my pinched nerve, shot rotator cuffs, arthritic shoulder thrown into the equation. Took about an hour all included. Haven't got under yet to deal with the drive shaft but it sure looks like it will make the rest of the job a lot easier. But after the mat shreaded it self looks like a non stock carpet is going to be needed. As my body use these folks or have any recommendations? https://www.stockinteriors.com/CutSewnCarpet.asp?Itemid=7461&ModelId=546

Hi I have a 1939 Ply Business Coupe, all stock. It was restored body off about 8 years ago. For safety currently in the process of upgrading front brakes to disk and change to dual master cylinder. Also considering adding a Mitchell's overdrive 1000 with a push / pull lever. Any one had any experience with this set-up? Two gear ratio's are offered: 26% and 36%. I live in N.J. , basically flat. Need the over drive when I run on intestates. The car will currently run at 50 - 55 mph comfortable and 60 for short periods however engine is starting to get tight and wouldn't want to run at that speed long. Inorder to keep up with traffic, would like to run 60 - 65 for 10 to 20 miles. Any thoughts on which ratio would be best. I contacted Gear Vendors several times, however have been unable to even get dimensions of their product. Figure if they won't send me dimensions, if I ever had problems they wouldn't be much help. Appreciate your thoughts. Regards, Richard

I acquired an R6 overdrive and when I removed the drain plug from the overdrive unit I could see a small piece of metal loose inside. I was able to remove it with a magnet, its a small cylinder shaped like a roller bearing or something, I included a pic of it beside a quarter. Trying to shift thru the gears on the OD and I cannot get it to go into reverse. The picture below showing the top of the transmission shows a small button from the overdrive unit pushing against the back end of the first and reverse shifting bar. This button is what is preventing the shifting bar from going into reverse. It needs to retract into the OD unit so the shifting bar can slide back and engage reverse. But it wont. Ive spun the input shaft while trying to shift, engaged and disengaged the OD lever but reverse is a dead stop. Metal against metal feels like. If anyone that recognizes the small piece that fell out could chime in and let me know what it is and does. Also looks like I may have to disassemble the OD unit to put it back in. I see the four bolts holding the OD unit to the main body, can I remove these bolts and split the two or will I need to disassemble the main unit as well. I read on a previous post that literature concerning the R6 OD is not available and I'm finding that to be true. An exploded parts diagram would be very helpful. Thanks, Lloyd

THANKS EVERYONE WHO ASKED ABOUT THESE PARTS. I moved the entire lot today to one buyer. Jim Good morning, I sold my P15 last April and am now longer in the hobby. LOOKING TO UNLOAD TO ONE PARTY or VENDOR. I have a disassembled overdrive needing some work, a complete (sans steering wheel) steering set up with good sector gear that was pulled from a '48 Desoto, but I believe the parts book says fits P, D and Desoto. I have some manuals, including a Master Index parts reference for 46-54 for all Mopar (has great exploded illustrations), some misc. trim parts, ignition parts, coupe quarter glass, wing vents and glass, distributor housings (some mostly complete) Vacuum modules, etc., If you can come pick up these are yours. Otherwise, by end of June I will need to dispose of. Please keep this hardware in circulation or use. Located in Lake County, IL, northeast Illinois. Jim Leman 847-840-0784.

File Name: SHIFTRITE PAGE 1a.jpg File Submitter: Mark D File Submitted: 01 Apr 2015 File Category: Instructions, Manuals & Templates Manufacturers installation brochure for the Shift Rite column mounted overdrive control. Click here to download this file

I have been looking for an R6 overdrive for my 1939 P8 but I am being asked what make and year cars they originally came out on. I don't know what to say to insure I get an OD that will fit my P8 without major mods to the linkage and driveshaft. From a previous post by Jim Wilson I know they were on 1939 Chrysler: http://p15-d24.com/topic/36973-overdrive-trans-questions/ Could anyone give me any other cars and/or years the R6 was on that would be a bolt in for my P8?

Hello all, as my name suggests I am traditionally a Pontiac guy. I have searched this forum already and found a lot of good info, but Im having trouble getting an answer to my Overdrive trans dilema. Any help would be appreciated. I had the opportunity to score a pretty solid 54 Plymouth Plaza (wagon) with the 230 and the 3 spd manual . Now, the work begins to make it like I want it to be. As I intend to drive it regularly, an overdrive trans is a must. I intend to keep the 230. As luck would have it, my friends uncle just scored a 52 Dodge truck. Also a flat 6 and a manual trans. He isnt using either, and I would like to know: 1) if his manual trans could be an overdirve trans. ie did they put OD trans's in trucks 2) how would I (he) identify the trans as an OD unit as opposed to a regular 3 spd. (I am in TX the trans in in MI) 3) what are the differences between his truck trans and my car trans. I have learned they are different and I think with the bellhousing I can mate his trans to my motor but i am not fluent enough to do this in a timely (and painless) fashion I prefer to use the factory trans for an overdrive because i want this car to remain factory looking. It will not be getting a modern driveline. If i get desperate I will T5 it though because the speed limit it 75 here and I dont want my flatty to come apart on me. Thanks in advance for any advise you can offer

Hi everyone, I'm a new guy on the old Dodges, so bear with me. Here' s the situation: My 74 year old father is looking to gain some speed/gear ratio on his old 48/49 1 Ton flatbed dually with the original (as near was we can tell) flathead six. He's a retired truck driver so the 4 speed crash box (Warner T9?) is fine other than he's out of gear & rpm at 45 or 50 mph. We live in SoCal and he wants to be able to drive to shows, etc. so there's a real need for another 10 mph or so. Since it's the 1 Ton and he wants to keep up original appearances, there's no real expectation of a taller rear being available - or am I wrong? He also wants to keep the flathead and a hydraulic clutch is not going to happen. What are the options from the experts? Are taller rear dif. ratios available for the 1 Ton rear axle? Are there sources for the old style "2 speed rear axles" still? I see from the factory literature that there were Clark 5 speeds avaliable that may have had OD in top gear. Can they be found or are they like hen's teeth now? A brownie box would be fine too but I'm aware of the lack of parts from my adventures with my oldish 60's Fords. How different is the flathead 6 trans mount from the later transmissions? Will anything later interface with the factory bell without adapters galore? I have a new level of appreciation for you Pilot House guys... After all the documentation I can find and have for my `67 Fords and `65 Jeep CJ5, this old truck is like sifting through a haystack looking for needles. Anyway, go easy on the assumptions about specific brand detail knowledge please. I've got the mechanical concepts and background down but I don't know jack for flathead era Dodges but I'm willing to learn to help my old man out. So what say you? Ideas? Options? Are am I just whistling dixie and dad's going to have to get used to being honked at on the fwy (again)? Thanks in advance!

Hey guys, while chasing some old Jeep parts and checking on an ebay 5 speed from a `48 that we didn't grab, I had an epiphany about a long convoluted way to get a poor man's OD for running behind the original 230 in my old man's Pilothouse 1 Ton. So bear with me: He wants to keep the stick and the original rear end, he doesn't want to cut the floor more than necessary, and really wants to keep his "deep first" granny gear for crawling up out of his long, steep driveway (I'm not exaggerating either - couple hundred feet and varies between about 10% and 40% in grade). So the truck has a T9 in it that he's fine with other than the 1 Ton having too short a pumpkin but he doesn't want to change the rear. So, after much research, I hit on the fact that the T8/T9 were the forerunner to the T98 and the grandaddies of the still quite common T18/T19. So what if we put in a later truck 4 speed that we can "somewhat cheaply" adapt to a Dana 18 transfer case that will accept a Warn/Saturn PTO overdrive? Options abound for Dodge New Process 435's as well as Dodge & Ford T98/T18/T19. There are lots of options for the Tcase adaptation and the extra weight is really a non issue in a 1 Ton that's already heavy and always running an empty flatbed. It sounds like a winner IF I can fit one of these later transmissions into the bell of the old 230 without going too crazy. So here are my questions: 1. Does anyone have the specs for the input shaft and bell housing back pattern on these? I know on my Fords the bell's rear is pretty much identical up until they went integral and the variables are all input shaft length, diameter, and spline count. What's up with the old 230 Dodge? I can't seem to find any specifications on this kind of stuff on the web (shaft length, spline count, pilot bearing diameter, etc.). 2. Given the above, the next question (or maybe the real question) is how hard is it to adapt the later truck trannies? 3. How big are the differences for the tranny interface specs (drilling a few mount holes isn't scary but finding a correct or adaptable input shaft is the question) between the old Dodge and my Ford trannies? For instance, I've got a 4x4 T19 sitting out in AZ that we could make a great start with... So what say? Does anyone have either the answers or the raw data so I can find my own? I know you guys have got something! Share with me for the old man's sake! ;-)

I just finished tearing apart and cleaning an R6 overdrive transmission and wondered if anyone here has experienced with one? I've heard of R7s but cant find much about the R6. It came with an engine that someone removed out of a 40 Chrysler, i was intrigued by the shifting arms on the top of trans, it is a top loader with a mechanism to move them to the side. A 1936 Plymouth style floor shift cover will bolt on if i swap the forks.

Does anyone out there know anything about R6 Overdrives? I know the R7 & R10 will fit and work with a P15 but what about an R6? Any help would be appreciated.

Okay, I have finally gotten to spend some time on the car. I've been stripping it down to prepare for lots of metal work. I know what direction I want to go for the suspension and body. My few goals that I have questions about and would appreciate any tips, advice, or things you've successfully done. 1. 12 volt upgrade, I have to completely rewire the car. I will probabbly buy a universal harness and I want to add some creature comforts. I have read about alot of the changes as far as the gauges, and voltage reducers. Any tips for the setup, or alternator would be appreciated. I also want to add A/C so if you've done both please let me know. 2.Overdrive, I have read a lot of threads about it but can someone please let me know some of the basics. Where to source the parts, can it be used with Fluid Drive? 3. Motor Upgrades, I know I need to change the ignition system so anything about an HEI upgrade. Also what other thing have you done or changed to make the motor more reliable, I plan on enjoying the ability to drive this car and will be putting miles on it. I am trying to get any mods in line in case they will have an affect on the rebuild, or need to prepare the body or suspension for them.

So I picked up this Borg Warner R-10 overdrive from a buddy of mine up north, for the price of "on the house". He said it came out of a '52 Plymouth, and he showed me the flathead 6 that it was mated to as well. Not knowing much about these trannys, I said sure, I'll take it, and see if it could be installed in my B-4-B. I did some research on these, and I'm now informed they're known for being bullet proof and easy to operate. If I were to put it behind my truck's motor, I could get 5 speeds, keep my rear end as is, and make my daily driver more enjoyable and economical to drive. But take cover, the big elephant looms in the room.... Taking some preliminary measurements and observations: 1. The mounting holes on the bellhousing don't match up. 2. The throw out bearing collar surface looks like a smaller diameter (from memory). 3. Not sure if the input shaft is the right length. 4. The e-brake control is on the other side. 5. The Speedo cable needs to be longer. 6. And, finally, the driveshaft will need to be snipped a bit. Anybody ever do a mod like this in their truck? Not sure if I'm wanting to violate the backside of my flathead with a different transmission, I'd like to get some imput on the items listed above, and any others, from y'all. I like this option for OD better than a T-5 because I can keep the column shift, which I like. I had also looked into a Gear Vendors divorced mount unit, which would be easy to install and provide great performance, but they're cost prohibitive ($3k +).