OK, I never have problems figuring out what to do with guys cars I have to work on. But making big decisions with my own cars is usually much harder, And this one has me in a tizzy! Probably a mix of time & money, lots of labor, and not a lot of experience with this vintage Mopar! Took the 61 out for the first time a couple weeks ago. (Poly 318, push ****on auto trans.) Shakes during acceleration, shudders at cruise speed. When I first put it into drive, I did hear a moderately loud clunk. Checked the driveshaft (very recently rebuilt) and rear, both tight. Without much experience with these ******s, I'm guessing that's what it is. Now the dilemma. I know a guy who can probably rebuild the trans. Probably the least expensive, and quickest fix. Unless..... BUT! I've always hated the engineering on this car! The engine runs OK, with a bit of blowby. So not 100% ideal, but I know it's a tough engine. I hate the parking brake on the back of the trans. Not crazy about the weird "ball and trunnion" driveshaft. And servicing the rear brakes is an issue with the tapered axles, and needing that special puller just to remove the drums. And since I don't trust these things, I've been thinking about a later model driveline swap. Not familiar with Mopar technology, will anything later fit easily into this ch***is? What components have compatibility with other ones. I've even considered putting in a 8.8 rear, and Chevy motor and trans, since I can easily do the fabrication work. But will the oil pan work with the suspension? Anyone have experience with these cars?
I’m no expert, but I am pretty sure the transmission is a Torqueflite that was in production for decades across the Chrysler car and truck product line. I don’t understand the disdain for the driveshaft mounted parking brake, either. That style was common in 3/4 ton and larger trucks and school busses for decades, and seems to be relatively simple trouble free. Arguably it’s more reliable than the rear drum mounted brake common in Ford and GM cars, which are mostly corroded and inoperable after two winters around here.
Cool car, I think the poly engines are cool also. I’m not sure which transmission you have but the 727s are near bulletproof if it was mine I’d keep the drivetrain you have unless you’re looking to move up power wise. Dan
I'm not versed in "Poly" architecture, other than it is an "A" engine, where the later versions were "LA". I'm thinkin' it has the small block trans flange. You will need to do your own research on that to be sure. If so, then a 904 (easier to find) or a "small block 727" would be what you are looking for. The small block 727 is much more difficult to find. High performance cars and some trucks. You have to be vigilant on transmissions fitted to 360s as they are external balance. 318s are internally balanced, which I "think" is also true of the Poly. Then it will be either the flex plate or the converter that has counterweights attached. The 904 is a perfectly adequate trans for a driver. Simple, durable and relatively cheap, since millions were made. If you are looking for something with overdrive, that's a whole nuther can of worms. As far as a complete powertrain swap, a 318 should easily fit. They are not as "boat anchory" as many make them out to be. They can produce more than adequate power. If you want to retain the push ****on shifting, I think, and I am guessing here, that those trannies were only a thing until the mid 60s. I had a '64 Dart that had one. I don't know how long they were produced after that
If it is a "shake", it probably isn't the transmission. If it is a "shudder" especially on acceleration, it could be a clutch slipping in the transmission. Is the fluid clean? Does the shake/shudder go away on float (neither acceleration or deceleration)? If it goes away on float, it could be the transmission. If it doesn't go away, I'd be looking somewhere else in the drive train. If it turns out to be the transmission, torqeflites are rugged and dependable transmissions. I'd have it rebuilt.
@jaracer has a couple of valid points, The shake probably is not a transmission problem (unless the trans mount rubber is bad, or something is loose). The shudder could be a motor miss, an old fuel, or fuel distribution problem (pump pressure, condition of lines and hoses), a transmission problem, or a defective motor or trans mount. The trans should be a cable operated 727. You would be limited to a 64 or older 727 due to the cable shift. If you wanted to eliminate the cable shift, you would still be limited to a 67 (or so) trans because Mopar changed the hub size on the converters about that time, and the more modern 727 torque converts won't work with your poly 318 (a motor) crankshaft. Swapping out the motor/trans will also require swapping out the rear end because of the lack of the parking brake on the axle. That change could also require a swap out of the power steering box (if the car has power steering). The steering boxes on a 61 are pretty strange (If I remember correctly), and they have a low pressure steering that doesn't work well with modern steering pumps. I believe I would start with a tune up, a valve adjustment, and check the fluid levels to make sure everything was correct. Then check the condition of the motor and transmission mounts would be next in line. Then I would be looking at the condition of the tires, and checking the balance of the tires and wheels.
The issue with those is you have to block one rear wheel if jacking up the back of the car to change a flat or it could roll off the jack. Mopar used to supply a wood block with the car...
If that motor/trans is original '61. Your torqueflite trans is not considered a 727, because the case is cast iron. The aluminum 727 torqueflite came out in '62. A aluminum 727 will not bolt up to a '61 crank flange. '61 back is a 6 hole crank flange. "62 up is 8 hole. ( could be vice-versa) Swapping a aluminum 727 to replace a cast iron torqueflite is rather complicated. I think the rear mounts are different between the two, plus several other items. Want to know for sure, go over to the Forwardlook.net/forums site. They will tell you EXACTLY what you need to do for troubleshooting/swapping!
It runs and drives. It just needs a little bit of troubleshooting. I think it'd be cheaper to fix it instead of replacing everything. I mean, what's the use of the car? I'm in favor of rebuilding the transmission if need be. Ditto the engine. But if you insist on a driveline replacement, you should keep it all Mopar. Plenty of options out there. even up to the late model, hemi, and transmission.
That is a pretty bulletproof combination in that car. Fix what is there unless everything else is extremely worn out. (even then I would rebuild it all) The brake stuff is really no big deal.
It's a pretty neat car, I don't recall ever seeing a '61 Dodge with the custom treatment. One of the coolest thing about Mopars from that era is the push****on transmission. I'd hate to get rid of that.
A friend of mine has a 1962 Plymouth with that combo, he was able to install a later LA 318 to the original transmission. As noted above, there may have been a transmission case change in 1962, so this post may not apply to yours.
One of my first cars was a '64 Fury 4 door hardtop. 318 poly, auto trans with a typewriter. Thinking it was a cast iron Tourqeflite (not an aluminum TF 727) but I don't recall it having the drum parking brake on the back of the trans. But that's been too many years ago for me to say for sure.
My opinion as well, the push****on is one of the best features of these cars, would be a shame to swap it out. I'm also not convinced it's a transmission problem based on what you're saying (although I'm far from an expert). At the very least, it's worth digging into it deeper to see if you can identify the issue before committing to a drivetrain swap.
You could have one of two transmissions. ***uming it still has an original it could be a cast iron torqueflite or a two speed powerflite. Either are good transmissions. A quick look at the push ****ons is all it takes. 5 or 4 ****ons. The poly engine is just as good as the later LA. Even shares some parts wit the later version. Capable of good power. I would opt to fix what you have. JMHO
Try to solve the problem before changing big $ items. hopefully that will solve the problem. ***uming it's the original engine/tyranny you'll need a 392 Hemi to 727 adaptor to put a later ****** in it. It works on all hemi, hemi based Polys and "A" Polys up to '61. After '61 the bell & crankflange is different. As someone said the cable will work on the next few years of ******s. Imperial Services (Bought by someone recently0 makes adaptors for newer Mopar ******s. On the Hemi & hemi based Polys ther's no clearance for the starter on a 904, don't know about the "A" Poly on that. The 426 hemi flexplates works you just have to tap out the crankflange with a 1/2-20 tap. The OEM torque converter bolts on with nutted studs, the newer ****** uses T.C. bolts. The 65 or so C body rear axle bolts in, but moves the axle forward 1" in most cases. 71-3 Mustang, various years of Ranchero will work with spring perch relocation.
Unless you drive it a bunch and have several cross country road trips planned I would think figureing out what is wrong and fixing is more prudent than doing and engine and drive train swap. Even then If I did a swap I would go with a 360, torque flite and matching rear end out of a donor rig that I could dial in before I did the swap. Mopar didn't mess with WMS to WMS rear axle width much year to year over the years And some hunting probably brings up a mid /late 70's donor sedan with good running gear and a doggy body/interior. Still that push****on setup is high bubba factor for Mopar guys. Not that you can't leave the push ****ons and run a discrete floor shift.
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