Allpar Forums banner

1940 Plymouth Coupe Transmission

6116 Views 9 Replies 3 Participants Last post by  68RT
Hi all
My friend just bought a 1940 pylmouth coupe. It's a nice stock car but I can hear a clunking noise in first gear. So the question is do we fix the existing trany of look for a later model trany? Can some one tell me what post war transmissions bolt up? The car has a base model three speed and clutch setup no fluid link.
Thanks for the help.
1 - 10 of 10 Posts
Not real familiar with the old transmissions, but I think they will swap all the way into the early 50s, those behind the flathead engines should have remained the same. At the same time, if you took the transmission to a shop and they could discover what the actual problem is, it may then be cheaper to simply do something like replace a gear, where lots of places will do a small teardown fee to be applied to the repair, but at least give you an idea of the actual problem. Only happens in first gear? Is the clunk shifting into first, or first taking off?
Is this a "cllunk" that is once or every revolution of the engine? Every revolution leads to a faulty gear which could be the first/reverse slider or the cluster gear. Once when getting on or off the throttle would more likely be bad u-joint or excess slack in the differential side gears.

ED: sp
Hi all
Dana44 I tried the local shops with a 47 dodge truck last year they all turned it down.

The noise is only in first gear under power. I costed it down hill in netural with the engine off and there is no noise. I would like to put a later better tranny in and a direct swap would be best. So back to the origional question what trannies fit in place of the 40 plymouth?
I know someone else on here has the cross reference parts books to see which years swap. Doing a little searching on the web indicates it may be the R-10 transmission which was updated in 1940 and may be the same transmission all the way up to 1953 (but don't believe everything you read on the internet, right?). The 1939 transmission is a different design, but I think it would work still, just not as smooth shifting. Sorry I can't help more, but I did locate a place that still has all the parts to rebuild if in fact there is a problem within the transmission, which is small and looks easy to disassemble/repair if you are able to go that route.
Another thing to think about is the engine itself. If the bolt pattern is the same all the way up through 1953 (the flathead engine), then a transmission will work. There may be upgrades internally, gearing improved, overdrive and the likes, but the transmission still bolts to the engine/bellhousing. Your critical measurements are, pilot bushing size at the nose of the transmission (bushing can be latered or swapped if necessary, but don't think that will be an issue), overall length for driveline installation, and transmission mount location, which can also be altered. has parts, and seem to bee pretty knowledgeable, you may be able to call them and find out which transmissions actually swap directly or what else to look for. It is a Mopar company, so they should not direct you in the wrong direction.
Thanks dana44 I will get my friend to call and we'll get a plan from there.
Sounds like you either have a pitted tooth or a partially broken tooth.
From what I can tell about the transmission it isn't so obsolete there isn't support out there. It is small and looks like the trans was available over a long enough time that parts are still available so it only takes a company that knows about the transmissions more than me.
Normally all gears can be inspected by pulling off a cover. Look towards the bottom of this ebay listing for the exploded view and you can see the side cover is pulled. It is easy to do (a few capscrews and lift off) and then all gears can be looked at without a teardown. It can be done without pulling the transmission even.
1 - 10 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.