I need to put a 4-speed transmission on a p-23 flathead engine. Can it be done???
Given that the goal of the Plymouth Owners Club is the preservation of (or restoration to) original condition, this board is not your best bet for getting the information you are asking for.
There is at least one fellow on the http://www.p15-d24.com/ discussion forum that has mated a four speed transmission to a Mopar L-head 6. There are also numerous people there who have converted to disk brakes. That forum is more likely to have people willing to help you.
With a good machine shop and lots of money, you can mate almost any transmission to any engine. Bear in mind that the high gear ratio is one to one in most transmissions so a 4 speed will not increase your top speed. Volare used a three speed with manual overdrive which would meet that goal. I have also seen a tech sheet which shows the S 10 Chev 5 speed will easily adapt to an early Plymouth, but neither of the later transmissions I have mentioned provide a parking brake.
The Borg Warner overdrive, which was available on the P23 and will fit any Plymouth from 40 to 56 provides a final drive ratio of .7 to 1 ( a 30% reduction in engine speed) It is a simple and reliable unit and though it might cost you a lot of money initially, it probably will be cheaper in the long run.
Try these folks, they have a pretty extensive selection of adapters.
http://www.wilcap.com/index.html
Cody52,
If you rethink your conversion idea, opting for an overdrive in lieu of a 4 spd., I have a friend that has a '55 Plym wagon with an OD trans that he is parting out. If you are interested let me know?.....Bill
Yeah, but why? Both types of transmissions are a 1 to 1 final ratio, so for highway driving you aren't gaining anything. What you need for highway cruising is either the OD s mentioned below which will net you a 30 % reduction in engine RPM at speed, or a 5 speed with OD. the exception would be a MOPAR A 833 OD 4speed. These were used in the mid to late 70's in Aspens, Volares, and light duty 6 cylinder pickups and vans. You would still need an adapter between your belhousing and the trans, and would need to modify the pilot bushing /bearing, and fab up linkage. You would also loose your parking brake, so a swap to a laer rear axle would also be needed. One with parking brakes built in. If you have looked at your car underneath, you whill note that the parking brake is on a drum on the back of the transmission. Swapping the trans, means no PB w/o further modifications. Anything can be overcome with enough time and money.
Contact Tom Langdon at Stovebolt Engine Company. Tom has helped many owners put a 5 speed overdrive into Mopar flatheads.
http://www.stoveboltengineco.com/
He also makes an excellent dual exhaust set up for Plymouths.
The Plymouth Dodge forum that discusses your concerns is here: http://www430.pair.com/p15d24/mopar_forum/
Quote from: Wm Steed on August 14, 2007, 01:48:59 PM
Cody52,
If you rethink your conversion idea, opting for an overdrive in lieu of a 4 spd., I have a friend that has a '55 Plym wagon with an OD trans that he is parting out. If you are interested let me know?.....Bill
If he is not, I am. Any idea how much he would want for it?
The only reason for the question is that I have never driven a 3 on the tree and people tell me they are notorious for hanging up in gears.
I will probably stick with the original but may be interesed in the overdrive trans.
Quote from: cody52 on October 10, 2007, 11:15:57 PM
The only reason for the question is that I have never driven a 3 on the tree and people tell me they are notorious for hanging up in gears.
It should shift smoothly and if not there are adjustments that can be made. A friend had a problem with his p15 shifter but it was only a matter of adjusting a nut on the shift linkage forgot the exact steps I did it it about a year ago but it is in the manual.