1949 Plymouth Coupe 3.6 VVT Powertrain Swap

[Mopar 49]

I have a 1949 Plymouth coupe that I am going to do a full powertrain swap on. 

Why not keep the flathead 6? It's a hotrod but it doesn't take off and stop like one.

I want to try and keep this as Mopar as I can. The powertrain donor is a 2016 Chrysler 300c with 3.6vvt motor and 8 speed transmission.

There are several parts needed from the donor car to make this happen. I had a line on a good running but bent front suspension 300C which made it the perfect donor.

I will be pulling  the wiring harness, PCM, ECU, WCM, TCM dial shifter, gas pedal, brake pedal, brake switch, fuel pump and fan and fuse boxes.

I have an HP tuner that I am pulling the 300 computer settings from and will be sending in to unlock tuning the motor.

The Pentastar engine puts out 300HP compared to my 100HP inline 6. So I need to swap the rear end to handle the extra power. Further down the line the 3.6 will get supercharged and tuned to about 450HP.

#1 Does anyone have a Chrysler product rear end they can suggest for this car? I know there is nothing that bolts directly and I will have to modify the spring/mount for whatever I end up putting in. What ever rear end I put in I will want it to have the ability to have rear disc brakes.

#2 For the front suspension I am having a hard time deciding. The steering shaft and gearbox are kind of in the way. Do I swap to an IFS mustang 2 kit which gives me all the space in the world to mount the engine. The drawback of the mustang IFS is I have to cut the whole front end off at the front coils and built a new frame to mount the IFS. Or do I try and so some minor frame mods to get the motor to fit, possibly having to articulate the steering shaft.

 

 

 

 

[Sniper]

Keep the donor till the swap is up and running properly.  You'd be amazed at the little stuff you can use from it.

 

As for a rear end, hmm, doesn't that 300 have one?  I know it's IFS, but hey you already got it might not hurt to see how hard it would be to swap it over.

 

As for the front, well how bent is that 300's front suspension?  If you could swap that as well you'd essentially have a 2016 Chrysler with a 40 Plymouth body.

[Plymouthy Adams]

first off where do you get tone....tranny or rear end....not sure but a few years back automatics was in the tranny.....stick shift in the differential

[Mopar 49]

The 300 has an IRS I haven't measured width but it would need a frame to mount it to that would mimic the 300. I'm thinking that shortening the driveline and installing new leaf spring mounts with a fixed rear might be easier. 

The main problem with the 300 is the unibody, not really a frame there to swap. It has lot's of good parts and some will move over to the 49.

My dream is for the 49 to run and drive like a new car with an everyday driver reliability and some punch when you hit it.

 

[Mopar 49]

The motor and automatic transmission will move from the 300 and replace the flat 6 and 3 on tree trans in the 49. I will have some sheet metal modification to the transmission tunnel. I will have some frame modification to the transmission carrier. 

I can't really find a whole lot of info on this swap I did spend some time reading through one that a guy did on his A frame.

If I did a mustang 2 IFS, I could bolt the 300 power rack to the frame but again so much welding and fabrication work. 

If I don't do the mustang 2 front suspension then I will rebuild the existing steering system and add disc brakes to the front as well as the rear.

 

[Los_Control]

The Ford explorer 8.8 will come with disk brakes on newer models, older is drum.

They come with many different gear ratio's. My 96 explorer 2 door sport had 4:10 ratio ... it was fun with the 5 or 6 speed auto trans.

They are a very common swap for these vehicles .. width and wheel bolt pattern is correct.

I hear they are not as strong as a Ford 9" ... but really close to it. You have to admit the 9" has a reputation thats hard to beat.

 

If you insist on mopar, the Jeep Cherokee also fits, comes with disk brakes and many different ratio ... is owned by mopar ... no clue in strength how they stack up against the 8.8.

[Los_Control]

Have you considered rebuilding the existing front suspension, adding a disk brake conversion ... tweaking it some maybe a stronger sway bar and better bushings etc? ... they really were a decent front suspension for it's time.

Possibly replace it later if it does not do what you want?

 

Just tossing a idea out there ...

[Adam H P15 D30]

I second the 8.8 Ford.  You could get away with the Jeep 8.25 with 300HP but add that blower and the 8.25 will be crying for mercy...  The 8.8 will just smile at it.

I would upgrade the axles in the 8.8 after installing the blower, that's it.

[Adam H P15 D30]

Oh, and if you want a "modern" driving vehicle, dump the OE front suspension for something more "modern."

I would do a Volare or GM clip before I put a Mustang II in. less work

 

Edited July 16, 2021 by Adam H P15 D30

[Mopar 49]

It looks like a Dana 44 might be a good choice. I used to run a few Jeeps and those axles never disappointed. I've heard those Cherokee Dana 44's are also hard to find and Fords are plentiful.

My coworker is a Chevy guy he says do the Dana 44 skip the Ford. 

[allbizz49]

Ironic that a chevy guy says skip the ford but most fast chevrolets have a 9 inch in them. Personally,  I'd find a mopar 8 3/4 to install.  They'll handle anything you will throw at it. Many lived behind fuel burning front engine dragsters 

[Adam H P15 D30]

1 hour ago, Mopar 49 said:

It looks like a Dana 44 might be a good choice. I used to run a few Jeeps and those axles never disappointed. I've heard those Cherokee Dana 44's are also hard to find and Fords are plentiful.

My coworker is a Chevy guy he says do the Dana 44 skip the Ford. 

6 cylinder Jeeps break Dana 44's.  

[Mopar 49]

In looking at availability it might come down to the ford 8.8 for the rear. It looks like people love them for rangers and jeeps. I can get a 3.73 for $265 which I can outfit with disc brakes the 4.10 not to be found. The older Mopar rear axles are quite a bit harder to find. At least the ford bolt pattern would be close.

[Adam H P15 D30]

The Ford pattern will be the same. No need to swap to disc brakes in the rear, drums are fine unless you’re planning to road race it. Make sure to measure the width and compare it to what you need. Rangers are narrower than Explorers. 

[MackTheFinger]

Nothing in particular to do with this thread but in 1971 I broke at least half a dozen 9 inch Ford differential cases, one right after another. They all broke at the pinion support. I was running a 406 4-speed in a '62 Galaxie. The only way I could keep a rear end together was to slip the clutch until you could smell it, otherwise KA-BOOM!! and you're washing pieces of differential out of the axle tubes. I later ran '56-'57 Olds and 12 bolt Chevy's and never had a problem but I was running small block Chevy engines in Chevelles and Novas then. Those cars were easy on parts. You could just dump the clutch and bang gears. More fun than should be legal.. Supposedly an 8.8 Ford is good for 400 hp. If I manage to cram a 500 Caddy engine into my '47 Dodge I'll find out.

[Sniper]

I ran a 64 300 with a warmed up 413, stick trans, N50's in the back with an 8 3/4, 4.10 gears, for years.  Tore an ear off the yoke on it once though.  Other than that I never had issues with the rear end.  Got another on the shelf for my Cuda.

[Los_Control]

I know my 1996 explorer  had rear drums. Thinking around 1999 or 2000 they came factory with rear disk brakes ... really not sure on the year of the switch but newer explorers have rear disk.

Just seems it would be easier to find a 10 or 15 year old car in the wrecking yard with rear disk, then a 30 year old with drums.

Not sure what search parameters you are using for your search. As far as I know, the widths never changed from older to newer explorers and newer will work fine.

 

I can see where the 4:10 may be harder to find, less of them made as the explorer was more of a family 4 door suv market.

My 1996 with 4:10 was the 2 door sport model. It had a badge on the fender that said sport.

Any 4:10 come available and the jeep'ers would snatch them up. But they are out there.

[Los_Control]

Just now, MackTheFinger said:

They all broke at the pinion support.

I have seen some videos on the strengthener of the 9". Seems they would add some gussets to the housing.

Now days they sell kits for them. Back in the day they were doing it in the garage with scrap metal.

 

While the housings had some weak points that needed some beefing up to handle the power, they did that and used them behind nitro dragsters.

Today they are still using the same concept.

Dennis Taylor building his car, He is hoping to get it in 6 seconds on the 1/4 mile. Rear end is all custom, no parts say Ford on it. But a custom built set of gears for a Ford 9" is the heart of it. He ordered his with larger side bearings etc ... he is running full floating axles on it like a 3/4 ton truck.

His thoughts is for safety, if it breaks a axle you wont lose the rear wheel. Might cost him some speed but his daughter is also driving the car.

[Plymouthy Adams]

any concern that a 8 3/4 even a 8 1/4 much less what ford has in 8.8 or 9 and who cares the junk GM has.....says you overbuilding for the street....get a rear axle from a golf cart, never in all the courses I have played nor of the matches televised have I ever see an golf cart off the fairway sitting on jack stands....?  I will stick with my mopar interceptor 9 1/4 sure track 2:88 

[MackTheFinger]

1 hour ago, Sniper said:

I ran a 64 300 with a warmed up 413, stick trans, N50's in the back with an 8 3/4, 4.10 gears, for years.  Tore an ear off the yoke on it once though.  Other than that I never had issues with the rear end.  Got another on the shelf for my Cuda.

That sounds like a great car!! 

[Plymouthy Adams]

AND.........that would have been a taper axle car also for those that have doubts to their abilities to stand up to power

[MackTheFinger]

45 minutes ago, Plymouthy Adams said:

any concern that a 8 3/4 even a 8 1/4 much less what ford has in 8.8 or 9 and who cares the junk GM has.....says you overbuilding for the street....get a rear axle from a golf cart, never in all the courses I have played nor of the matches televised have I ever see an golf cart off the fairway sitting on jack stands....?  I will stick with my mopar interceptor 9 1/4 sure track 2:88 

Now, PA; your anti GM bias is showing..  ? I agree with your assessment that almost anything will work for the street, unless you're one of those guys who thinks anything less than 500 HP is for sissies.

There's flat track racing at DuQuoin today!! ?

 

update: Just heard, races are cancelled.. ?

Edited July 17, 2021 by MackTheFinger

[Plymouthy Adams]

me GM bias.......never.....hater is more correct....!   Nothing wrong with putting a bigger engine into anything...what is wrong is when you take that path and have seemingly no clue as to what will work and you run to a forum....especially one catering to flathead engines of very low output even in their max HP dress....some folks do the occasional run on the track...also good as they drive it on the street at the same time....most of these guys know their happy place...

[MackTheFinger]

1 hour ago, Los_Control said:

I have seen some videos on the strengthener of the 9". Seems they would add some gussets to the housing.

Now days they sell kits for them. Back in the day they were doing it in the garage with scrap metal.

 

While the housings had some weak points that needed some beefing up to handle the power, they did that and used them behind nitro dragsters.

Today they are still using the same concept.

Dennis Taylor building his car, He is hoping to get it in 6 seconds on the 1/4 mile. Rear end is all custom, no parts say Ford on it. But a custom built set of gears for a Ford 9" is the heart of it. He ordered his with larger side bearings etc ... he is running full floating axles on it like a 3/4 ton truck.

His thoughts is for safety, if it breaks a axle you wont lose the rear wheel. Might cost him some speed but his daughter is also driving the car.

Mine were breaking internally, at the pinion support. There's a thin place in the casting there. I was using junkyard parts and a lot of them were already cracked. The nodular iron housings would have worked better and the aftermarket diffs are hopefully beefed up there, too. Wheel hop in the Galaxie was killing them. If the rear end of the car shook you knew the diff was busted.. Once I learned to slip the clutch I didn't have that problem anymore. It was operator error as much as anything else..

[Mopar 49]

With a little more looking I found a half dozen explorers at pick n pull if they have the rear end in them they would work, they came with factory disc brakes just before they changed to a IRS. They all would have a 3.73 a couple of the older ones might even have a 3.55 and drum brakes. It looks like the sport had the 4.10. 

I found a sport axle out of state with a 4.10 online with factory discs. If I have it shipped to my house it's almost $300 shipping if I call the local auto recycler on Monday I should be able to cut the price down a lot by shipping to the LKQ distribution center about 5 min from my house.

I would love to get an old rear end under the car but most of the cross over vehicles tend to go for more than my Plymouth and the parts are 3-4 times the cost for a rusty pumpkin with tubes attached.

The first stage of the build will be a little more than 300 HP after the motor is running and tuned and the vehicle is able to drive.

The second stage will be to add the supercharger kit to boost to 430-450HP. I'll keep my fingers crossed that the 8.8 can handle it.

Part of my build idea is to run parts that I can easily get, the Chrysler 3.6 is super plentiful as is an explorer rear.

I will need to sell the parts I pull to help offset the build cost. Someone who isn't running a hotrod will probably appreciate finding them.

I will also be putting some progress pics and design ideas in case someone else is crazy enough to do this.