I recently purchased a '41 Plymouth Business Coupe with the original 201 Flathead. I want to replace it with a V8. I have been looking at different options as to the front suspension and was wondering if the stock suspension would be able to handle a V8? Seems that putting a Mustang II in it requires some cutting out the frame and adding new frame rails to accommodate it. I have all the pieces to "Clone" a '57 Plymouth Fury Poly 318. Thanks for your responses.
This is going to get bumped to OT. The stock IFS works, but a few have replaced them with other suspension systems. I'll try to find the old posts about this, but I will wait until I know this isn't going to go ****. Look into Gene Koning, Need Louvers, and Rockable here for more Mopar info. You can also check the P15-D24 site, although they are mainly stock style.
The front independent suspension on your 41 Plymouth was first introduced on the 39 Plymouth. By 41, Chrysler was putting that same suspension under every car that came off the ***embly line, including the top of the line Chrysler. It was way ahead of any other front suspension at the time. Chrysler made a few minor changes over the years, but they used that suspension through the 56 model year. As of a couple years ago, every replacement part was still available. Improvements to the 41 system would be: 1) Relocate the upper shock position. Originally the shocks were connected between the upper and lower control arms, that was what gave the car the "floating on a cloud" ride people liked at that time (from a performance standpoint, it makes the car feel "mushy"). Moving the upper shock mount from the upper control arm is simply a matter of adding a shock bracket to the frame, and bolting the shock to it. Many use a 50s Ford truck front shock mount (easy to find) or a harder to find 60s Dodge pickup front shock mounts, both can be bolted to the frame. There are also several weld on shock brackets available. That simple addition removes the mushy feel, and provides a much more firm feel when corning a bit hard. coupled with the next step makes a huge improvement in how the car feels. 2) Most of the early cars came with out a front anti sway bar, or with a very small diameter anti sway bar. A modern Jeep sway bar can be added simple by using the Jeep bar mounting brackets on the Plymouth. This one can make the original suspension a bit more sporty if one chooses to go that way. It is also an improvement from original even if the upper shock mounts are not moved. Together they make the car feel completely different, and on par with most modern swapped front suspension systems used. 3) Modern brakes. Not really the suspension, but the original brakes worked pretty good, if they were adjusted properly. There is a correct method to adjust them correctly. Improperly adjusted, the original brakes were pretty questionable. There are disc brake conversions readily available, and may be cheaper the replacing all of the original brake parts. 4) Power steering. Originally, the manual steering was not bad with narrow tires, a huge steering wheel, well greased front suspension, and some vehicle movement while steering. Removing any one of these 4 things makes you start to look like Popeye the Sailor man. If power steering is a must, you will work for this one. Since the thread has already moved, modern electric power steering columns have been successfully used to add power steering using the original steering box. There have also been a few different rack and pinions set ups used, which require a lot of things to be changed. The original steering shaft that the steering wheel attaches to, is part of the steering box. Some people have swapped in power steering boxes & pumps from other vehicles with success. Any steering alteration will also require a steering shaft and column modification to work. Just one note concerning swapping in a V8. If you shift the motor and transmission 1.5" to 2" away from the steering shaft, exhaust manifolds will clear the steering shaft. Keep the center line of the crankshaft and trans mission at a 90 degree angle from the rear axle as it sits side to side. If your frame has a center X, you may need to modify the center of the X for extra driveshaft clearance. With drive shaft clearance at the center of the "X", there should be plenty of movement in the U joints to accommodate the motor/trans shift. Build the motor mounts and the transmission mount to accommodate the side movement. You will probably need to "adjust" the head clearance between the firewall at the right side (as you sit in the car) and the head. A hammer usually can provide enough clearance. I have also put a notch in the center cross member for belt pulley clearance. On those, I cut the chunk out, flipped it over, and welded it back in place. It was just for additional clearance. I have only built about a 1/2 dozen original framed 39-48 Plymouth cars over the last 25 years, in addition to the cars I changed the entire rotted out frames for something more modern.
If like the 40 I would keep & make my own disc brake if wanting. Back in 70's we cut off the original front Was Bad mistake @ 10 , Befor cutting front off we had Sbc in stock frame with new Nos kit first out & 70 12bolt
When I built my 41, I tried to work with the original suspension but finally gave up and installed a Fatman clip. I am glad I did. It still rides and drives great. https://www.jalopyjournal.com/forum/threads/41-plymouth-sb-mopar-engine-swap.498434/page-21
And on the other hand I did the same shocks, sway bar and discs changes on my ‘51 with a 318 and a torqueflight and have been more than happy with the results for 22 years now.
Thank you for the information. I knew about the Shock relocation and Disc Brake conversion but not the Sway Bar. My car has one so if i measure the Dia. and compare it to the Jeep it will let me know if it is worth it. I was concerned about the lack of space between the steering box and the Engine, thanks for that info.. I also read about using a Rack and Pinion from an 80's Cavalier, probably just more problems. Is there a way to lower the front in a stock suspension? Would boxing in the frame make the difference in handling worth it? Just Mo Money! Thanks again.
Ours was P10 with sway bar . Coil's was cut to lower , now days more options / ideals then back then , coil over shock's up front , To clear steering box tight radius tubing. I feel the frame was built quite well being X frame , not maybe for autocross. With stock front are set up was 3-1/2 on front & L60's rear & stock leaf We did break a rear leaf one time replace with another stock one
I have not experienced the power or R&P conversions, but of those who tacked it to the stock stuff have not reported great results. Lowering is the same as any SLA suspension, shorter springs which changes the suspension arcs, or dropped spindles, which I'm not aware of. Boxing a frame is reference to a C channel frame. If you look at the front frame of a Mopar of this vintage, you should know that it's big heavy curved and already 'boxed' in front by the engine and front suspension. If you look at the back of your frame, it is a C channel but is not in an area that gets twisted.
As already stated by someone else, the stock frame is a formed, boxed tube back to where the X starts. If its not rotted out, that frame will support a lot of abuse without a problem. Years ago, (2001 or so) I may have been one of the first guys that started the Cavalier rack and pinion steering. The GM rack and a Dodge Intrepid rack share the same design, except the Dodge rack is a front steer and the GM rack is a rear steer rack. Both racks have the inner tie rod pivot point at the center of the rack rather then at the ends of the racks, like most other racks were at the time. I had 3 complete Dodge racks, that included the tie rod ends, but couldn't get it to work with the rear steer 39-48 Plymouth set up. When I heard that the GM rack was a rear steer, and had the center inner tie rod ***emblies, I picked one up immediately. What I discovered was that the Dodge inner tie rod set up bolted in place of the GM inner tie rod set up. Being the Mopar guy I am, I worked with the Dodge set up. What I discovered was that the dodge tie rod ***emblies were 3 piece units. A standard outer tie rod end, a threaded sleeve, and a very lone inner tie rod section. Compared to the 39 original outer tie rod ends and their threaded sleeves were almost exactly the same length, although the Intrepid ends and sleeve were a larger diameter. The tie rod end itself fit into the same tapered hole that the original 39 tie rod fit into. The inner Intrepid tie rod was a much different configuration. The end that attached to the rack had an eye with a bolt p***ing through that threaded into the inner tie rod connection on the rack. The length between the center connection and the threaded end that matched the sleeve was about 6" (or 8", long time ago) too long. I'm a certified welder, cutting a chunk out of a forged tie rod length then welding it back together posed no issues. The bracket to mount the rack to the frame was very simple. A wedge shaped bracket with a flange to hold the original Intrepid rack to the frame, was welded in the proper location onto the frame and the rack simply bolted to the brackets using the Intrepid rack mounting hardware. The power steering rack was connected to a donor 85ish RWD Chrysler 5th Ave power steering pump. The GM rack needed a special (at that time) steering column to rack coupler, from there to the wheel was a standard 80s Dodge steering column. The end result was a car that drive fairly good, but at highway speeds, (70mph +) it became a bit quirky (most likely a reduction in the pump pressure would have solved that problem). The only other issue was that the turning radius was larger then it was with the original steering. Not horribly larger, but enough you had to keep it in mind. That too could have been corrected, had I known what I know now. I drove the car nearly 40,000 miles, the sold it in pursuit of a different dream ride. The question was asked about lowering the front suspension. With the earlier production cars (I suspect older then 48 but would have to look), the mounting pad for the coil springs were riveted to the top surface of the lower control arms. If a guy pulled the lower control arms off the car, and drilled out the rivets, he could move the coil mounting plate from above the control arm to under the control arm. then all that would be required would be to use grade 8 bolts, nuts, and lock washers to secure the plate to the bottom of the control arm. Re***embling the lower control arm using the same spring would lower the front of the car about 1.25". I have also been told that a Ford Arrowstar minivan (if a coil spring from one of those can still be found) supports the same weight as the OEM Plymouth spring, but is 2" shorter. All other things equal, that should drop the front end 2". I didn't mess with much front end lowering, it was not my thing. As far as the font sway bar, sorry, don't remember, but the bar was common, and around 1" in diameter.
On my ‘46 we cut one coil to lower it and in conjunction with the shock and sway bar changes rode and handled well.
Sometimes a person's desires over-shadow their abilities, that is where i am at this point. All things considered, I probably made a mistake overall. Thank you for your advice. Time for some inner reflection.
Since this is in the Off Topic car build section, I also have a 1941 Plymouth Business Coupe and I am going to change the front end as well. I was looking at the TCI universal IFS kits, their most narrow offering (Outside frame width 30” with 57.5” track width), for my build. I haven't decided between their version of the Mustang II or their in house designed Pro Touring kit. A lot of the insight above are great suggestions for augmenting the original IFS Chrysler made (all very sound and does make for a better riding car [not sure what Chrysler was thinking about the upper mount of the front shocks]), however as Rockable pointed out, there is some things left to be desired depending on how you want to drive/experience your car. I am still a ways off from digging in on the project, however, Gene-Koning has some great suggestions. One thing not mentioned is also removing the lower A arm spring plate and mounting it under the arm which will give you about a quarter to half inch approximate lowering (https://www.jalopyjournal.com/forum/threads/very-easy-way-to-drop-your-early-mopar.685246/). Also using a Jeep XJ front sway bar is a cheap and easy upgrade to your existing front end if you keep everything stock, see: Gimpy's comments and pictures in this thread (https://www.jalopyjournal.com/forum/threads/53-dodge-front-suspension.1256314/), same advice for that 53 applies to your 41. If you want some real interesting ideas for scrounging junkyard parts, the OG Mustang II/Pinto front end is something that Need Louvers? used when he built his 47 Plymouth, which has a lot of road miles: https://www.jalopyjournal.com/forum/members/need-louvers.67915/ Reach out to him and he will share ideas and what he did.
I have clipped a few 46-48 cars with a Dakota front frame, (88-90 have 5 lug wheels, 91 -96 have 6 lug, but can easily be converted to 5 lug by swapping the rotors from the earlier version Dakota. The 97 and up have a different hub and bearing, changing those to a 5 lug is very difficult. The 04 (or 05) and newer have a 5 bolt wheel as well, but the bolt pattern is larger then the original car bolt pattern was). Those older Dakota frames are getting tough to find, not rotted out. At one time there was a member on here that was building Dakota front clips. The last I heard, he had quit building them, but was recently considering building them again. The Dakota (and Dodge Durango) front clips (88-02) match up perfectly with the 39-50 something Plymouth, Dodge, Chrysler frames at the firewall (the Dakota frame slides up inside of the old car's frame at the firewall. Cut the car's inner frame and the front part of any center "X" in the car. You can remove the Dakota front cab mounts then add the car's front body mounts to the Dakota clip. You will have to build your own radiator support and front bumper mounts. I would suggest you make measurements from where you want the Dakota spindles to sit in relation to the firewall (and fender openings), and retain the Dakota front frame clip to the rear side of the transmission mounting point. Unfortunately, i no longer have the pictures of the cars I did the Dakota front clip on, I lost them in a computer crash years ago.
I just finished building a '40 Deluxe Plymouth 3dr sedan. I rebuilt the stock front end with all new available parts and adapted disk brakes with an available kit. These are great suspensions, do not swap in a MII!! One change I made to the system was dump the factory steering column, gear and drag link and put in a GM tilt column and Saab power R&P gear. Needed the switch since the '54 3312 hemi was too wide to clear trhe stock steering. Needed power steering anyway! Had to *** a 2" square tubing R&P gear mount behind the stock crossmember. Really easy to do. Note I used a MII gear for mockup. Very close to the Saab gear I finally used. Can't use a MII gear since they go in front of the axle, putting them behind the axle makes them steer backwards. Saab does it correctly. Aftermarket disk brake conversions are not that expensive and bolt right up, np problem. I adapted the '40 steering wheel to the GM tilt column. Easy conversion.
I don´t know about the later models, but I´ve been running the stock 34 IFS in my Plymouth for about 100 k miles powered by a healthy Chevy Small Block. Only thing I did was add tube shocks. It´s still running strong with a new owner.
@willys36, are you still keeping the shocks between the upper and lower control arms? It looks like your car has the factory sway bar as well? Does the extra weight of the Hemi reduce the "floating on air" ride of the shock original position? I like that Saab rack, and the extra cross member you installed.
*Might* be worth mentioning... Since most older cars are designed w/a slow(er) steering-ratio, due to manual-steering design, one way to speed that up, is to use shorter steering arms. Sometimes called "fast" steering. This works w/racks, too. There were some racks designed w/quick(er) steering ratios too, although not overly common. The racks-issues have been covered, & done, by the Stude guys for a fairly long time now, & unless it's done correctly, not really worth the trouble. Doesn't mean it's not worth doing, but.... . Stude offered "fast"(read: shorter length) steering arms for the Avanti, & so since the early 60's it was common to do that swap. Trade-offs are harder steering(manual) when stopped or at very slow speeds, esp if suspension isn't perfect(including greasing those kingpins- not kidding...) & larger &/or wider tires, incl changing to radials. Stude had separate bolt-on steering arms from at least '51->'64. IIRC, so did chevy from ~'41->~'54. Chrysler too, in that same are. Thinking even the camaro/firebird guys got into that act ~70's/80's(???) These older front suspension designs are actually quite good, esp for rough(er) roads, usually designed to deflect some of the road-impact(s) away from the ch***is & absorbing the rest. They are not, however, in the same handling-category as new corvette/ferrari/etc. & they are nowhere near as fragile, either. Better springs(variable-rate), new kingpin bushings/systems, much better shocks, & an anti-roll bar sized correctly for the car(probably need a rear one too for proper balance), will make a world of difference. . Fwiw; SAAB racks provide very nice steering feel, in both the 9-3 & 9-5 variants; the ones I'm familiar w/are the Aero versions. Don't think they're any different a**** the various models, something I'd have to search-out, also haven't had to look for re-man's, mine were ok still after 20+ yrs. As mentioned, GM made center-steer( tie-rod attachment point), that if used, can allow the rack to sit rather close to the crossmember, but you'll get approximately the same small-ish bump-steer the factory built-in, which wasn't bad at all. If you do a version of the "fast" steering arms, you can move the rack forward, the equal distance, of the length-difference 'twixt the "fast" arms & the oem "long" arms, giving you abit more room. This is ***uming that the rack is positioned correctly in both vertical & horizontal(fore-n-aft) location. If you really wanted to ****(read: correct/proper) about it, the rack-tie-rod-pivot-end-position needs to also fall w/in a plane that is defined by all four of the A-arms' frame-mounting/pivoting-points. This makes for a very short rack & very long tie-rod-arms. So as usual, it's a compromise. . Willys36 work looks like a very nice compromise & excecution. . Marcus...
Here is a picture of the steering box and the tie rod ***embly from my 48 Plymouth . Sorry, that is the only picture I have of the box and tie rod ***emblies, but as you can see, both of the inner tie rod ends are very close to each other. The "center" positioned inner tie rod connections on the Cavalier (rear steer) and Intrepid (front steer) racks are have identical inner connection spacing. The differences between both racks and the original tie rods on the Plymouth is that both racks have bolt through inner connections in stead of having the tie rod end stud.
Stude, since '51, used a conventional steering box, w/the pitman arm & draglink mounted *inside* the frame, which went to a bellcrank w/2 arms 90* apart, that pivoted on a kingpin at the center of the frame-n-crossmember. That was hooked to 2 equal-length tie-rods that connected to the steering arms, (all 4 ends) via tie-rod-ends. Sounds complicated/etc, but it was - & still is - good for 200+mph stability at Bonneville, & good road manners elsewhere - as long as the components are in good shape(but that is no different from any other mechanical contraptions). Point is: rebuilt correctly, this eras' front-suspensions are worth keeping & going thru to rebuild correctly. Unless you're going autocrossing or roadracing or somesuch... . There are *fair reasons* for going to a rack, but rarely for hacking the whole suspension off. I'm not a purist, but just looking at, & considering, various & sundry practicalities. . Marcus...
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