I saw this on an OLD forum and decided to try it out. Ill be as detailed as possible though its a pretty straight forward conversion. Be warned!! It lowers the front end ALOT. At least 3 inchs. For this conversion you dont need ANY NEW parts. You re-use all existing components. As far as i understand, it works for 1951-52 plymouth. But it may work for older/newer ones as well, im just not familiar with the suspension set up on other years. As you can see on the pictures, the front spring lower perch (or lower mount) sits on TOP of the LOWER CONTROL ARM. The goal is to remove the factory rivnuts and relocate the perch (or lower spring mount) to the BOTTOM of the LOWER CONTROL ARM. Its pretty straight forward. With a lift and tools. It took me 4-5 hours to do both sides. Tools i used: Grinder Air hammer Hammer Drill Rachet Impact gun The first thing i did was removed the factory front sway bar and the sway bar mount that is mounted onto the lower control arm. You may want to find a way to reuse these parts but i will be upgrading the front sway bar later. Then i removed the top bolt from the knuckle to seperate the knuckle from the top control arm thus lowering the knuckle and lower control arm and removing the front springs all together. Now that the control arm is hanging about, i used the grinder to remove all the factory rivnuts and hammer the lower spring mount / perch out. From there, all i did was used the same hole from the top of the control arm and drilled a hole on the bottom of the control arm. Thus keeping the perch in the same "location" but it went from the top to the bottom. After drilling two holes, i mounted it up as a guide to drill the remaining holes. Before putting the mount back on the control arm, i had to grind down the edges as it had a lip from factory. I also removed the factory bump stop as its useless now. After mounting it back up, simply put the spring back in place and put everything back together. Here is a before and after of the car. It REALLY lowered the front. So much so that i had to change the shocks. Another common conversion on these cars is the shock relocation conversion and i did that as well. But after lowering the front. I had to go with a different shock all together. Ill post those pics as well. BEFORE AFTER I havent taken her out yet but the front suspension is still bouncy and not super firm. This conversion was priced at $0 and 0 cents. Other than changing shocks, it was the easiest thing i could do to achieve a better stance and lower the front WITHOUT sacraficing performance. Thanks for checking out my post.
If you don't weld new stationary upper shock mounts on, it's always going to be bouncy. Study the original layout. It is senseless. They are pretty simple. Google it and you can find information on P12D24 forum and here. You still are going to have 2 unequal length tie rods and that short one is going to bump steer badly. Eventually, every US manufacturer saw the light and introduced front steering with an idler arm and equal length tie rods.
Thank you guys for the replies. I said the suspension is "bouncy" but i didnt mean its bouncy as a bad thing. I ment it as it feels the same as it would from the factory. The upper shock mounts ARE welded. After installing the shocks, the suspension is firm but not too firm. Im not worried about bump steer or tie rod length. Its got a rack and pinion, i spent some time doing research on that and have a good solution for that. This was just to show how to lower the front at no cost. Thanks again.
I only have one suggestion in the name of this being more safe and reliable. Replace the lock washers that you used to bolt the spring pocket on with locking nuts. The lock washers will come loose after a period of time from exposure to vibration. You could do them one at a time and it will probably take less time than a bathroom break. Other than that everything looks sound and the pics and write up are well done and informative.
After having "split" lock washers come loose and seeing the gouged burr left behind,(potential stress crack) everything that's semi permanent with lock washers or nylocs gets replaced Nordlocks. Watch the Heinkel test on YouTube and you'll see what I mean.
I think the qusetion, if OEM is upper arm to lower arm like on the 46-48, is did you relocate your upper mount to the frame where the shocks actually do something...
Yes i used shock mounts off of a 1951 ford and welded them onto the frame, raising the upper shock mount. I went with Monroe Shocks 37187 , they fit well and have the perfect compressed and extended length for use.
If I remember correctly, 51 Plymouths had quite long coil springs in their front suspensions…which lends itself to cutting a coil out, without screwing up the ride quality much. Sorry, can’t remember if 1 coil is enough or not.
Nice trick, if i just would know that in 1996 when I cut 1 ½ coils off the springs. Make it low enough, but messed up the geometry. Original shock mounted between upper and lower control arm, became useless. That was cured same way as you did, making new upper mount bolted to the frame. But still have problem with tire wear, cause can’t adjust camber enough. Maybe I should be brave enough to put upper control arm to the press and straighten them little to make them longer. Also that long tie rod to the right front wheel cause bump steer to right wheel, but that ain’t too bad, but right wheel wears out even quicker than the left one. But still I have driven 105 000 miles with that thing and I’ll keep on driving lots more, so even it is not perfect, it ain’t too bad either. By the way, it is -54 Dodge Kingsway, export model, technically same as -54 Plymouth.
In 1965, when I got my 52 more door I just got the hot wrench out and lowered it. As I remember, keep in mind I can’t remember what, if anything, I had for breakfast, it didn’t ride too bad, and looked pretty cool to my 15 year old self. This was way before I had the ability or knowledge to cut the springs. The smart stuff would have to wait.
Cool low buck no buck drop...as with any suspension work, exercise safety..A loaded coil spring can cause serious injury.. happened to yours truly...
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