Front Shocks 49-54 Plymouth

[Loren]

My P17 was the lightest and cheapest of the MoPar cars. That's why they were raced in NASCAR's early days.

Lee Petty proved they were capable of finishing a 500 mile race ahead of the Oldsmobile V8s. Petty was in racing as a business and he was all about the numbers.

Petty did some smart shopping in the Chrysler parts bin to be competitive. In a 1954 interview he said he used Imperial wheels, tires, springs and shocks and the old photos seem to prove it.

My coupe came without a front sway bar so I got one. Big improvement!

I went shopping for stiffer shocks and found there is only one part number for all the MoPars now. I guess we should be glad there is something available.

 

For off road racing two shocks are better than one stiff one (and three were pretty standard).

So rather than go the relocation route with something available and stiffer, I thought what about a second shock?

Finding a place for additional shocks is always a challenge however.

But I seem to recall that the 1955-56 Plymouths & Dodges used a shock mounted inside the spring on the lower control arm to a simple hole in the frame near the upper A-Arm pivot.

That would allow you to keep the stock shock and add another one without a whole lot of drama.

I also remember my Mother's 55 rode very good and seemed to handle nicely too.

 

So here's a question, has anyone seen this or done this? I'll be darned if I can get the search function to find a post on this.

[FarmerJon]

I believe I saw some old discussion on the HAMB about converting to the later "shock inside" set up, but the OP didn't really have a strong reason to do it, so the consensus was that it wasn't worth the effort, that there wouldn't be enough space for a very long shock, and to just do the F1 shock mount relocation, which allows the use of a longer, more available shock.

 

 

[Bryan]

7 hours ago, Loren said:

So here's a question, has anyone seen this or done this? I'll be darned if I can get the search function to find a post on this.

The search default goes to "any of the words".  I always have to remember to click on the "all of the terms" to get anything meaningful. Then it's trying to pick common terms people might use.   Wish the default was changed.

[Plymouthy Adams]

there are other search modifiers.....but I do not recall a thread of anyone working multiple shock mounting for the front suspension.  The stock shock is so weak in design though it did what it was intended, check spring oscillation, it does this independent of the chassis no spring oscillating anymore the overall floating of the a-arms continued as the chassis was unchecked control arms to chassis.   The use of F1 or Dodge truck or the two different sized arms offered in the rodding market or the different other mounts advertized will allow the upper shock mount to go to the chassis and be very effective.   If you have not moved the shock mount to the frame, this would be a good starting point, buy a quality shock and fit to the new location and tame the beast.  Could well be all you need for the front given you installed a sway bar...maybe a heavier sway bar is in order down the road.  These heavy tubs will never have a sport car ride of feel but for sure can be improved a bit.

[Adam H P15 D30]

Why reinvent the wheel.  If you want a firmer ride, relocate the shocks...

[Loren]

I am loathe to make changes to Chrysler's designs.

I figure the engineers know a lot more than I do (It doesn't take much imagination to reach that conclusion. lol)

When I remembered the 55's characteristics and it seemed like a great idea to use that update, but...those are not real common shocks either being two years only. The stock set up was not made for "spirited" driving to be sure. It was made for long service and wear. One of the great charms of the Plymouth.

 

I am softening to the idea of the 1948-52 Ford F1 upper mount (www.speedwaymotors.com has reproductions in two lengths) because of the availability of a better selection of shocks. The modification is something that could have been done during the time period that the car was made so there is that.

While the shock travel is more than the 55-56 design (and much more the 49-54) I would expect similar or better characteristics.

Now to find the right shock.

 

[Plymouthy Adams]

THINK..in time, the father of the modern IFS did indeed make advances on its own design with the shock upper mount going to the frame.....how can you entertain multiple shock as NOT A MOD but the position of upper shock to the frame a MOD...

[Loren]

2 hours ago, Plymouthy Adams said:

THINK..in time, the father of the modern IFS did indeed make advances on its own design with the shock upper mount going to the frame.....how can you entertain multiple shock as NOT A MOD but the position of upper shock to the frame a MOD...

 

Easy. The between the A-arm set up was a clever Chrysler innovation to improve the longevity of the shocks, which it did but...all choices in engineering are compromises. When the speed limits were 45-55 mph it made a lot of sense. At 65-70 mph not so much.

We have to remember what we think is an "improvement" is just a compromise with different goals. The 1955-56 compromise kept some of the short travel long life goal but added better road holding.

Now we have a different set of goals, better handling of course with future access to replacement parts at reasonable prices.

From my research there are limited choices for stock shocks, limited choices for the 1955-56 design, so I have to make a decision (or a compromise if you will).

Right at this moment I am leaning toward the F1 mount. What would cinch it would be to know the right shock to use. Any suggestions?

[Adam H P15 D30]

I enjoy the ride my stock shock set up gives me on my 49, but to each their own.  70-75 MPH, no problem even on California roads.

[FarmerJon]

 

 

Looks like several suggestions, good and bad here. Doesn't sound like there is one absolute answer.

[Eneto-55]

If you look at the front shock mount for the solid axle 37 0r 38 Plymouth, you will see that it is the same design Ford used years later - it looks to me like a direct copy, but maybe that same design was widely used by many of the auto manufacturers already back in the late thirties.   (Photo below.)

 

As to the upper control arm mounted shock design, some here have said that they made the modification, and haven't seen that much of a change.  I don't know - I still have the stock shock design, and my car isn't road-ready, either.

 

It's a common idea that highway speeds were a lot lower back when cars of this vintage were the normal transportation, but from what my dad told me, that is not really the case.  I remember very well riding in my folks' 53 DeSoto, and the speed limit on even back roads then (around 1960, in Oklahoma) was 60 MPH.  And my dad often drove faster than that on trips across Oklahoma.  (Before I was born he had a 37 Dodge, and he had that up to 75. As to other brands, my grandpa had a 39 Ford that would do 75 in second gear - he had a 49 Merc engine in it.  That was his car before my parents married - early 50's.)  

But as to the design, I suspect that the upper control arm mounting point was chosen to deal with the much rougher roads of that era. (At least in Oklahoma, but the auto designers didn't live there, so maybe not.)

Edited May 27, 2022 by Eneto-55

[nonstop]

I tried the F1 shock upgrade.  It certainly improved the ride at speed.  Probably my error in figuring out the proper measurements, but ended up cracking my frame in the area of the mount.  I repaired the frame, went back to original shock set up and now enjoy the float of the ride.  I also stopped trying to make more mods.  Some have worked well, others have not…..

[Loren]

1 hour ago, nonstop said:

I tried the F1 shock upgrade.  It certainly improved the ride at speed.  Probably my error in figuring out the proper measurements, but ended up cracking my frame in the area of the mount.  I repaired the frame, went back to original shock set up and now enjoy the float of the ride.  I also stopped trying to make more mods.  Some have worked well, others have not…..

 

This is exactly why I trust the factories engineers over my version of what passes for engineering.

The notion of using the 55-56 design along with the original location seemed to cover the engineering issue but not the supply issue.

The thread from 2015 never got to the point of identifying the right shock. It seems the fellow closest to a solution couldn't say exactly what he was using. "Original" meant what was on his car when he got it but not necessarily what was OEM stock.

So...we don't have an answer as yet.

I have a new set of OEM spec shocks and I have ordered the short F1 mount from Speedway.

The only way to prevent bottoming is to remove the spring from one side and measure the wheel travel at the mounting point of the shock.

I might even drill an old shock to release the oil and any resistance. The idea being is to avoid any binding or tweaking of the shock.

Hopefully I can generate enough data to pick the right shock.

 

 

[Sniper]

I found a set of much stiffer gas charged shocks that fit in place of the original shock's envelope.

 

It's for my 51, which is a different shock that yours calls for.  What I did was measure out the center to center height if my stock shock collapsed and extended, then I used Speedway Motors drop downs to find a shock that met the specs I measured out.

 

Ended up with these

 

https://www.speedwaymotors.com/CPP-DT-4809G-1955-72-Chevy-Truck-Front-Gas-Shock-Lowered,440140.html

 

Had to drill out the bushings to 5/8" (I believe) to get them to mount over the stock studs.  the replacement shocks have a shorter collapsed and longer extended length than my stockers, so no worries about bottoming out or overextending them.

[Loren]

After considerable effort I got the coupe into its new garage/shop.

The neighbors told me they hadn’t seen the door open in 5 years. I now know why. I will be rebuilding the door.

 

Once inside I pulled the front wheels and did some brain storming.

First off I rejected the Ford F1 mounts. Plymouth uses a boxed frame and the pick up used a channel frame. Not surprising as pick ups were cheaper than cars back in those days. Plymouth even though a low priced car was built to a higher standard than pick up trucks.

Boxed frames being inherently stronger can also be lighter or at least made from lighter material and that is the case here.

For several reasons I rejected bolting the F1 mounts to the frame.

I looked at the possibility of using fabricated mounts as well. I didn’t like that idea either.

Welding to a frame is done all the time I know and folks will question my sanity when I mention my objections to doing it.

If you weld across the frame member, if it is going to crack, that’s where it will crack. The rule has always been if you must weld, it should lengthwise or better yet use rivets.

Rivets or bolts can use doubler plates which is difficult with welding most of the time.

So I am not keen on relocating the upper mount….still.

I did more research on the 55-56 shocks. You can order them front all the regular suppliers but….since there is only one outfit making them they are out of line price wise.

I don’t want to experiment with pricey parts I have no use for if it doesn’t work out.

That said, the concept of mounting a second shock inside the spring (like the 55-56 Plymouth) sounds appealing as you only have to drill three holes.

I found two shocks which might work but I am going to do more measuring.

The first came on the 1975-80 AMC Pacer. Don’t laugh.

The second one will require a plate to mount it on the bottom of the lower arm. This shock has been fitted to nearly all the GM brands at one time or another, Fords, Studebakers and interestingly the 1961-72 Volvo P1800, which means you have all sorts of great choices in shock brands such as Koni, Bilstein, KYB etc.

So that is the latest in my thought process. When I get the dog gone door rebuilt, I will be able to do a test drive.

[andyd]

From my understanding of the 55/56 front shock mount setup it is not the lower mount that is a problem but the upper mount as the upper 55/56 shock mount goes thru the frame and the upper inner A arm pin and bush assembly lives in that area on the 54 and earlier frame..........but I am happy to be mistaken........andyd

[Loren]

30 minutes ago, andyd said:

From my understanding of the 55/56 front shock mount setup it is not the lower mount that is a problem but the upper mount as the upper 55/56 shock mount goes thru the frame and the upper inner A arm pin and bush assembly lives in that area on the 54 and earlier frame..........but I am happy to be mistaken........andyd

 

You are not mistaken at all.

In fact you are right on the money.

 

The 49 has 4 bolts holding the upper A-arm pin while a 55 has only two and very likely is wider and the A-arms longer (if not mounted in a slightly different spot).

That is the fly in the ointment. Right about where you would want to drill the hole for the upper shock mount is almost exactly where the pivot pin passes over the spring seat. It could be done if you are willing to saw the pivot pin near the bolt bosses and weld on a flat bar with a hole in it for the shock mount. Of course that means a disassembly of the front suspension.

Sounds like a whole lot of work to me.

It could be done and it really is an elegant solution if you need to do that much renovation to your suspension.

In my case the car has only 38,000 miles and doesn't wander. My front shocks were worn and so I've replaced them with new stock ones.

 

In the mean time I think I will be on the hunt for someone who has replaced the front frame clip. If I have to do that much work, I want to clean and paint every piece.

The ideal way to do it would be to get a front clip that you can turn over and find the perfect spot for the upper mount, drill it, modify the upper pin with the flat bar and transfer the hole to the bar. Then when you trade pieces on your car you can use the pin as a drill jig.

The lower A-arm might benefit from welding spots to bolt the plate to the bottom for the lower shock mount.

Since I have lots of other high value projects I think I will put this one on the back burner till I get a front clip.

 

[Adam H P15 D30]

Sorry if I read your last paragraph incorrectly, but if you're going through the trouble of clipping a car, I would go with something more modern than a 50s front clip.

 

Here is on I did on my 47, has all the characteristics you are trying to achieve plus a lot more.