Question about lower control arm and torsion bar

[MoPar~Man]

How does this shaft get removed from the lower arm? Do I just pound it out from the other side?

This shaft, the visible part in the photo, that runs through the frame, I assume it does not move or rotate? I was sort of wondering if it did, why no grease fitting. But I guess it doesn't?

And regarding this torsion bar, where does it rank in terms of I guess stiffness?

Naturally it's 47" long, I measure the diam to be 0.96 inches. If different C-bodies came with different torsion bars, is it possible to know which model this would have come from?

I have no information as to the year/make that this frame came from, I'm assuming somewhere between '65 - '68.

 

[CBODY67]

The length and diameter specs are in the FSM. Spring rates, per se, are not. In many cases, the factory a/c cars got the same bars as the HD suspension cars. The Chrysler parts book will define that.

The length of the bar will be determined by the carline. How do the bars compare to the ones on your car?

Take the bar mounts to a machine shop so they can press the shaft out, replace the bushing, and press it all back together. MUCH better than beating them.

Just some thoughts,
CBODY67

 

[MoPar~Man]

I can find a dozen or so lists of torsion bars showing length and diameters, and some of those also have part numbers, and some of those include C bodies.

Thing is, I can't find ANYTHING showing a 178 P/N. The last 3 digits of the P/N for this bar would have been 178. But none of the lists I've found on the interwebs show a matching P/N.

And what about this shaft being free to rotate inside the frame sleeve it's mounted in? I don't see anything that locks it in place. Just the nut. But I guess that's enough?

 

[CBODY67]

On the Build Sheet, in the torsion bar spaces, there usually is a 3-digit number in the space for "left" and "right", which are not the same. Possibly THAT is the only place you might find that number? All the FSM will state is length and diameter. Length is specific to which C-body is involved. As in Chrysler, Plymouth, or Dodge.

Be aware, too, that with a torsion bar, the more pre-load the bar sees past the basic ride height adjustment (where the base of the rocker panel is parallel to the road surface), more pre=load will raise the front end and also make the spring stiffer. Opposite when the basic pre-load is lessened.

Only place you might find the spring rates is in the A.M.A. Specifications document for the car. Still no ref to the cast numbers on the bars, just "spring rate" and "ride rate" for each end of the car.

Perhaps Firm-Feel or others who sell replacement C-body torsion bars might help with the decode of those cast numbers?

The rubber is in the pivot of the lower control arm. It and the shaft are pressed in. No rotation. just flex a bit when the suspension twists. Just like the rear, the bar slides into the hex in the LCA, in the relationshop spec'd in the FSM.

Enjoy!
CBODY67

 

[MoPar~Man]

The 7-digit part numbers for the torsion bars are usually (or always) consecutive for Right and Left. The Right bar P/N is always an even number, the Left is odd. The last 3 digits of the P/N are the ones stamped into the end of the bar. That much is a clear fact. So there are lists and tables of these P/N's but none of them that I've found show a P/N ending with 178.

 

[330dTA]

0.96”, 47” torsion bar was the ”standard suspension” bar in many Chryslers from ’65 to ’71, at least, and possibly in ’72 and ’73 (I haven’t checked on those). A Heavy Duty bar, which was used in AC equipped cars, would have been 0.98” in those years. Later models (’74 to ’78) used sturdier bars.

 

[MoPar~Man]

I've looked through the 1967 and 1968 Mopar parts catalog (PDF files, one is 138 mb, the other is 87 mb) and there is a single page in each one that lists the torsion bar PNs for the various car lines, various options (taxi, police, heavy duty, etc). There is no P/N that ends with 178. And on those pages it does say exactly that the 3 stamped numbers are the last 3 digits of the PN.

I agree that just looking at the diam and length that this would be a standard bar. I'm just curious why I can't find this PN listed anywhere. There are threads on the net where someone posts a photo of a bar with the 3 numbers being, say, 058, and the response is "well that's the date code - 5'th month of 1968". I think that's a bit of a crock, why would the date code be so important to track, why 2 different schemes for coding the T-bars? In my case, 178 would code for the 17'th month of 1968. Obviously not correct. I'll check for paint spots on these bars next.

 

[Boydsdodge]

How does this shaft get removed from the lower arm? Do I just pound it out from the other side?

View attachment 648537

This shaft, the visible part in the photo, that runs through the frame, I assume it does not move or rotate? I was sort of wondering if it did, why no grease fitting. But I guess it doesn't?

And regarding this torsion bar, where does it rank in terms of I guess stiffness?

View attachment 648538

Naturally it's 47" long, I measure the diam to be 0.96 inches. If different C-bodies came with different torsion bars, is it possible to know which model this would have come from?

I have no information as to the year/make that this frame came from, I'm assuming somewhere between '65 - '68.

145 ft lb of torque on the nut is what stops the rotation of the pivot pin. You will need to torque that nut at ride height or you will ruin your new lower control arm bushing that you will be installing while it is all apart. Look for the bar number on the other end.

 

[Elvis Lean Burn HP]

On the Build Sheet, in the torsion bar spaces, there usually is a 3-digit number in the space for "left" and "right", which are not the same. Possibly THAT is the only place you might find that number? All the FSM will state is length and diameter. Length is specific to which C-body is involved. As in Chrysler, Plymouth, or Dodge.

Be aware, too, that with a torsion bar, the more pre-load the bar sees past the basic ride height adjustment (where the base of the rocker panel is parallel to the road surface), more pre=load will raise the front end and also make the spring stiffer. Opposite when the basic pre-load is lessened.

Only place you might find the spring rates is in the A.M.A. Specifications document for the car. Still no ref to the cast numbers on the bars, just "spring rate" and "ride rate" for each end of the car.

Perhaps Firm-Feel or others who sell replacement C-body torsion bars might help with the decode of those cast numbers?

The rubber is in the pivot of the lower control arm. It and the shaft are pressed in. No rotation. just flex a bit when the suspension twists. Just like the rear, the bar slides into the hex in the LCA, in the relationshop spec'd in the FSM.

Enjoy!
CBODY67

You mentioned (Firm/Feel)

Last year I purchased a pair for my 77 Newport. I rebuild the front steering system during that time I install these new torsion bars approximately $600.

Big work properly as advertised. Pleased with the product.

 

[MoPar~Man]

I've now checked all parts catalogs 1965 to 1969. For each one I found the torsion bar page. None of them show a 178 bar. They all say the numbers are stamped on the anchor end, which I assume means the end inserted into the rear cross member. They all say the 3 numbers are the last 3 numbers of the PN. No mention of a date code stamping. No mention of any sort of marking on the other end inserted into the lower control arm. I will look today on the other end of the bar.

This is the Right (passenger side) bar that I've taken out. I note that this side of the suspension seems to have been worked on, the upper control arm bushings and bolts and ball joint are much newer looking vs the driver's side. The t-bar anchor socket was full of grease. I'll be taking out the other side soon.

 

[Trace 300 Hurst]

You will need to torque that nut at ride height or you will ruin your new lower control arm bushing that you will be installing while it is all apart.

Exactly, absolutely correctomundo. This tiny detail is often overlooked, with the shaft nut being tightened with the control arm hanging down as far as it can go. This is an easy, "seems normal to do" mistake to make. Once the car is on the ground at ride height, the rubber in the bushing would be twisted to maybe 20 degrees instead of being "neutral" at ride height and thus in permanent torsion. And early failure.

A thin film of grease on the shaft where it goes into the crossmember allows it to easily rotate when put under load. Mechanics who are well-experienced with this job pretty much know where the control arm should be at "ride height", and simply jack it into that position and then torque the shaft and strut nuts and then continue with reassembly. That's close enough, if you really know what you're doing.

As for removing and replacing the shaft/bushing assembly in the arm, you really do want to find a shop and have it pressed in/out. When I was a lad and didn't know about arbor presses, I pounded the shafts out and in on a crummy old Valiant, but that was in a very well equipped garage with a big vise, lots of pieces of steel pipe to act as arbors for the pounding, hand sledge hammers, etc. And grown, experienced men who counseled me! Do yourself a really big favor and find yourself a shop.

 

[CBODY67]

DO make sure the rear hex area is well-greased when assembled. This protects against water intrusion and rust (which can make the bar snap, after a while). That rear seal was added after rust-related failures on '57 cars started to happen.

 

[Trace 300 Hurst]

And that shop I worked in had an anvil on a stump. Makes a world of difference you have to pound on something.

50 years later, I'm sure that massive anvil is still in use somewhere....kinda hard to wear one out, and kinda hard to throw away!

 

[CBODY67]

Yep, definitely hard to tear up!

We had a long-time service manager who claimed that some people could tear up an anvil in a sand pile, though. We had some service customers who had that capability, too.

Enjoy!
CBODY67

 

[330dTA]

OT: I once heard of a bunch of boys to whom you could only give a three foot long piece of an iron rail as a toy. If it was longer, they would break it. If it was shorter, they would lose it.

 

[MoPar~Man]

Allright, the mystery is solved. This end shows the 178 stamped on both bars. But also note that R and L are also stamped on this end.

But on the other end:

There is a barely visible 620 and 621. Which would make these bars 2269620 and 2269621 ('65 to '69 big block Chrysler). It even has the silver paint marks:

I've seen one example of these same bars for sale on ebay (from a vendor in Quebec) and they're stamped 620R and 621L. The R and L are stamped with the 3-digit code, not on the opposite end of the bar.

And yes, there was a ton of grease jammed into the anchor sockets. The seals were still there, but were soft and broke apart easily. I guess I'll need new ones. I'm going to do some research and see why these bars are oriented Left and Right and, I guess also directional (front to back).

One more question, about the front struts. It seems to me that you have to knock the lower control arms out to be able to remove / install the struts. No other way to do it. Yes?

 

[330dTA]

Left and right? The bars were pre-tensioned at the factory, in order to reduce the diameter and weight of the bar. Consequently, if you mix them up, the suspension will fail.

 

[MoPar~Man]

So the front / back orientation doesn't matter? I'm trying to imagine if I switch the front/back is the twist direction being reversed when loaded.

And just noticed this: The '67 Monaco/Polara service manual shows a plug at the back end of the anchor socket, in front of the lock ring. I found no such plug on the frame I'm taking apart.

 

[MoPar~Man]

I have not yet pushed these pivot pins or shafts out of the lower bushings, nor removed the bushings themselves. But I'm making an observation here. There is I think more play than I'd want to see between the arm assembly and this shaft/bushing assembly. There's about 1/8 inch of motion range at the end of the shaft, for example. The yellow arrow shows where the play is happening. The shaft / bushing / adjuster arm is one solid assembly that can freely rotate in the lower arm, but the play between the two, I don't think should be there.

This lower-control arm / shaft arrangement is, to me, a very sloppy design. There should be no play here, but still allow for rotation. But how should it be done, and stand up to wear and tear? A bearing?

Would this have been a better fit when new, but there is simply no parts substitution or replacement possible here? I can't quite tell if this play is due to wear of the outer jacket of the bushing, and that a new bushing will tighten this up. Comments?

Also, note the space, about an inch, between the shoulder ridge on the pivot shaft and the bushing. When the shaft is pressed into the bushing, will it automatically stop there?

 

['66 Fury I]

Remember that the only time there will be movement at the point indicated by your yellow arrow is when the adjusting bolt is turned to set ride height. other than that, the assembly moves as a unit, held tight by the torsion bar preload.
The space you pointed out is "set" when the shaft is pressed into the bushing and the bushing is pressed into the control arm.
As a side note, I made a tool for pressing the bushing into the control arm from a 1-inch galvanized pipe coupling. I ground the thread out of one end with a carbide bur and threaded a piece of pipe into the other end of the coupling. As noted in the FSM, I had to reduce the diameter of the shoulder ridge on one shaft on my bench grinder. The outside diameter of the shoulder is not machined by the manufacturer and is, essentially "random size"! Lindsay