Good morning,

I need to replace the torsion bars on my 1974 Petty NASCAR Dodge Charger. The length of the bars is 37 inches, which is much shorter than the 41" of the B-Body and 44" of the C-Body torsion bars.. The HEX size on both ends is much larger as on the B-Body torsion bars. It could be the C-Body size HEX ends, but I have no C-Body handy to check that. Please find a sketch of the bar attached, which I draw after unbolting it from the car. The end of the bar is stamped with the numbers "37" and "1100". I'd guess that those are the length of the bar and the spring rate.

Is there a sizing chart where I could see the diffenrent HEX sizes ?

Would you know if there has been 37" long torsion bars in older MOPAR, like in the 1950's or on Pick-Up trucks ?

Uhh, sorry can't help other than perhaps suggesting contacting Firm Feel . . . they have lot of the suspension dialed in . . .

www.firmfeel.com

cheers

NASCAR guys back in the day were "get er done" types who used anything and everything. Those torsion bars could be from a tractor or a forklift or anything in between. Dick Ross at Firm Feel might know. He has a fair amount of NASCAR stuff sitting around his shop. Good luck, you'll most likely need to have some bars custom built for the car.

Definetely a custom deal. B body hex is 1.25, C body hex is 1.4x. No factory bars were 37" long. A body are 35.8, then B/E at 41. Older cars and C bodies are even longer.

Once upon a time, there were a number of different companies making a variety of torsion bars for mopars and sprint cars. Sprints still use them but have splined ends now days.

A bodies are about 36" (35.8") long I believe. I don't know the size of the hex heads though.

A body hex is 1.25 also.

Thanks for your replies. I'm already in contact with Firm Feel on that matter.

I just wanted to double check that the Hex ends are of C-Body size. Here is a picture of the crossmember housing where the torsion bar end goes in.

and here is a picture of the A-Arm where the other end of the torsion bar goes in.

That is some really neat info you shared. I have never heard such details before. A 37" bar with a 1 1/8 working dia must have a spring, guessing, around 400/lbs/in? Wow, superspeedway set-up no doubt. There is math to actually calculate. Sorry can't help with a solution, but do you need that high of rate for your application? They can be fabricated, I have done some research on install C body TB in my E body.

IIRC, the hex is based on an early torsion bar car like late 50’s early 60 imperial or something.

The lower control arms changed at some point in late 60’s

I don’t know what your chassis history is. The 1974 Petty Catalog shows a bunch of torsion bars with only diameters listed. They have Chrysler part numbers (that doesn’t mean they were ever installed in production cars)

Then they show 41” torsion bars with 1 1/4” hex and 1 1/8” dia. Those have “PE” Petty Engineering part numbers

Greg K at will know at odcics2@comcast.net

the spring rate on those Grand National torsion bars is 325 lbs/inch and those are the Riverside road course variety. They come in even much higher specs for oval speedways as listed in the 1974 Chrysler Circuit parts catalog.

Need to say, just in case, not all B bodies That's are 41" long. 73 and laters are 43"

Right ! I looked for those MOPAR part numbers throughout the internet, but nothing came up. On my Petty car, they are of the shorter 37" length. I'd assume that the lower A-Arm's are modified C-Body parts.

Here’s more from the catalog.

What’s the difference between the 11 torsion bars in the first group from the two torsion bars with PE numbers ??

Mine are from the first group. They are 37" long. The 2nd group look like B-Body sizes.

I'm wondering what the 1100 stamped on the bar means. Since it is not the spring rate, it might be the total spring load.

It's quite impressive to see on that page 17-1 of the catalog that the torsion bar diameter is actually bigger than the HEX end !! On my bars the hex end diameter is 1.610"

the early T-bars were adjusted at the transmission cross member.
i'm thinking the lower arm adjuster for B-bodies came in 62, [the year B-bodies came to be ?] while the C-body change came in 65-66 ?