C-2 Trailing arms
I see trailing arms advertised for 65 - 82. Are they all the same ? If not what is the difference.
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Re: C-2 Trailing arms
There are some differences along the run.
The 63-4 are drum brake and have difference axles and arms
63 have no webbing in between the bearing support legs
63-73? have small ends on the support legs, around 74-82 have larger ends but all accept the same shock mount
The support bores changed from having a well to a straight bore
The backing plates changed from silver to gold in 77?
the 80-82 have a yoke on the axle where as the 63-79 used a flange.
The 82's had a 030 shim on the outside of the inner bearing cone race -
Re: C-2 Trailing arms
Glad to help, one thing to keep in mind is there is a date code on the supports so if you send yours old for an exchange set of arms you most likely will not get the same date codes back if that matters. In most cases it is better to rebuild your arms.Comment
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Re: C-2 Trailing arms
Robert-------
Gary has well-covered the spindle and bearing support section of the trailing arm assembly. I'll cover just the arms, themselves.
The 1965-74 arms are the same. These were GM #3874769, lh, and GM #3874770, rh.
The 1975-77 arms were GM #3864035, lh, and GM #3864036, rh. How these arms differed from the above I do not know. Whatever it was, I expect it was a very minor difference. These arms replaced the 3874769-70 for SERVICE in, respectively, January, 1977 and November, 1976.
The 1978-81 arms were GM #475103, lh, and GM #475104, rh. I believe these are the same as the above except that the parking brake cable bracket was slightly re-positioned in order to accommodate the 255-15 tires used on some 1978-81 Corvettes. These arms replaced the above for 1965-77 SERVICE in, respectively, February, 1979 and July, 1979.
The 1982 arms were GM #14035663, lh, and GM #14035664, rh. I believe these are the same as the 475103-4 except there are 4 holes drilled around the circumference of the bearing support orifice. These holes are for the installation of the self-tapping screws used to retain the u-joint shields used only on 1982 Corvettes. These arms replaced the previously mentioned arms for all 1965-81 Corvette SERVICE in September, 1982.
As mentioned above, each set of arms was REARWARD compatible. However, that does not mean that earlier arms were necessarily FORWARD compatible. I think that possibly with "minor adjustments" the earlier arms would be forward compatible, though.In Appreciation of John HinckleyComment
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Re: C-2 Trailing arms
Very good points Joe, and you have all the numbers.
One other thing, not as much a difference in the arms but an overall inspection.
Look at the end overlaps, they should be flat. If they show spreading there is rust in between them. Check the area around the support opening in the arm and pinch the metal, it should be flat. If you feel bumps it is rotted.
Measure from the flat plate welded to the arm with a 2' level to the arm by the bushing. To the arm not the bushing, it should be 1.920-2.000" There is a window there but anything over .125-.150" means the arm it bent.
Look on the side of the arms near the bushing for any signs of impact from a hydraulic tool or plain hammer- methods used to set the toe when the shims and bolts are seized.
IF you find any of the above, toss the arms as they are not safe to use.
While talking about arms, I have found new rotors are now coming through with the rotor hat ID too small. I have been machining the new ss star wheels shorter for about 15 years now due in part to this issue but over the past 6 months I had 3 new rotors I had to rebore the hats to allow the rotors to be used. Some were new NAPA, some were "high performance" drilled and slotted, and others were those sold as correct with the rivet holes. Some were so bad they would not fit over the shoes, the others would but the shoes hit them. If you assemble arms or get in rebuilt ones and hear a ticking noise that might be the issue.Comment
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