nascar truck arms?

Why don,t people try to build there own spark plugs instead of suspension parts, at least than if it,s not right they can,t hurt anyone else. Good luck guys.

 

i plan on useing 1/8"X3"X3" tube split and welded back to back with bushings at the front, one thing i know is that when i replaced the arm on my 70 chevy 3/4 ton i noticed it had a piece of 3/16"FB spot welded to the top, the arm i was using to replace it came off my 66 GMC 1/2ton and i just made a new piece of 3/16" and plug welded it on, just something i noticed working on truck arms.

 

I haven't seen that plate, but I haven't seem them all. We have two cars in the shop now getting tuck arms. Neither has it. I wonder if it is a 3/4-ton thing. All of the arms I have used were from 1/2-ton trucks.

 

60-72 Chevy does NOT have any kind of plating for C-10/C-20/C-30 (1/2, 3/4 and 1 ton). There are a few aftermarket companies that offer them, but those companies may not actually understand the need for these arms to flex, as their instructions are to weld these plates on.

 

Looks like that comes with polyurethane bushings too. All kinds of not understanding how this system works.

 

maybe it was a Canadian thing, they were on from new, it also had helper springs, maybe a camper special? it was only on the top and as i said spot welded.

 

Perhaps. You Canadians put gravy on french fries, so you never know...

The GM Heritage Center "packet" on the 1966 Chevy (you said yours was GMC, and Canadian) doesn't mention anything about it. This is, of course, not a very detailed document... but interesting nonetheless.

http://www.gmheritagecenter.com/gm-heritage-archive/docs/Chevrolet-Trucks/1966-Chevrolet-Truck.pdf

 

i had a 66 GMC 1/2 ton just sitting when my 70 chevy 3/4 ton's drivers side trailing arm rusted through, so after doing a little measuring i found that the 66 GMC's trailing arm was the same, it wasent till i pulled them both off and had them sitting side by side on my shop floor i noticed the extra 3/16" strip, i bought the truck from the son of the orginal owner, the truck was bought just to install a camper on and was used for nothing else till i bought it.

 

I think that extra flat bar welded to the trailing arm *may* have been a 3/4 ton deal. I have an American '68 C20 3/4 ton Chevy 2-wheel drive and it DOES have the extra flat plate/bar on the trailing arms.

I had to replace one of them, and just as you mentioned, the 1/2 ton replacement trailing arm didn't have the extra plate.



Malcolm

 

Those re-inforcement plates were/are factory GM. My 66 Chev camper special had those, as well as the backwards facing quarter elliptical leaf spring "helpers"...mounted behind the rear axle, with the tips resting on the tail end of the truck arms.

 

OK, so we Americans put gravy on chicken fried steak, so...

My "expertise" is with 67-72 series, and I've had a BUNCH of them (including CSTs and C-20/30's)... and never seen the extra plates or any documentation that describes them. But, I'm willing to learn something every now and then. Great info!

 

Just one question.

Why are people so intent on using an old pickup suspension under a hot rod?

If you say it's because NASCAR uses them, then think about why they use them. It isn't because it is the best suspension. It is to limit the traction the cars have. That is why it is a RULE. It isn't decided upon by every team that it is the best solution.

Just sayin I think there are better solutions out there.

 

It's incredibly simple, rides very well, has a much lower travel arc than many "car" trailing arm designs because of its length, parts are readily available, and you can get LOTS of travel if you're doing an air suspension.

"Better" solutions? Possibly, but I think you mean "more sophisticated."

 

Yea, I guess "better" really is subjective.

 

well, I'm "just sayin", for some applications IT IS the best solution, though not for any and all applications. But for cars like Buicks, with torque tubes and coil springs, it is a GREAT solution when converting to open driveline, as I am doing on my '40 Super. '49 /'51 Olds is another good app...there are more.

Sure, one can put in a Jag or Corvette or ???? and improve the unsprung weight equation. But, for simplicity on my '40 Buick, It's a natural.

Ray

Edit: While I have made numerous posts on various threads about 'truck arms", they have not been for the purpose of convincing anyone they should be using them. My posts have been in an effort to (often unsuccessfully) persuade people that the geometry and materials used when thay make their own facsimilies are important to get the potential benefit and not create worse problems.

 

If you plan on making continuous left turns, it's perfect!

 

or...more "street roddy"

 

It also allows you to keep more or all of your floor on a very low or bagged car. On almost every car I have put them on, I was able to keep the back seat, even with the frame or rockers nearly on the ground.

The ride quality is very nice on everything I have put them on, and installation is easier than many other systems, too.

That's why. Haven't found a downside yet.

 

Here's a photo I took to compare the two from the Chevy pickups.
1/2 ton on left, 3/4 ton on the right.




(sorry to the original poster for taking this thread slightly off track)

 

Just curious (I am thinking I did not see the specific dimensions for the factory arms anywhere in this post) .... if one intends to split some square (or rectangular) tube down the middle (creating two pieces of "C channel) in order to make their own truck arms ... what tubing should be used, or what tubing would best be used to replicate the factory GM arms? (For example 2x2x1/8, 2x3x1/8, 2 1/2x2 1/2 x1/8" etc.)

 

If somebody else does not post them first, I will post the dimensions. Not at the shop today. They are probably about 4"x5" overall.

 

Hmmmmm....
I always wondered why GM used a HOT ROD suspension under an old pickup!

The whole setup is very forgiving and neutral in handling...easy to use...bulletproof once its in there and takes up no foot room on most cars.

I think Ron Popeil may have invented it....you "set it and forget it".

 

I think in HambAndys A we used 2x4x 1/8" split and stitch welded into I beams. We tapered them too...
Now thats in a Flattie powered car with a C4, but it still looks like it could hold some decent horsepower before needing to be upsized.

I wouldn't use 2x2x1/8" in an I beam configuration. You lose the look if it gets too thin anyway, IMO...

 

It seems to me a method that may offer some benefits over spiltting a square or rectangular tube wouid be to have some 11ga stock bent into channels at a steel shop. You could have it bent with the desired taper easy peazy. Now, that assumes that a brake can form a pair of 90 degree bends so close together, and therein may lie the rub.

Any sheet metal guys online tonight?

Ray

 

Sounds very workable.
With a bit of planning a crafty guy could even have the plate bent so the arms tapered from the TOP view as well as from the side....

 

Now that's thinking!

 

The only problem with the stock style trailing arm is they rust inbetween the c channel. Sure the average hot rod doesn't see the abuse a daily driver does. Just food for thought.
Clark

 

Bit tricky with the little kick at the axle end but very doable.
Need a tall upper and off you go. If its really tight maybe an offset dog leg upper, not every shop will have that one of those.

If someone has at least a napkin sketch, ill see what I can come up with.
I had a early 70s truck with that set up on it but it was 20 years ago. CRS....

 

I didn't expect the 'bent' part at the rear could be formed with this method, but that the fabricator would saw a 'V' notch through the upper flange and web, bend and weld.

The same would be required if made from split square stock as some are doing/proposing.

Ray

 

Could do that too, less work on the layout and brake.