trailing arms?
 

Ok...im sure im just nuts but......my trailing arms have holes, abot 2 inch diamiteralong the length of the arms...do they all have them?? i dont remember seeing it b4, almost like someone lightend them or something

lightening?
 

Big Jim,
Of all the places I could think of to lighten a truck that would be the last!

Must be sabatoage!

here's a pic. of mine. see if you can see where your talking about.
by the way dose your's have plates like mine? want to know if that was stock.
Thanks
David

Plates
 

here's the plates I was talking about.

It's not a very smart way to lighten up a truck. You want those arms as stong as possible, no flex. If anything beef them up and find other areas to remove weight. You might loose 3 lbs by drilling out some holes but your going to loose 40% of the stifness, it's not a good trade off.:bowtie:

My arms have the plates on the bottom, but no holes.

I think those plates are on C-20's and C-30's

Any unsprung weight removal will noticably improve acceleration.
Lightened trailing arms are a must, if you're racing. One of the first things we do on our modified. Properly lightening these arms is the trick. We lighten in non-stress areas, add support to the stress points. Depending on where those slots are, what your purpose is for this truck, all plays a part. Slotting the entire length, is new to me. I'd have to see a pic.
Stepside

I think her talking about a street truck here, loosing 3 or 4 lbls off the arms will not make any noticable differance. Running it over a pot hole or a rough road will . The arm is a strees member and you don't want it to bend, thats why special trailing arms for Cameros and Mustangs are boxed for added performance. if you look at one of these arms, it's just two pieces of stamped steel that are rivited together. That plated the 20 and 30 arms becuse more strength was needed and to holed them together better. you can loose a lot more weigth somewhere else and you can improve the handling with springs, shocks, and sway bars. It's a bad idea to drill these arms. If you want lighter arms, spend the cash and go with a 4 link setup.:bowtie:

holes and plates
 

Plates: My trailing arms have those plates as well........but I'm not sure what they came off of.

Holes: It is possible to drill holes (reasonably sized) in THE EXACT CENTER of a beam only to lose a negligible amount of stiffness. A good example would be the holes that are sometimes put in floor joists for plumbing and electrical conduit. At the exact center of the beam, there are no tension or compression bending stresses. On top, the beam is under compression, and down below, it's under tension. If you keep the hole small enough for the size of the beam, and the amount of weight it's expected to carry, you should be ok.

Personally, I'd be weary about whacking into my trailing arms with a holesaw if I hadn't done some precise calculations.......especially if it sees any towing or heavy hauling.

My $.05

plates
 

68 suburban,
The trailing arm plates only being on c20 and c30 would make sence, concidering this is a pic of a c20. the c10 I used to have didn't have them. so I'll buy that.

Stepside,
Unsprung weight huh? got any pictures of a properly lightened factory trailing arm? would like to see that. how much weight did you put back on with strenthening it at its stress points?

67 LS1
I am all to familar with structural loads on dimentional lumber, and the amount of material that can be safely removed. but there is on way in h@ll I'm leting a plumber, electritian or HVAC guy anywhere near my trailing arms!!:)

David

wait a minute..im an electrician.......lol... :)

electritian
 

Presant company excluded.:)

you guys missed something here,.... lol..... no C30 used trailing arm rear suspension lol., only leaf spring,.all C20 trucks used welded on bottom flkat stock like that. C10 did not.
whoever drilled the holes in the arms does not need to be owning a 64-72 GM truck

good luck

yeap, neat cars!

Re: holes and plates
 

67 LS1 SWB is correct.
If you don't know how to calculate E, I, S or Fv, then don't do it.

bigjimzlll You may want to box yours at the ends to be safe. I would do it at 1/3 of the distance at each end, minimum or replace the trailing arms.
If one of those fails it wont be pretty.
MHO,
Denny

Re: plates
 

Hey, I got a sawzall.........can fix you right up.....roflmao!http://personal.clt.bellsouth.net/cl...s/rotflmao.gif

Yes, 72 custom C-20, unsprung weight. Yes, I have pictures and no, I will not post them. Not now. The topic was lightening, and why. I just gave a racers point of view. Your pessimism was well taken.
Stepside

un sprung...
 

Stepside,
Started a debate today in my head about this. Now whith the forgone conclution that I am not a racer, just a street guy. That if you could or have, Increece the strenth, eliminat flex and twist, and by removing material (with confidence, or should i say complex formulas) in unnessary areas, and equal the same weight, you would be an idiot not to. So I stand corrected and please forgive my pessimisim. :)

David
Some ruler I'd make, with all my doom and gloom :)


ahh come on, just post one pic. just one little pic. :D