trailing arms? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bigjimzlll · 06-11-2002, 11:28 PM

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

72 custom C-20 · 06-12-2002, 12:18 AM

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

72 custom C-20 · 06-12-2002, 12:21 AM

here's the plates I was talking about.

slam33 · 06-12-2002, 09:49 AM

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.

Patrick Sullivan · 06-12-2002, 02:12 PM

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

68 Suburban · 06-12-2002, 02:47 PM

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

Stepside · 06-12-2002, 06:17 PM

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

slam33 · 06-12-2002, 06:43 PM

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.

Wasted Income · 06-12-2002, 07:17 PM

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

72 custom C-20 · 06-12-2002, 11:02 PM

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

bigjimzlll · 06-12-2002, 11:28 PM

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

72 custom C-20 · 06-12-2002, 11:38 PM

Presant company excluded.

*Fast68Chevy* · 06-13-2002, 02:07 AM

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

imaindianoutlaw · 06-13-2002, 09:01 AM

Have you guys ever seen a swiss cheese catalina?

**68SWB4x4** · 06-13-2002, 03:20 PM

yeap, neat cars!

DennyB · 06-13-2002, 05:47 PM

Quote:

Originally posted by 67 LS1 SWB
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

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

DennyB · 06-13-2002, 05:53 PM

Quote:

Originally posted by 72 custom C-20
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

Hey, I got a sawzall.........can fix you right up.....roflmao!

Stepside · 06-13-2002, 06:23 PM

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

72 custom C-20 · 06-13-2002, 11:10 PM

Quote:

Originally posted by Stepside
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

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.

06-11-2002, 11:28 PM	#1
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	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 __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

06-12-2002, 12:18 AM	#2
72 custom C-20 Registered User Join Date: May 2002 Location: Southampton, Pa. Posts: 27	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 Attached Images __________________ 72 C-20 custom/deluxe med. blue 350 64 oldsmobile F-85 deluxe 330ci. 86 KX 125 Old school, mint Southampton, Pa.

06-12-2002, 12:21 AM	#3
72 custom C-20 Registered User Join Date: May 2002 Location: Southampton, Pa. Posts: 27	Plates here's the plates I was talking about. Attached Images __________________ 72 C-20 custom/deluxe med. blue 350 64 oldsmobile F-85 deluxe 330ci. 86 KX 125 Old school, mint Southampton, Pa.

06-12-2002, 09:49 AM	#4
slam33 Registered User Join Date: Aug 2001 Location: Long Beach, Ca Posts: 1,432	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. __________________ 71 LWB 350/350still working on it but it's going tp be sweet. www.geocities.com/stevemau/slam33page.html " TARGET=_blank>http://www.geocities.com/stevemau/slam33page.html?1004806705410 </A>

06-12-2002, 02:12 PM	#5
Patrick Sullivan Transcendental Trucker Join Date: Dec 2001 Location: Rockaway Beach, OR Posts: 374	My arms have the plates on the bottom, but no holes. __________________ Patrick Sullivan \| sullivan@oregoncoast.com Rockaway Beach, Oregon 1972 Chevy Cheyenne C-20 1998 Dodge Dakota 4x4 So, fill to me the parting glass And drink a health whate'er befalls... Then gently rise and softly call Goodnight and joy be to you all!

06-12-2002, 02:47 PM	#6
68 Suburban Registered User Join Date: Oct 2000 Location: From Chicago, Live in Phoenix, AZ Posts: 6,802	I think those plates are on C-20's and C-30's __________________ Just sitting here contemplating contemplation.

06-12-2002, 06:17 PM	#7
Stepside Gasser Join Date: May 2000 Location: Thomasville,NC USA Posts: 456	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 __________________ :thud 70 sstep tubbed, Muncie, double hump, snowflake,

06-12-2002, 06:43 PM	#8
slam33 Registered User Join Date: Aug 2001 Location: Long Beach, Ca Posts: 1,432	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. __________________ 71 LWB 350/350still working on it but it's going tp be sweet. www.geocities.com/stevemau/slam33page.html " TARGET=_blank>http://www.geocities.com/stevemau/slam33page.html?1004806705410 </A>

06-12-2002, 07:17 PM	#9
Wasted Income Boosted Member Join Date: May 2002 Location: Mackinaw, IL Posts: 2,200	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 __________________ 1972 2wd K/5 Blazer Turbocharged 370 LSx - 941 rwhp / 1093 rwtq 1969 Chevy K-10 L33 5.3 / 4L80E / NP241 / 4" lift 1964 Buick Skylark Twin TURBO 383 LS pro-touring project 2014 VW Passat TDI - Daily Driver Turbo diesel 2015 Sierra Denali HD Duramax Turbo diesel 2023 Ford Explorer ST - Twin Turbskis 2023 Ford F150 RCSB - Whipple Supercharged 2017 Polaris RZR Turbo 2014 Nor-Tech Center Console - Twin Supercharged Outboards *TURBO ALL THE THINGS!!*

06-12-2002, 11:02 PM	#10
72 custom C-20 Registered User Join Date: May 2002 Location: Southampton, Pa. Posts: 27	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 __________________ 72 C-20 custom/deluxe med. blue 350 64 oldsmobile F-85 deluxe 330ci. 86 KX 125 Old school, mint Southampton, Pa.

06-12-2002, 11:28 PM	#11
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	wait a minute..im an electrician.......lol... __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

06-12-2002, 11:38 PM	#12
72 custom C-20 Registered User Join Date: May 2002 Location: Southampton, Pa. Posts: 27	electritian Presant company excluded. __________________ 72 C-20 custom/deluxe med. blue 350 64 oldsmobile F-85 deluxe 330ci. 86 KX 125 Old school, mint Southampton, Pa.

06-13-2002, 02:07 AM	#13
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	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

06-13-2002, 09:01 AM	#14
imaindianoutlaw GMC SHORT FLEET F/S Join Date: Jun 2000 Location: SOUTH WILLIAMSPORT PENNSYLVANNIA Posts: 2,117	Have you guys ever seen a swiss cheese catalina? __________________ CHARLES WADE HEIN HVACR FOREMAN. LEWISBURG U.S.P.

06-13-2002, 03:20 PM	#15
68SWB4x4 Strongman Garage Join Date: Apr 2000 Location: Salinas, CA Posts: 10,241	yeap, neat cars! __________________ Kalle 68 GMC Suburban 1500 4x4 SOLD 69 Pontiac Lemans 99 Silverado 4.8 5 speed ECSB [ Facebook Instagram Subscribe on YOUTUBE



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06-13-2002, 06:23 PM	#18
Stepside Gasser Join Date: May 2000 Location: Thomasville,NC USA Posts: 456	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 __________________ :thud 70 sstep tubbed, Muncie, double hump, snowflake,

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