trailing arms: Goodmark vs. ECE vs. OEM

[69Tom]

After doing some research on here, I'm beginning to think my trailing arms are a little too rusty to keep using.

Therefore, I'm looking for a set of new (to me) ones.

I was considering pulling the trigger on a pair of the ECE arms. However, people say not to used boxed arms, as they don't flex enough. Not sure how true this is or not.

If it's true, that leave me with a) finding a clean set of OEM arms, or b) buying some Goodmark repops on RockAuto.

Any opinions here? I'm a little confused based on all I've read. At the end of the day, I'm a pretty original guy so I guess maybe I should go with a nice set of OEM arms if I can find some nice ones close by.

Thanks.

[Richard]

A pair of sandblasted trailing arm on the parts board https://67-72chevytrucks.com/vboard/...d.php?t=786364

[Mike C]

Not using boxed arms because they don’t flex enough is a bizarre statement. Eliminating flex allows the suspension to do the work it is supposed to.

IMO, the more rigid the better when it comes to things like trailing arms. I would run the ECE with no worries if that is what you want.

[SCOTI]

Originally Posted by Mike C

Not using boxed arms because they don’t flex enough is a bizarre statement. Eliminating flex allows the suspension to do the work it is supposed to.

IMO, the more rigid the better when it comes to things like trailing arms. I would run the ECE with no worries if that is what you want.

The engineers designed the Truck Arms to allow some flex. That flex & rubber bushings in the front mounts are what helped keep things cheap yet still survive the articulation stresses of daily use. The T/A arrangement binds @ the limits in OE form. Take away those areas of flex & you get bind much sooner.

By swapping in hard poly bushings up front vs. rubber, the set-up will bind sooner or will require more flex of the arm.
By swapping the I-beam arrangement that allows for some twist in it's length to a solid steel beam that doesn't will induce bind sooner.

There are ways to improve the original for sure. The solid steel beam (tubular or square) promotes consistency vs. 'unwanted' flex when subjected to more aggressive loads (side loads/cornering or straight line/drag strip launches). The key to prevent the bind issue is to use a bushing that allows for some flex. Either the OE style rubber (which defeats the intent of eliminating flex) or something that allows articulation w/o being sloppy (a spherical joint).

Yes, steel tube arms & poly bushings are a common 'upgrade'. That doesn't mean they are better just because the materials are stronger.

[bigmac73]

i have a set of tubular rectangle trailing arms I installed with new poly bushing , simple and easy install, just make sure you get the correct lube for the bushings. I have had no issues with them at all. I think i got them at ECE.

[SCOTI]

Originally Posted by 69Tom

Question: are 3/4 ton and 1/2 ton 115" wb arms the same length?

Yes. The 3/4 ton arms have plating on top & bottom for gusseting.

[biketopia]

Originally Posted by SCOTI

Yes. The 3/4 ton arms have plating on top & bottom for gusseting.

To prevent flex??

[SCOTI]

Originally Posted by biketopia

To prevent flex??

More for increasing the structural strength is my bet. Since the arms were originally 2 pieces of C-channel butted together & spot welded, they could in theory (reality) come apart. I had one split on my high-school ride in the 80's.... Scared the crap out of me when it happened.

Imagine if it happened under severe duty apps (heavy towing/loads)? The plates added that additional strength/security. The entire arm was not plated, just the top/bottom F/R sections close to the bushings/U-bolts where the flex/twist would be minimal since that's where they're bolted solid to the mounts/rear end.

If I'm upgrading OE arms, I clean between the seams as much as possible w/a wire brush & use air/water pressure to get the funk out. Then I'll do some short 1-1.5" length stitch welds in the horizontal seams about every 6-8 inches of the length. I also weld the vertical seam @ both the front & rear of the arm. Less weight vs. plating & stronger than OE.

[69Tom]

So has anyone ordered the reproduction Goodmark arms? They're $200 each at RockAuto, so a little cheaper than the ECE box arms.

[SCOTI]

Originally Posted by 69Tom

So has anyone ordered the reproduction Goodmark arms? They're $200 each at RockAuto, so a little cheaper than the ECE box arms.

Seeing your avatar suggests you're in/around AZ? I would think you'd be able to find a clean, rust free pair of T/A's easy.

[69Tom]

Originally Posted by SCOTI

Seeing your avatar suggests you're in/around AZ? I would think you'd be able to find a clean, rust free pair of T/A's easy.

One would think! Heck, I can't even find a rust free cab at a decent price anymore. I think the stock is getting lower out here and is harder to find part-outs.

[SCOTI]

Originally Posted by 69Tom

One would think! Heck, I can't even find a rust free cab at a decent price anymore. I think the stock is getting lower out here and is harder to find part-outs.

Wow. That's a scary thought if you're struggling to find rust free stuff. I guess it's harder here in TX as well but suspension stuff usually isn't bad.

I'm parting out the OE suspension from my 64 now & will likely clean the crust off the parts & sell them locally. Didn't notice any rust , but wasn't necessarily looking for it either. I suppose I'll look closer just to be sure.

[69Tom]

Well, I decided on "none of the above."

I wanted to retain the stock look. I don't really trust Goodmark. I also didn't want to be attempting to sand EDP coating off these things.

So I went with these. https://www.summitracing.com/parts/c...el/c10-pickup/

CPP seems to have a decent reputation, I maintain my stock look, and they're bare steel so I don't have to sand anything. Plus, Summit is close by, has super cheap shipping, have a discount going now, and I had a coupon. So win - win, I think.

Hopefully they work out. Thanks all for the comments.

[special-K]

Let us know how they work out.

I don't buy the no flex from boxed arms being bad. I wouldn't use poly bushings since the point of the boxed arms are to give a more positive feel, as well as more strength. The trailing arm is a rigid member of the suspension. If stock are flexing in up and down motion they are also flexing side to side. They are built to be strongest on the vertical plane. For those lowering trucks, it lessens required range of motion anyway. The fact that 3/4t trucks need that plate tells me the design could use a little help. They are one part of these trucks, which I always say were designed so well, where GM cheaped out and that is showing up now even in AZ trucks. I've only ever run stock trailing arms and have only had a few trucks with them. I never had any problems. But if I needed new trailing arms I think I'd consider ECE's better design.

[SCOTI]

Originally Posted by special-K

Let us know how they work out.

I don't buy the no flex from boxed arms being bad. I wouldn't use poly bushings since the point of the boxed arms are to give a more positive feel, as well as more strength. The trailing arm is a rigid member of the suspension. If stock are flexing in up and down motion they are also flexing side to side. They are built to be strongest on the vertical plane. For those lowering trucks, it lessens required range of motion anyway. The fact that 3/4t trucks need that plate tells me the design could use a little help. They are one part of these trucks, which I always say were designed so well, where GM cheaped out and that is showing up now even in AZ trucks. I've only ever run stock trailing arms and have only had a few trucks with them. I never had any problems. But if I needed new trailing arms I think I'd consider ECE's better design.

Define "bad"? The T/A set-up is basically a triangle right? When looking @ it from a birds-eye view, it utilizes horizontal front mounting points & angled c-channel links that are solidly attached to the rear end/rear mounting point.

If the rear mounting points are @ different heights (driver side goes up 3" & the pass side droops 3") vs both sides moving equally up/down in relation to the front mounts (which remain constant to each other), the triangle needs to be able to flex somewhere to allow the changes. Where does the flex occur to allow the different heights for each side when the suspension cycles?

The C-channels can twist slightly along their length (not bend up/down or side/side). That's why I-beams are used. That ability to twist plus the front mounting points encapsulated w/rubber allows the flex. The aftermarket rigid bars/arms don't allow the flex along the length. Poly bushings limit the ability to flex. Stack the two together & it's worse.

[Aus69c20]

If anyone’s worried about the lack of flex in the trailing arms I thought these were a great idea. They replace the bush in the trailing arms and allow less restrictive articulation.
https://www.hotchkis.net/product/196...k=&yr=&md=&sm=

[scottofksu]

Originally Posted by Aus69c20

If anyone’s worried about the lack of flex in the trailing arms I thought these were a great idea. They replace the bush in the trailing arms and allow less restrictive articulation.
https://www.hotchkis.net/product/196...k=&yr=&md=&sm=

Those were what I was thinking about... Clean up, seam weld, and plate stock arms and use these for more predictable articulation.

[SCOTI]

Originally Posted by scottofksu

Those were what I was thinking about... Clean up, seam weld, and plate stock arms and use these for more predictable articulation.

Exactly.

[ElKotze]

Originally Posted by SCOTI

Define "bad"? The T/A set-up is basically a triangle right? When looking @ it from a birds-eye view, it utilizes horizontal front mounting points & angled c-channel links that are solidly attached to the rear end/rear mounting point.

If the rear mounting points are @ different heights (driver side goes up 3" & the pass side droops 3") vs both sides moving equally up/down in relation to the front mounts (which remain constant to each other), the triangle needs to be able to flex somewhere to allow the changes. Where does the flex occur to allow the different heights for each side when the suspension cycles?

The C-channels can twist slightly along their length (not bend up/down or side/side). That's why I-beams are used. That ability to twist plus the front mounting points encapsulated w/rubber allows the flex. The aftermarket rigid bars/arms don't allow the flex along the length. Poly bushings limit the ability to flex. Stack the two together & it's worse.

Dear fellow enthusiast, please allow me to respectfully disagree. You say: "the triangle needs to be able to flex somewhere to allow the changes", and that's where I think you are wrong. That kind of flex is unwanted, why else would one install a rear anti-sway bar? Just my opinion, correct me if I'm wrong. P.S. I'm planing on fabricating my own T/A out of square tubing.

[SCOTI]

Originally Posted by ElKotze

Dear fellow enthusiast, please allow me to respectfully disagree. You say: "the triangle needs to be able to flex somewhere to allow the changes", and that's where I think you are wrong. That kind of flex is unwanted, why else would one install a rear anti-sway bar? Just my opinion, correct me if I'm wrong. P.S. I'm planing on fabricating my own T/A out of square tubing.

So we respectfully agree to disagree.

Yes & no.... Flex beyond articulation is unecessay. Flex for articulation is quite necessary & the triangle (the rear T/A susension on C10's) used the original material choices for that. No flex for articulation means binding. Binding vs. smooth articulation can unsettle the suspension. A suspension that gets disturbed @ the wrong time is unpredictable.

On the subject of rear sway bars.... Rear bars are used for specific reasons. Many install a rear sway bar 'because'. Because why? Because it's necessary? Because other guys have one? Because different vehicles have them & this GEN of C10 didn't so adding one is 'better' vs. not having one? If you install a rear sway bar, what size bar are you specifying?

A rear bar if needed is supposed to compliment the front so the size up front matters when deciding what rear bar. Adding a sway bar to a T/A set-up that utilizes solid tube arms & non-flex style front bushings won't hurt simply because the set-up is already limiting articulation.

It's your truck so use whatever you think is best (solid tube arms, poly bushings, & add a rear bar). Normal driving down the street to the burger joint, Cars & Coffee, or local show won't stress the suspension enough to notice a difference.

[ElKotze]

Originally Posted by SCOTI

So we respectfully agree to disagree.

Yes & no.... Flex beyond articulation is unecessay. Flex for articulation is quite necessary & the triangle (the rear T/A susension on C10's) used the original material choices for that. No flex for articulation means binding. Binding vs. smooth articulation can unsettle the suspension. A suspension that gets disturbed @ the wrong time is unpredictable.

On the subject of rear sway bars.... Rear bars are used for specific reasons. Many install a rear sway bar 'because'. Because why? Because it's necessary? Because other guys have one? Because different vehicles have them & this GEN of C10 didn't so adding one is 'better' vs. not having one? If you install a rear sway bar, what size bar are you specifying?

A rear bar if needed is supposed to compliment the front so the size up front matters when deciding what rear bar. Adding a sway bar to a T/A set-up that utilizes solid tube arms & non-flex style front bushings won't hurt simply because the set-up is already limiting articulation.

It's your truck so use whatever you think is best (solid tube arms, poly bushings, & add a rear bar). Normal driving down the street to the burger joint, Cars & Coffee, or local show won't stress the suspension enough to notice a difference.

Good points, and I agree in part. For my next build I was planing on tube arms because in my (simple) mind they would partly act like a sway bar IF used with poly bushings, regular rubber would support binding, as you stated. This pickup will be a street truck, no off-road use, that can go down the straight line slightly quicker than stock. And I agree, a binding suspension would be undesirable in any circumstance, while a rather stiff rear end would (hopefully) enhance traction.

[SCOTI]

Originally Posted by ElKotze

Good points, and I agree in part. For my next build I was planing on tube arms because in my (simple) mind they would partly act like a sway bar IF used with poly bushings, regular rubber would support binding, as you stated. This pickup will be a street truck, no off-road use, that can go down the straight line slightly quicker than stock. And I agree, a binding suspension would be undesirable in any circumstance, while a rather stiff rear end would (hopefully) enhance traction.

I'm no expert but in a track application, I wonder if any binding impacts the ability to tune the set-up? So if I was doing tubular T/A's, I'd use a Delrin or Spherical set-up on the front mount so it pivots freely & both rubber/poly don't. There are also guys putting down sub 1.50 60ft times w/the factory T/A's. I'd make a decision to use tubular vs OE on any possible weight difference.

[stsalvage]

This is a funny one for most people that don't know what is what. Most hot rod builders go with them style Arm's thinking there better then factory Almost all custom builders say the factory stuff is stronger than the aftermarket.

If you're going for look's go custom if you're going to pound on it and use it for work stay with the factory.

[special-K]

The rear suspension is articulated through the bushed mounts. I have no experience with tubular trailing arms, so I have to ask how drastically do they affect the suspension? What are the negative results?

Hey Aus69, I wondered if something like that was possible?

[Metaldoc]

Custom made by me with lowering angle included. I've put over 7000km on the truck without an issue.