Why You Don't Box Rear Upper Control Arms

[oldtinsmith]

I do not see any benefit to boxing a upper control arm. lowers get boxed because on hard launch they can bend having to move the entire weight of the car but uppers get pulled on so the only thing I ever see is people welding thick washers around the frame bolt holes to avoid the frame hole becoming egg shaped from the constant pulling. Having a roto joint on the uppers is a real good idea.[/quote]

This is true! Replacing a stock upper arm with an adjustable one (with a "roto" type joint) will let you adjust the axle to center it with the frame and to adjust pinion angle.

Doug

 

[jetsetw31]

This is true! Replacing a stock upper arm with an adjustable one (with a "roto" type joint) will let you adjust the axle to center it with the frame and to adjust pinion angle.

X2, Well put.

 

[Clone TIE Pilot]

The bad thing about adjustable arms is that the threaded sections are stress risers.

Last year my grandmother hired a tree romover who backed his truck into her porch railing that was made out of threaded pipes. The non-threaded sections just bend, while the threaded section broke right in the thread valleys like in the picture from LS1tech above. Everything has it's downsides.

 

[pontiacgp]

The bad thing about adjustable arms is that the threaded sections are stress risers.

Last year my grandmother hired a tree romover who backed his truck into her porch railing that was made out of threaded pipes. The now threaded sections just bend, while the threaded section broke right in the thread valleys like in the picture from LS1tech above. Everything has it's downsides.

You should not just post a picture without giving the details on what caused the part to fail.

 

[liquidh8]

The bad thing about adjustable arms is that the threaded sections are stress risers.

Last year my grandmother hired a tree romover who backed his truck into her porch railing that was made out of threaded pipes. The now threaded sections just bend, while the threaded section broke right in the thread valleys like in the picture from LS1tech above. Everything has it's downsides.

You should not just post a picture without giving the details on what caused the part to fail.

http://ls1tech.com/forums/suspension-brakes/1460370-lower-control-arm-just-snapped-2.html

Here is the post this picture came from. So I don't pull bits and pieces from another thread and misconstrue what is happening.

 

[pontiacgp]

thank you liquidh8 ... from that thread this should have also been posted with the picture...

It was a poor bushing end choice on our end. The poly bushing binds as the suspension tries to travel. Because of the bind the weakest point of the arm breaks, which is our threaded bushing end. We no longer off this style like this. So in reality the A-Arm itself didn't snap but the bushing end broke, still an issue and we have corrected it.

To fix it we replaced it with a Roto-Joint or rod end, both which allow the suspension to travel freely with little friction. We are sending the customer two Roto-Joints to replace the poly ends.

Sorry to see this happen. Thank you,
Ryan

problem solved

 

[Clone TIE Pilot]

Wow this thread is really for jerks then. There are short comings with using track racing parts for eveyday street driving and you people just want to pretend that isn't the case and just stick your heads in the sand or up a certain body part. Look at AR-15 rifle buffer tubes, noticed how the militery spec tubes are threaded differently from commercial spec tubes? That with military spec they go through the extra effort and expense to machine the tubes so the threads valley is the same dia as the tube and that the threads stick out unlike commercial spec which just cuts the threads into the tube so the thread valleys are thinner and weaker creating stress risers. But oh no that can't be the case according to Pontiacgp. The military must be wrong and foolishly speeding extra money for stronger buffer tubes. Also according to him GM had no idea what they were doing and that aftermarket parts designed for race use are always better even for normal everyday driving even through he contradicts himself.

The point of my post was to show adjustable arms are weaker than non adjustable and poor for street driving but pontacgp just tried to twist it into another petty attack at me. He argued poly doesn't cause binding yet he agrees with the LS1tech post about the poly bushing binding causing the arm to break at it's weakest point (the threads even through he disagrees threads create weak points), contradicting himself again! Even through Pontiacgp has stated poly doesn't ever bind, ever. Threads just cut into a tube creates stress risers like it did with my grandmother's railing, broke at the threads where the tubes were rendered weaker, like with the pictured adjustable arm, (guess LS guys never heard of flash rust either). The fact is, most aftermarket arms are poorly designed especially for daily long term use use, poly bushings are useless crap that binds and grabs, and GM engineers knew what they were designing hell of alot more than any of us ever will. I know gearheads and hotrodders like to pretend they "know" more than the car engineers, but the sad reality is the engineers know much more than them and the aftermarket preys on their ignorance.

If UMI was so smart, they should have known to use a roto-joint in the first place to prevent binding problems, GM knew to prevent binding problems with a 4 link suspension, UMI should have too being suspension experts. Maybe pontiacgp should do some real research instead of spewing garbage and bad info, especially with starting out with one true fact as bait, then twisting it to spread his agenda.

 

[pontiacgp]

Wow this thread is really for jerks then.[/quote}

there is no need to throw insults unless you feel insecure....

 

[liquidh8]

I only posted the link because there is nothing but partial truths spread throughout, and posting a picture from another thread without explaining the reason it really broke is the kind of thing I see all over the place. I am not disagreeing with either one of you guys that track parts are for the track. That is what is being said. 😀

 

[pontiacgp]

liquid8, I wasn't criticizing you for posting that link, I was actually looking for it myself. Any company or engineer can make an error, it's how they take responsibility and correct it. GM comes to mind with their 57 cent part that killed 13 people.