SPL Parts Discussion

[ZX_man]

I just installed SPL's billet aluminum camber links in the rear. But at the time of purchase I did not realize that SPL also made a steel-tubing version. Unless I'm missing something glaringly obvious, here is my discussion:

I'm a little nervous with my install because 4130 steel is a significantly stronger material than 6061-T6 aluminum. The aluminum has a yeild strength about 60% that of the steel, and it has a young's modulus (deflection rate) about 30% weaker than the steel. Not to mention aluminum is generally considered a much softer material. While the billet version is beefier than the tubing version it still has thin flanges where the arm attaches to the upright.

What I'm wondering now is, how much load is actually going through the rear camber arms under cornering, and is it enough that it could potentially be an issue? The billet version is also newer, have there been any accounts (yet) of them failing? I understand SPL is very well respected in the community for making quality parts. And seeing how NISMO also makes a similar billet aluminum camber arm there should probably be no cause for concern. This is most likely me just being paranoid... but I also couldn't find any other threads discussing this topic so here we go.

links:
https://www.splparts.com/products/re...t-version.html - Billet Camber "Link"
https://www.splparts.com/products/re...-370z-g37.html - Steel Tube Camber "Arm"
ASM Material Data Sheet - 4130 Chromoly (Steel) material properties
ASM Material Data Sheet - 6061-T6 Aluminum material properties

[BettyZ]

SPL has the best rep of any manufacturer on the market. I wouldn't be worried. Unless you plan on parachuting your Z out of an airplane.

Sent from my SM-G955U using Tapatalk

[ZX_man]

I don't think the fear is jumping your Z out of a plane with a parachute, it's jumping your Z out of a plane WITHOUT a parachute

[Spooler]

Originally Posted by ZX_man

I just installed SPL's billet aluminum camber links in the rear. But at the time of purchase I did not realize that SPL also made a steel-tubing version. Unless I'm missing something glaringly obvious, here is my discussion:

I'm a little nervous with my install because 4130 steel is a significantly stronger material than 6061-T6 aluminum. The aluminum has a yeild strength about 60% that of the steel, and it has a young's modulus (deflection rate) about 30% weaker than the steel. Not to mention aluminum is generally considered a much softer material. While the billet version is beefier than the tubing version it still has thin flanges where the arm attaches to the upright.

What I'm wondering now is, how much load is actually going through the rear camber arms under cornering, and is it enough that it could potentially be an issue? The billet version is also newer, have there been any accounts (yet) of them failing? I understand SPL is very well respected in the community for making quality parts. And seeing how NISMO also makes a similar billet aluminum camber arm there should probably be no cause for concern. This is most likely me just being paranoid... but I also couldn't find any other threads discussing this topic so here we go.

links:

The Nismo part is an SPL part. They make them. No issues with SPL period. Stop worrying.

[cv129]

Originally Posted by ZX_man

What I'm wondering now is, how much load is actually going through the rear camber arms under cornering...

Not sure how one would accurately measure that. Maybe call SPL.

FWIW....

Seen a car lost control, jumped a center median then a curb, landed on opposite side pedestrian sidewalk. Alignment didn’t change an ounce. Car had full SPL arms.

For this platform, SPL is the best money can buy.

On the other hand, playing devil’s advocate , reading the SPL product description, the billet version is machined (I assume that means the body is carved out of a block of aluminum), whereas the steel version was tig welded in the middle (where it curves). So, if we are reeeeally nip picking here, wouldn’t you also need to account for potential weakness in weld, and cannot just compare the strength of the two material?

I understand a properly executed weld would be just as strong as the metal itself (I hear that enough times from various groups).

[Rusty]

OP, you're paranoid and over thinking it. Have not heard of any SPL parts failing so far. SPC parts. Yea, there as been a few of them. Z1 parts. There has been a few of them too. i have just about the whole SPL catalog on my Z. No issues so far.


As for the welding on the steel version. There is an CNC angled piece in the tubing to give the welded area strength.

[bpchaos]

Also, shouldn't these pieces only be loaded in tension and compression? Should be plenty strong for that since they're made from a billet of aluminum. The struts do the load bearing, these only help to locate and control the wheel and upright. It's not like the toe arm replacement which has a load structure right in the middle.

[ZX_man]

Originally Posted by Rusty

i have just about the whole SPL catalog on my Z. No issues so far.

Yeah I was skimming your suspension build threads earlier. IIRC you installed yours before the aluminum ones came out. Unless you've upgraded since?

Originally Posted by bpchaos

Also, shouldn't these pieces only be loaded in tension and compression? Should be plenty strong for that since they're made from a billet of aluminum.

Yeah they're only in tension and compression, but there's still pretty high bearing stresses on the upright flanges given their small cross-section.
Also the camber arm is one of the lower members on the upright. This means it experiences high cornering loads since it is closer to the contact patch.

[redondoaveb]

Originally Posted by ZX_man

Yeah I was skimming your suspension build threads earlier. IIRC you installed yours before the aluminum ones came out. Unless you've upgraded since?



Yeah they're only in tension and compression, but there's still pretty high bearing stresses on the upright flanges given their small cross-section.
Also the camber arm is one of the lower members on the upright. This means it experiences high cornering loads since it is closer to the contact patch.

If you want, buy a set of the billet one's and I'll trade you my steel one's for the billet one's

[Rusty]

Originally Posted by ZX_man

Yeah I was skimming your suspension build threads earlier. IIRC you installed yours before the aluminum ones came out. Unless you've upgraded since?



Yeah they're only in tension and compression, but there's still pretty high bearing stresses on the upright flanges given their small cross-section.
Also the camber arm is one of the lower members on the upright. This means it experiences high cornering loads since it is closer to the contact patch.

I haven't up-graded.

[BettyZ]

If there's been a single instance of anything SPL failing posted on this forum, I've not found it. My geometry is all SPL. Not to be all fanboi but SPL really is the gold standard for this platform.

[OptionZero]

i would worry less about the strength of SPL's materials

and more about why you didn't get the rest of the SPL suspension components needed for full adjustability

[ZX_man]

Thanks everyone for the responses. I wanted to say a couple more things just for the sake of getting thoughts down.

The small titanium screws that thread into the alumninum are torqued to 12.5 ftlbs per SPL spec. I've ran FEA on alumninum threads in the past and the safety factors are pretty low for stripping, so I'll be careful not to over-torque these screws.

While it seems the yield strength of 6061 aluminum is sufficient to withstand cornering loads in this application, the modulus of elasticity of the material is 68.9 compared to steel's 205 (gigapascals). An alumninum part will therefore deform three times as much as a steel part of the same geometry under the same load case. For a suspension component, this mean your allignment is going to change slightly under heavy cornering. This is most likely a moot point because the camber arm seems to have a larger cross section->lesser stresses->lesser deflection. I'd be curious to do strain tests on both of these camber arms and compare.

Originally Posted by OptionZero

why you didn't get the rest of the SPL suspension components

Later down the road, yes that's the plan. Currently I'm not tracking the car.

[OptionZero]

If you're not tracking the car, you're REALLY wasting your time on this thread

There's nothing you're going to do to the SPL parts on the way to the grocery store thats gonna to break it when racing teams across many applications have beaten on their SPL-equippped cars without failure

I mean you're really just kicking up dust in your own yard

turn your engineering student brain off and your real world brain on

[JARblue]

Originally Posted by ZX_man

While it seems the yield strength of 6061 aluminum is sufficient to withstand cornering loads in this application, the modulus of elasticity of the material is 68.9 compared to steel's 205 (gigapascals). An alumninum part will therefore deform three times as much as a steel part of the same geometry under the same load case. For a suspension component, this mean your allignment is going to change slightly under heavy cornering.

You are waaaaaaaaaayyyyyy over-thinking this.

Heavy cornering is not enough load on the links to deform the parts enough to affect the alignment.