Interesting SPL Tension Rod Factoid

[Nismo_Freak]

The rod ends have a static load rating of over 10,000 lbs.

[rbsileighty]

Was that a tensile strength load? Is that when it start to neck or break?

Nice to see some of the companies are doing testing and showing some numbers!

[SmithSR]

How do Cusco, Battle Version, Tanabe, Tein, etc compare? What are the material differences between brands, and who's is built strongest?

In short-- Does price reflect quality, wth this type of product?

[Def]

How do Cusco, Battle Version, Tanabe, Tein, etc compare? What are the material differences between brands, and who's is built strongest?

In short-- Does price reflect quality, wth this type of product?

I guess you could make some tension rods that would fail at 1,000,000 lbs, but what's the point? 10,000 lbs is FAR beyond what these pieces would ever see, so making them "stronger" isn't buying you anything but a lighter wallet. The SPL parts seem very finely crafted to me, so I don't see how one could improve the subjective quality of a piece like this any futher.

To answer your question though, I doubt most tension rods are any stronger if even this strong. Your whole wheel assembly would be ripped off from the car before 10,000 lbs of tensile load were placed on the tension rod(with the other stuff still attached that is... there is always a way to break stuff ).

[SmithSR]

Then what of the reports of cracked OEM tension rods, which see no significant change other than Energy suspension bushing kit.

What is the strength of OEM tension rods?

[barrigas14]

never heard of the tension rods cracking...they bend but not crack.

[Toahk]

Maybe you meant the lca's cracking?

[s13sr20chris]

are the spl rods steel? i have tein rods that i got a bargain on. i took the bargain specificlly because they were steel and not aluminum.

[Exar-Kun]

Maybe you meant the lca's cracking?

yeah, the only reports I hear are the LCA cracking because of stiffer bushings with no "give" under impcats, like the NISMO or ES bushings, the heim joint however has a small rnage of movement, preventing that problem.(you hit a bump, it tires to force the LCA backwards, with a stiff T/C bushings, this wont occur....CRACK)

oh well.-chet

[Nismo_Freak]

yeah, the only reports I hear are the LCA cracking because of stiffer bushings with no "give" under impcats, like the NISMO or ES bushings, the heim joint however has a small rnage of movement, preventing that problem.(you hit a bump, it tires to force the LCA backwards, with a stiff T/C bushings, this wont occur....CRACK)

oh well.-chet

No, cause with a Heim joint you have even less movement of the LCA. The heim joint on the other hand pivots which reduces the torque load when you put them on a lowered car. When the suspension moves up and down the tension rod will try to twist. Polyurethane resists this twist and causes the load to be placed on the LCA. Based on what I just mentioned, the heim jointed SPL tension rods don't have this problem because the heim joint allows for this movement.

[Nismo_Freak]

are the spl rods steel? i have tein rods that i got a bargain on. i took the bargain specificlly because they were steel and not aluminum.

They have a large billet aluminum shaft, steel buckle, steel hardware, and a very large steel rod end.

[Nismo_Freak]

never heard of the tension rods cracking...they bend but not crack.

The only way people have destroyed our tension rods was installation error, and running over things, like curbs, Explorers, and a number of other larger objects.

[Nismo_Freak]

How do Cusco, Battle Version, Tanabe, Tein, etc compare? What are the material differences between brands, and who's is built strongest?

In short-- Does price reflect quality, wth this type of product?

Tein is about the 8,400 area, and I'm sure Cusco is either that or close to us.

Tanabe, Battle Version I can't comment on but generally they are around the same quality as Tein / JIC.

Less we not forget the ebay stuff lol.

[Def]

When the suspension moves up and down the tension rod will try to twist. Polyurethane resists this twist and causes the load to be placed on the LCA.

Alan's got it! The polyurethane binds, thus setting up a shear force on the LCA. Eventually the LCA fatigues on the inside portion(due to most the stress coming when the suspension is suddenly compressed). It cuts right through it, very similar to well... a shearer or if you want a more common example, scissors.

[Exar-Kun]

No, cause with a Heim joint you have even less movement of the LCA. The heim joint on the other hand pivots which reduces the torque load when you put them on a lowered car. When the suspension moves up and down the tension rod will try to twist. Polyurethane resists this twist and causes the load to be placed on the LCA. Based on what I just mentioned, the heim jointed SPL tension rods don't have this problem because the heim joint allows for this movement.

yeah, you hit a bump, the LCA moves, the heim joint since it can twist, does..thats what I meant/said.-chet

[aither]

I destroyed one SPL T/C rod thanks to a curb impact. I didn't really expect it to break, but it broke along where it bolts into the LCA. Note, Their T/C rods work very well, and I have been very please with how they have performed. This was me being stupid.

[Dori Dori]

Alan's got it! The polyurethane binds, thus setting up a shear force on the LCA. Eventually the LCA fatigues on the inside portion(due to most the stress coming when the suspension is suddenly compressed). It cuts right through it, very similar to well... a shearer or if you want a more common example, scissors.

Def, I didn't think this was what binding is...wouldn't the stress be due to the fact that polyurethane bushings don't allow for deflection...something the stock TC rods were designed to do and that a heim jointed TC rod would do?

[VA240]

Where did you get that rubber boot?

-VA240

[Def]

Def, I didn't think this was what binding is...wouldn't the stress be due to the fact that polyurethane bushings don't allow for deflection...something the stock TC rods were designed to do and that a heim jointed TC rod would do?

A hemispherical bearing has almost zero radial deflection when it is not worn out and needing replacement. My SPL rods were absolutely solid before I put them in. You can feel this effect when you go over something like the reflector "dots" on the highway. You can really feel it with the hemispherical bearings allowing no back and forth play in the wheel assembly.

Polyurethane on the other hand, WILL have some radial play. Not much, but some unless they use a really REALLY stiff urethane(doesn't seem that way from the ES bushings I gave the scientific "finger-poke" test).

Polyurethane though is a very "grabby" material. It doesn't slide at all on ANY metallic material from what I can remember from my Machine Design class(unlike how steel/bronze have a naturally lubricated interface). So really you only have the steel/steel interface between the bolt and bushing sleeve. Steel/steel is only a partially lubricated interface based on their material composition IIRC. So while grease will help some, you are dealing with a very small bearing area relative to the radial forces experienced while there is rotation required with the suspension compressing.

You'll compress most of the grease out after a while and get a huge amount of friction from the interface and create a cyclical shear stress on the edges of where the tension rod bolts to the LCA. This is partially reversed(meaning the shear is experienced in both directions) due to the suspension flexing both ways, but I'd speculate that the stress is greater when the suspension rapidly compresses rather than slowly returning due to shock rebound. But regardless, that's about the worse type of stress situation, because it will RAPIDLY fatigue everything involved.

So that's why you eventually see a small rip in the LCA that quickly grows to a large crack.

Probably more than anybody wanted to know, but that's my take on why the rips are happening. The stock LCA's are pretty thin in that area too, so I imagine that after the bolt/sleeve interface gets all the grease pushed out of it things fatigue relatively quickly. So it seems about right on the ~6-12 month timeframe most people see this type of failure.

[s13sr20chris]

break out the welder!