Lets talk front suspension regarding Afshin's TR failure.

[Guest Looking for apt in Alb Ny]

My question is. What if the front was made without a tension rod. A control arm that bolts on the ends rather in the middle. I am very surprised at how much stress the Z endures and the front control setup is rather small. We are pushing it hard by far. I have thought to myself what a stupid setup the tension arm is. I mean it flexes rather following a controlled pivot path. Well its me blabbing 4 30 in the morning. I have alot on my mind. When I do its a good thing. Brain waves are kicking and ideas are flowing. hmmm Well let me know. would me machining tensions rods be a better alternative to old worn out ones. What would the material be made from? These are ideas and we can all dream right? We can call this idealism. The innovative comes on the finished product. Thanks Juan

[JMortensen]

There's not that much machining to do really, but if you started to make rods like Mike made, I'm sure you'd sell them. It's not the material that makes the stock TC rods weak, its the poly bushings. They are way too stiff for that particular job. But the stock rubber bushings cause the Z's to be nervous under braking. Some type of swiveling joint is needed, IMO.

 

Adjustable is nice so that caster can be easily changed, that's the best part about changing the TC rods; gaining more adjustability.

 

Jon

[Guest Looking for apt in Alb Ny]

Interesting..... I understand what you mean. MSA sells that pivot end. Is that the simple solution? Would only the adjustable TR be needed. Thanks

[auxilary]

jeez man, how many usernames do you have?

[blueovalz]

I mean it flexes rather following a controlled pivot path

 

Ideally, the tension rod never flexes but instead the rubber bushings flex instead. Stiffening the material of the bushings reduces this intented flexibility which then transfers the stresses or forces into the rod itself. Something that should be kept in mind and is of minor concern here is that all of these bushings (including the control arms) should be tightened into place with the suspension compressed (e.g. normal ride height configuration). This keeps the bushing unstressed at normal ride height. Yes, the TC rods look rather spindly to me too, but remember, these rods are designed around forces applied along the length of the rod (hince the name Compression/Tension rod). Place a slight bend in this rod, and all those forces (mostly compression) can quickly bend or snap a rod. I've seen bent rods before, so I know they will bend before snap, so I have to assume the "snapped" rods are due to metal fatique associated with constant flexing until the rod gave way. I replaced mine a while back with OEM rubber ones.

[Afshin]

Hi Juan and blueovalz. I wrote a new reply in the scary tension rod failure post Take a look if you can, I would appreciate your input.

[johnc]

I have thought to myself what a stupid setup the tension arm is. I mean it flexes rather following a controlled pivot path.

 

That setup has been used since the 1950s on many, many vehicles around the world. Its simple, cheap, and strong. The tension rod is only a fore/aft locator for the lower control arm. It comes into play primarily under braking and most of the time just goes along for the ride.

 

The failures we are discussing are the result of improper modifications and/or a lack of inspection. What many people forget is that modifying a vehicle to perform beyond its design requires more frequent inspection and maintenance. I've yet to see a tension rod failure on a competitive ITS 240Z and that's a result of frequent inspection and replacement as necessary. BTW... the ITS racers put far more load into the suspesnion then any street driver 240 ever sees.

[johnc]

I used the term "improper modification" above. I should have just said "modification."

[srgunz]

Where are they breaking? At the bushing end where the dia. is reduced?

[Guest BigWhyteDude]

hey Afshin do you have any pictures of where your tension rod broke??

[Afshin]

The rod broke right where it enters the first bushing. i will take a picture tomorrow and see if I can figure out how to post it. It looks interesting.

[Afshin]

I posted some pice in the scary tension rod failur post

[Guest Looking for apt in Alb Ny]

Hey man I didn't meant to start a different post here. Is there anyone making these adjustable TR's. At the shop we do solid steel bars with taps on the ends. I'm sure all I would need is to make it proper sized and get the ends for them. I asked once before what is needed to make the adjustable control arms but I got little help and some others are taking that on. Ill stick with the billet stuff for now but would like to see the billet pieces come together to make an intrigued item. I guess thats where intakes will come in. Whos knows Juan

[Guest Phil1934]

If you extended the pivot bolt for the lower A arm, does it line up with the tension rod bushing? If so a simple bushing pivot is all that would be required. A lot of street rod suppliers offer this type of setup to replace the large ugly M II bushing. They offer no adjustability as you weld the support one time and you are done. If Datsun varies here and you wanted to make something that bolted up to th eexisting mount, I'd just add shims withh the kit instead of the expense of adjustability. They also offer a full A arm, but there have been a few failures of the pivot bolt as the mount is still narrow. A full A arm would only work if another support was added outside it.

[VRJoe]

I noticed from the posts that this seems to happen on lowered cars. Is it possible that the rods are hitting things like speed bumps, steep ramps ..... and getting damaged ?? If they get hit enough times it could create a stress fracture which would result in failure. Could the combination of stress induced by lowering plus the stress of Poly bushings coupled with getting banged a few be the cause of the failure ???

 

Just a thought

 

 

- Joe