Beefier tension rods (T3) needed when running OEM bushings? (Racecar)

[turbogrill]

Hi,

 

There are many reports of OEM tension rods snapping when poly bushings are being used.

 

But how about OEM tension rod bushings and stock tension rods? Is there any reports of stock tension rods snapping in this scenario as well?

 

Car is a chumpcar racecar, it's an 1980 280zx with some suspension upgrades.

 

If this is the case I will get a pair of Techno toy tension rods.

 

Thanks

[NewZed]

For the 280Z's, with the rod in compression under forward braking, it's polyurethane on the back of the rods that causes the problems, especially if the worn out rubber inner control arm bushings are kept.  Puts a bending load on the tip.  Rubber on the back and PU up front is the recommended way.

 

But you have a 280ZX, with the rod under tension when forward braking.  I haven't seen much on those rods breaking.  It's a different design than the 280Z.

[JMortensen]

ZX has the same issues as the Z, despite the rods being reversed. If you run poly in front and rubber in back, should be OK, or TTT or any other TC rod with an easy moving pivot will work as well.

[NewZed]

Edited for general confusion.

 

Wrong >>>>  If it's the same mechanism shouldn't it be PU (poly) on the back and rubber in front?  Opposite of the Z.  The PU takes the braking load and the rubber lets the rod end wiggle freely.

Edited September 9, 2016 by NewZed

[Evlevo]

If it's the same mechanism shouldn't it be PU (poly) on the back and rubber in front?  Opposite of the Z.  The PU takes the braking load and the rubber lets the rod end wiggle freely.

 

Its in the same position due to the forces on the wheel not the position of the tension rod. If you were referring to them as inside and outside, then it would be different. I think this is a case of reference location confusion.

 

Rear tension rod, under braking it compresses the inner bushing.

Front tension rod under braking it compresses the outer bushing.

in both these cases they are the "front bushings" on their respective cars. 

Edited September 8, 2016 by Evlevo

[NewZed]

Front is where the headlights go.  Just keeps things so much simpler.

 

Wrong for the ZX >>>>  (The rubber bushing needs to go on the side with the nut).  Edited.

 

The mechanism I was talking about is the one that breaks the rod tip off.  The hard PU puts a side load on it as the rod moves up and down.  I broke one on my car.  It took a couple of months of groaning over the driveway entrances.  You could hear a lot of load on them.  Rubber on the nut side is quiet now.

 

Always an interesting topic.

Edited September 9, 2016 by NewZed

[260DET]

The stock design is basic and good enough for a stock car but certainly not good enough for a race car. Just to move freely a ball type joint is required which is why aftermarket rod ended replacements are available and used. They incorporate caster adjustment too which is a good thing.

Edited September 9, 2016 by 260DET

[JMortensen]

The rubber bushing needs to go on the side with the nut.  The mechanism I was talking about is the one that breaks the rod tip off.  The hard PU puts a side load on it as the rod moves up and down.  I broke one on my car.  It took a couple of months of groaning over the driveway entrances.  You could hear a lot of load on them.  Rubber on the nut side is quiet now.

Evlevo and I have this right.

 

You want the stiffer bushing on the side that takes the braking forces. On a Z or a 280ZX, that's the front bushing. On the Z, the control arm tries to move back under braking, pushing directly on the front bushing. The rear bushing is basically along for the ride. On a ZX the control arm also tries to move back, and the bushing that resists this movement is the front one again. The rear one is still along for the ride.

[NewZed]

You're right.  And I was half right until I got back in to it.  Not sure what I was thinking.  Corrected.

Edited September 9, 2016 by NewZed