Slapper bars

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thatold.chevy
Posts: 112
Joined: Fri Oct 28, 2022 8:44 pm
Location: Perth, WA

Slapper bars

Post by thatold.chevy »

Hi all,

Can someone please assist with my understanding of this?
Capture.JPG
This clause perplexes me a bit. I deal with legislation daily, especially building.

When a constructed solution can mitigate a specified concern as to why something shouldn't be done, that solution is deemed compliant.

In other words, if a rule says something can't act like duck - and your proposal walks like a duck, quacks like a duck - but actually doesn't act like a duck , it's compliant.

Slapper bars pitch down under braking. The image below is a standard slapper arrangement. It bolts under the spring perch and the red stopper end rises and contacts the spring, stopping diff rotation under hard acceleration.

On lifting off after hard acceleration, the red stopper end does the opposite and can gouge the ground as the spring "flicks back". I've seen it, personally.
standard slappers.jpg
This yellow slapper bar below, though, has an anti-dive hoop attached to the front of the spring. It doesn't limit upward movement, but stops the slapper extending below the tyre line on deceleration as it literally hoops the leaf spring.
anti-dive.jpeg
I read the street rod manual as having detailed a very specific concern with slapper bars. In my opinion, if the yellow bars are used, that concern is mitigated and therefore their use is compliant. It other words, as much as it looks like one - it's not acting like a duck.

Caltracs do the same thing as slappers in reducing cornering ability - yet they're perfectly fine to adapt.

Can someone with more builds under their belt than me provide some advice? Because I have a yellow pair I want to run.
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zuffen
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Location: Sydney

Re: Slapper bars

Post by zuffen »

If the restrained version of the bars can drop below the scrub line (below the rims) they would fail under ADR's and could well fall into Engineering concerns.

If you could show the bar can't drop below the scrub line or hit the road I would think most sensible Engineers would approve them.

One question; how would you stop them rattling when the limit the downward travel of the bar as it a metal on metal contact?
Never argue with an idiot, they will drag you down to their level and beat you with experience.
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thatold.chevy
Posts: 112
Joined: Fri Oct 28, 2022 8:44 pm
Location: Perth, WA

Re: Slapper bars

Post by thatold.chevy »

zuffen wrote: Thu Jan 19, 2023 8:11 pm
One question; how would you stop them rattling when the limit the downward travel of the bar as it a metal on metal contact?
I kinda like the clinky clink of the slapper bars, but I'd realistically just run a solid (ir not split) swaybar bush over the U bolt.
Harv
Posts: 413
Joined: Fri Mar 22, 2013 9:11 am

Re: Slapper bars

Post by Harv »

I agree with you opinion. I believe the ASR manual has overstepped the mark.

Traction (slapper) bars are not prohibited by NCOP. My intention is to run them on a vehicle engineered in NSW under the VSCCS. My engineer has no issue with doing so.

Some info I worked up on the theory of how the bars work here, including details of how I built mine:
http://www.fbekholden.com/forum/viewtop ... v+traction

Cheers,
Harv
Twin Spinner
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Posts: 1391
Joined: Mon Jan 02, 2012 7:45 pm
Location: Brisbane.

Re: Slapper bars

Post by Twin Spinner »

Old time tramp rods, still have a set from the 60's off my Zephyr, can't remember who made them now :?:
If it has tits or wheels, you can expect trouble.
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