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Trunk bar location on leaf spring car

Posted By: 1mean340

Trunk bar location on leaf spring car - 11/07/22 11:58 PM

Any chassis guys here? working on mocking up a 10 pt cage for my 70 challenger. The car is going to have a caltracs mono leaf with assassin sliders. Wondering where the best spot for the trunk bars of the cage to land in would be (see pic) and if either at the crossmember vs further back towards the rear leaf spring perch has any benefit chassis wise?

Also, if there any major disadvantage to using bent trunk bars for passenger headspace vs straight bars? I don’t NEED the bends, probably won’t ever have passengers in the back but I like the look of the more hidden bent bars and it would be easy enough to throw a bend in them. I know straight bars are usually stronger but not sure if it makes enough difference to matter.

Thanks!

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Posted By: polyspheric

Re: Trunk bar location on leaf spring car - 11/08/22 04:06 AM

The force required to buckle a straight bar (in compression) is wayyy more than a bent bar, which begins to bend in either direction very early.
Posted By: crackedback

Re: Trunk bar location on leaf spring car - 11/08/22 07:03 AM

Run a bent bar from the roof line through package tray to spot one, just on top of the shock crossmember if you are using it.

If you are concerned about the very back having stability issues. Run a J bar from the first down bar at 1, up tight to the trunk gutter/lid, and drop it at spot 4

Give yourself enough room to get the battery out easily.
Posted By: 6PKRTSE

Re: Trunk bar location on leaf spring car - 11/08/22 02:45 PM

Mine I removed the upper shock mount piece. I added a bar between the frame rails that my rear window bars go through the trunk and land on this bar. It is also my upper shock mount bar and my anti-roll bar tie into that same cross bar. My car is also still leaf springs with Caltracs.

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Posted By: 1mean340

Re: Trunk bar location on leaf spring car - 11/09/22 04:04 AM

I love the anti roll bar setup, that might be a little more involved than I want to go right now but just wondering, what is the main advantage of running a parallel shock setup like that vs factory location?
Posted By: cudaman1969

Re: Trunk bar location on leaf spring car - 11/09/22 02:27 PM

Since my Duster will be running in stock class I ran my bars similar to 6pk s but I ran the trunk bar back to the top on spring box. In fact both front and back spring boxes are tied into the cage. These places are where your car rotates from so they need to be strong. I also have bars going to top of shocks from those back bars. IMO you want the car as stiff as possible with the least amount of bars, a triangle is the strongest configuration in the universe.
Posted By: 6PKRTSE

Re: Trunk bar location on leaf spring car - 11/09/22 03:11 PM

Originally Posted by cudaman1969
Since my Duster will be running in stock class I ran my bars similar to 6pk s but I ran the trunk bar back to the top on spring box. In fact both front and back spring boxes are tied into the cage. These places are where your car rotates from so they need to be strong. I also have bars going to top of shocks from those back bars. IMO you want the car as stiff as possible with the least amount of bars, a triangle is the strongest configuration in the universe.


My rear trunk bars tie into the rear leaf spring perches and has a bar tieing them between the frame rails that is also my parachute mount bar as well. I also have bars running down from my main hoop through the floor to the top of my front leaf spring perches as well. Unfortunately, they punch right through the rear seat though.

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Posted By: racerx

Re: Trunk bar location on leaf spring car - 11/09/22 04:18 PM

What is the white case/box in the rear seat area?
Posted By: 6PKRTSE

Re: Trunk bar location on leaf spring car - 11/09/22 05:06 PM

Cool Shirt, pumps ice water through my fire suit at the race track and for beer, water and pop at cruise nights and car shows.
Posted By: cudaman1969

Re: Trunk bar location on leaf spring car - 11/09/22 08:03 PM

Originally Posted by 6PKRTSE
Originally Posted by cudaman1969
Since my Duster will be running in stock class I ran my bars similar to 6pk s but I ran the trunk bar back to the top on spring box. In fact both front and back spring boxes are tied into the cage. These places are where your car rotates from so they need to be strong. I also have bars going to top of shocks from those back bars. IMO you want the car as stiff as possible with the least amount of bars, a triangle is the strongest configuration in the universe.


My rear trunk bars tie into the rear leaf spring perches and has a bar tieing them between the frame rails that is also my parachute mount bar as well. I also have bars running down from my main hoop through the floor to the top of my front leaf spring perches as well. Unfortunately, they punch right through the rear seat though.

I still have all your pics when you where building car
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