Author Topic: A arm vs straight axle.  (Read 5939 times)

Offline H.G. Wells

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A arm vs straight axle.
« on: October 05, 2015, 02:02:12 PM »
I could use some advice. Starting a new build and planned to re use my torsion bar and axle from my old bent car. Well, as I am pulling parts from the old car before we start to lay out the new pipe I see that my axle is a little bent. If I cut my torsion bar off and clean it up and to re-weld to new car I think it would be ok. Probably. If I have to buy new axle, spindles/torsion bar/radius bars etc it will add a lot of $$ to the build too.

Old car was original 1969/70 and was very flexible. (to its detriment) I actually welded the torsion bar arms so it would not bounce as much.
New chassis will be much stiffer so I had hoped to use a front suspension and to keep the nostalgia look.

Builder has a jig for the A arms and will go either way I decide.

What are the advantages and disadvantages of an A arm?   
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Offline rooman

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Re: A arm vs straight axle.
« Reply #1 on: October 05, 2015, 02:29:01 PM »
What happened to the spindles etc off the old car?  I personally don't like A arms on nostalgia cars from a visual point of view. Most of my cars run a rigid mounted dropped axle but Glen opted for a torsion bar on his, again for the "look".

Roo
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dreracecar

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Re: A arm vs straight axle.
« Reply #2 on: October 05, 2015, 02:49:05 PM »
A torsion is not needed because the rear tire design does most of the work towards weight transfer during squat and not from front end rise.
 A-arms give more room in that area between the frame rails and are so much simpler to construct and incorperate offset. And those of us that can build an axle (straight & offset) are a small club, and that sets the car apart from the rest of the super comp dragsters out there.
Handleing wise, the front end does not know any different

Offline H.G. Wells

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Re: A arm vs straight axle.
« Reply #3 on: October 05, 2015, 06:01:21 PM »
This is the info I am looking for. Roo, the old spindles are fine and could be re-used. I do remember having to turn the bushings since the kingpins did not seem to be any standard size.  The drive-ability difference is really my big question.  I had thought about having a new axle built with my spindles and bolting it directly to the frame. And the nostalgia look is a big deal for me. The drivers compartment is not tall, it will be a 5pt cage and will build a body that is more curve and less break.

From a weight standpoint what is the lightest?
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Offline rooman

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Re: A arm vs straight axle.
« Reply #4 on: October 06, 2015, 04:59:53 AM »
"From a weight standpoint what is the lightest?"

   A welded on A arm package will weigh a little less but a bolt on with tabs and hardware would probably be pretty close to a dropped axle. The difference would be insignificant, especially is there is the possibility that you would have to add weight to the nose anyway to tune the chassis.
  As for driveability there should be no difference if each is built right.

Roo
Yeah, I am from the south--any further south and I would have been a bloody penguin.

Offline Scott Krieger

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Re: A arm vs straight axle.
« Reply #5 on: October 07, 2015, 08:12:34 AM »
When I built my daughters Front Engine car I went with bolt on A arms. So I could set the car up with 0" roll-out, 1" roll-out or 2" roll-out.

So at 0" roll-out, I added tabs 1" back to move the A arms on one side back. On the other side of the car I added tabs 1" forward.

We mostly bracket race in the Pro no-E class with a .500 full tree here at LVMS. So we need the 2" roll-out.
If we run the .400 pro tree I set the car up with 0" roll-out.

Also we run 25" fronts on the .500 full tree leaving in second gear with a turbo 400. When racing .400 pro tree I put on your normal 17" fronts and leave in first gear.

I would never ever use a electronic delay aid as a crutch for the driver. As I have way to much fun bringing the car to her.
When she raced Jr.s I had a straight axle front end that I could set-up anywhere from 0" to 2" roll-out


Good luck.