4 Bar

I'm thinking of putting a 4 bar set up in the back of my Model A. Is their a certain minimum length for the top and bottom bars?

 

i'd say the longer the better. the shorter they are the more back and forth action the axle will get when bouncing up and down. but i have no experience with this. just guessing with a slight knowledge of geometry

 

Mine are about 23" to 24"..got em from welder series..if that helps you any

 

Thanks for the speedy replies, the reason for my question was that I can get a set with 12" and 14" lengths.

 

Heres a picture of mine.Not the best picture.If you pm me tomorrow I will measure mine.

 

sorry mis- read your title ..mine are 4 link dimensions..

 

that's sounds a bit short

but to be fair , you should really clarify....is that a parallel 4-bar or triangledaded ?

 

That would be parallel 4 and I did think that it was to short.

 

I would think it'd be too short, too. See like everything would be scrunched up together.

 

If you use a true parallel 4 bar, it's a mter of suspension travel. The shorter the bars, the more the wheelbase will vary during suspension travel. If suspension travel is limited, it's not a big deal. The areas of concern would be driveshaft slip and wheel position. Depending on shock mounts, there could be some binding there.
If the bars are not parallel, you will also see a variatio on the pinion angle.

So you can relate, a 24" bar shortens wheelbase only .050" in 3" of travel, 1.5" up, 1.5" down. If it's all 3" in one direction, wheelbase is shortened about .188". With 13" bars, the same would be .095" and .350", respectively. The bars would have to be really short to be an issue.

 

http://www.zigsstreetrods.com/Techtips/c07938.html

http://www.afabcorp.com/tech_pages/4link.shtml

Hope this helps.