Technical Model A Suspension

Building a 30 mod A into a hot rod.What is the advantage of hairpin radius rod set up vs 4 bar set up. Were talking both ends of car.Thanks, tom

 

Simpler, but not always correct. A tube front axle often uses 4-bar instead of a pair of hair pins. Out back, you can control amount of acceleration lift or 'squat' height change by the angles of a 4-bar setup, intersecting at, or above/below the center of mass.

 

Hairpins = Hot Rod

4 bars = Street Rod

But that is just my opinion.

Don

(yeah, I know someone will bring up Grabrowski's T, but I am speaking generally)

 

Endless options. Hairpins are kool, but then again so are split 'bones. 4 bar? I dunno, kind of hard to warm up to but they work. I guess how you choose to spring it matters. If coil-over rears are in the mix the 4 bar is a good choice, but on an A those would stick out like a sore pen.., uh, thumb Good shocks, sway and panhard bars will make any system responsive and secure. Sometimes it boils down to little more than visual/personal appeal. A frame or Deuce? A frames that I was starting to warm up to were split 'bones and nice brackets to carry them.

 

My old ass opinion also Don

 

Once again for Don and wbrw32 opinion. The HAMB has been hugely responsible for un-blending the lines between hot rod and street rod and this is one of the primary distinctions between the two...imho.

 

I agree. No 4 bars on a traditional hotrod.
No airbags either even if ONE had'em. (the AlaKart)

 

I like what Missysdad1 said above:
"...un-blending the lines between hot rod and street rod..."
Yeah, I vote no 4 bars or bags...

 

4 bars just look funky...

 

Remembering when four bars showed up in some rod magazine as the "new hot lick item" I'd say as far as appearance goes the guys are right on the money. The claim at the time was that they rode a bit smoother than split bones or hairpins. That they seem to work better with tube axles by not putting the pressure on them that split bones. That said I didn't have an issue with the ride quality of my T bucket with split bones and plan on running split bones on the Model A.

 

There were a whole lot more than just one.

 

In practical terms, there is no advantage at the front. If you look at a stock A you'll see where the ball socket for the wishbone is mounted. ANY variation in the driveline means this has to be re-thought, therefore bones were split and mounted at the next convenient location, i.e. the frame rail. Hairpins are merely a pretty aftermarket version of factory bones.

4- bars came about as a technically superior solution to the same problem. They work very well, but in practical terms on a front suspension with not a huge amount of travel (talking hot rod) there is no real difference. It gets down to old style (traditional) hot rods or later style.

At the back you are dealing with acceleration and deceleration forces through the diff, the need for articulation and also the movement of the driveshaft. Once again 4 bars work well. But so do converging ladder bars (or heavy duty hairpins if you want to think of it that way.) You make them converge because they articulate better that way. Parallel hairpins at the rear are bind prone.

Look at the Pete & Jakes website, there are lots of pictures that explain it all.

I hope this helps.

 

Correct but generally used as a helper and static to set ride height or for load leveling. Not like utilized today with pumps and adjustment on the fly. There were higher end cars factory equipped with active leveling suspensions but I've never heard of components being transferred to custom cars. More often just discarded due to maintenance issues.

As far as 4 bars vs. hairpins, 4 bars work and ride great but look like total ass to me. A bit more acceptable on a fendered car.

 

Luckily, history is not based on just what you have heard.

 

I vote for split bones on both ends of a traditional AV8..A sign of the times.

 

correct me if wrong but 4 links can keep the axle traveling straight up and down and the split bones/hairpins make the axle travel in an arc. So I guess the 4 link is a more "correct" axle control method. With that being said, I agree with what others have said, 4 link - street rod, hairpins/split bones -hot rod.
A buddy of mine has a Model A truck with store bought hairpins up front and once when in a panic stop the hairpins folded. The axle slid back tearing up a lot of stuff. He has disk brakes up front. After seeing that I would go with split FORD bones.

 

Yep, when you are talking about a front susp. setup.