SUSPENSION, Homemade Hairpins.

[HardLuck]

I know I'm putting "the horse in front of the cart" (in my case) but was wondering...
Has anybody here made their own hairpins?
What's involved, what did you use. ect...
-HL

[Sean]

I'm pretty sure SamIyam's built a set of his own. Maybe he will post some info if you ask him. Send him a PM.

[36-3window]

i've made them using 7/8" OD .188 wall DOM tubing. you need access to a lathe to tap the ends of the tubes for the clevis's....do this before you put a bend on the other end to join the two bars to some sort of short threaded tube for the frame rod end.. you will also probabilly need to put a bend on one or both bars,depending on your design , that can be done with heat as the thick wall tubing won't collaspe..take a look at pete & jakes and So-Cal to see how they are made..i built a simple fixture to hold the parts while tacking/welding to insure operfect alignment, i'd recogmend doing that

[HardLuck]

Why I'm askin' is lookin' in all my old '50s car mags most everybody seemed to have made their own. Some pretty rough but some pretty cool ones.
One nasty set I saw once was at the Chickashaw swap meet a few years back. On a '29 Ford Tudor with an overly long set of hair pins made out of re-bar. Wish I would have had my camera with me.

Sean,
thanx, I'll hit him up.

36-3W,
Thanx, that will sure get me started. Got some questions.
You happy with the clevis'? Seems like everybody making hair pins now are using the rod ends like on the four-link set ups. Personally I like the look of the clevis' better, but would like to know the advantages an disadvantages of both. The obivious one that the rod ends would have some shock absorbing ability because of the bushing but how critical is that?

Anybody know the diff between the asymetric and the symetric hair pins? Seems like I see more asymetric ones on track cars.

-HL

[C9]

36-3Window is right on the money with the construction technique.

Only thing I did differently was to use 7/8" x .156 wall tubing - DOM - because I had a couple sticks on hand for making tie rods and drag links.

The assymetric ones are like shown below?
I chose to make this style because I thought they would be stronger with a straight top tube due to the compression/tension loading they would undergo in normal use.
And . . . they look a little different from the SoCal rods that everybody seems to be using nowadays.

Threaded ends with poluy bushings on all three corners.
The front plugs into a Deuce Factory stainless batwing.
The batwing looks pretty good, but I think the clevis arrangement is a little better looking.
Used the batwings cuz I had em.

Far as bending them goes, I used one of the Harbor Freight pipe (not tubing) benders and it worked well for this particular size. The 1" die fits the 7/8" tubing just fine.
Note too that not too much of a bend was cranked in.

Having said all that I saw a very good looking pair of home-made radius rods couple days back.
Adjustable clevises up front, tie rod end on the back.
The tie rod plugged into a short piece of straight similar to what the SoCal rods do, but the straight piece looked to be about 8" or so long and extended forward where it had a machined tapered point on it. Said point was blended in and looked good.
What made this set of rods great was the back ends of the upper and lower rods were mildly bent and welded to the 8" straight piece.
Some of these were done in the good ol daze with the upper and lower tubes remaining straight and welded to the center threaded piece. Not as good looking as the subtle and not too sharp bend at the end of the rods I saw.
Nice part about the subtle bend was that the individual tubes are still loaded in mostly straight ahead compression/tension mode and the bends are so mild more than likely the rods will not flex there.

[Stevie G]

Do you have to use a lathe to thread them?
Why not just use a tap?

[C9]

[ QUOTE ]
Do you have to use a lathe to thread them?
Why not just use a tap?

[/ QUOTE ]

You do use a tap.
The lathe is needed to drill them to size because so little metal is cut away the drill grabs the tubing and the strong 1/2" drill motors will just about break your wrist.

Once they're drilled, it's best to at least start the tap in a lathe so you're assured of a straight thread.

Not sure what 36-3Window used for the threaded ends, but I used 5/8-NF to match my home-made poly bushing rings.

A thinking guy could set these up to drill in a floor model drill press without too much of a "lash-up."
You could start the tap in the drill press as well.

As a small fwiw there are tap handles designed to mount into the chuck of a drill press so as to assure accurate alignment. These are nice to use because you can go all the way with the tap handle connected to the drill press chuck rather than just start the tap with the tap mounted directly in the chuck, open the chuck, install the regular tap handle and finish the tapping.

[Roothawg]

Kevin,I built a set. Call me if ya need help.

[HardLuck]

C9:
"The asymmetric ones are like shown below?"
Yep, just like those.
You runnin' a tube axle or I-beam?
You make your bat wings, what did you use?
(more pic's if you don't mind)
I agree with you and like the looks of the clevis bat wings better than the rod ends but have to go with function in the end.

Steve:
I have seen threaded inserts you just weld in if you don't have access to a lathe.

Root:
thanx, It’s all academic right now, but will take you up on that later.

Anybody know what's going on with hair pins structurally? I would be interested.

-HL

[C9]

"You runnin' a tube axle or I-beam?"

SuperBell I-Beam.


"You make your bat wings, what did you use?"

Deuce Factory stainless bat wings - they look pretty good with the poly bushing ends, but roadsters need somewhat delicate and small looking stuff imho.


"(more pic's if you don't mind) "

Front end pics? Anything in particular?



"Steve:
I have seen threaded inserts you just weld in if you don't have access to a lathe."
Fwiw - if you're running 1" x .120 wall rear 4-bars the HeliCoil 3/4-16 fits in just fine. Drilling and tapping is required and the kit can be expensive, but it's a way to use the .120 wall stuff if you're limited to what you can buy/locate.
Even so, I'd still use 7/8 x .156 for front radius rods.
The slightly smaller diameter looks right and it has the strength required.




"Anybody know what's going on with hair pins structurally? I would be interested."

4-bars are loaded in compression and tension with no vertical bending forces due to suspension travel/twist or braking forces.

Radius Rods - or hairpins if you wish - as well as split wishbones are loaded in compression and tension and do have vertical bending forces.

The vertical bending forces are applied by the twist - or attempt to twist - in the axle when a bump or rise hits one side.
Vertical bending forces also come into play from braking forces.
I've seen demo photos in one of the rod mags where a radius rod is clamped down on one side and the other is raised by muscle power alone so as to demonstrate the twist in the axle. Beam axles anyway, tube axles don't twist.
Granted there are guys out there getting away with a tube axle and hairpins, but other things enter into it.

What is happening here is the poly bushings - used in all of the radius rod/tube axle combo's I've seen - are compressing to allow for the lack of axle twist.
In fact, if you really pursued it, you'd probably find the beam axle doesn't twist that much in normal down the road driving.

Somewhere in the not-so-dim past a mag writer who I'm guessing was a bit of a mathematics buff did an article about the differing arcs between suspension components and the drag link - whether fore & aft or cross steer - to show how bump-steer comes about.
Good article and well done, but somewhere along the line the writers article was compromised/prostituted/lifted/plagiarized or whatever term you like to use and the differing arcs theory (a correct one by the way) was felt by some to be a major problem.

It's not far as I'm concerned and here's why.
The amount of suspension travel we're dealing with during normal driving is minimal.

To decide for yourself, measure the length of your drag link.

Measure the length of 4-bars/radius rods/wishbones.

Measure total suspension travel. Suspension travel means just that, up and down.

Draw a horizontal line on the garage floor.

Draw a pivot point.

Measure out and mark the drag link length, note it with a right angle vertical mark drawn on the floor.

Take a piece of string and tie a pencil/chalk/Sharpie/whatever on the end duplicating the drag link measurement.

Anchor the other end of the string on the pivot point and swing an arc. Go several inches above and below the horizontal line.

Do the same using the 4-bar/radius rod/et al measurement.

Figure in the amount of suspension travel, mark that at the arc area - use the above and below ride height figures - above and below the horizontal line.

Use a right angle based on the horizontal line, draw a vertical line at the extreme laft and right side of the arcs to determine the fore and aft movement of the arcs.
Note the very small differences between the two. The arc differences should be quite small unless you've put together a combo with very short drag link and long 4-bar/radius rod or vice-versa.

This small difference is easily compensated for by the suspension cushioning system in use.

You do need a cushioned point somewhere in the 4-bar/radius rod setup. Granted, you can use Heim joints all the way - and many have, but their suspension components are flexing to compensate for the differing arcs.
That includes the old standard of split wishbones and tie rod ends. Much better in my opinion to use a poly bushing at the back end of the split wishbone.

The guys who are running tube axles with radius rods/wishbones and getting away with it - contrary to popular thinking - are taking advantage of the poly bushings compressibility. It seems to work ok, but I'd opt for the beam axle anyway.

The cushioned joint can be something as unsophisticated as a modern Polyurethane bushing or as old school as the GM steel sleeved rubber bushings.

Granted, if you measure the extremes of travel that are present when entering a steep driveway at an angle you're gonna get a considerable arc difference, but . . . it makes no difference because bump steer at low speeds is not a problem.

Did that help?
Hope so....

[hammeredabone]

C9,
I tried the drill press method and found too much runout for my tastes, I have since bought a lathe and will be threading them properly.

[JOECOOL]

Be cautious about tapping anything National Fine that is mild steel . Fine thread is usually reserved for grade 8 and up use only . Thread engagment and depth is not as good as regular thread.

[HardLuck]

C9,
thanx, that explains alot.
Any ideas on the asymetric vs symetric rods?

As far as pic's goes, front end stuff would be great, if you don't mind. I just knockin' this stuff around in my head right now.

Appreciate the help.
-HL

[SamIyam]

I made mine out of "tap tube" that you can buy from Lefthander chassis. I did a how'to when I built them... bit it, and the pics are long gine by now.

Anyway, the tap tube is just 1" od tubing with a wall thickness very close to what you need for tapping. I think I drilled it out for the 5/8" ends that I used (to the correct size for a 5/8NF tap.

I ended up making an Eddie Dye (sp?) styled hair pin. If you look over on my Traditional Trailer thread... you can see them on the Bomb Factory Digger.

I did the by making a short tapped piece... oh, maybe 7 or 8" long. Then welded two longet pieces along side it. After that, I simply heated the two long pieces up near the small piece and bent them out to the size of the batwing.

Done deal.

Sam.

[LUKESTER]

I built my own hairpins..... I used 1" .095 wall moly, with spuds you can get similar spuds from www.chassishop.com...... LUKE
http://my.vbe.com/~vcarlson

[LUKESTER]

I built my own hairpins..... I used 1" .095 wall moly, with spuds you can get similar spuds from the chassis shop in michigan.....LUKE
http://my.vbe.com/~vcarlson

[Roothawg]

Kevin, you can order the DOM tubing from Boyd steel over by the airport. We have an account there. Just tell em it's the Eliminators CC. They may have to order it but they can get it in a day or 2.

I used a conduit bender and had to heat the tubing a bit. Used it against the garage floor. Worked good and saved 250 bux. It's the set on the front of the fly.

[C9]

[ QUOTE ]
C9,
thanx, that explains alot.
Any ideas on the asymetric vs symetric rods?

As far as pic's goes, front end stuff would be great, if you don't mind. I just knockin' this stuff around in my head right now.


[/ QUOTE ]

For the most part asymmetric vs. symmetric is choice in design.
The straight top bar resists compression and tension forces better than a bent one, but the doubly bent ones seem to have enough strength to do the job. As witnessed by the lack of failure of all the commercial double bend radius rods that are available.
My thoughts anyway.

I have quite a few front end pics and have posted many of them several times so I'll just post a couple here.
I have or can obtain close-up shots on either car so just tell me what you want to see.

This pic, another angle of the 31's home-made radius rod.
Don't be confused by the steel stored under the car. It makes it look like the radius rod bend has a kink, but it doesn't.
I should have the 31 rolled out a ways today - so I can access the mill for another project - and I'll try to get a pic of the radius rods that won't be so confusing.

Incidentally, Roothawg's use of a conduit bender plus heat is a great idea. Packing dry sand in the tube like AV8 pointed out a while back is a good idea as well, but for a modest bend doing it without sand should work ok.

[C9]

Referring to the pic in the post above, that's a commercial pitman arm on a Vega box and it will be heated and bent about up 3/4 - 1" or so for a little better ground clearance.
Makes me nervous to see - and I've seen a lot of them lately - pitman arms pointing at a downward angle and they're the lowest point on the car.

The head-on pic in this post is one of my favorites.
Catches the flavor of the car pretty well.
Disregard the about 1" too high upper windshield bar - it's a mockup and the windshield will be a touch lower.
We're making our own frame and have the curved lower pieces rolled out already. Right now, that's off in the future.

For those who remember the hood fitting/cowl line extravaganza - ended up in Tech O' Matic I think - this is where the grille shell sits and the too tall radiator that was in the car now resides in a cross-town Deuce roadster.
Mit fenders . . .

Anyway, this shows the basics.
Commercially available stuff for the most part, but I made some of it.
Namely, drag link, tie rod, panhard bar & brackets, front crossmember/spreader/trans oil cooler, radius rods as mentioned as well as all the steel rings for the poly bushing.

Also seen - barely - Camaro disc brakes with 10 1/2" rotor.
I like cars that stop well. Granted drums will do it with these light cars and I don't think you'd run into a problem on the twisty mountain roads I drive on now and then, but I like having the disc brakes.
The Camaro's slightly smaller rotor should give roughly equal stopping power to the Mustang 11" rotor disc brakes I have on the 32.

[Digger_Dave]

[ QUOTE ]
One nasty set I saw once was at the Chickashaw swap meet a few years back. On a '29 Ford Tudor with an overly long set of hair pins made out of re-bar.
Sean,

[/ QUOTE ]

I'm sure everyone knows, BUT FOR GOD'S SAKE, (and your own) DON'T USE RE-BAR !!!