problems with straight axle bumpsteer

Who's had to fix a serious problem with bump steer when using a mid fifties axle under a g***er type street car. heres what I am workin with.Yeah Im replacing the bushings in the springs..........so where do I go from here,and did it work from you

 

you need to be using a draglink setup for straight axle steering .that set up allows the bumpsteer because it is all hanging wrong..jmho.it needs to be like the draglinks offered from speedway motors...go check them out. i've never seen a straight axle setup use the exsisting idler arm from an independent front.

 

Start be throwing away the stock steering stuff. You need to run a tie rod from the steering box to the p*** side steering arm and then a drag link from the p*** side arm to the drivers side steering arm.

 

hotroddon is correct.....that's what i saw

 

oh...and don't drive that thing very fast until you get that ifr **** out and the straight draglinks in...it's a death trap.....i've seen them go crazy.

 

I was looking at it and thinking, 'This doesn't look right' well spotted Don! I'm glad I'm not alone in being scared by it, at least its not a bank breaking fix!
Doc.

 

ahemmmm!!!!!

 

DITTO!

Do not have a connection in the middle of the link between the wheels.
Tie the right and left wheel together with one long tie rod, then run a link from the steering box to the farthest point on the other side of the car, just as he said.
That way, any suspension travel will make the very least possible changes in angles of the links or the wheel-aiming.

Keep in mind that the longer the rod, the less it changes the wheel-aiming as it goes over bumps.
The shorter the rod, the more drastically it changes the angles and makes the wheel change it's aiming back and forth as it moves up and down over bumps.

 

Aww sorry man! I didnt scroll back up enough!!
Im not normaly such a cad, but I am working on it!!
Doc.

 

that's ok...it's not often i'm right about anything..but this needs fixed.

 

thanks guys.......this thing scares the **** outa me,and even worse when I grab a gear.no wonder itwas in storage since the early 80s the guy that had it said it rattled him to much to drive it

 

Go look at a 35-48 Ford car stock setup as to the way the tierod /draglink is done ,that's what yours should look like.Also the closer to parallel the draglink is to the ground the better.

 

You can look at any modern day straight axle truck to see how the steering goes. You might want to figure the arc of the axle travel up and down, and then check the arc of the draglink. Find the position where the 2 arcs are as close as you can get them. [least amount of difference.] Thats where you want your draglink to be. Then mount your steering box in that position.

--) / )

 

Scary.......as was stated above, tie the left and right together with a single rod ("tie rod") with a single steering input rod from the steering box to the right side steering arm. Keep them as close to parallel as feasible as well as parallel to the road surface.

Don't forget positive caster......7* is a good starting point. Wouldn't suggest more than 9-9 1/2*.

 

OK, Put 200 pounds of weight in the drivers seat area before starting. Check the king pins.....or replace them. The easiest mod would be to retain the bottom tierod, but get new ends.

**** can the top linkage and make a custom steering arm on the top bolts from the right spindle. It should be pretty close to the pitman arm level, requiring minimal tweaking. Measure the pitman arm travel from lock to lock to get an idea of the new steering arm length. Do a custom one piece long drag link from the pitman arm to your new steering arm.

Remember: When making the new steering arm, Use 1/2" steel plate (minimum) and have it blasted and magna fluxed before installing. Use grade 8 bolts.

Done it. Worked for me, but your mileage might vary. MIZ

 

One more thing-

Don't forget to get the toe in correct AFTER you fix the tie rod situation.

If the toe is off, it can often mimic a very mild-to-medium bumpsteer situation.

To quickly illustrate, picture a toe-out -- both front wheels have equal traction and reasonable aim = straight. as you drive.

the right-side wheel gets a tiny-tiny bit better traction for a instant; a tiny pull to the right.
an instant later the left wheel gets a tiny bit better grab compared to the right = a small tendency to want to go left.

When you feel that tendency for the car to dart left and right, or it feels like looseness when everything is in good shape, it could be the front tires trading "traction dominance" back and forth because they are not aimed on the same path.
Too much toe-in is often easy to miss, but even a tiny bit too much toe-out and the car gets squirrely.

Several times I have seen the steering on several pickups improve greatly when a tiny bit of toe-in was introduced. Often the owner tried too hard to get too close to a "neutral" toe-in/tow-out setting in the interest of gas mileage or tire wear. If you try to get too close to neutral or zero, the normal road and tire frictions will try to pull the wheels into a small amount of toe-out.
SO- just keep in mind that if you try to get too close to zero toe-in you could still possibly get some "toe-out" squirrely steering while underway.

If your car only gets squirrely and feels like wandering back and forth only when the brakes are applied hard, it is also likely that the braking load is pulling the wheels outward into a slight toe-out situation. First check for loose parts, then you might want to think about adding a tiny bit of toe-in if you are too close to "neutral". If a reasonable amount of toe-in does not make it act better, start looking for loose parts, or way too much wheel offset, bad angles in the steering design.....

sometimes wide tires and big offsets (big offset = think of a longer pry-bar) will need a tiny bit more toe-in "preload" in order to run straighter when the bigger friction forces are pulling them back (toe-out-pull) on the highway.

I hope I said it in a way that makes sense to people reading this.

 

Did no one notice there IS a tierod connecting left and right wheels?
Did no one notice the linkage from the RH idler to the RH wheel is not there?

This setup is using the LH tierod from the stock steering as a drag link.
There may not be anything wrong with that concept BUT that whole mechanism needs to be serviced even if it wasn't on a converted car.
It needs to be removed, cleaned up, inspected for wear, rebuilt if necessary and reinstalled, the steering box should be adjusted to correct factory tolerances, teh front end and steering mechanisms lubricated, wheels aligned, caster checked(very very important in this kind of setup) and corrected if necessary.

THEN give it a drive and see what you've got. Just a few hours work and a little bit of dough might save you and show everybody else a NEW WAY to do this without forever jacking up a good old car.


OH yeah, on straight, beam, tubular, axle front ends...the drag link connects the pitman arm and steering arm at either R(cross-steering) or L(fore-aft steering) wheel, the tierod connects the R and L steering arms.

 

we are here to promote hotrodding and safety as well. there is nothing safe about using an independent steering draglink on a straight axle.not safe for the operator nor the general public,which is our wives,kids and grandkids. please rethink your reasoning for advising another hotrodder to get on the street with a death machine guided by ****....
there is no way if you put solid gold new parts on that existing setup that would make it safe..it actually has a half dozen things going wrong for it now.
so before anyone puts in a straight axle and decides to use a setup like this...don't do it and get on the street,keep it in the garage,i have 13 grandkids i would love to see daily.

 

As I said: Copy the design of 35-48 Ford car as to where everything is hooked up and angles etc. Workrd well on millions of Fords.

 

i'm with you john all the way..that independent draglink is not what anyone wants controlling their steering on a straight axled front.

 

bottom line is I gotta clean this up and make it safe and more simple,,,,,,,thanks guys for the heads up....now time to fab some parts (MS)

 

good luck on it meatball. a couple of rods and some rod ends will cure it.

 

Ive never seen that before. You got all the advice to fix it Im just in shock. Nice car to.

 

sometimes we get it right....other times we are just hanging out and bothering the natives...nice pooch.

 

Meatball- If you want or need, you can check out a DVD I made with Steve Magnante, called How To Build an Altered Wheelbase Funnycar. We kinda went into depth a bit on the "scariness" of bumpsteer. These guys are right on when they say its a wild ride!! What most here are referiring to is called "cross-steer", where the steering arm is attached all the way over to the p***enger side, then back acorss to the driver side. This is indeed the best scenario. Unfortunately, its not always feasible with oil pan configurations. Then "near-steer" comes into play. Alot shy away from this, as it really will get you into bumpsteer issues if done incorrectly, due to the short distance from the drag link over to the driver side. But, there are tens of thousands of old cars out there that have this built straight from the factory. You can do it, and its safe. My Altered wheelbase Dart is built this way, and it is extremely stable at high speeds, with zero bumsteer issues. Albeit, it took four tries to get the geometry correct. Our final test was to jack the car a couple feet of the ground, and rip the jack out and let the car bounce, all the while watching the steering wheel. If you have bumpsteer, the steering wheel will rip outta your hand quick. One more good rule of thumb that I don't believe anyone touched on is the spacing of the drag link and the steering rod going back across to whatever side you go to. They should be as equal as possible. If your steering bar coming from your pitman arm lands 8" in back of the centerline of the spindle, the cross bar going over to the opposite wheel should be the same spacing. Or else you will loose quite a bit of your turning radius. Good luck, and have fun!!

 

good advice from a pro...

 

An old Gemmer box 4X4 geometry works good too. I have a steering stablizer on the tie rod, but the drag link goes fore and aft connected to the left spindle like a 35-38 Ford car with a long center link in front of the axle. Caster is critical. I have 5.5° positive on mine if I remember right. It goes straight as its on rails, and its seen some air. Be sure you have the strength in there to hold it though, first time you lift the front wheels it can change coming down until you get straightened out if its not strong enough. No dime store stuff there, caster wedges can be made, but they have to be carefully made to pin the perches at the correct angle and not shear under impact. It has to hold its settings with the wheels both off and on the ground or it will bumpsteer or worse. I can't see the setup. so i can't comment on whats there. I broke my magnifier.

 

My bad there, got typing to fast and brain and fingers weren't connecting.

I will stand by my suggestion that he needs a Drag Link that goes from the steering box ot the P*** side steering arm.

To the guy who suggested reversing the shackles, Please search and read the straight axle installation thread that I started and many chimed in on that has to do with shackle placement and steering. You will see that this setup on a rear steer car works fine.

 

don is correct again...i respect the safety he promotes along with the good advice...we need a lot of this to go around