Projects Question about axle wiggle

I can slow down or speed up and it fades away. It actually seems like it goes away in it’s own after a few moments. It really seems like a bump just rattled the car more than it should.

Everyone mentioning how scary or bump steer I don’t really feel like that’s it. It’s not scary,it’s just annoying

 

The only weight that’s not in it in the pic is the super light aluminum radiator and shell/aluminum intake. The shackles look exactly like they do in that pic as they do with it together. I’ll get pics in a moment

 

Did you ever have your car checked on a 4 wheel alignment machine?

 

Shackles look to be at a good angle to me. The spring is slightly angled but even before the flat crossmember is had this problem. The front suspension moves up and down just fine.im not really concerned about that part.

It’s a SoCal axle with a posies spring. I bought them together so they should be the right setup

Picture shows things more crooked than they actually are. Not sure why the shock looks goofy

 

I can push on the driver tire and it APPEARS the tie rod flex’s s very small amount. I need another person to check it better.

And the front caster is indeed 8 degrees I just verified. Tie rod is angled from heading the steering arms,but I don’t think the tie rod knows that. Spring has a slight angle,doubt it’s causing the issue,just something I observed

 

And there you have it. More than about 5 degrees can bring on death wobble, depending on the rest of the geometry. 3 degrees doesn't sound like much at all, but I have seen dialing back a little caster stop the wobble on race cars. Won't happen under hard acceleration, but can really pucker you in the shut off area!

 

Sounds like death wobble that's masked by the dampener. Don't know WHY you wouldn't have a panhard, but without it the axle WILL shift as shackles and bushings are meant to move by design.

 

Maybe loose adjustment in your spring-loaded drag link ends?

 

I’ve already listed it had less and did the same thing.. geez

I wrote that no matter what changes I have made it still acts the same. If anything it drives better now than it ever has. Just still has the wiggle that I’m getting sick of living with

 

Because I’m not cross steer. Many side steer hotrods don’t run them. It’s more of a cross steer thing. At least from what everyone on here seems to say. But I’m thinking it possibly could help

 

That’s a good idea (hasn’t been mentioned) but no,they are tight. That’s something I check every once in a while to be sure.

 

Most of the people I know run 7 degrees caster and I believe Henry recommended 5-9 degrees.
After looking at your picture, the one thing that stands out to me is your front shock absorbers. They appear like they are almost bottomed out because they are too long. I also see someone has modified the top mount by extending it to try and make this shock fit. You don't even have the radiator and coolant in it which will make the front go down even further. The first thing I would do after checking for any play in the front end would be to call up one of the specialty shock manufacturers and get the right length shock setup for the weight of your car.

 

You guys really need to readwhat I said,. I commented that first pic is not the same shock setup as now. The ones I just posted are current. They are clearly not close to bottomed our not ‘modified’ they are different mounts and shocks entirely

You are right about caster,most I e heard run around 7 also

 

Actually the drag link down at the box can be better in terms of steering geometry in a trad steer set up.. if interested in investigating further you can read the cowl exit thread..

https://www.jalopyjournal.com/forum/threads/cowl-steering-just-stop.1101046/

But having a more of a traditional steer car MAY explain why the steering input is un-affected.. the drag link can more easily compensate for side to side movement of the axle as apposed to a cross steer car.. I Think? That would also point to a lateral axle control problem.. No guarantees... just a thought..

Dean may be onto something.. the more the axle is laid back the more it inputs side to side movement threw the rest of the car.. but a panhard MAY be able to compensate with 8 degrees of caster??.. Again May...

 

For a guy who seems to ask for help on a fairly regular basis you certainly have a snippy attitude towards those trying to help. So someone missed something your wrote, it doesn't call for the snarky comments.

 

Excuse me for not going back and reading all the updated posts that came in within the last 30 minutes since I saw the only picture you had posted and it took a little while to copy it to my hard drive so I could blow it up and try to find some details. I won't waste mine or your time replying to any more of your posts.

 

Your comment doesn’t help or attemp to help.

It’s frusterating because it clutters the post and others get confused.when something has been answered and it’s mentioned a few times most looking in here will ask again.

 

Agreed,I do think it’s a lateral axle movement but I’m unsure,the comment about the traditional steer taking less of the input over cross steer I believe is correct also

I’d like to add I can’t raise my box though. It’s almost hitting the spark plug. I do agree the angle is steep.i can’t do cowl steering because of under my dash is a of my hydraulic stuff. There’s a clutch master cylinder and brake cylinder with swinging pedals. I can’t wven fit the speedometer in my dash because of that stuff (53 ford dash)

 

No one has mentioned anything about toe, or is it that it won’t cause this?

The outsides of my tires wear, I flipped them that’s why the insides are worn in the pics

 

Thanks for adding some photos,an yes by those, your shackels are a bit lower then 45*so can let axle float{jerk too side in a bump= needs a panhard bar on. If your rear/butt,check rear bar for play too. Just as a side note,I see the front shocks are close to straight up,so with out more lean of at lest 15*,they don't work to also help axles shift,so with the combo of shackels being low and shocks not helping ether=you need a panhard bar or fix one of both.

 

See,this comment makes sense to me.the shackles may be a little more that 45 I can’t get a anglefi see on them.

My shocks are at 23 degrees though.

I’m also thinking the crossmember was welded on at 5 degrees and my wishbones are a bit short causing that spring to look a little twisted. I’ll have to cut the bone mounts off and move them forward a bit and go back to 5-6 degrees or drill holes up higher.unrelated,just a thought

 

Dr. Dean mentions the prefered 5* caster. With all connections tight, you still have 'bump' induced oscillation. My guess is your chassis 'mass' needs the stiff arm, of a panhard connection. That would limit the side-to-side motion. Moving the bones' mounts should help too.

 

Yessir, I used to run this car at 5* and a regular crossmember. It still did it. But I added the flat crossmember and obviously my caster changed. I liked how it steered easier so I left it.

But I think I’ll have to change the rear bone mounts and get that little bit of twist fixed and add a panhard. I think I’ll also try to slide a pipe over my tie rod and weld it up to be stronger. It appears to have a very small amount of flex.

So there’s a few things I can look into here. Probably won’t happen till October since I’m driving the car every weekend till then.

 

You have incipient death wobble - it just hasn't gotten as bad as it might, but its the same animal.

Connecting the stabilizer to the wishbone is worthless - it needs to be hard anchored to the frame. Whether the stabilizer itself is any good, I don't know.

I think you have one or more other contributing elements such as shackle angle. IMHO shackles are intended to control the axle IN CONJUNCTION with stock wishbones. Add a panhard bar or bell crank.

Yes, you want to maintain 1/8" toe IN. If your tie rod is so weak that it's bending/buckling in use, t5hat's an obvious problem and obvious fix.

 

To the guys bitching about the Op's "attitude": I can see why he's frustrated, as many of the comments and questions offered in the latter half of this thread were answered in the first half.
I think some of us are just in too big a hurry to take time to read what has been posted already and it is frustrating as all hell to have to keep coming back to the same answer to a question or respond to a comment.
A question that I don't think has been mentioned is: Hooligan, is this the first straight axle car you've put miles on? Or do you have seat time in more straight axle cars than this one? I ask because after 65+ years of driving vehicles of every description, condition, and design, I do know that a straight axle front end feels very different than the more modern designs. Please don't take offense at this question, but I don't know you or your history and I think this question's answer could be pertinent.

 

I agree with everything you said.

I was wondering about the stabilizer. I’ve seen it done this way but wonder if it’s optimal

 

Thank you!!!!!! I appreciate you understanding. I’m not rude,just slightly frustrated cause I’ve included a lot of the info.I don’t try to be rude,just text can sometimes be taken that way also.

And yes,this is the first straight axle I’ve put miles on.no offense taken at all. That’s why I’m asking,I don’t know what it’s supposed to drive like. I just imagine it’s supposed to not do what it does.

 

It has the Wobble with all different setups and tires, Tells me there is Geometry issues. Ackerman put in play with Steering alignment and Pivot points has Limits, you have to find which one is out.

 

No way! If you attach one end of a steering stabilizer to the frame the bit of rocking the axle does on the shackles will induce a kind of bump steer.

 

You have a good point.and you’ve given me good advice before.