Projects Question about axle wiggle

one thing I notice, and it's something I look at hard when I build a car with a drag link like this, is the line drawn from the drag link is supposed to meet up with the wishbone mounting ball/link. I noticed your drag link is mounted to the top side of your steering arm which is incorrect. it should be mounted to the bottom side. if you don't have room, change out for a standard tied rod end instead of the slightly larger adjustable unit. this is a change that WILL help death wobble.

also, you mentioned the inside of your tires wearing. if you have the tires laid back at 8 degrees and are running toe in you could get wear like that, but it would have to be pretty substantial toe in. as someone suggested earlier it may not be a bad idea to get the car on a front end machine to check alignment. or at least get a rough idea if the spindles are giving the wrong camber.

another suggestion, take someone for a ride and try to get some video of what it's doing. maybe mount a go pro on it.

my guess is the combo of angle, shackles, and drag link angle are causing your issues. my roadster was over 7 and just switching to big and littles lowered the angle enough to make bump steer go away.

correct drag link mount:

 

your drag link:

 

one more I forgot to add is your wheel offsets?? large wheel offsets can make things worse.

 

Generally speaking adding positive caster increases steering effort and directional stability. Earlier you said that the steering wheel didn't return to center, but you seem to have fixed that. Caster in conjunction with KPI are responsible for that. It can also be caused by binding in the steering and suspension components. Its hard to tell in the pictures, but the edge wear on the tires looks, to me, to be smooth which would indicate excess positive camber. If it is feathered then taking a little toe out, like Pitman suggested, would help.

Have you played with tire pressure. If they have too much pressure they will transfer small bumps into the suspension rather than giving a little and absorbing the bump.

Also you might want to find a place where this happens consistently and define the exact conditions of its occurrence. Steady speed, accelerating, decelerating, turning.

Maybe you can get a friend with experience to drive the car and see what he says.

 

I said my tires wear on the outside. Not inside. And that I’ve had 4 different wheel sets. All different and all did it. It did it with 40’s drums and 35 wires even. My spindles are original ford squarbacks.

The drag link on top/bottom is a good point. It have to bend my steering arm again but.. at this point if it works that’s fine. How can I get a regular tie rod end to fit wit the male threaded drag link?

Yeah I’ve been thinking about a go pro also

 

The wear is on the outside edges and very smooth. I e tried different tire pressures. I didn’t seem to get the wear before I lowered the car more.

 

I'm trying to picture this scenario. taking in everything said so far,, and acounting for all of it and not leaving anything out and come up with at least someplace to look.

Now if I read something wrong or you described incorrectly then of course I'll be off.

It almost has to be the chassis & the body& you within your seat doing all the wiggling while the axles and wheel track/contact patch on the road remain steady.

You see the engine move not because it's loose but because you are moving.
You feel a violent wiggle but the car stays true because you're are moving.
The wheel has no movement because your person and your personal space in the cabin is wiggling.

What's the chassis like ?
Are your engine mounts that loose sloppy?
What happened with your clutch?

 

See if you can crank a little more pressure on those drag link ends. The internal spring is a possible point of "springyness" in the front-back use as a drag link.

 

Does Hooligan drink too much coffee?

 

Lol
Idk but folks with Parkinson's live in a shakey world with the rest of us on solid ground.

 

I got the clutch to work! Kinda cool you remember me. I put a 1” clutch master, learned a better bleeding method and it works. Gear ratios suck now but that’s another story

Well I know the engine is shaking around. I have it mounted flathead style

 

Hey guys I found something if interest,when I jump up and down on my front splitter,my front axle is twisting with the motion. As in it gets more caster and less more and less. Why!!!? So confused as to how it’s doing it but I bet that’s a big source of the problem. It don’t move more than a few degrees but.. probably shouldn’t at all

 

that one is easy. because you have one connection point, the wishbone. it hinges on them. it's not twisting, it's rotating around the rear mounting point

it's the whole reason you need to either understand front end geometry or religiously adhere to the tried and true methods.

 

By the way you never answered my question!

 

That change in caster he's seeing should translate into bump steer

 

not if everything else is correct. think about it... you cannot have a solid axle mounted to a single point and not have a change in caster when the suspension compresses and rebounds. proper steering design will allow for that movement with minimal change in steering geometry. it's why the relationship between the radius rod mount and the drag link angle is important.

 

Okay guys I’m going to move my rear wishbone mounts up to get 5* right? I just took them off

No it’s not been on a 4 wheel alignment. I try to do it all myself. To answer that fellas question

 

Check it out fellas. That much higher is about 5 degrees. Straightens the bones out too

 

This is what shocks me....no one has mentioned bump steer, this car DEFINITELY has some bump steer, it has split bones and side steering, the drag link is half the length of the split bone, the bone moves in a slow arc, the drag link moves in a faster, more pronounced arc, and bump steer is the result, at any given speed, period.
The wear on the tires indicates too much toe in, so you've swapped them side for side, cut back the toe to 1/8 positive, as in….the tires closer together by 1/8 than the rear of the tire, and live with the bump steer. I'm not being critical, but honest here, your front end in my opinion is poorly set up, so make some small changes and drive it, in my opinion a panhard bar will not fix your complaint. You're probably good at 8 degrees caster, but toe'd in too much, got a bit of bump steer, move the drag link to the bottom of the steering arm, load up your buddy, go for a long ride and diagnose what you actually see happening. Just my two cents.

 

Just for giggles, have you checked the chassis for cracks?
Andy

 

if it was me, I wouldn't go right to 5 as that's on the low side imo. looks like you have room for two more holes to be drilled.... mark it out and see what it looks like at about 6 degrees...

 

It's been mentioned several times already

 

Haha yeaaaah

Isnt bump steer when the steering wheel has input? Cause I have zero of that.not saying it’s right at all. I’m just saying nothing seems to bother the steering wheel at all. It’s all felt in the front of the chassis to me.

 

I just don’t really feel any negatives in the steering at all. It’s all felt in the body.

I’ve heard some doing toe out by 1/8, I think that’s what you are referring to. Yeah I could very well be toe in too much. I just know most cars are that way so that’s what I did since the wheels would force out during driving. But I’ve heard going the front out rather than in by some old guys on here. I’ll have to look into that.

 

Bump steer occurs is when the car gets steering changes through suspension movement but with no input from the steering wheel. Intuitively one might expect a feeling through the steering, but seemingly that's not necessarily the case. I've had it with side winds and fucked rear suspension causing the car to rock and then steer itself - I'd have thought it was just the side wind blowing the car off course, but new springs and shocks made the problem vanish.

Excess toe in can result in a shake at the point the wheels no longer skid cross the blacktop but instead rhythmically break away or skip. Scary when first experienced on a busy So Cal freeway after having just been messed with.

Chris

 

Everyone describes it as scary. In my case nothing is scary at all. Not in the least bit. It’s just a shake that I feel in the car that’s annoying cause it makes it feel like the ride is bad. Nothing really scary at all. It just feels like I’m going over crappy road for longer than I really am.

So does anyone know if there’s a female style tie rod end I can get to use my drag link?

I’m currently working on getting the front caster to 6*,moving the stabilizer a bit more straight in line with the tie rod,so I can have room to add a pan hard. Maybe add some pipe over my tie rod also to beef it up

 

OK, I've read this entire thread and no one has even mentioned tolerance stack. My tub does the same thing, and the steering and suspension is spot on. What you are experiencing is when you hit a bump, it affects the wheel(s). As the suspension is violently thrust upward, it transfers that movement to the front crossmember. This is in turn transferring to the entire car, which makes the body and related parts shake. You need to soften the front suspension up some so that the axle assembly can move without moving the whole car. Plus, when the axle hits the bump, every bit of tolerance in all of the suspension and steering components is taken up, causing the front to have a slight shake or wiggle. As was mentioned, tighten up the tie rod ends some and see it that doesn't help.

 

There's 2 ways to experience bumb steer and there is an infanant number of degrees of it.

Any car with bumpsteer geometry can display either and switch back and forth between them.

Here is the first way-
You hold the steering wheel tight and the bump causes the car to steer.
Here's the second -
The car hit the bump and stays true on its track to the road but the steering wheel moves within your hands.

 

Again, I'm thinking bump steer is more of an issue here, you say you don't feel the input in the steering wheel, take it down some gravel, hold the steering wheel lightly and watch the input.
I don't know that I'd go to 5 degrees caster, I like 7, seems to work for me after a number of cars, at 5 degrees you'll notice it steers faster and turning effort on the wheel is lighter, but all you can do is try. I'd try one correction at a time till you get to a place you can live with. Maybe it's time to have someone follow you on a place you know the car is worse, see if they see any odd movement?