Front straight axle help

[SugarRay8]

We had a problem, mainly during right hand turns, with the front wheels “flopping”.

It did it on two right hand turns (both very sharp turns) and once on a straight stretch when we hit a good bump.

So, I’m not sure what I need to change on the front end.
I’ve seen a lot of front panhard bars on cars, is that what I need to add to fix this?

I can get some better pictures if needed.

The front shocks are mounted to the radius rods and the frame, spring is on the radius rods at each end then the center perch on the frame and then we have the drag link tying the steering arms together.
We set the axle at 7 deg. Not sure about toe, caster, camber angles. Also, we followed the Ackerman theory when we set up the pivot points on the steering arms and drag link.

So?? [S

 

[Sam_Fear]

Uh.... what exactly is 'flopping'? Like one wheel is changing direction slightly? Or like your toe is wrong in a corner?

Kinda sounds like what my F100 does - it has a axle bore egging out on one side. Feels kinda like a loose kingpin.

Any matter, jack up the front end and make sure it's all tight. Don't grease anything before you check.

My truck feels tight until the wheels are turned one direction. Grab the top and bottom of each wheel and rock it while some one turns the steering wheel back and forth.

Clear pics of your front suspension would help.

 

[SugarRay8]

The wheel looked like a fish out of water (almost looked like a paint shaker), it was both sides, looked like they could just come right off the car.

Everything looked and felt tight on the ground, but I’ll get it all jacked up and see how it feels and see what changes when we turn the wheel.

Nothing should be worn out, it’s all new: Kingpins, spindles, bearings, etc. and it all has at best, 10 miles on them.

I’ll get some better pictures up soon.

 

[Sam_Fear]

You have to check it all when it's in the air. It'll always feel tight on the ground because of the weight on it. That sounds like the dreaded 'death wobble'.

What I was describing with my truck feels more like bump steer.

Your caster is set by the 7 degree axle angle. The camber is preset on the axle/spindle angle. If you check them, make sure both sides match at least. The caster angle could be the culprit - at least in part.

Check your toe in. If you had the toe too far out, it would always be wanting to wander. If it's set too far in, it may cause your problem at least in part, but usually the tires will kinda squeal - not sure if skinnies will?

Somebody with a little more experience with it should be around soon.

 

[dmw56]

Those skinny Model A wheels were never designed to support the weight of a V8.

 

[Bamamav]

Sounds like the wheels are turning too much, going over center on the steering arms/draglink. When you turn, the steering arm at the wheel end should never get to the point that it's straight with the draglink. If it does, it can then bounce the opposite way, turning that wheel more than it should be, and the drag by the tire causes it to bounce back, a sort of wobble.

Do you have a steering stop to keep the wheels from turning too deep? If you don't, or if your's isn't adjustable, you might want to put on an adjustable one.

 

[SugarRay8]

Those skinny Model A wheels were never designed to support the weight of a V8.

You’re absolutely right and that’s one thing we are looking at changing. We LOVE how they look, but we can’t even get them on a good wheel balancer, had to use an old bubble balancer and you can see a wobble in them still.

Sounds like the wheels are turning too much, going over center on the steering arms/draglink. When you turn, the steering arm at the wheel end should never get to the point that it's straight with the draglink. If it does, it can then bounce the opposite way, turning that wheel more than it should be, and the drag by the tire causes it to bounce back, a sort of wobble.

Do you have a steering stop to keep the wheels from turning too deep? If you don't, or if your's isn't adjustable, you might want to put on an adjustable one.

No I don’t have stops, but I will certainly look into that. They are adjustable. We don’t have a really great turn radius, so we do end up cranking it pretty sharp to make a turn.

**************************
I think I see the main problem with our set up.

Rainman had warned me of it very early on and I seriously thought we had it addressed. However, when I went over to look at it and get some pictures last night, the problem looked very obvious.
My shackles on the spring are way too steep and the spring itself has little to no room to move.

Looking at it and talking it over with my son, we feel that we are going to have to cut the spring mounts on the radius arms and redo them so that the shackles are correct.
Also we realized that the one on the driver’s side is worse than the passenger side, which could be why it does this turning right but not left. Not sure what happened there, I went back through some earlier build pics and we had them the same at one time, so???? [S

I really hate to cut it apart and redo it, but it isn’t the first time we had to do it in this build.

 

[Dirtyrat]

Glad you sorted it out, I think thats the sort of feeling that makes the ole you know what pucker when you are driving...

I guess if ride height was not an issue, a stiffer spring would also put the shackles at an acceptable angle too.

 

[Sam_Fear]

Kinda OT, but I just went back to your build for a minute. Your interior is awesome!!! The gauge pod and windshield a crazy. Like the tin ceiling door panels too - very good choice. It's hard to keep up with all the builds. Well done sir! [cl

 

[SugarRay8]

Kinda OT, but I just went back to your build for a minute. Your interior is awesome!!! The gauge pod and windshield a crazy. Like the tin ceiling door panels too - very good choice. It's hard to keep up with all the builds. Well done sir! [cl

Thanks Sam.

The glass cutter was concerned about the radius to clear the headlight bucket, but he did it! He cut that from the same safety glass they use on school buses. Guess they have to make a cut on both sides of the glass due to the film in the center, makes it tricky, good to have a guy who’s done glass for 40 years.

 

[jfg455]

I see a second issue that would make your wobble worse. Look at the first pic of you wheel and brake setup. If you draw an imaginary line down through your king pin to the pavement it should intersect in the center of your contact patch of your tire. This way the tire contact patch pivots around the intersecting oint. On your setup the contact patch is way outside of that point. This puts more mechanical advantage (or leverage) on the hub pivot. So when you hit a bump it will "kick" the wheel back easier. This coupled with every bit of play between the wheel and your steering wheel IE: tie rod ends, box, etc. and you get the wobble. Add your shckles hanging straight down and it lets your axle move side to side like a swing. of course your drag link wont move as it is tied to your frame so when the axle swings it makes the wheels turn, then the tire grabs, swings, grabs, swings, flop flop ... you get the picture. Clear as mud? Thought so! Carry on![cl

 

[Sam_Fear]

If you draw an imaginary line down through your king pin to the pavement it should intersect in the center of your contact patch of your tire. This way the tire contact patch pivots around the intersecting point.

I just learned something new.

 

[jfg455]

Race car guys are always trying to get it so the center of the tire pivots right on that point. This makes it a Zero scrub design. no scrub means a free rolling front end that takes less effort to move through the corner. Less effort = faster lap times. [cl

 

[SugarRay8]

Took the car back out this Saturday, sure did look a lot better with the new shackle mounts.
No shake and seemed to handle/drive good.

Jfg455, I ran a steel dowel on the center of the kingpin down to the pavement. The contact patch on the tire is on that line (if you drew a line on the ground across the front of the car), but like you stated, over about a 1-1/4” from the center of the tire to that point of contact. A lot of this is due to us spacing these Model A wheels out to clear the brake calipers. We should be a little better if/when we find some steel wheels to run.

Still looking for some wheels to use in place of the 29’ Model A’s. So if anyone knows of something that used a 16 x 4 with a 5 on 5-1/2 bolt pattern, let me know. We’re not locked in on the 16 x 4, but would like to get something very close to that. We are pretty much locked in on the 5 on 5-1/2.

 

[Blue Eyed Devil]

The angle on those shackles looks much better. Now ditch those wheels and you will be getting closer. '40-'48 Ford passenger car wheels are 16x4 or 16x4.5 and they have the 5.5" bolt circle. They will work well for you, and they aren't too hard to find...

 

[SugarRay8]

The angle on those shackles looks much better. Now ditch those wheels and you will be getting closer. '40-'48 Ford passenger car wheels are 16x4 or 16x4.5 and they have the 5.5" bolt circle. They will work well for you, and they aren't too hard to find...

Thanks, I'll look for some '40-'48 wheels and see what I can come up with.

 

[SugarRay8]

Got some 1940 Ford wheels at a swap meet this Saturday, they even had the tires on them!

It lowers the front slightly, but they should work great.

This let us get rid of the spacers up front and puts our tire contact patch in line (very close anyway) with the king pins.

Taking them to the tire shop today for balancing, but otherwise we’re good to go.