Technical Straight Axle Caster on a drag car, lets talk about the mechanics

That's no fun!!!

 

That's in the works.
However, the launch is good. It's when I am fixing to turn off on the return road when it usually happens.

 

Keep in mind that DW & wheelhop can be initiated from the rear......I know this is a drag car , but if you could run it up to speed slowly to see if it's speed initiated or weight transfer .....

 

This is my 2 cents (about 3.7cents American) worth. At rest you have 4-6 degrees of caster, wheels up, doesn't matter. When you come back down the front dives so you go back to less caster but as you accelerate you are back at your 4-6 or better because of crossmember rotation. As you decelerate to turn onto the return road the front dives a bit which rotates the crossmember slightly and your caster is back at less than 4-6 which makes the front wheels toe in slightly.
Think of it this way. If the car was sitting at rest with 6 degrees caster and you let the air out of the rear tyres, because of crossmember rotation you would possibly be at 8 or 10 degrees. It's so simple I've confused myself.

 

What happens to the steering wheel if you jump up and down on the front to the frame?
Pete

 

Replace the friction shocks with hydraulic ones.
Install a steering stabilizer.
Install a proper adjustable drag-race 4-link in the rear, and have a chassis tuner set the instant center in the proper location.
Install wheelie bars.

 

Okay, I'm looking at this way kool photo and wonder if it's just photo angle or??? You are running spindle mounts. That puts the tire rim on center and should have the King Pin contact point near center of the Tire patch. It looks like you have a Truck Load of toe in. Your also running Fat tires. Were this my set up I would have tread patch no wider than the actual rim width, less if possible. If the king pin hits the ground on tread center I would have 1/32" to max 1/6" Toe In. What I see here looks like a Tire Fight between the two trying to decide who is going to go strait ahead. How much Toe In are you running? When checking this without alignment tools I use a pair of Florescent light tubes.
The Wizzard

 

Every loose rod end worn king pin bushing and slop in steering box contributes to death wobble, I feel adding more caster will probably just make the death wobble more violent as the wheels will be more isistant to try to return to center correcting back and forth

First and for most is your steering box in center of travel when wheels are straight?, and how much slop is there at box then follow through the rest of the moving parts, if everything has a small amount of movement it adds up to a big margin when it’s all said and done good steering stabilizer will help a lot also

 

It is definitely getting tires. I have hated those tires ever since I bought them. It’s probably the photo angle on the toe in. It’s set up with an 1/8” or so. I am going to buy one of the toe gauges though to make sure.

I’m going to lock the wheel and check for play throughout the system. I may see if I can rig up some tube shocks as well.

I won’t ever add a 4 link. I know they work and they are more efficient by far, but this car is pretty much period correct sans a few safety features. It handles just like a car from 1962 and that’s what I wanted to experience.

I can’t do anything that costs money for a while. The wife and I are furloughed. All I can do is plan and pipe dream.....

 

Well, you wanted to experience a car from 1962 and that's what you are doing! LOL. My dragster usually ran about 17 deg caster. You know when you have too much caster is when you back up too fast and the steering wheel breaks your thumbs. lol. Lots of great advice from everyone. I agree with check for slop and re-check the toe. And look at those front tires closely. Lippy

 

Over the years we learned the more Faster the more Caster. On F.E.D's we set up at 15 and often add a kiss more. If it was going to B-Ville and expected to tip 200, start at 10 then add some more as you sort things out. Finding the sweet spot on the Heal of the tire was often a 1 or 2 degree kiss. We have also learned travel has a lot to do with how much you have to Drive the car. On tube chassis strut cars I like 1" drop and 1" up from static ride height loaded at the line. The more you have, the more things move around past static strait ahead = you got your hands full.
Question; What is your Tie Rod made out of? To light or even stock early Ford and you may have just plane Flex or Dance from the tube itself. Ya gotta remember the tires are actually dancing in opposite directions of each other.
The Wizzard

 

Thanks for the advice guys. My plan is to sort of start at the front and work my way to the back. That way I spend the time I need, to ensure the car is right. It's been sitting for 10+years.

 

Good luck pal. I know the feeling this photo was taken 18 years ago. That's the Good Dr. Earl Floyd doing a little blessing of the Carb and Jed the pinstriper in front with him. The guy by the Van is Bruce Cassidy of F.E.D. fame. I'm driving the camera.

Here's the same Truck today.
Working for a living sucks, retirement isn't much better. Never give up!
The Wizzard

 

Is that Chuck Jedoin ? Sp.?

 

My question how does a wedge at the spring change caster with a transverse spring? Stock Ford caster from 35-48 6 3/4 degrees. this style perch will let you change caster with out putting twist on the spring https://www.ebay.com/itm/Forged-Adjustable-Spring-Perches-Polished-Stainless-/261869315433

 

Those are neat. Never seen anything like that before. That would definitely help my issue! I know some people were mentioning adjustable perches, but my mind went somewhere totally different.

 

Then longer ladder bars.

Hydraulic shocks and steering stabilizers both existed in 1962.

 

No need, it's a solid mount rear. I will probably go to tube shocks. I had a stabilizer on it, but it started leaking, so I trashed it. I'll wait to install a new one when I get closer.

 

Just for giggles I emailed Radir to get a weight on a pie crust 1200-16.
46 lbs! Dang.

 

Has he changed so much since you last seen him you can't recognize him?

 

They would work well and I use them on my '31. It didn't look like the OP had adjustable perches from the pics posted which is why I responded as I did.

 

Every time it lands on the pavement, it should increase caster

 

I misunderstood what you were talking about Mr. T Body.....

 

There's a thread on here somewhere about cowl steering geometry. It's a bit of a rant but there's a lot of good information. I think maybe Rod Powell was the original poster? In summary, most people set up cowl steering wrong and experience death wobble and bump steer.

if you just want to add more caster, can't you just lengthen the rear radius rod mounts to rock the axle backward?

EDIT- the thread was by Pete Eastwood, "p-wood". Thanks DDDenny for the correction.

 

Dan
I'm sure there have been a number of discussions here on the +'s/-'s of cowl steering, you may be thinking of the recent one titled "Just stop it" by P-wood, no doubt to be considered anything but a rant, he has probably "fixed" more wrongs done to these cars than most.

 

1/8 toe in hmmm. i run 1/4 on a beam axle at 135 mph. no wobble. one way to find out if its in what you expect is to lock that front end down using the friction shocks. just my 2 cents

 

Sort of. Except I welded it all up solid when I first built the radius rods. I'll build another set with adjustable rod ends, it only takes me a couple hours.

 

https://www.instagram.com/p/BsqEQRhhO9I/?utm_source=ig_share_sheet&igshid=6x89l93f96ai

Saw this pic on my IG feed today. Note the lack of a front spring at all.

 

Kool, must have a limit in the friction shock arms. Did you notice the King Pin angle?

 

Roothawg, look closely, I think I see a spring eye behind the axle connected to the hair pins or what ever you call those things. Maybe.




Bones