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Just going back over some of the straight-axle cars we've had in our shop , and the gassers we've raced , the light just came on . Not one of those cars was built like yours . We've always put the shackle to the REAR of the leaf-springs , so the axle never changes position for/aft . When your front-shackle axle sees a bump in the road . the whole axle can move to the bump . I see another problem when rubber bushings are used on leaf springs on a steering axle ; it's one more slight deflection the steering doesn't need . More "bump-steer" is caused by the soft bushings in the spring-eyes they're in there for the soft ride ; not something you need in a straight-axle car . Just another set of eyes ... Be safe...Bob.
Shackles should ALWAYS be on the opposite side the axle steers on. If the drag link is in front of the axle, then the shackles should be in the rear, and vice versa. Chrysler found this out the hard way with their Jeep Cherokee when they steered their axles on the same side as the shackles, and the steering pushed the axle side to side with shackle flex. Their cure was a recall that involved changing the shackles to the opposite side, and cured their problem with steering issues.

The big problem I see with Carmine's setup is the sloppy steering box, and that driver's side drag link connection! The drag link really needs to be relocated to the passenger side, so it will work properly. The short length will always emphasize and exaggerate whatever other problems exist. I know this is a huge deal to change, but it will make your car steer and handle so much better!
I also haven't seen any mention of what you set your toe in at? Straight axles should always have 1/8"-1/4" toe in, and if you have less it will add to the death wobble issues. Get a measurement on the front and rear of your wheels/tires, and make sure you've got the proper toe in.
 
Short of rebuilding the whole thing, I see two things to fix.
1. Caster readjustment, with shims.
2. And this is more work, run the drag link to the passenger side spindle. Yes, you are gonna hafta change the oil pan.
After that, clamp/band the leaves, tighten/check nuts and bolts.
I do agree about the shackles in the rear, but that is not a "deal breaker", lots of cars and ALL stock chevy pickups are the way your car is now.
Chevy trucks, or any vehicle that has push/pull draglinks, are different. A push/pull steering setup doesn't care which side the shackle is mounted, as it wont deflect the axle while steering.
 
Probably just got loose from the constant back and forth motion of driving the car. I have had all sorts of bolts and nuts work loose on builds, and usually not critical parts.
I would suggest that anything critical should be assembled with Loctite Blue, even if you use lock washers, or nylock nuts. This is my preferred method, and I use Loctite in conjunction with lockwashers on all steering components that don't have castle nuts and cotter pins. I use it on anything else that works loose, before I tighten it back down, to prevent further issues.
 
I've known people who connected a GoPro camera to their suspension on the front of a straight axle car to view the movement during normal driving. It will show there is a slight deflection or side movement without a panhard bar, but it is so slight (even on a fairly high gasser) that I really think a panhard bar is not needed. If a person used a monoleaf spring setup, or a very pliant spring, then this might be an issue, but with most multi leaf spring packs I doubt you'll get enough side movement to even notice.
I've done a lot of parallel leaf straight axle builds, and never used a panhard bar. It sure wouldn't have any effect on "death wobble" with or without a panhard.
 
For all the guys on here that are desperately trying to make
an old outdated drag race deal work on the street , the high
in the sky straight axle idea was to go fast down a drag strip
and transfer weight to the rear for inhanced traction period .
You will never make this deal happy and fun to drive on the
street , it was never intended to have that function !! You
would have a better handling and more fun car to drive by
just putting a set of gas shocks on your stock Tri-five
suspension . Believe me , I tell the truth Kemosabe !!

easy

( the happy wabbit )
I will respectfully disagree. It is quite possible, and done all the time. I own, and have owned numerous straight axle cars that handle and steer without any problems, and in many cases you forget it's a straight axle car because it drives so well.
If straight axle cars could never be made to drive well or be fun, there wouldn't be so many of them doing exactly that on the road today. Do you really think that the hundreds of thousands of factory built straight axle cars were ill handling, or scary to drive? They were well engineered, and if a car is properly engineered today, it also will be fun and safe to drive.
 
You could put the steering box in front of the axle. A couple of u- joints, some steering shaft and a box mount. You've got the stock front sheet metal? It'll take some imagination, but It could be done, I think. Or notch the oilpan, that was how it was done back in the day.........
This is the perfect solution. I'd never want to remove that old W motor in your gasser! It's just way too cool to not do whatever it takes to retain it! I had the same problem you have when I dropped the 464 BBC into my '63 Falcon, and realized the oil pan was right in the way to steer off the back side of the axle!
I simply mounted the steering box in front of the axle, and flipped the pitman arm 180 degrees towards the axle. Then a drag link across to the top side of the pass. side backing plate. It made the install easy, and only required a joint and DD shaft to adapt to the forward mount box. The drag link is so level that it has zero bump steer and clears the oil pan easily.
Since you need to replace your steering box anyway, I'd suggest trying to find a late 70's Courier or Mazda truck box, as they are tall and will place the input shaft above the frame rails, but the pitman arm below the frame rail, and make the swap much easier.
As you can see in this old picture from my build, the Courier/Mazda box sits outside the frame rails, but over the rail, so it's perfect to adapt to almost any older car. I used a junkyad Camaro column, and kept the factory joint with it, then DD to a Flaming River joint to adapt to the box splines.
 
Thank you very much for sharing that pic and your experience. I really appreciate it, Carmine.
You're welcome! Wish we weren't on opposite coasts. I'd enjoy coming over and assisting in sorting out your '56! I love everything about it, but especially the W motor and straight axle!
 
here's a picture of my sweet little baby rat 60 over 427

Image
If those are ARP studs in your 427, you should test fit the heads and headers! I got them for my 464 and discovered AFTER torqing them down that my header flanges hit on all the bolts along the bottom edge of the heads! I couldn't get my headers to seal up against the gasket because ARP makes the stud too long, and with the excess stud sticking so far up they hit the flange.
I had to take a parting wheel on my die grinder and carefully cut them flush with the nuts. I still had to also grind on my header flanges a bit also, as the nuts on the ARP studs were taller than head bolts, and needed more clearancing to fit. Was a little unnerving to have to grind around my new aluminum heads, but fortunately I didn't slip and hit them!
You can see in this picture how far the studs and nuts stick up before trimming. A good thick flange will definitely not clear under the exhaust ports!
 
I had the front death wobble in mine when I built it. chased the shake for some time, I then talked to some of the sprint car guysand they told me a 1/16th-1/8th Toe -OUT not Toe -in and your wobble will go away. (with correct caster) Quick adjust to the toe out, and she rode clean thru 45-65 miles per hour. I almost bought a steering dampner, and shims,and a new vega box. Sure glad I talked with someone with experience. Toe out will not ware tires anymore than toe in and it solved my problem with the shakes

Video of front end while driving
http://www.youtube.com/watch?v=souOe-J2uQI
I've never ever heard of putting toe out on a straight axle to cure anything? All the factory axles were spec'd to 1/8"-1/4" toe in, and every axle I've ever installed or worked on I did this toe in on.
Not sure about a dirt track, and why it might work there, or apply to a street axle? I'm stumped on this one!
 
I'm with you.

Toe out is used on a circle track car to help it turn, especially initially.
Thanks for the clarification! Makes sense in the dirt where you'd want the wheels to react quickly with minor steering wheel movement. But on the street it would make an axle dodgey, and constantly require correction, even when going straight.
 
I was thinking about this a bit more.

I'm now thinking that excessive toe in or toe out could excite the "death wobble". And excessive bump steer causes excessive toe in or toe out depending on the geometry. Which Carmine's original setup has.

The thing that made me think of this was when my 67 Nova slipped one of the eccentric adjusters years back and it would chatter the tires going around a corner. So I'm equating the chatter with death wobble under somewhat different conditions.

Maybe it's a stretch, maybe not.
I'd definitely agree as it relates to toe out, since toe out will make a front end "search" and get "twitchy". Had that issue with the first straight axle I did in 1968 on my '57 Chevy! Had I not gotten good advice from my elders back then, I'd have either pulled it back out, or sold it! It was scary at anything over 35 mph! ;)

But toe in usually does the opposite. It makes the response less touchy, and helps keep the car going straight.
 
Trouble is, with bump steer you could have both toe in and toe out under different conditions.

Hopefully that's all getting cured for Carmine.
Yes, bump steer is not caused by toe in or out, but would be worse with toe out when you try to correct after the bump and the steering is twitchy.
 
By most definitions, bump steer is when toe in/out changes with suspension movement.

So with bump steer you could start with toe in, and end up with toe out. Or vice versa.
No, bump steer is when the wheels turn under spring compression, not toe in or toe out changing. Bump steer is created by the drag link that attaches the steering pitman arm to the wheel. The steeper the angle, the more it pushes the front wheels one way as the springs compress. The drag link is fixed at the pitman arm, and the wheels moving up and down create an arc in the end of the drag link's travel. The arc makes the arm get shorter or longer, and as it does so it pushes the wheels, steering the car, even though you're holding the steering wheel still.
All straight axle cars have bump steer, regardless of how they're set up. The ones with the least bump steer (or least felt bump steer) are the ones where the drag link is nearly flat. I prefer mine slightly downhill static, so as the springs compress the drag link becomes level, and if compressed further it begins to become slightly uphill. This slightly moves the wheels, and less than if it starts level and becomes more angled up throughout the spring's compression.
The longer you make the drag link, the less bump steer you'll have, and the more level you make it the less bump steer you'll have.

Toe in and toe out can only change if the tie rod length changes. I've actually seen that happen when someone had a very wide straight axle, and a thin or lightweight tie rod that bends like a spring. That can often create the death wobble as the tie rod whips from straight to bent and back, which changes toe in and toe out. If you can grab the tie rod by hand and pull it like you were trying to bend it, and it moves much, then you really need to replace it or make it stiffen with a welded sleeve over it.
 
Learning a lot more about straight axles and bump steer/death wobble as this thread continues. Thank you everyone.



While I have your attention, I have one other question. I apologize if I asked it before. This would be in re. to toe-in. The way things are going, I don't believe I will be getting to an alignment machine anytime soon. I would like to set the toe-in while the car is in my garage. From reading these threads I will be looking for 1/8" toe-in. I understand that part, but how do I tell when both tires are pointing perfectly straight ahead so I can set the toe-in?? How would I measure for this?? Can this actually be done at home?? If so, in laymans terms, how can I do this?? Many thanx, Carmine.
I center my steering wheel to ensure the tires are straight ahead. Just turn the wheel to the left and right and count the turns. Then turn it halfway back and it should be centered, and the wheels straight forward. Before setting the toe in jack the axle up so the wheels are off the ground and this will release any tension on the wheels. Then you can adjust toe in.
I use a couple pieces of box tubing and pick a spot as close to center of the wheel as possible, or a good spot on the tire sidewall that's consistent all around. This should be at 9 o'clock and 3 o'clock if possible, but sometimes there's an obstruction that makes it hard to get to this spot, and that's where the tubing comes in. I use vise grips to clamp a small piece of metal to one end, and the other gets a piece the same size permanently attached. Mine is welded on one end. This makes the tubing like dial calipers, so you can sit it on the floor and the ends sit against the point you measure.
By measuring in front of the axle and to the rear, you can compare the widths once you lock the one adjustable end to the tubing. The measurement in front should be 1/8"-1/4" narrower than the measurement in the rear at the same point. Adjust the tie rod until you get that, and then lock the adjustment, and sit the car back on solid ground.
That will be as good as any alignment shop does, unless it's a truck shop and they have equipment to bend an axle to set camber. So far I've never set one up and had to take it to an alignment shop. They always drove well once I set the king pin angle, and toe in.
 
Regarding the different things "bump steer" means applied to a straight axle, my tube axle actually bends noticeably if I jack it up right next to the leaf spring; it would be interesting to measure the effect that might have on toe in, assuming that driving might cause similar axle flex.
And where you put the jack stands might have an effect on your toe setting.
If your tube axle bends it would affect camber, but not sure it would affect toe setting. Usually the slight bend would be more if jacked up in the center, not near the spring mounts?
 
I wouldn't try to jack up the car (BB) by the center of the axle, and the axle is above the springs so I put the jack just inside of the leaf.
Like you said, the camber- it changes visibly, never bothered to try to measure how much...
Well, I went out to the garage and set a block touching the tire sidewalls, and jacked the wheel off the ground; a solid 1/4" gap opened at the bottom sidewall, measuring about 1 1/2 degree camber change.
Or calculating the movement at 6" below the axle center line (where my tie rod is), my tie rod end is pushed in about .075", which would actually change the toe. I wasn't expecting this, but got to thinking.
This is going from weighting the axle 16" outside of the leaf spring (on the wheel), to 5 1/2" inside of the leaf spring on the jack, so most of the flex is happening with the weight on the wheel, and it's more returning to straight (a little past) when on the jack.
So when hitting a bump the toe would move more out, and coming off a bump the toe would move back in.
This would probably not happen at all with a forged axle, and mine might be more flexible than whatever Speedway sells now. No idea.
So Carmine, have you noticed this?
I wonder what the change or flex would be in your axle if it was raised under the spring plate where it's supported? 16" outside the springs sounds pretty normal, but the key is how far the springs are apart also. I'd guess most Tri 5 cars will have spring spacing of around 38"-41" centers on the springs.
I've actually cut the tube in half on a Speedway tube straight axle to narrow it. They are pretty stout material, and the wall thickness is just over 3/8" thick. It's also seamless tubing, which helps strength a lot. I think most tube axles are 3/16" to 1/4" seamless wall tubing.
 
32" width makes a fair amount of axle outside the springs, since most Tri 5's use an axle width of around 60"-62" to the wheel mounting surface. That will definitely put some stress on the axle and test it's wall thickness.
I always set mine with the axle in the air and supported under the spring plates. Then lower it to the ground and double check my settings. I don't like the tires on the ground while trying to adjust the tie rod.
 
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