Death wobble....axle problems

I,m having problems with the 32. At low speeds, when I hit a bump it goes into a death wobble. I have to come to a stop to get it to stop. It doesn't happen at speeds above 25 mhp. It's not safe to drive til I get this fixed.

The axle has about 10 degrees caster to it. I've tried everything form 1/8 toe in, no toe and toed out just a little. As for the camber, I think the top of the tires lean out just a hair.

Any suggestions???? This is driving me crazy! Between this and the clutch problems I'm getting really tired of this car.
Clark

 

Check the Caster on the axle, Regret was doing that last summer and turn out there was 7 degrees!! put it at 5 and everything is cool..

I'm having a brain fade...is it caster or camber.....Drag cars have a **** ton of it so the cars don't like to turn....? I'm an idiot

 

Ten degrees caster may be too much.

Used to see altered roadsters and coupse at the drags back in the day.
They usually had quite a bit of caster plugged in and it was common to see them get into the low speed wobble bit.


The tops of the kingpins lean toward the back do they not?
Try 6 degrees and see how it works.

Measure the caster with the car on a level surface.
Caster is relative to level and not referenced with the frame.

Note that many home garages have a one degree pitch down to allow liquids to drain out the big door.
Double check your caster by switching the car end for end in the same spot and averaging the readings.

Any chance the wheel bearings are overly loose?

 

I'm thinking panhard bar or steering damper. Add one or the other and it should cure it.

 

Do you have really small tires on the front? I had the same thing happen years ago and ended up putting slightly larger tires on.
Don't ask the reasoning behind it. It worked.

 

That's almost a textbook description of what can happen when the caster is double what it should be on the street.

 

If you have some really bigs and really littles they will minimize the caster if the caster was originally set with fairly even sized tires.
Dropping the front end takes away caster as well.

Many times not enough caster can be recognized by the lack of steering wheel effort at highway speeds.
Sometimes a light touch will take you further than you wanted to go.
You'll also get a rear end disconnected from the front end feeling in some cases.

A larger front tire gives you more caster.

 

I've done several cars with close to 10 degrees of caster and never had this kind of problem. Lobeck even said the caster looked right.

I would have to cut the wishbones to change the caster.

I guess my next step is to try a steering dampener.

Front tires are 600x16....pretty big.

 

The reason I put more caster in it was cause my RPU was set up with 10 degrees caster by mistake. Larry's truck was at 6 degrees. His truck wanted to wonder at highway speeds and mine did not. We ended up adding more caster to his eventually.
Clark

 

Clark, The Problem Explained Must Be Address In A Series Of Operations. Initial Experience Is That You Have Rolled Too Much Caster In Your Axle, However Tire Shake Can Be Caused By A Series Of Other Cir***stances. First Lets Address What The Caster Really Is. Go To The Hardware Store And Purchase A Bubble Leveling Protractor. This Is Accurate Enough To Measure Caster. Step One Is To Check The Air Pressure In The Tires. Most Light Cars Require Between 24-26 Lbs In Fron Tires Less Causes Problems With Distortion And More Promotes A Harsh Ride. Adjust Air Pressure! With The Car On A Level Spot Place The Protractor On Top Of The King Pin, Leveling Front To Back And Check The Measured Caster. Should Read Between 5-7 Degrees. If This Is Ok Then Next Step Is To Jack Up The Front Of The Car And Begin Looking For Signs Of Excessive Play. Check King Pins, Radius Rod Bolts, Tie Rod Ends And Finally Check The Play In The Steerring Box. Excessive Wear Or Loose Conditions Will All Show Patterns Of Shimmy But Usually Over Longer Speed Ranges. The Toe In Should Be Between 1/8" To 1/16" In. The Camber Outward Is Common To I Beam Axles And Does Not Produce Shimmy. Since You Did Not Indicate That This Was A Cross Steer Car Or A Parallel Steer Car And Did Not Indicate The Car Was Spooky To Drive At Higher Speeds, I Am Am ***uming That You Have The Correct Locating Panard Rod. The Use Of A Shock Style Damper Is Only A Band Aid To Hide Existing Problems And Should Not Be Relied On As A Cure. Hope This Gives You A Place To Start. ****

 

Your Caster is not a problem Clark.....My 30 has at least that and will track good to 85 OK- so I say its play in a suspension part.
there is even in new parts a minimul amount of combined play a few thous here and there add up to enough to initiate the movement that in turn magnifies as it"rebounds".
I had a 35 Ford Coupe years ago with an Olds engine-and what did it on that car wa the axle would actually move right to left in the spring shackles when steered.
Have someone sit in it while parked and see if -when the steering is turned slowly the axle creeps right to left-ANY- amount....
Good luck.....Kenny

 

I double checked the caster and it is 10 degrees. I really don't want to cut my wishbones. I'm gonna try everything else first.

The car doesn't have a panard bar. With the cowl steering I wouldn't think it would need one.

Above 25 MHP the car drives great. No wondering, no shakes no, shimmies. One hand on the wheel. It's like it wanted to be on the highway. Do I have to drive under 25
Clark

 

I had close to the same problem with my roadster and contacted cornhuskers for a solution. His answer was.....

Should have 5-7 degrees of caster with an 1/8+ toe in. Once in a while I have experienced shimmy at that speed., and have not been able to isolate it. I have cured it with a realignment and one with a steering dampner from So-Cal. They use one on almost every car they build. Gary at Cornhusker

Bent the axle to achieve this caster and walla no mo-shimmy and no need for a dampner.

 

I say get a steering dampner, did it on my Modela A roadster..
you can find the at the junkyard, under VW's and Audi's and i guess a lot of more cars.

 

I chased the same problem on my '32 drag car. Everybody said I should just put a damper on it and be done, but I wanted to fix the problem not just the symptoms. Checked, measured, adjusted and tightened everything we could think of, it still shook while slowing down at the end of a run. This went on for several months as we don't get to the track that often and couldn't duplicate the problem on neighborhood streets. Finally just put the So Cal damper on it and haven't had a problem since. It's a nice little unit that you don't even see unless you're looking for it.

 

Hey Clark. Caster ain't your problem. The rolling bones guys run 10 degrees and Ken has over 40,000 miles on his with no problems. They run small 4.50 x 16's also, and they DO run steering dampers. Larry

 

Clark, I just went through this on my just completed 26' Modified. I have 12° caster(checked it on the level with one of those magnetic devices from ACE Hardware). Anyway, I also have cowl steering. My car would go crazy at 25mph to the point that I would have to come to a complete stop. If I accelerated fast it would not happen, but then I was affraid to slow down. I purchased new tires, tie rod ends, etc. to no avail. The problem turned out to be too much toe-in. On a tip from an old T-bucket builder, we started reducing the toe-in and going over the same stetch of bumpy road, same speed, over and over. It's completely gone now and I'm at 0° to maybe a +1 or 2°. I was faced with pie cutting the wishbones to reduce caster but got lucky. I agree with others that a steering dampner will only mask the problem. As others stated, check your steering box for excessive wear and check to see if your drag-link is flexing. I use a full length ford tie-rod for a drag link and was told that they can flex. That problem can be cured by removing a tie-rod end and driving a wooden dowel through the drag link. You can soak the ***embly in water to swell the wood if necessary. Just some tips, good luck. Sam

 

I went through exactly the same thing with my T....we checked everything and still it did it.....last resort was a steering damper and its never done it since

Monkey

 

Clark, C9's description is the big difference between my truck and your car. Mine has 16's on back and 15's up front. Clarks are 16's all the way around. Somehow makes sense to my pea brain. Just put the steering dampener on. Or I'll give you 10 grand for that pain-in-the-*** car!!

 

Well this seems like a computer conference, checking your reply still didn't address the issues. First what is cowl steering? What type of steering do you have? Type of box. Did you check the air pressure? 10 degrees is a little too much and with this caster it will produce a low speed shimmy that goes away as speed increases. It is not necessary to cut you radius rods to change the caster but you were not specific in how you mounted them or if they were split units. The use of a shock absorber damper is not a cure to the problem, so all those guys that tell you to do that probably give their girl friends a pushup bra too. I do not think that you have a major problem just too much conflicting info. I run the tech phone line everyday so mabey a call is in necessary. ****

 

i had the same problem. cut a pie piece of of my wishbones, and now its good. i was going to try a steering dampner, but decided to just cut.

trey

 

Well I got the car in the garage and jacked up. I think I found my problem. The king pin on the p***enger side is loose in the axle. The axle is a dropped stock axle and I quess in dropping it it got egged. That's what I get for trying to be cool and using an old axle. I even had a new one for it. From now on I stick to new axles!

So...how do I fix this. Oversized king pins? Bushing? New axle?
Clark

 

****...how'd you know my wife wears a push up bra?

Here's a pic of the car. The wishbone is mounted at the body line in the frame. I could move it up but it would look dumb. You can also see the cowl steering.

Air preasure was 28 pounds. The steering box is nice and tight.

Hopefully the axle is my problem.

Larry... what i think C9 was saying is if you put a taller tire on the front of the car it will change the caster. Putting a taller tire on the front will reduce your caster.
Clark

 

It's probably the axle but...

Don't you have air bags in the back of that car Clark?

Cant you just raise the back up a bit to set caster?

My 49 was a street-strip car before I got it with bigs and littles...

I wint to 15" rims all the way around and dropped the back end a bit and picked up a wobble in the process. Not bad but it was a PITA at times.

 

Brush..thanks,but right now the car is nothing more than a poser. I want to drive the damn thing! I guess Columbus is out for me and I'll have to get it ready for Bville.
Clark

 

To all the guys that suggested that it's the caster I think you are right in a way.

I'm guessing that when you have more caster everything has to be 100 percent or you'll have problems. The up side is they hadle better at high speeds with the more caster.

Now about that axle. Can I get oversize kingpins? Where? I think the new axle is just a little different than the stock one (perch bolt to perch bolt) and may be a pain.
Clark

 

May be a pain, but could you get it sleeved back to the correct size/shape?