Death wobble truble???

[chopper tom]

I finally got it on the road and been trying to figure out all the bugs .
The biggest problem that i have right now is the front tires hopping wene i hit 50-60 mph,after that she smooths out till ihit about 70 or so and themn the rear starts to shack the whole bucket all over the place.
I have been talking to RPM and have some good ideas but wood like to here what some of you have been though on yours with similar prblems?
I am running a 50 chevy truck front axle and it does great except for that bounce?

 

[Noob]

Well there is certainly a lot of info here about the dreaded death wobble. I fixed mine by making sure that all the front end pieces were tight and right. Check your alignment, mine works well at 1/8 inch toed in, make sure your kingpins are shimmed so that there is no movement. check your caster for a 5 to 7 degree lay back. I know it sounds elementary but make sure everything is TIGHT. Check for roundness on your tires. Bias tires tend to go out of round if they have sat for an extended period of time. Take them and have them balanced. I had a bucket of trouble with mine and I know that a lot of other guys on here have dealt with the same thing. Keep working on it and good luck.
The Rat

 

[putz]

Try some hydraulic shocks that should cure your bounce .JMO

 

[donsrods]

Could be the picture angle, but I would check your toe in. Looks like it is toed out a little, but hard to tell from pictures.

Don

 

[mr27t]

THE SAGA OF THE DREADED DEATH WOBBLE WILL FOREVER HAUNT US!!!

It haunted me for nearly a year. Every car is different and what works for my car may or may not work for your car. There is no set setting, it's trial and error until you find YOUR cars sweet spot. Once you find that sweet spot be sure to write it down so that later on you wont have to go through it all again.

This is how I solved my troubles with the death wobble.

I began with a common starting point with information obtained from the T bucket forums, the NTBA, CCR and TCI. The general concensensus was;

With '40 Ford Spindles:
5 Degrees positive caster
1 to 1 1/2 Degrees positive camber
1/16" - 1/8" tow in

I began with the above specs and hit the road with some wrenches, a graduated measure stick (1/32" increments) and an angle protractor.

Begining with the starting point was a lot of help and I made one adjustment at a time begining with the caster until I had good steering return and good straight forward tracking. I found with my car, more caster gave me better road feel, better steering return and better straight forward tracking but the death wobble became much worse as I increased the caster angle.

I began with the caster setting going 1 degree each time from 5 - 10 degrees positive and then from 5 - 0 degrees possitive. I liked the feel of the steering at a setting of 2 1/2 degrees positive caster. at this point I had good steering return to center and dead on straight forward tracking with very little death wobble.

Next was the tow in setting, I began with 1/8" tow in and I adjusted in increaments of 1/32". Strangely enough, My car's death wobble was all gone with 1/32" toe out.

Now my steering is very responsive and smooth. I do have a very sllight wander at 70 mph but that could be me as I tend to use as much of my lane as possible while smelling the roses on the side of the road and of course I got's to have me parade wave and smile going, LOL!!!

Wheel balance and tire presure is critical with such a light front end on these cars so wheel bounce is yet another problem, especialy if your running without shocks so be sure to get a good balance done on the wheels and try to keep the tire presures even.

There is no set setting, you just need to do it by trial and error. begin with a starting point and do one adjustment at a time like the caster until you are comfortable with it then try toe in/out.

You can find a measure stick and the angle protractor from Lowe's, Home Depot or your local building supply that is graduated in 1/32".

I wish you all the luck in the world with it and be safe out there!!!

 

[RPM]

I also find that toe out works better for me than toe in. Seems none of these cars are the same.

 

[Lee_in_KC]

Wobble or bounce? Let's clarify... wobble is movement around the king pin in the steering plane with the tires moving in unison left and right. Bounce is one or both tires moving vertically, often opposite of each other. Wobble is cured with caster, toe-in, and pre-load on the wheel bearings. Bounce is cured with tire pressure, spin-balancing the wheel/tire combo, preferably on the car, and shock absorbers, preferably hydraulic.

I see you're running Hoosiers. My experience with them is they can have some heavy spots. One of my Hoosiers took 22 ounces to balance, the other 12 ounces. I'm guessing balance is the cause of your rear-end shake.

Since wobble tends to occur at lower speeds, I'm guessing your front end bounce is also a balance issue. First thing I would do is get all four corners spin-balanced.

 

[putz]

If the shake comes at 30 and then again 60 it is most likely a balance problem.

 

[chopper tom]

Well heres what i have done so fare ?
I had the front tires balanced ,thr caster is at 6 degrees,1/8th tow out ,and i finnally got the friction shocks put on [the work really good for home made shocks ,allways wanted to try a pair and i think that i like them] and installed .
Every thing that i have tryed hasnt helped except for the caster ,i came from about 12 degrees [when iu first got it on the road ]to about 6 degrees and all it did was move the bounce from about 30 miles an hour up to about 55 mph.
But i have not got a woble ,it's a bad bounch[very bad,the tires come off of the gruond,very wild !].It starts on one wheel and then the otherjumps and then the other jumps back and forth the faster i get untill i hit about 60 mph ,then it disappears all at onced.
Ihave built a bunch of hot rods and never seen this happin before?Its like its teetering on the spring or some thing..

 

[putz]

I would try and just clamp some hydraulic shocks to it temporarily. and try that. I know quite a few people have had no luck with friction shocks.Because that is what it sounds like is happening your axle starts to rock and just start gaining bounce.Where Friction shocks aren't really shocks at all they just slow down what is happening.They basically have the same restriction through all of the stoke where hydraulic has more the more you travel.Sorry I got long winded.

 

[Rick]

Well heres what i have done so fare ?
I had the front tires balanced ,thr caster is at 6 degrees,1/8th tow out ,and i finnally got the friction shocks put on [the work really good for home made shocks ,allways wanted to try a pair and i think that i like them] and installed .
Every thing that i have tryed hasnt helped except for the caster ,i came from about 12 degrees [when iu first got it on the road ]to about 6 degrees and all it did was move the bounce from about 30 miles an hour up to about 55 mph.
But i have not got a woble ,it's a bad bounch[very bad,the tires come off of the gruond,very wild !].It starts on one wheel and then the otherjumps and then the other jumps back and forth the faster i get untill i hit about 60 mph ,then it disappears all at onced.
Ihave built a bunch of hot rods and never seen this happin before?Its like its teetering on the spring or some thing..

I have the Total setup and when that happened to me no one believed it just bounced like crazy but now you know it scares the bejesus out of ya.The thing i did was put hyd.shocks on the car and it never did it again.Ron at RPM motor Sports or Jim at Wintec sell a bolt on kit for the Total frame.It uses Pete and Jakes shorty shocks.Its the best ride in a tbucket ive ever had.

 

[mr27t]

Have you checked for a tire/wheel being out of round? I once had a wheel with the universal oval lug holes. the wheel balanced in good but when I put it on the car I had a serious wheel hop. I jacked up the car and just spun the wheel on the car and I could see the wheel was out of round and not centered properly on the hub.

Mr27t

 

[chopper tom]

Well fellasi think igot it fixed?
I took my rear wheels and got them balanced. one wheel was 10 ounces and the other was 6 ounces[ i thought it was a lot ,for such an exspencive set of tires].
That fixed the rear ''and'' the front ????
''Weird'' but i'm glade to get it driving right finally.
Any one ever had this happin before? Dont undestand how it afected the front?

 

[chopper tom]

Man i was wrong ? It's back again,and its driving me crazy!!!!
Its at 55 mph,i cant even keep up with the flow of trafic.
About to through in the tawl and tack a brack fromit for a while ?
I have tryed it all except a 3degree caster setting ,i guess i'll try that next?

 

[Duke]

Have you checked the pre-load on your wheel bearings ?

 

[Wild Mango]

This is why all the manufacturers went to independant front ends. That way what happens on one side has no effect on the other side. Unlike a beam front..........
The only way to truly eliminate the tendency is with hydraulic shocks which dampen out the oscillations before they magnify. You can "tune" them trampers out with balancing etc. but it'll still be there waiting to scare the bejeepers out of you some time in the future.
I see some discussion about panhard bars on the front, without one when the dreaded "tramps" start the front end goes nuts hingeing away on the shackles. Not my idea of a good time.................................

 

[mr27t]

I fought with mine for nearly a year! I had to go one degree of caster at a time from 0-10 until I found it.

1 1/2 degrees caster and 1/32" toe out is the sweet spot for my car.

I know how your feeling about tossing in the towel and I had wanted to toss in the towel and put it all up for sale so many times but I am glad I didn't. Stick with it and you will get it!!!

Sometimes you just got to think outside the box and ignore the "It's got to have XXX caster or XXX toe-in or toe out." because that just does not seem to work with these little cars.

Maybe toss out the tape measure and angle finder and just do it by seat of the pants.

I have very little caster (it's nearly straight up and it's toe-out)

You said you had it fixed earlier... Think back, what has changed. did your tires loose a little PSI? Look for a lost wheel weight. Don't forget the rear of the vehicle... It's strange but I can make a slight adjustment in my differential or even if a rear tire is a little low, it will affect the handling and I could swear theres something wrong in the front end but it's not.

Wheel bearing pre-load will cause lots of trouble. I set mine much tighter than I normaly would. I think it was Ron (RPM) that sugjested to back off the brake shoes/pads and then tighten the front wheel bearing pre-load so that I would have no more than 1 - 1 1/2 free turns of the wheel.

This setting works AWESOME!!!!

Normaly I would tighten the spindle nut by hand (two fingers) as tight as possible then snug it to the next point with a wrench where I could insert the cotter pin. This had always worked for me in the past.

Doing it with Rons spin the wheel method was more than a full turn more of the spindle nut than I would usualy have done and I worried about it being to tight and burning a bearing.

I've put close to a thousand miles on my car with Ron's spin the wheel pre-load method and it has not burnt a bearing yet and I don't believe it ever will.

If it was going to smoke a bearing... it would have done it a long ago. (Thanks Ron!!!)

Mr27t

 

[meangreen]

Try decreasing caster down to 3.5 - 4 degrees. If the wobble is still there, try setting the toe IN 1/16, then 1/8, then 3/16. If it persists, try setting the toe OUT 1/16, then 1/8, then 3/16.

Years ago a friend of mine bought a channeled Model-A coupe. He got it cheap because the guy who built it couldn't get the front end to quit shaking. Nice car; dark green with light green velour interior, Pontiac 400 engine, air conditioned, green lexan roof insert. Unfortunately, the front end was a bit cobbled - the split wishbones were cut way too short and there was no adjustment for caster. At 40 mph the front end would just go crazy. I loosened the clamps on the tie rod and gave it a half-turn to increase toe-in. We went for a ride and the "shake speed" was at 45. We stopped, I gave it another half-turn - speed went to 55. Stopped, another half-turn, and wobble was completely gone. When we got back home, I tightened the clamps on the tie rod. We checked the toe and it was 3/8" in! That's pretty extreme, but it worked for that car and my friend had many happy miles in it after that.

 

[RPM]

We talked on the phone about your driveshaft, did you ever check the run out on it?

 

[WMG]

One other place to check is the steering gear box. With my car had a wobble from 30 mph to 55. Did all the things with toe in/out, caster etc. Now set at 3 degrees caster and no toe in/out. All the wobble that is left is between 25 and 30. Good on the highway but bad around town. The gear box did not seem to have much movement, the steering wheel only mover 2 inches. Tried a couple of bungee cords on the steering linkage and now unless I hit a real hard bump the wobble is gone. Going to take the box off and take most of the movement out of it.