Dreaded death wobble has returned... AAARRRGGGHHH!

[Lee_in_KC]

I don't understand this. I drove the T 400 miles in Mountain Home last week without a hint of wobble. Driving around this Wednesday afternoon it came back... with a vengeance!! Spent the day today trouble-shooting and testing. Checked tightness of all fasteners (they were tight), changed caster (less and more), changed air pressure (down to 20, up to 40), and tried a range of toe settings, as much as 1/4" in and out. Nothing changes the behavior. At about 30 mph, if I hit the slightest bump with the left wheel, both wheels start wobbling and it gets progressively worse until I stomp on the brakes and skid the tires. The entire steering train is tight. Hardly any play in the steering wheel, maybe 1/2". Steering shaft mount is tight. Steering box is mounted tight. Heims on the drag link and tie rod are tight.

This is not wheel hop. I had that and the shocks cured it. This is side-to-side wobble around the king pins.

This is driving me crazy! :hooray:

 

[putz]

[ame=[media=youtube]wj9PNNChVm4[/media] - death wobble[/ame]
Here is a video of bad death wobble.
It seems jeeps have this alot and they always point to a track bar.Are you by chance running bias on the back causing uneven tracking.Just a stab to start with.

 

[rooster57]

Lee my front tierod jamb nut backed off a couple of weeks ago and i just put it back where i thought it should go and man when i hit a bump it was very bad, So i placed two 1 by 1 boards on the side of each tire measured back 2 foot from center rear and front. So the board had 3 marks one center then 2 foot from centerline both ways so 4 foot between lines Place the centerline on the hub one board on one Tire one on the other tire. I used a bunge to hold them on LEVEL then with a tape measure from front line right to front line left and the same in the rear. I added 1/8 toe in and probem solved. I tried measuring accross the tread and had no success.

 

[Duke]

I have one of these and it works good. I put a torpedo level on mine to make sure it is level.
Alighment Toe Guage

 

[Lee_in_KC]

All tires are radials. I measured toe using Toolman's method, hanging a plumb bob from the center sipe in the tire... accurate to about 1/16". I tried toe settings in 1/16" increments from 1/4" toe in to 1/4" toe out. It made absolutely no difference in the wobble behavior, which surprised me.

I'm thinking caster is the issue. I only tried two caster adjustments... minus about two degrees from the original setting of about seven degrees, and plus two degrees. I'm going to try a lot less caster, like maybe three or four degrees.

What I can't understand is that this just suddenly appeared without me having changed anything on the car. It's just wierd!!

 

[railroad]

I don't have a T this week, but may change by the end of next week. From what you state, nothing changed that you know of. I wonder if the wear on the front tires changed your contact pattern enough to change the angle and amount of rubber you have on the ground under each front tire. Maybe pushing the front end through a puddle of water onto dry concrete would show any surprises as to what your front tires are doing on the asphalt. I am sure there is a sweet spot where the tires are not slipping and a max amount of tread is flat on the road. Maybe the wet tread marks will show which direction to adjust.

good luck,
railroad

This could be very educational for me. Keep us informed.

 

[terrymac]

Check the free play in your steering box. I've run into it a few times that a little extra play (and not much ) between the pinion and sector with the right tire combination will cause the front end to wobble. Check you tire balance as well could be a number of small things making a big problem
Good luck

 

[terrymac]

Opps should add be careful not to get the box too tight It's just like driving on the edge of a knife if you do

 

[Lee_in_KC]

railroad, you may have a point on tire wear. My tires were wearing on the inside more than the outside. I assume this is because I had been running about 1/8" toe out for the last year or so. This cured a previous bout of wobble I had, although it was not nearly as bad as it is now. I assume that I would need a lot of toe in to correct the uneven wear issue?

terrymac, my steering box is pretty tight. Only about 1/2" play at the steering wheel.

Jerry (Ma-n-pa-T) Cook suggested I check the pre-load on the front bearings. I'll do that this morning. If that doesn't work I'm going to start taking out caster one clevis turn at a time. I'm currently at about 5 degrees. I guess I should get an inclinometer and be more accurate. Hmmm, what time does Home Depot open on Sundays?

 

[Francis Blake]

Lee this is just a shot in the dark, but have you checked your wheel balance?

 

[Lee_in_KC]

Yep, wheels were spin-balanced on the car last year. I guess I should check to see if I threw a weight.

 

[putz]

Home depot in Overland park is open 8 am till 8 pm sundays.

 

[donsrods]

I think it might be your tires Lee. I had the same thing with my 27 years ago. It never had any handling problems from day one but suddenly DW showed up. I did everything, and all was tight and ok. Finally noticed my tires were cupping slightly on the inside so I changed them and it went away. You might also have them rebalanced.

Is your tie rod out front or behind the axle? If it is behind you might consider adding one of SoCals stabilizer shocks. I'm redoing my 27 for the Billetproof Drags and am adding one of those to the car. No way am I going full tilt through the lights and have any hint of wobble show up.

DW is a sonofagun. My current T started doing it and I had to do the same routine you did, hit the brakes hard. I finally changed out my front shocks which were a little weak, and it seems to have gone away.

Don

 

[Lee_in_KC]

Holy crap... calibrated eyeball way off!!

I ran to Home Depot and picked up an angle finder to check my caster. Wow, was I off on my guess of 5 degrees. It's actually 11!! Before I changed it last it was probably 15!! Don't know if this is the wobble cause yet (just got back), but it sure would explain why my car is harder to turn than it seems like it should be. I'll report back after I re-set the caster and test drive it.

Don, my tie rod is out front, so steering stabilizer probably isn't an option. I also think my shocks aren't adequate. They're P&J's shorties.

 

[putz]

Qa1 shocks seem to be what the racers are using and is making a dramatic difference on dirt. So you be the judge. 11 degrees of caster that could cause some real issues.

 

[Rick]

I have the Pete and Jakes shorty's on my bucket.I had one hell of a wobble on mine with friction shocks put the shortys on and bingo rides perfect now and has ever since.I think your on the right track with the 15 degrees man thats a ton.Like the old dragsters had like 15 or 20 on them.The wheels wanted to flop to either side when you released the wheel.

 

[AZCOWBO]

Just a thought! Have you checked the worm gear inside the steering box? I had a similar problem with another T. I replaced the worm gear and it went away.

Ron H.

 

[Ma_n_Pa T]

Re: Holy crap... calibrated eyeball way off!!

That explains the tire wear too, just make sure you re-set the toe-in again after the caster, I e-mailed you a few web site articles to look at. How did you ever turn the wheel??, I'm sure not going to mess with you!!

Jerry

 

[Duke]

I agree with Ma & Pa T

 

[Lee_in_KC]

Progress... some good, some not so good...

Caster is now set at 5 degrees. Just drove around the block... results:

> it's like I have power steering now!! It turns sooo much easier.

> the wobble is almost gone. As I pass through about 30 mph it wiggles just a couple of times then smooths out. It feels much more stable otherwise.

The only thing I have done is reduce the caster from 11 to 5. I'm now going to re-set the toe and check the pre-load on the wheel bearings. King pins are tight. Camber is about 1.5 degrees out at the top.