Death wobble.....really low speeds

If it's a do-able deal, put the backs on the front and the fronts on the back.

Make sure your test drive is done where your pals won't spot you.

No use proving you really are crazy....

 

i have some radials mounted on some straight steelies if you end up wanting to try them and see what happens.


they are 5 on 5.5.

 

C9-- I've tried to raise the air pressure on the front of my light T roadster with 5.00x16 dirt trackers. I ran it up to 30, drove it and brought it back down 2 at a time till I was back at 20. The added pressure didn't help my wobble but made the car really rough on bumps and bad roads. At 20 the ride is nice.
I think the light cars are OK at 20 in the front. The front tires don't get any warmer at 20 than they did at 30. 1/16 to 1/8 of toe in also keeps the tires cool. More toe in or less (actually toe out) gets the tires warmer. Cooler tires are our freinds, right?

Frank

 

somewhat unrelated....and not trying to take anything form the post, but anyone want to post pics of how they installed and where they installed there dampner?

 

was there any brake shoe drag?

 

not buy em,
don't you have a friend that has a set to swap out just for a couple miles?
thats all!
TP

 

i had the same problem i went to bow wow vw and got a bus dampner $20.00
welded 7/16 stud to right side frame rail p***erger side other end of dampner
cut a piece of dom tube welded 7/16 stud to piece of tube then took 3 small
exhaust clamps 1-1/6 for emmision tubes works perfect now no death wabble
any more any you cant see it unless you look really hard dampner was even painted black.
just my 2 cents ....jeffrey

 

Ya get that damper on yet? (I kept this comment short so it would fit up my ***)

 

are you running any front shocks at all?

 

Eric, my coupe is real finicky with tire pressure like has been stated by a few. Like C-9 I run way off the map in "real world this is what you should run numbers". Bigs and littles for tires. Rears at 14 max and fronts at 24. Smooth as gl***. If I drop in the front to 20 it shakes like a dog ****ting gl*** at low speeds.

I'll pm you my cell number and call if you want to walk through it. Or I can stick my phone up my ***...no LOL. Call me if you need more.

It can be fixed it just takes a little walk through, thining, trying and patience.

 

Could be the scrubbed tires. Can you get them turned around on the rims?

 

I had the same problem.. finally attributed most of it to the excelsior tires. Ordered up a new set of 600 firestones and no more shake... expensive, but worth it to be able to drive without my **** biting a hole in the seat..

Brian

 

dont know if this any help but my dad calls it top fueler syndrome
watch a rail job in reverse it happens to them almost every time.

my model a does it
it doesnt mean that something is not tight or worn out
caster and toe in are the sole cause of this
on transverse spring front ends it either happens or not
all i do is when it happens i jerk the wheel in and out of it
goes away immediately

 

What kind of drums are you using and what kind of wheels are you running? if you are running ford drums (pre-48) and spoke wheels your problem might be that you still have the drum weights on the drum face. If so your wheels are not setting flush with the drums therefore causing your wobble. Knock them off and your problem should be solved. Hope you can get this fixed I know its a pain in the ***.

 

I'm having the same death wobble, particularly when im headed downhill on a little bumpier road at slow speed. everything seems tight so i ordered a socal damper. i'll let you know how it goes when i get it installed.

 

If toe-in isn't the issue and spindles are true and tire/wheels are balanced properly and without any defects or buldges then are the bearrings seated properly? Or maybe the races are warped from overheating...were they packed properly?

A damper will hide the problem, not fix it. I'd want to know the underlying cause first.

 

Hey Fidgiter, What have you found out? When you go to the alignment shop have them check the Ackerman angle. You should be able to string a line from the center of your kingpins through the center of the steering arm tie rod end to the center of your rear-axle housing. Check both sides. A lot of shops don't check this basic adjustment and if not correct the inside wheel during a turn will not turn tight enough. There are many books that cover this and one is the SoCal Speed Shop Ch***is book. Hope you have found the problem, you should be driving your rod with no worries. The FOGGER

 

Fidgiter,
When you cut your bones let me know how much you have to pie cut them I've got some on the T I'm building and that's one of the questions I have. I guess the rake of the car will have some impact on the amount of the cut but haven't figured out how to properly do it yet.
TIA

 

Well the problem with mine, ***uming it is a bad caster angle, is that I mounted the bones really low on the frame. I didn't think the car would be this low when I did that. And I've got so much time and chrome work invested in the mounts that I don't want to change them. When I set it all up I didn't have nearly enough weight on the front end, so the axle is leaned back a little too far. They shouldn't need to be pie cut at all if it's done right.

Sin Ticket - I've got F100 brakes on it and adapters to run the early wires on those flat drums. The wobble happened both with these wheels on it and the steelies on it (without adapters) so thats not an issue. I did have to get rid of a few weights on one of the rear drums because of wheel clearance issues though, so it's a very valid point.

 

I'll agree with the caster thing. My Duece was doing that back in the 60's after I installed an axle and wish bones from a Drag Master ch***is. I thought it
looked neat with the wheels leaning when I turned like a rail, but it went
thru the wobble thing oc***ionaly. Back in those days it would straighten out
when you stomped on it( with the big Olds of course). You'll figure it out
Good Luck

 

Fixed a case of this last month on another car, but with IFS (old mustang). Everything was new, tight, and installed right. At low speeds the car would wobble - REAL bad. Turned out that he had put in longer bolts in the upper control arms so that he could add enough shims to get 8 degrees of caster. Way too much for an early Mustang.

If some caster is good, more must be better, right? Ever grab a bad shopping cart with a wheel that whacks back and forth? Same damn thing.

We pulled it back to 3 degrees caster and the car is tracking straight and true now. No more wobble.

 

That 30 degree sweep your talking about reminds me of that lowrider bike mark had at the shop in irving.. remember how if you were rolling too slow and made any turn that thing would just fall right over on you..

 

I posted early on in this thread about a friends 34 that is still doing it. Since then, he did:
- A new front spring from speedway because the old one was too sagged-no change in wobble.
- took the fronts off and put them on the rear and ran it on stands to see if they were running true or vibrating, they looked true. Took the original fronts for spin balancing/no change.
-put donor used wheels/tires on ; still wobbled but not quite as often.
-he did find the true center of the Mustang box then adjusted the draglink accordingly. Also has the pitman 100% vertical with wheels pointed straight ahead.
-new tierod ends, draglink ends are near new and zero wear.

Todays new posts goes along with his latest thoughts: Too much caster?? He did already change the caster more positive last week, and now wants to go to like 2-to-3 degrees???..grasping at thoughts at this point. Does anyone here run that little on a dropped 34 I beam??

I give you guys the courage award for "go faster, drive out of it". Yes, when the tires get up enough speed to act like our childhood gyroscopes did, the tires almost act like dampners, right?..if you try to turn a gyro, it resists that movement. His car can't take too much more of the roadtests & wobble; it is so bad and violent that I wonder how the radiator has not cracked yet.

 

Something about the force of the friction of the rolling overcoming the force of the wobble is what helps it not wobble. I think thats why the dampers are effective, they add resistance to the system.

Sometimes I got high speed 20-30 mph wobble, and some times slow speed 5-10 wobble. Seems to be related to the toe setting, which is changing all the time, maybe from the **** bending?

Whichever one it does, quickly accelerating is a faster way to stop the shake than to brake to a stop.

With the skinny bias plys, a little toe out seems to be better than toe in. But I don't like that just because it ain't supposed to be that way.

I've been lubing the plastic or rubber shackle bushings, this is helping a lot. I'm really thinking about making metal bushings and using a grease fitting, like Henry did. for no friction in the shackles.

Frank.

 

Update on my friend's 34. He bought a Mercedes Dampner off ebay stores. He made a bracket off of 2 of the front spring U-bolts, and the other end was bolted through one of the tierod adjusting band clamps.


The car drives perfect. No more wobble or anything even close to even a twitch. It honestly does not "feel" like covering up a problem when you are in the car. We even went over potholed dirt roads, too.


Before ordering the dampner, he talked with Chick Brignolo who you M*** guys know, and he claims he's found "no one common cause" and, "some use a dampner, and some use a Panhard" and "either will work".

 

To me it sounds like a bump steer problem. Every link travels in a arc. When you hit a bump those arcs steer the car somewhat. At low speeds they can build a rhythm (death wobble). Watch a sprint car under yellow, half of them will have a very visible wobble in the front. To minimize it caster, camber, and toe must all be just right. I'd have a professional alignment done and then add the dampener if it's still needed. The only way to completely do away with bump steer on a beam front axle is to mount a rack and pinion steering box directly to the axle, but that wouldn't be very traditional would it?

 

As mentioned earlier, I adjusted the toe in at the same time I put the damper on. Well, I had the engine/trans out this weekend and before we put it back in the car, decided to tighten up the steering box some. It's mostly back together, only lacks some wiring I have to re-do.

But just as a 'what the hell,' I'm going to pull the damper off and see if the toe in and steering box adjustments had any effect on it at all. I'll report back soon.

 

Hey All,
I installed the SoCal steering damper and it knocked it right out. No more death wobble! Make sure to give that a try if all else fails.

NK