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Yes, More Death Wobble Questions.....

DirtDonk

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And it’s not really clouding anything up Bill. You’ve been saying it right from the first reply.

It’s not exclusive to live front axles either, but certainly seems more prevalent. My first experience as many of you may remember me relating many times over the years, was with a ‘67 Buick Wildcat with a bad front tire.
Not a new phenomenon, but as tires got larger and larger and had more input into the dynamics, I’m sure that carried over to death wobble as well.

And even back then (this was in 1970) an old timer at a mechanic shop knew immediately what it was. Not sure how he narrowed it down to the individual tire because I don’t think he had enough time to rotate one side of the time and drive it, but he got it fixed and us back on the way quickly.
Hmm, I wonder if after all these years, I forgot, he simply replaced both front tires rather than just one.
That would explain a lot of things!😱🙄
 

sprdv1

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I'm really glad you posted. Your empirical evidence is every bit as valuable and relevant as any other data point. And I do love data!

You did get me with the Hotchkis front axle though. But maybe you meant Hotchkiss. But Hotchkiss suspension is a live axle supported by longitudinal leaf springs. So maybe you meant something else? Anyway, "Hotchkis" is a sport suspension company out of Moorseville, NC. "Hotchkiss" is a suspension as you would find under the rear of your Bronco.

So either you have converted your Bronco's to leaf spring, or you are driving with custom suspension, or you really meant "live front axle" 4x4. But in any case...I appreciate your post.

Wealth of knowledge w/that guy for sure
 
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Ol'Blue

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I replaced the 2* C bushing with 4* and dropped the axle and let it hang from the limit straps with shocks and coils removed. I can still rotate the front driveshaft by hand but there is a little bind in one spot. Going to pull the driveshaft out and do some clearancing and hope for the best, but will look to rotate the inner Cs maybe this summer.

++ While I had everything apart I decided the replace the trackbar bushings and found the lower bolt on the axle side had broken the weld. The hole is not damaged but could this contribute to the wobble?

I already have the WH track bar riser and may go ahead with installing it. I had plans of going tie rod over someday, but maybe thats gunna happen now.

I may start a fresh thread on that since questions are many and off this topic.
 

jamesroney

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I replaced the 2* C bushing with 4* and dropped the axle and let it hang from the limit straps with shocks and coils removed. I can still rotate the front driveshaft by hand but there is a little bind in one spot. Going to pull the driveshaft out and do some clearancing and hope for the best, but will look to rotate the inner Cs maybe this summer.

++ While I had everything apart I decided the replace the trackbar bushings and found the lower bolt on the axle side had broken the weld. The hole is not damaged but could this contribute to the wobble?

I already have the WH track bar riser and may go ahead with installing it. I had plans of going tie rod over someday, but maybe thats gunna happen now.

I may start a fresh thread on that since questions are many and off this topic.
WH Trac bar riser? Hmmm… might think about removing the top hole, trimming the top (in your mill) before you weld it on. Someone accidentally deleted the logo on mine. Here’s why:

The WH riser is really well suited for a 4.5-5.5 lift. 3.5 is a tricky height, because you have to choose whether to use the top hole, (4.5 higher) or the lower hole. (3.5 higher). When you go TRO, and you get rid of your Trac bar bracket on your frame…the correct angle happens at the 3.5 hole.

But the extra hole on the bracket make the bracket stick up an extra 1.5 inches. So at full stuff, and with improper and inadequate bump stops (which I use) the bracket WILL impact the frame. Since I’m never going higher than 3.5, and I like the extra inch of up-travel, I chop off the excess bracket.

Tie rod over is a problem with factory drum knuckles and the factory Trac bar nut. The WH Trac bar riser fixes that.
 

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Ol'Blue

Ol'Blue

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Thanks for point that out James. That maybe an issue for me too, but I do have the higher bump stops but we'll see. I also have the heavy duty coil cups that are interfering with he riser bracket. Bracket will have to be trimmed to clear that too.

My contact issue is on the other end where the drop backet hits my heavy duty coil cup at full stuff, so that plan is to install the riser and drill a higher hole in the drop bracket and cut off the excess. Phase II later would be tie rod over or maybe now as I have the three way adjustable tie rod/drag link but tie rod end may hit my rims.
 
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jamesroney

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Thanks for point that out James. That maybe an issue for me too, but I do have the higher bump stops but we'll see. I also have the heavy duty coil cups that are interfering with he riser bracket. Bracket will have to be trimmed to clear that too.

My contact issue is on the other end where the drop backet hits my heavy duty coil cup at full stuff, so that plan is to install the riser and drill a higher hole in the drop bracket and cut off the excess. Phase II later would be tie rod over or maybe now as I have the three way adjustable tie rod/drag link but tie rod end may hit my rims.
I spent a fair amount of time installing my Trac bar drop bracket before I realized it hit my new tie rod. Then I spent a fair amount of time cutting off my freshly welded Trac bar drop bracket so that I could use the factory hole. All of this happened after the frame was in Powder, so it hurt my feelings a bit.

I would be very interested to see your limit strap design. Unless you have one at each wheel, then I’m not…I’ll send you a PM later.
 
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Ol'Blue

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Here are a few pics. Its not the best design but has worked so far. Im not thrilled putting the extra shear stress on the upper radius arm through bolt and the strap in not in perfect linear travel. The upper mount needs to be moved outboard on the frame and a separate mount welded to the radius arm.
 

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Ol'Blue

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James I noticed your picture the c caps don't come in contact with your radius arms. In order to get 100 lbs of torque on my bolts the caps touch the radius arms and smash out the c bushings quite a bit.
 

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jamesroney

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James I noticed your picture the c caps don't come in contact with your radius arms. In order to get 100 lbs of torque on my bolts the caps touch the radius arms and smash out the c bushings quite a bit.
Oh, yeah. Thanks. In another thread, I mentioned that I had this set up for 4.09, but changed my mind, and got a set of 4.88 gears for free. But I also had an extra set of 4.56 rear gears, then changed my mind again when I got a set of 4.88 gears along with a semi-float Dana 60 rear for $100. The carrier split for the 44 is at 3,73-3.92, but for the 60 it is at 4.56. So when I installed the ARB, I didn't want to buy a low speed ARB front, with a high speed ARB rear...and be stuck at 4.10. Especially if I decide to run 37's...which I was going to run, but got a set of new 35's cheap. So I went ahead and put in the 4.88 set, and haven't bolted the axle back in yet. It's a darned good thing my labor is "free."

You will notice that there are no cotter pins, or zerk fittings, or anything else buttoned up. (And the factory coil cups won't fit if you aren't tight.) But the transfer case goes in next week, and then I can set the rear pinion, and then I will tidy up the front. I'm stuck on whether I'm going to run those fancy Duff spring coil cups to have a sway bar. Which I should have answered before I detailed my old ones. But we shall see.

I needed to figure out the rear brake parking cables in order to figure out the rear caliper location, in order to decide how to route the rear caliper flex hoses. But that is now done, and so I had to route the front brake hoses. I never liked the steel line to flex hose to pumpkin to tee to steel line to caliper flex hose up front. My combination valve already has a second port for two front brake lines. So it's frame mounted single brake hose for me. Which gets the steel tube off the front axle, so the chains and straps don't cause trouble. But that has to be done before the engine goes in, and I'm not stabbing the engine twice. (maybe) So the tunnel needs a hole, the rear cross member needs to go in, then I can hang the D20. Then the engine can go in. But that couldn't happen before the EFI harness hole got cut. Which brings us up to date.

Gotta run.
 

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Ol'Blue

Ol'Blue

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Gotcha and that is looking great! Also, making sure to noticed the pics of the limit straps above.

I started a track bar riser TRO thread

 

toddz69

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++ While I had everything apart I decided the replace the trackbar bushings and found the lower bolt on the axle side had broken the weld. The hole is not damaged but could this contribute to the wobble?
X2 on this as I know James has already replied in the affirmative. I broke mine on my truck years ago. The one on our '69 1000-winning Stroppe racer was broken, and we broke the welds on the front axle of our NORRA Bronco numerous times. I think anyone that exercises their front suspension on a regular basis, in conjunction with poly bushings on both ends of the bar, will likely experience that failure.

Todd Z.
 
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Ol'Blue

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Just the wrap up this thread. I decided against the track bar riser and TRO option for now since it would reduce my up travel by about 2". Track bar will hit oil pan and tie rods will hit TB bracket.

Here's what I ended up doing:
Replaced the tires
Installed the frame reinforcement plate at the steering box
I did find the trackbar lower bolt to frame weld had broken lose so that will be welded up on Monday.
Replaced the TB bushings
Installed 4* C bushings
replaced the drag link - this was my fault. I stripped the threads on the TR to pitman arm and couldn't fix them with the die.
Reduced the torque on the upper ball joints. The spec of 100 lbs on the eccentric/adjustable sleeves was too much causing the knuckles to bind contributing to wondering

Alignment numbers are looking good and it handles much better now. Im still going to play with the toe this weekend, but very happy now.

Turning the outer Cs is definitely in the future but working on swapping in a 351w and 4r70w which will change my driveshaft angles a little so I think its best to wait.

Thanks for all the advice and I hope this helps others in the future.

Cheers!
 

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toddz69

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Glad to hear that it's handling much better now! We sure got a lot of tech in this thread though :).

Todd Z.
 

jamesroney

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Alignment numbers are looking good and it handles much better now. Im still going to play with the toe this weekend, but very happy now.


Cheers!
How did you end up with .7 degrees of toe per side? And how do you get that awesome alignment printout?

I am asking because toe should be the easiest thing to measure, and somehow yours got to the alignment rack without being close to spec. So I'm baffled as to how you ended up installing new parts, but not bothering to set the toe?

Now that you have the caster correct, and the front end buttoned up, you will notice that your Bronco is much more tolerant of the incorrect toe. Once you fix that, then you will notice that your Bronco is much more tolerant of other variables.

I have to admit that I have never paid for a wheel alignment on my Bronco. But when everything is right, alignment is kinda pointless.

I got the D20 transfer case installed, along with the NV4500, and I'm working on ride height. Front driveshaft drop angle is about 12 degrees, and rear driveshaft drop is 16 degrees. (I'm running a D60 in the rear, so don't use my number) Oddly enough, with 0 degree rubber bushings, my radius arms ended up pointing my pinion to 16 degrees, and my caster is 3 degrees. So I somehow need a 4 degree C bushing to straighten out the pinion. Didn't see that coming.
 

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Ol'Blue

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How did you end up with .7 degrees of toe per side? And how do you get that awesome alignment printout?

I am asking because toe should be the easiest thing to measure, and somehow yours got to the alignment rack without being close to spec. So I'm baffled as to how you ended up installing new parts, but not bothering to set the toe?

Now that you have the caster correct, and the front end buttoned up, you will notice that your Bronco is much more tolerant of the incorrect toe. Once you fix that, then you will notice that your Bronco is much more tolerant of other variables.

Honestly I didn't even try and get the alignment right. I just eyeballed it and drove it a 1/4" to the alignment shop. Here are the after numbers. Thought I attached this to my summary previous post. I asked the tech to shoot for .25-.5* total positive based on some suggestions on this site. He got it pretty darn good. Yes I love this type of print out. Its from a tire shop, Big Brand Tires, used to be USA tire and was Goodyear before that. The tech has a lifted Jeep and I asked to speak to him before doing the alignment, after our chat I felt conferrable that he could handle it.

* I should add, that I did change a lot of things in this process, but my gut (and all the comments here) tell me the death wobble was probably the 8 year old tires and the weld that broke lose on the axle side of the track bar bolt even though I had tightened the crap out of it. However, I still don't know if its cured, only miles will tell as its only happened three times in about 2,000 mile period, but the ride with the new tires feels so much smoother. Fingers crossed.

Good luck with your build James and keep us posted!
 

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Ol'Blue

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Glad to hear that it's handling much better now! We sure got a lot of tech in this thread though :).

Todd Z.


Yes we did and hopefully it will help the next dude! Thanks to all for the info!
 
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