need alignment advice. Got alignment. Now have Death Wobble. What to do?

[Chaski]

Crossover steering can contribute to death wobble. Conventional GM drag link geometry is impervious to the truck moving slightly left to right compared to the front axle. As soon as you go crossover when the frame and steering box deflect to the drivers side compared to the axle it makes the vehicle turn left, and the opposite is true. I have three friends who run crossover steering, and they all have hydraulic assist. The hydraulic assist not only helps turn large tires, it acts as a super steering dampener and will eliminate any unwanted steering from suspension deflection. If you look at any OEM crossover steering setup they all run a large panhard bar to keep the side to side movements from happening and causing wobble.

 

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I got under the truck today, intending to shim the kingpin springs. I ordered replacements, but they'll take a while, and I'd like to know now if that's the problem. A heavy thunderstorm hit, delaying my plans. We've had 7" of rain in the last 24 hours.

I was down there long enough to learn that the alignment guy lubricated my kingpins for me. He mentioned lubing the tie rod ends, but he didn't mention the kingpins. The kingpin spring zerk clearly shows fresh lube. That might explain what gave me the death wobble. If the kingpin springs were on the edge of failure, but poorly lubed, I can understand how fresh lube might push them over the edge.

At least I now have a theory that fits the facts, how the alignment change caused the death wobble. Everything else in the front end is tight.

I also noticed that TM9-2320-289-10 calls for tire pressure of 45 PSI on the front and 80 on the back. The truck came with 65PSI all around. The truck has TP45 stenciled above the front, and TP65 stenciled above the back. So I'll lower the pressure on the front and see what happens.

For the shelter carrier (m1028 ), the TM calls for 65PSI unless the shelter is loaded, when it calls for 80PSI. The M1010 "shelter" is always loaded, so 80 PSI makes sense. So why is it stenciled 65PSI? I'm guessing the stencil guy screwed up, but is there an authoritative answer out there? I searched SS and read a bunch of threads, and I'm still wondering.

 

[86m1028]

I did not read all 3 pages but here are a few helpful tips

1 You need it toed in slightly (check alignment specs)

2 Dont go by the tm's for tire pressure, go by what's on the tire !!!

3 Death wobble is NOT only caused by WORN parts !!!

 

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Thanks.

What alignment specs should I check? Alignment shop checked their specs, and it said 0 toe-in. They checked multiple sources. TM says within 0.375" of 0. ORD & Conventional Wisdom says I want toe-in. I had them give me 1/16" toe-in.

Tires are 80 PSI max. They came set to 65PSI. TM says use 45 and 80 front and back. Truck stencils say use 45 and 65 front and back. Tire mfg says refer to vehicle manual for appropriate tire pressure. What would be the correct pressure(s) for highway driving an M1010 with a light load?

I've been reading a lot about causes for death wobble. I'd appreciate any pointers to reliable info.

I did not read all 3 pages but here are a few helpful tips

1 You need it toed in slightly (check alignment specs)

2 Dont go by the tm's for tire pressure, go by what's on the tire !!!

3 Death wobble is NOT only caused by WORN parts !!!

 

[fitz]

Let us know if the springs & bushings help.

 

[MakersTeleMark]

Tires are 80 PSI max. They came set to 65PSI. TM says use 45 and 80 front and back. Truck stencils say use 45 and 65 front and back. Tire mfg says refer to vehicle manual for appropriate tire pressure. What would be the correct pressure(s) for highway driving an M1010 with a light load?

I run 70 all around on my 1028 with 10 plys.

 

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I asked Goodyear customer service what pressure they'd recommend for their tires on my truck, given the min and max loads. They said 65 front and 80 back. 65 front brought back my death wobble.

I gave up trying to find documentation that would tell me the appropriate pressure for a tire with a given load. I just went to Toys R Us and bought a box of chalk. If it ever stops raining, I'll figure out the right pressure using the chalk test.

(Incorrect theory deleted.)

I note that the TM calls for 45PSI in the front tires, a pressure well outside the range that causes the death wobble on my truck. I also note that the GM docs recommend 50PSI as the minimum pressure for a max-loaded K30 at highway speeds (65MPH).

Now, I need to determine the proper inflation for my tires in terms of tread wear. I'll use the chalk test for that. You chalk a line across the tread, drive a little on a smooth, level road, and look at how the chalk wears. If it wears in the middle, the tire is over-inflated. If it wears on the edges, the tire is under-inflated. If it wears evenly, the tire is properly inflated.

I have shims in hand, and a Crane urethane spring on order, but I need to get my tire pressure figured out first.

CUCV maintenance has been more of a learning experience than I expected.

 

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CUCV alignment specs

I found the CUCV alignment specs! 1/16" is 0.065", which is close enough to the 0.07" +/- 0.07" spec. Caster and Camber are not adjustable, though you could shim them.

TM9-2320-289-34 Table G-1

 

[Chaski]

What are these Clark urethane springs you speak of?

Personally I run around with the 5 coil Spicer kingpin springs and have not had any problems with plain Jane Spicer bushings. The old springs were 4 coil, and once they get a little weak they create problems. I know some people have posted that the vehicle weight is somehow supported by the kingpin springs... It is not. All the vehicle weight is supported by the tapered roller bearings on the bottom of the housing yoke and knuckle. The upper kingpin is conical in shape, and the bushing that makes contact with it is tapered on the inside to match the taper of the kingpin. The spring basically controls the preload of the top tapered bushing and the lower tapered bearing (they oppose each other). I think the only connection between tire pressure and your wobble is this... With your tires inflated more the forces imparted on your kingpins are "sharper", more of a hit than a push. Because your kingpin springs are most likely the old 4 coil style, and have degraded spring rate they are incapable of keeping the two opposed tapered bearing and bushing surfaces preloaded enough to keep the knuckle steering axis rigid. So you drive around with kingpin springs on their death bed, really rigid tires, and your steering gets a bit of a jar, your upper tapered kingpin bushing gets shoved up into the cap a bit because the spring isn't doing its job, and presto your knuckle is now deflecting quite a bit from its desired axis, and you are mid death wobble. Once it starts it is self sustaining.

I have seen a 1008 where the springs were so bad that the front end had negative camber from the tapered bushing deflecting into the cap, just from the side load of the knuckle. I know you are planning on replacing them, and I believe that once you do the clouds will part, the sun will shine, and angelic music will chime from some part of your CUCV.

If you want another diagnostic test to judge the health of your kingpin system jack up and support the front of your vehicle on the axle housing. Leave the tires and wheels on for more hanging weight on the springs. If you can go under the vehicle and pry between the bottom of the bottom yoke on the housing and the top of the bottom of the knuckle with a small pry bar and cause any movement your springs are junk. There is a seal pressed into the bottom of the bottom yoke on the housing, so pry in a way that won't damage it. Basically you are trying to move the knuckle towards the ground, which is going to compress the bushing spring.

Keep me posted, I'm curious how this will turn out.

Also, you can adjust camber on a 60 with a different bottom pin that bolts into the bottom of the knuckle. The pin is eccentric compared to the bore in the knuckle.

http://img.photobucket.com/albums/v...a-2535-4977-a126-681712d8ba5a_zpsegdvrva9.jpg

See if the link to the picture works. You can pry where the red dots are. The picture is a cross section on the entire knuckle system.

 

[sweetk30]

its not clark its crane offroad .

http://craneaxle.com/Product/32/Crane-Axle-Dana-60-King-Pin-Spring-Eliminator-Kit.aspx

 

[MakersTeleMark]

CUCV maintenance has been more of a learning experience than I expected.

I think you are under some kind of green spell. It is a stupid '80's truck. Replace your KP springs and steering stabilizer and fill all 4 known good tires equally with air 10 psi below their max, and you are done.

 

[Recovry4x4]

Well, in regards to death wobble, my contact truck suffers. Saturday morning I generated enough time to swap out the spring and nylon bushing on the passenger side with new Spicer stuff. I will do the drivers Thursday. Fixing just the one side took away the wobble.

 

[infidel got me]

I think you are under some kind of green spell. It is a stupid '80's truck. Replace your KP springs and steering stabilizer and fill all 4 known good tires equally with air 10 psi below their max, and you are done.

opcorn:opcorn: That's funny

 

[coecamo]

I had similar front steering wobble and found nothing worn. simple check with lockout hubs in
free, front wheels straight heach into steer knuckles and rotate axle shafts should turn easily. start truck turn wheels leave wheels turned stop engine now turn knuckle axle shafts. If more resistance is felt replace knuckle U-Joints. Mine were very stiff
COECAMO



steering

 

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Update: The chalk test confirmed that 65 PSI front and 80 PSI rear are appropriate tire pressures for my truck, as Goodyear recommended.

I installed the Crane Axle Dana 60 King Pin Spring Eliminator Kit on the driver side, and that fixed my death wobble. I'll install it on the passenger side next.

I considered putting in new springs, but I thought the urethane block sounded like it might better prevent the problem from recurring. Several folks recommended it. When I placed the order, I didn't realize the new Spicer springs have an additional coil, that's intended to solve this problem. The prices were the same, so one could go either way.

I also rotated the driver-side tires, which had no impact, as expected. (One theory was my front tires might be out of round, but they're not.)

So I consider my death wobble mystery solved. Thanks for all the help and education.

 

[sschaefer3]

I put new TRE's on mine and it still did it. Did a yard tape alignment and it stopped. The shop screwed my alignment up, they used the specs for a 1989 IFS Chevy truck. I'm good now too. I had already rebuilt my entire front axle.

 

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My alignment guys also used the wrong spec. They were completely confident they had it right. In the future, I'll bring this, from the -30 TM:

I don't think alignment shops are capable of looking up the alignment specs for our trucks.

 

[sschaefer3]

I agree with you !!!

 

[fitz]

Glad to hear you got it fixed.

 

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Replaced the passenger side kingpin spring with the urethane block, and rotated the tires front to back. Took the truck on a long test drive, trying to reproduce the death wobble. I drove it on the interstate, good secondary roads, bad secondary roads, and unpaved roads. No death wobble.

Thanks SS. The death wobble had me worried. Now I return to debugging my electrical system.