Speed Wobble

[98_k1500]

I have done a lot of searching on here and cant seem to find any info. Truck is detailed in signature. I'm having a wobble/sway issue at 65+ mph. I,m 99.999999% sure its not in the front end. The truck feels like a improperly loaded trailer is being towed behind it. It develops that rear side to side sway and it gets worse with speed. I have 3 buddies that all have 94 blazers with 35 inch tires on them. All of theirs do the exact same thing. I have talked to other Blazer/Tahoe owners that cite the same issue with even 33 inch tires. This is the first truck i have seen with the problem. It only developed this recently, this same setup has been on the truck for over 3 years. Has anyone ever dealt with / successfully fixed this problem? Any help would be appreciated. I'm out of ideas. I know there is an issue somewhere because the truck has been 120+ on 35 inch mud grips without a complaint on multiple occasions.

 

[SkyHighColorado]

Does the load rating of your 35's cover what you are hauling?

BTW I wouldn't take 35's over 100mph that's asking for a failure.

 

[dowsewashere]

Yeah dont take 35s over 100 unless their speed rating good for that. Also i see keys and blocks. Are your blocks shifting?

 

[oohunter04oo]

Make sure your tires are properly balanced, maybe look into balancing beads instead of the traditional wheel weights. Also thoroughly inspect your frontend. It's probably worn out being cranked like that on 35's. I highly doubt you got 4" of lift out of lift keys even if you flipped your balljoints... If you did then your upper control arms have to be sitting on the droop stops. If you did crank if 4" higher than were it was the truck must have been decranked before.

 

[southern_z71_92]

my buddies 93 had a bounce and a wobble and we thought it was out of balanced tires. we replaced his tie rod ends and no more issue. however his issue was only at the 35 to 45 range. and he has a full lift kit.

 

[K15 Blazer]

"DEATH WOBBLE"

if your truck is lifted enough to fit 35" tires your steering geometry is strained from the driveshaft's angles and your suspension is now completely worn out... you need to completely rebuild your suspension, bushings and all, and find and correct the misaligned angles.

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[oohunter04oo]

my buddies 93 had a bounce and a wobble and we thought it was out of balanced tires. we replaced his tie rod ends and no more issue. however his issue was only at the 35 to 45 range. and he has a full lift kit.

Very common issues slack in the tierods will cause the tires to wobble in and out.

"DEATH WOBBLE"

if your truck is lifted enough to fit 35" tires your steering geometry is strained from the driveshaft's angles and your suspension is now completely worn out... you need to completely rebuild your suspension, bushings and all, and find and correct the misaligned angles.

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A 2" block isn't enough to cause a driveshaft vibration, unless he has a problem with the driveshaft or ujoints themselves. The front driveshaft angle does not change when you crank the torsion bars. The cv angles do change, and they could be causing the issue because the angle is to bad.

 

[98_k1500]

The blocks are not shifting, already checked that. The U bolts are tight and properly positioned. The truck is not being used to tow anything at the moment. It feels like someone is rocking the bed side to side. Its very subtle and gentle at first, becoming more pronounced if you don't back out of the throttle. I forgot to mention, the truck has aftermarket upper control arms to address the droop stop issue. The front end is tight, and has always been kept well greased. It has had this same setup on it for 40,000 miles with no issues. The tires could probably use a balance. Its been a while since mine have been done. I have never used balance beads. It definitely feels like the problem originates in the rear of the truck. I had a jeep that had "death wobble" and it is nothing like what my truck is doing. BTW... I do not advocate 100+ mph on 35s. Just making the point that it had been done before without this issue, so i know something is wrong.

 

[98_k1500]

The feeling is exactly like an improperly loaded (back heavy) trailer. Like a gentle push in the rear, getting more pronounced and aggressive until you reduce throttle.

 

[98_k1500]

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You can see my cali rake in this pic. I could clear 36s with this setup... And i still have the front valence under the bumper.