Chevy 'crump' update

[2x4]

Took Chevy 2009 Suburban to long-time trusted front-end shop. They jacked it up & did all the front-end recommended tests & found nothing wrong! We double checked but all is good, much to my relief but they had never heard of the complaint that it would shift or 'crump' ( my expression of the feeling) before. Long experienced driver here so I'm not mistaken but it's apparently not serious. Maybe its designed to do that?

 

[Janicholson]

Took Chevy 2009 Suburban to long-time trusted front-end shop. They jacked it up & did all the front-end recommended tests & found nothing wrong! We double checked but all is good, much to my relief but they had never heard of the complaint that it would shift or 'crump' ( my expression of the feeling) before. Long experienced driver here so I'm not mistaken but it's apparently not serious. Maybe its designed to do that?

The reality might be dangerous even if tests were made. Did you take them for a drive and demonstrate the "crump"? if not do that. Some stressed/cracked frame members make noise when the body and frame are stressed in ways not found in static testing and prying. A body to subframe connection, or hidden failure of a stressed member is a nasty surprise. Jim

 

[Mule Meat]

Never heard of 'crump' when it concerns a suspension system.

Did they check the spring cushions or for bad shocks? Loose steering box, idler arm bracket? What about the rear control arm bushings and shocks?

 

[used red MN]

Now that you (and us) have been reasonably assured that there is no major suspension wear problems look at “Ackerman Angle” in section 8 in the attached.
Alignment info
These angles are calculated by the design engineers and incorporated into the chassis suspension. For acceptable tire wear these tolerances need to be followed quite stringently up through a certain amount of steering angle. Just as a rough example any angle you would sharply steer to at 25 mph or more up to the point that you or your passengers would be dislodged from your seat if you didn’t have a seat belt on could fall within the stringent requirement. So in other words the adjustment for Ackerman Angles are made by the suspension very closely at the steering angles used during most road travel. Again just for example at steering angles beyond that the tolerance between the calculated Ackerman Angles and what the steering knuckle and tie rod geometry provide in actuality during a tighter turn may drift apart. In layman’s terms, so most can understand the toe-in/toe-out becomes out of adjustment in a tighter turn. So one wheel will begins to scrub or slightly slide sideways, during a short turn. Sometimes when vehicles make short turns the tires may leave faint black marking on pavement this is what causes that. The reaction of the vehicle from this may be what you are feeling. The lesser concern for proper Ackerman Angles at higher steering angles is because your vehicle travels very minimal distances at high steering angles like that so the extra wear to tires is not really a consideration over the tread life of the tire. The manufacturer knows you probably aren’t going to lock the wheels and drive in circles for a 1/2 mile on the odometer. Do you have aftermarket wheels on it? If so and they are a different offset than the stock wheels this will change the Ackerman angles.
I not saying this is definitely what you are experiencing, I am just saying it is a possibility. Also per your description I don’t think you are at full steering angle lock when you experience this. In steering lock the contact between stops of the lower control arm and the steering knuckle places limits on suspension travel. So in this situation the suspension may react abnormally especially if the vehicle is traveling over an uneven area.
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BTW, in this new software if you would have went back and added this to your first post all the information would be together. The majority of members would see it come up as and updated post and would have gotten the update as well. Only those who turn on those goofy filters would have missed it. My apologies if you are one that chooses to do that. It is up to you to post however you like.

 

[rustred]

you fail to tell us what size tires u have on it. are they the factory size or bigger? oversize tires will make a noise when turning sharp as i have experienced that.

 

[sotxbill]

Took Chevy 2009 Suburban to long-time trusted front-end shop. They jacked it up & did all the front-end recommended tests & found nothing wrong! We double checked but all is good, much to my relief but they had never heard of the complaint that it would shift or 'crump' ( my expression of the feeling) before. Long experienced driver here so I'm not mistaken but it's apparently not serious. Maybe its designed to do that?

I hav3e had problems when running hard "truck" tires.. when hitting bumps, one tire looses traction, and the toe-in makes the other tire "shift" the car sideways, in a violent manner. In those cases. on several vehicles,,, changing tires to a softer tire fixed the violent "shift" problem. Dont know if this will help you or not. Look at your front tires, and the air pressure also.

 

[Brown David]

What is "crump"?

 

[DoubleO7]

Took Chevy 2009 Suburban to long-time trusted front-end shop. They jacked it up & did all the front-end recommended tests & found nothing wrong! We double checked but all is good, much to my relief but they had never heard of the complaint that it would shift or 'crump' ( my expression of the feeling) before. Long experienced driver here so I'm not mistaken but it's apparently not serious. Maybe its designed to do that?

Take it to a vacant parking lot and put it thru some maneuvers to replicate the phenomena.

And maybe...
Check your seat.

 

[used red MN]

What is "crump"?

Helen Crump was the school teacher on AGS! Not trying to downplay the concerns of the safety of his vehicle in any way.
According to its actual definition, it refers more to a sound than an actual felt motion.

 

[jwal10]

Does it have a sway bar? My HHR has "plastic" bushings that seem to "stick". Some times when turning or going over steeper angles into parking lots it will feel like the steering shifts sideways and makes a noise. Have been assured it is just the bushings "letting go". One mechanic said he has used some kind of lube that helps keep the noise down. I know new bushings come with some kind of "grease"....James

 

[2x4]

you fail to tell us what size tires u have on it. are they the factory size or bigger? oversize tires will make a noise when turning sharp as i have experienced that.

factory LT 235-75/65-16

 

[2x4]

Helen Crump was the school teacher on AGS! Not trying to downplay the concerns of the safety of his vehicle in any way.
According to its actual definition, it refers more to a sound than an actual felt motion.

don't hear any sound because I'm near deaf but can sure feel the motion.

 

[2x4]

Does it have a sway bar? My HHR has "plastic" bushings that seem to "stick". Some times when turning or going over steeper angles into parking lots it will feel like the steering shifts sideways and makes a noise. Have been assured it is just the bushings "letting go". One mechanic said he has used some kind of lube that helps keep the noise down. I know new bushings come with some kind of "grease"....James

torsion bar

 

[DoubleO7]

torsion bar

There should have a factory sway bar also.
Torsion bar replaces what coil springs do, sway bar reduces body roll when turning.

 

[kencombs]

The reality might be dangerous even if tests were made. Did you take them for a drive and demonstrate the "crump"? if not do that. Some stressed/cracked frame members make noise when the body and frame are stressed in ways not found in static testing and prying. A body to subframe connection, or hidden failure of a stressed member is a nasty surprise. Jim

Excellent suggestion. A visual exam looking for a 'felt' issue is not the best fault isolation technique.

 

[Hobo,NC]

Took Chevy 2009 Suburban to long-time trusted front-end shop. They jacked it up & did all the front-end recommended tests & found nothing wrong! We double checked but all is good, much to my relief but they had never heard of the complaint that it would shift or 'crump' ( my expression of the feeling) before. Long experienced driver here so I'm not mistaken but it's apparently not serious. Maybe its designed to do that?

I have had to put ball joints in them at 75K so nuttin will surprise me on a GM. Another common issue is broke engine mounts they normally show up on acceleration and can be a violent bump. Something I have not ran across in awhile showed up last week on a 2012 F150, the driveshaft slip yoke is binding. I have seen that mostly on chebbys.

 

[Mark-Ia]

On my 2000 Silverado, the rear mount for the torsion bar rusted away and would make a thump when turning or going over a bump.

 

[Hobo,NC]

I have had to put ball joints in them at 75K so nuttin will surprise me on a GM. Another common issue is broke engine mounts they normally show up on acceleration and can be a violent bump. Something I have not ran across in awhile showed up last week on a 2012 F150, the driveshaft slip yoke is binding. I have seen that mostly on chebbys.

And Ford cap mounts issues, they have been making vehicles for over 100 years and ford figgers out how to muck that up.

 

[RBnSC]

How about a wheel bearing? Our 2004 Tahoe made a rumbling sound when turning left. Bad wheel bearing.

 

[NDIHC]

We recently had a car in the shop that would make a crunching noise that you could hear coming from the left front, and could also feel in the floorboards. The car was the same as new, only a couple hundred miles on it. It turned out that there was a stray nut wedged between the lower control arm and subframe. It wasn't visible during a visual inspection, but since we were sure the noise was from that corner, we unbolted the lower control arm and the nut fell out. The nut appeared to be an upper strut mounting nut and was probably there from the factory. I've found things like bolts and nuts or rocks that got flung up into suspension parts and make noise when the suspension would move.