Shock and upper control arm contact

[Trynian]

I have been investigating the phenomenon for a while now ever since on member had a blowout due to the upper control arm digging a hole in the shock housing.

I first started to think it was from bushing wear and noticed the first nick on my passenger side shock a couple years ago. It only seemed to happen in extreme articulation situations and was very light at first.

This weekend I finally figured out why, at least on mine.

That shock was slowing getting nicked more and more when out wheeling and while out this past weekend it really started to make contact. I heard the very subtle scraping in certain situations so on inspected it was apparent that the arm was hitting pretty good now. I assumed it may be from bushing ware on the upper arms.

When back out on the pavement at speed I started to get a suspension fault as well. Reading the codes it was an out of range sensor fault on the same wheel as the nicked shock.

I pulled over to clear the fault and when the car was back a normal height I pulled the suspension fuses under the hood to keep the vehicle raised and drove home.

First thing I noticed when pulling the wheels off the front was that I had to raise the car higher to get the nicked shock wheel off then I did the other side. With the wheels off it was clear that the nicked side was articulating out much further than the other side, to the point that the arm was in full contact with the shock. I measured the distance to verify but still assumed it may have to do with the bushings or something else that had worn to allow the extra articulation.

So I swapped the shocks and the same symptoms now occurred on the opposite side complete with the same suspension fault now on the opposite side.

It turns out that something has slowly worn out in that shock to allow it to articulate more and more over time until the arm starts to hit the shock. An easy check is to jack the car up with both front wheels off the ground and see if they articulate down until the arm contacts the shock or if one is articulating more than the other.

I have a new shock on its way and will post more info after it is installed and I retest the articulation.

 

[Mack73]

Wow interesting finding. The droop limit is built into the shock. I wonder what material the stop is made out of. Guess it is wearing or deforming and therefore allowing the shock to extend further than normal.

Also how many miles on yours now?

 

[Houm_WA]

Ryan may have something to say about this conclusion. He got a new shock and it didn't take long at all before the new shock started getting ding'd...but if we find a common denominator and your theory grows legs, that's GREAT! That would tell us that when the shock starts getting ding'd, the LR3 is self-diagnosing and telling us that it's time for a new shock...

 

[Trynian]

Wow interesting finding. The droop limit is built into the shock. I wonder what material the stop is made out of. Guess it is wearing or deforming and therefore allowing the shock to extend further than normal.

Also how many miles on yours now?

Just over 75k, but with a lot of heavy offroad use as well.

 

[Trynian]

Ryan may have something to say about this conclusion. He got a new shock and it didn't take long at all before the new shock started getting ding'd...but if we find a common denominator and your theory grows legs, that's GREAT! That would tell us that when the shock starts getting ding'd, the LR3 is self-diagnosing and telling us that it's time for a new shock...

Yes, it could be it or a combination of things. It only seemed to occur on the same side and even after the all the bushings upper and lower were changed. I will know more once the new one comes in and I can take the old one apart and see if it is something in the upper part of the assembly or if it is down in the shock abssorber strut.

The parts guys that I get parts from told me that they have seen it in the air spring that can get unseated and allow the assembly to extend further then normal. I was not sure exactly how that worked but it may be more clear when I take the bad one apart.

I also may have to take a look at the new after market shocks someone posted recently.

 

[ryan-in-oregon]

The parts guys that I get parts from told me that they have seen it in the air spring that can get unseated and allow the assembly to extend further then normal. I was not sure exactly how that worked but it may be more clear when I take the bad one apart.

I took the old assembly apart (infact I still have it). As I recall the the air bladder bolted to the top of the shock piston and had a plate that it hooked to on the shock body. That being said I'm just not sure how the bladder portion of the assembly could cause the problem. The thing I would be interested in is how far the bilstein shock extends on the arnott units. If it is a bit shorter then stock I'd say that is the way to go. I also came to the same conclusion originally as you have on the problem be internal to the shock. Good Luck. Maybe I'll have to bolt some accessories back on and keep it if the real problem can be figured out!

BTW mine failed at 59k with just 15k miles of somewhat heavy offroad use. I'm now at 73k and there are signs of the problem happening again.

 

[blackforestham]

Good info Boys! Keep us posted.

 

[Trynian]

I took the old assembly apart (infact I still have it). As I recall the the air bladder bolted to the top of the shock piston and had a plate that it hooked to on the shock body. That being said I'm just not sure how the bladder portion of the assembly could cause the problem. The thing I would be interested in is how far the bilstein shock extends on the arnott units. If it is a bit shorter then stock I'd say that is the way to go. I also came to the same conclusion originally as you have on the problem be internal to the shock. Good Luck. Maybe I'll have to bolt some accessories back on and keep it if the real problem can be figured out!

BTW mine failed at 59k with just 15k miles of somewhat heavy offroad use. I'm now at 73k and there are signs of the problem happening again.

Looking at the diagram of the shock breakdown I can't really see where the failure could be in the airback either so my first assumption is that the internal stop in the shock itself may get worn to allow more articulation over time. It did occur on the passenger side that I tend to hit things harder due to visibility, that could play a part.

 

[ryan-in-oregon]

Was passenger side the first time and now again for me. I wouldn't say I have hit anything ******* that side not any harder then the driver side but who knows I am definitely curious as to what you find.

 

[Trynian]

Finally had a chance to replace the bad shock. First obervation when I started to test the new is that it was definately not traveling as far as the bad one. At full extension there was quite a bit of room between the shock and the upper control arm. I also changed the upper control as I noticed that the ball joint was fairly loose, the bushings were not bad, but figured I would get it done while I had it all opened up.

I also was able to see that the other original shock that is not bad yet extends more then the new one by almost and inch. So I plan to change that one also soon.

Side by side pressurized comparison between the bad and the new before I put the new one on showed the bad one would extend about 2 inches more than the new one. Takng the old one apart did not show anything since I couldn't disassemble the acrual strut. All I can figure is that over time something inside the shock wares out allowing over-extension. So I will take full extended measurements. Once a shock starts to extend about 1.5 inches more then it does new, it might be time to replace again.