Hey guys,
So when I was working on replacing some parts this winter I noticed some damage on a part and need help identifying it. I was thinking it has something to do with suspension but I am not sure. It looks like both sides this part is damaged, one side the cap looks to be missing.

 

thats called a bump-stop. It limits the lower A arm from going up too much when the suspension cycles upwards so you dont damage other stuff. Shouldnt be too expensive to replace.

 

It's actually an active part of the suspension of all torsion bar IFS vehicles.

They are not actually just "bump stops" they are progressive dampeners used as part of the entire front suspension on a GM IFS system. They bend and flex to give you better control and a softer ride. The Non-GM "bump stops" do not have the same progressive rate of compression/deflection in them and will exhibit different ride qualities.

You may notice that the LCA on the GM IFS seems to be resting on its upper bump stop. This is not only a bump stop, but what is called a progressive dampner. It compresses at a progressive rate, simulating a progressive rate spring, and letting the torsion bars achieve close to a progressive feel. Another con is as you increase the ride height by adjusting your keys, the ride gets worse. Now it’s a common misconception that there is more of a load on the bar and this is the cause. That is impossible since the LCA moves as well, so there is no more torsion on the bar than before, the spring rate does not actually change like many belive. The twisting action does not change the pre-load on the bar directly, so cranking your bars is just like adding a block in the rear or a coil spacer. It is simply changing the position of the spring. Just to clear things up, pre-load is the amount by which the torsion bar can't return to its original (unloaded) position due to be installed in the truck. The reason for the bad ride quality is instead a combination of things. First of all, when you adjust the height up, the angle between your LCA and the ground is increased which effectively does reduce your pre-load by reducing the leverage your LCAs have on your torsion bars. This negativly effects the ride by taking the torsion bars out of the preload range they were designed to work in. In combination with that, if you crank too far your UCAs have very little room left between them and the lower bump stops, reducing downward travel. You also pull the LCA away from the progressive dampner, making it ineffective and putting yourself back into the position of having a linear spring. These are the reasons the ride gets worse!

I hope this helps out with some of your questions.

 

You can order them online here, they are #7 on the diagram. You can also get the directly from any GM dealer regardless of make.

 

You can order them online here, they are #7 on the diagram. You can also get the directly from any GM dealer regardless of make.

FRAME. Fits: 2009 Hummer H3 | Nalley Buick GMC Brunswick

 

They are also very easy to change.

Just pry out the old ones using a large flat blade screwdriver or pry bar.

Lube up the new ones with soapy water and push them in.
DO NOT use oil or grease to lube them. You want the soapy water to dry afterwards and not remain slick.

 

Thanks much TAINTER ! are these the GM originals or after market? I thought you mentioned its better to get GM parts.

nm I do see its original

also thanks to Curtis and Bunger

 

Nice. Ideally, we learn something new every day! Thanks for the knowledge.

 

Does anyone have a link to how to replace these? I am a bit afraid to just take a screw driver to it not knowing exactly which part to yank off

 

Just yank the old rubber looking pieces out. I use hairspray as a lube to get the new ones in. You may need a flat head to push the last little end in too.