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Finally got around to replacing the updated rear cab mounts that I've had sitting in the garage last night. First drive with them this morning was totally different. Can't believe how much smoother the ride was, bumps that would jar your teeth, vibration between 45-55mph was completely gone. Rides amazing. Not really the reason I'm posting this, the real reason is the other body mounts on the cab. The ones in front of them were completely loose! I could turn the bolts by hand, one was about to fall out any time. I torqued them back down. Just wanted everyone to make sure to check theirs as I would never imagine the bolts would have backed out. Glad I checked it. Chris
 

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What mounts did you use? I have been shopping around. What would you suggest?
 

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The NBS truck may a;lready have these mounts--

""GM Campaign #PIT3009J: Suspension Vibration Or Frame Beaming At 40-60 MPH (64-80KM/H) - keywords front rear shake shock spring tire - (Sept 18,2008)""


Condition/Concern:

Beam shake vibration is usually felt and occurring at speeds between 40-50 mph (64-80 km/h). Hertz readings using an EVA tool are normally bewtween 8-24 HZ. This condition is most common on extended cab and crew cab models but has also been noted in other models.

Recommendation/Instructions:

The severity of the beam shake may vary from vehicle to vehicle. To determine if the concern is beam shake, please perform the following:

1. Test drive vehicle to confirm the condition. A beam shake condition will usually respond to concrete type pavements more than asphalt, so the vehicle should be driven over both surfaces if possible.

2. Place 200-500 pounds in the pickup bed between the closed tailgate and the wheel wells. A beaming condition should dissipate.



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If the concern is determined to be beam shake, this a characteristic of the vehicle. GM Engineering has released updated body mounts to reduce this concern for the Crew and Extended Cab Models. There will be no changes made to the Regular Cab Models.

FOR CREW AND EXTENDED CAB MODELS, REPLACE THE REAR CAB MOUNTS WITH UPDATED PARTS LISTED BELOW. THESE PARTS SHOULD NOT BE USED ON REGULAR CAB MODELS.

New upper and lower mounts should be installed at the left and right rear cab position. The new LOWER mount is a two-piece design, meaning there is a rubber mount with a metal washer. Some models may use a one piece lower mount, meaning the rubber mount has a metal washer molded into it. If the vehicle has the one-piece lower mount design, washers (PN 15854745, Qty 2) will be needed to be used with the new lower mount.

Upper Mount 25791031 Qty 2

Lower Mount 25791032 Qty 2

Washer 15854745 Qty 2 (if needed)

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
 

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What mounts did you use? I have been shopping around. What would you suggest?
GM Parts Direct

25994881 - CUSHION

GM PART # 25994881
CATEGORY: All
PACK QTY: 1
CORE CHARGE: $0.00



List Price: $71.21
Price: $45.71
You Save: $25.50 (36%)
 
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Man, I'm glad I found this post. Havn't double checked with weight in the back but I get a bad bounce in the front between 45-50 mph.
 

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So, I'm confused about this. I've read that our trucks (LMM and newer) should already have the updated mounts, but mine rides like s!!t and I have the weird bounce. How can I confirm that I need them?
 

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I think the 2010 models all had the improved mounts. Earlier years did not. They are a huge improvement in ride quality.
 

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I need to look into this to. Thanks for the info.
 

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Guys, just like the OP, I changed the cab mounts on my LMM and it made a world of difference. Money well spent. Got the mounts from GM Parts Direct. Here is a pic of my old mounts. Notice that the one on the left did not have the rubber attached all the way around the mount.
 

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Agreed, thanks much for the info. My truck rides much better with some weight in the bed, hoping these help.
 

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So, I'm confused about this. I've read that our trucks (LMM and newer) should already have the updated mounts, but mine rides like s!!t and I have the weird bounce. How can I confirm that I need them?
JB, my LMM did not come with the "improved" cab mounts. If you will look at my previous post picture, to give you an idea, the "improved" mounts are at least 50% bigger than the original mounts. The only true way to know if yours have the newer mounts or not is to get under the truck and look. Believe me, the new ones are MUCH bigger with an improved design than the original ones that came on my truck. Here is a pic of my right side mount. This should give you an idea of what you are looking for. Notice how much rubber sticks out from the mount.
 

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I think i need to order some of these... *sigh*

What exactly needs to be ordered? Only QTY (2) of PN 25994881?
 

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I think i need to order some of these... *sigh*

What exactly needs to be ordered? Only QTY (2) of PN 25994881?
I got the following from GMPD:

(2) 25994881 - Upper Cushion - $46.99/ea
(2) 25791032 - Lower Cushion - $32.34/ea

I chose the get the lower mounts as well, but most people just get the new upper mount and have great results. The new lower mount does have a different durometer rating than the factory piece, so I chose to get it. There is also a third PN that is a washer, but I live in the south so I did not get those because I will reuse my own. If you have a rusty truck, I would get the washers as well.
 
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