Jack's 2007 Chevy Build
- Thread starter locrwln
- Start date
motrhed
Observer
Tuesday morning, I decided to add my new rear cab mounts. Owners complained of "beaming" with ex-cabs and crew-cab trucks, so GM designed some new rear cab mounts designed to help eliminate the problem. So for about $120 and with people reporting a much better ride, I wanted to give it a try. Took me about 30 minutes from the time I pulled it into the garage until I was done.
Stock bushing on the top with the new "improved" one on the bottom. Looking down on them, you can see a big difference.
Serious difference in shape.
Can't wait to give everything the test.
Jack
What do you mean by "beaming"? I have an '07 DMax Crew Cab Long Box that will groan when on uneven ground (particularly with the camper on). I always assumed that it was just frame flex / suspension noise.
locrwln
Expedition Leader
It is when the front and rear of the truck are moving at different frequencies. Especially noticeable on concrete freeways and when the truck is empty. My Ford is much, much worse. If you have any weight (approx. 500lbs) in the bed, it stops it. I have never felt it in my Ford when loaded, but it can make you a little ill if it goes on long enough. We drove the Pasadena Freeway one time in my Ford (empty) and by the time we got to our destination, we were both a little queasy. Mostly happens at 70 mph, if you go faster, is barely noticeable.
Having said that, I never felt it in the Chevy, but I had a pretty decent coupon from the place I ordered them from and I figured it couldn't hurt and after comparing them side by side, I was impressed. It did help with the vibrations that were noticeable with the rear extra cab doors.
""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.
-----------
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 ccomplete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
END.....
I believe the part numbers have changed, but that should give you an idea.
Jack
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locrwln
Expedition Leader
Redline
Likes to Drive and Ride
Experienced this many times, though have always referred to it and heard it referred to as freeway hop, but beaming sure makes sense. Largely a function of wheelbase, freeway design, and suspension.
http://www.youtube.com/watch?v=R8Ti5I-NJTM
Above is Dodge telling us how much better their 1/2 ton with rear coil suspension is better than GM or the Tundra, probably so.
Glad your Duramax is not bad in this area, I don't think the Tundra is bad either compared to my old Ford, but I haven't driven the Tundra very far yet, we shall see. Both our new trucks have much shorter wheelbases than our F350s, also more advanced suspension design.
bob91yj
Resident **************
I've never had an issue with this in my Dmax, but mine have always had something in the bed. My son's 04 F-150 was horrible in some sections. There is a particularly bad section on a local highway, he pulled over the first time he went through there thinking he had a flat!
locrwln
Expedition Leader
Got the last of the known "weak" links fixed on the Chevy today. GM's are known for the infamous "pump rub," which is when the oil pump ends up rubbing a hole in the rear portion of the transfer case. It of course leaks all of the fluid out and will destroy the t-case when it does (if not caught in time). Merchant Automotive makes a kit that replaces the factory oil pump housing which a much improved version that prevents the oil pump from rubbing through the housing. I figured since I was going to have the t-case out, I might as well add the t-case brace that MA sells. The brace mounts on top of the t-case and to the rear of the Allison. The rear housing of the Allison has been known to break when the truck is used aggressively offroad, while not extremely common, it can happen.
T-case on the work bench.
The little clip that eventually breaks and where the "rub through" occurs.
The rear portion of the case removed.
MA oil pump housing on the left and stock on the right. As you can see, the stock housing is shaped like a knife while the MA is much wider and every tab is like that.
New oil pump housing assembled and ready to back in the t-case.
Got t-case back in and everything buttoned up. Good news is that everything worked, all ranges engaged and dis-engaged correctly.
That should take care of most everything that could leave me stranded in the backcountry.
Jack
T-case on the work bench.
The little clip that eventually breaks and where the "rub through" occurs.
The rear portion of the case removed.
MA oil pump housing on the left and stock on the right. As you can see, the stock housing is shaped like a knife while the MA is much wider and every tab is like that.
New oil pump housing assembled and ready to back in the t-case.
Got t-case back in and everything buttoned up. Good news is that everything worked, all ranges engaged and dis-engaged correctly.
That should take care of most everything that could leave me stranded in the backcountry.
Jack
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locrwln
Expedition Leader
Forgot to add the platform that I built a month or so ago to replace the back seat. It's nice to have a flat platform to load things on. Plus I was able to mount some tie downs to secure everything.
The fridge is now in the camper, but I still use the tie downs to secure my tools.
Jack
The fridge is now in the camper, but I still use the tie downs to secure my tools.
Jack
HenryJ
Expedition Leader
Thanks so much for sharing this. I had no idea this solution was out there. I have fixed more than one of the "missing clip cases".
I'll likely add the MA upgrade to mine at some point. THX
spressomon
Expedition Leader
locrwln
Expedition Leader
Nice work Jack- be gone with you weak links
Thanks, I'm trying.
You're welcome, hope it helps.
Yeah, no kidding. Just jinxed myself, but at least I am trying to prevent the obvious ones. There can always be a sensor or some crap that will die in the most inopportune time.
Jack
24HOURSOFNEVADA
Expedition Leader
Nice job Jack. Looks like it's getting dialed in.
24HOURSOFNEVADA
Expedition Leader
Was this post sent from Alaska, or are you back?