Wednesday, March 17, 2021

Rear trailing control arm upper mount replacement aka rust trap aka "mount pockets" aka slits

 

 Here is a vid of someone replacing their "trailing arm" or rear control arms. 

Fairly common to see a bit of rot on the outside of the frame just in front of the the front spring perch, right where the bracket is. the small slit that sort of lets water drain through gets clogged up and the dirt and wet stuff sits there and rots the frame from the outside in..

 Reach up in the inside of the pass side rail, right by the gas tank, and the fixed (front) hangar for the rear spring. That is where it goes first, because dirt gets stuck on the lip of the tank and sits right against the frame, and rots it out. I've seen many of them here that are too far gone.

 So from the other side it looks like this:

 And then on other side again - the lower "trailing arm" or rear control arm also goes into a frame mount.

 You can see on the right side - the open bolt hole where the mount is. He calls it a "little pocket...I'll probably spray some rust proofing...."

So then people get "new" mounts welded on - after they rust off. This is the left or driver's side.

20190604_190320.jpg Many places will not touch suspension mounting points.
IMG_2956.JPGIMG_2948.JPG
This place is in Cranston RI in specialize in frame repair

 https://gmtnation.com/forums/threads/got-my-rear-trailing-arm-mount-replaced.19923/

 the mount pockets of the upper control arms in back.
I own 3 TB... 02,03 and 05... ALL have required frame repairs in the area of the mounting pocket of the control arms.

 https://www.autorust.com/in-house-service/

Our unique service has helped 1000’s of customers get years of additional use from vehicles that looked ready for their final destination – the scrapyard.

 I might have to take a road trip out east. haha. I looked at the Trailing Arms - and I didn't see any major rust. So my "treatment" plus car washes - must have helped somewhat.

Still I need to scrutinize these pockets and spray some phosphoric acid - just to be sure.

So where are this "mounting pockets" on the frame precisely?

So the local mechanic said how rust accumulates in the chassis frame just in front of the rear wheels. I couldn't figure out what he meant - until NOW! He must have been talking about these "mount pockets" for the trailing arms!


So NOW we get a very CLEAR view of that "slit" or "mounting pocket" or "mount pocket" that's PART of the Chassis frame!! So right or passenger side.

In the front - these slide out as brackets.

So here is a rare vid of the Support Brackets being replaced in the front.

But if they rust out in the back - then you need to find a very creative mechanic or specialist.

OH I GET It - the "autorust" experts SELL a repair kit! Cool.


 Now I understand how that fits on the chassis.

OH so the Upper "mount pocket" is BEHIND the chassis - that's why you can't see it in their other image:

.  In order to reach the fastening hardware for the upper trailing arm mount, the factory put an access hole in the frame.  Consequently, this introduced an area for large quantities of dirt, mud, road salt and moisture to enter the frame.  Because there were no coinciding drain holes installed, everything collects inside, and creates a rust out condition, from the inside out.  Because the upper trailing arm mount is located on the inside of the frame rail, it’s very difficult to see the corrosive process, before it’s too late.  We also added a large drain hole, to help prevent a repeat problem in the future. 

OK so that's the left side or driver's side rear. So if you look really closely you can see the UPPER mount bracket sticking out from behind of the "new" repair weld kit.

right or Passenger rear upper "mount pocket."

So now for the driver's side - you can REALLY see the upper mount pocket on the chassis:

David Ortiz

Good video. But man , where my trailing arm goes to that chassis mount , that piece is Rotted out/broke and caused my control arm to snap. Do they make any aftermarket brackets??
1
That’s a typical spot for salt and mud to collect . I’m not sure if they sell brackets but they would likely sell since it’s a common issue. Might be able to fabricate something if you’re a good fabricator
1
 @MrJohn613 Budget Builds  yeah it's definitely a common issue on these .I found out the hard way 😂, but pretty much that's what I'll have to do. Fab up some steel brackets to replicate as best possible 💪🏽 thanks brother for you input 💪🏽💪🏽💪🏽

So again what do these "mount pockets" REALLY look like? see the bolts? Upper and lower for passenger side trailing arms. The upper trailing arm is blocked by the brake line. Still the Mount Pockets are very visible. Looks pretty hard to clean but I could definitely spray phosphoric acid up into those mound pocket slits.


https://gmtnation.com/forums/threads/got-my-rear-trailing-arm-mount-replaced.19923/

And someone DID get their SAME chassis fixed at the http://autorust.com

in Rhode Island! So cool. I'd like to drive out there.

  o

https://www.trailvoy.com/threads/frame-broken.211174/

It doesn't look that different - must have rusted in the BOttom of the "mount pocket" - so lost the strength. Oh it was not in the first photo - top is busted off:

 

https://gmtnation.com/forums/threads/both-upper-rear-control-arm-mounts-rusted-off.18647/

here's another good vid



















 

 

 

 

 

 

 

 

 

 

 

 

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