Gross Vehicle Weight Rating. What does GVWR mean? It is the maximum loaded weight of your vehicle (or trailer), as determined by the manufacturer. GVWR isn't just the weight of passengers and cargo but also the vehicle itself.
1/4 thick steel would safely hold 4000 pounds
So it would appear to be very over built. Someone stated their frame was swiss cheese but it did not break in half.
another shot of the frame for a Trailblazer or Envoy.
so this is the same frame I think.
The good news about lengthening the frame is that it is constructed in two halves. Theoretically, grind the circular and linear welds and slide the front frame section forward. The guy who delivered it said they take them apart routinely. The frame sections overlap about 4.5" so I could get 2 to 3 inches out of it and weld a plate or two on the outside for strength.
hmm. So it is double thick at the joints.
So there's what I got the Weld Plate done last summer! Amazing.
yeah looks like it's the same place where I had the Weld Plate done.
OH that's the REAR of the car - so the frame joint is farther back.
No it's right in the center of the length of the frame.
So right in the center between the two holes. I'll check again.
OK there's the weld plate on our frame - so it's not quite over the "joint" - it's a bit in front of the frame joint.
Interesting.
I wonder if that's why it rusted out - if the joint collects the moisture.
joints and cracks that allow water and debris to collect on steel support elements
So that's definitely a factor - and it's on the driver's side so there is more spray from passing cars.
Often, the corrosion occurs on the top, sides, and in the corners of the frame, where moisture-soaked debris collects—and it can be difficult to detect during an inspection.
So to restore an old frame - they soak it in hydrochloric acid overnight and this eats away and dissolves the rusted weak iron.
That's a 1965 frame though.
Importantly for boxed frame sections, the top seam of the rail is left un-welded so that the installer can more easily adjust its final fit.
The idea of Phosphoric Acid is NOT to "dissolve" the metal but rather to convert the rust to Iron. Ferric phosphate. It looks some strength since it's more brittle.
the dirt gets in all the frame factory holes and when water also gets in it(mud) rots the kick ups,,,rocker channells
So I'm not seeing any mud by using my inspection camera.
I'll go take another look to see if the PHosphoric acid has changed things since I last checked.
If you have a 98-03 Dodge chassis Van, do yourself a favor, and remove your bumper/brackets and check out the INSIDES of these forward frame sections. They are super easily accessible, and you might be surprised what you find. These guys most definitely are rusting inside out, and it can look good on the outside but be pretty badly corroded on the inside, and if your start seeing trouble on the outside it’s too late for sure.
yeah I have not done the FRONT of the box frame - under the engine.
I tried last year - I got some of it.
It seems a lot of work to remove the front bumper. I think I'll just spray the front frame with the Cosmoline. It should not rust as much due to the engine drying off the metal.
Also getting the car washed regularly as I do.
https://ck5.com/forums/threads/frame-thickness-thread.235499/
Wow so the chassis is only what?
All the measurements were taken on the right frame rail, in front of the front crossmember and behind the bumper.
There is some minor differences, I imagine it is the steel discrepencies.
1988 1/2 ton 2wd suburban -- .162
1981 4wd Blazer ------------- .164
But how thick now?
Hydroformed steel frame side rails form a strong foundation for the truck'
A stripped down frame:
another
Ok I'll take a closer look at that round cross tube in the back.
I sprayed phosphoric acid inside of it.
better look at the front
It just seems like a very overbuilt frame for sure. There's a lot of cross support pieces.
Built on an all-new, body-on-frame chassis platform, the 2002 TrailBlazer features the
industry’s first fully hydroformed steel frame side rails, designed to improve overall
strength and ride quality. The new frame dramatically increases torsional stiffness, which
assists the performance of all the suspension components. The ladder-type frame consists of
eight cross members — traditionally there are four to six in a vehicle of this size — to
ensure overall stiffness for improved ride comfort, handling and reduction of noise and
vibration. The frame’s cross members, which in some cases are supplemented with gussets for added strength and support, come in a variety of configurations. Hydro-mounts (donut-shaped powertrain mounts that are filled with hydraulic fluid) replace the traditional
solid-rubber bushings in many locations on the powertrain. This is said to provide maximum engine isolation to the frame, which in turn helps to achieve very low levels of engine noise and vibration.
https://www.wholesalegmpartsonline.com/showAssembly.aspx?ukey_assembly=396983&ukey_product=3109240
https://www.genuinegmparts.com/pdf/techinfo/frame-repair-procedures.pdf
So that's a 2002 Hydroformed Chevy frame.
The all-new 2002 Chevy TrailBlazer marked the first time hydroforming has been used for the entire length of a truck frame’s side rails.
maybe this is it.
our new boxed frame rails, constructed from 10-gauge (true 1/8”) sheet steel
well that's 1955 Chevy!
Remember most that posted did 1 ton frames which are thicker, his is a blazer and it's pretty much 1/8".
hmm. Seems thicker than this.
So the Silverado is high strength steel hydroformed box frame
TrailBlazer uses hydroformed steel frame side rails, which form a strong foundation for the truck’s overall strength and solid feel, even on unpaved surfaces. A double A-arm suspension is used in the front work with a system of 12 specially tuned body mounts using hydraulics and rubber pads to dramatically reduce vibration and harshness on any kind of road or trail. A thick stabilizer bar minimizes body roll.
The rear suspension features a solid axle with five-link location, with a stabilizer bar. A long, 113-inch (2,869 mm) wheelbase stretches between the wheels, enabling a smooth ride, particularly over choppy pavement or unpaved roads. A rack-and-pinion steering system responds quickly to driver inputs and delivers good feedback.
So they advertise the Silverado as "high strength steel" but do NOT say that for the Trailblazer...
the frame of the new trucks is fully boxed, while 80 percent is made from high-strength steel. But here’s where it gets interesting: the levels of high-strength steel in the 2019 Silverado frame vary from two to five millimeters in thickness, with every millimeter optimized for performance. This is done using a variety of processes, including hydroforming, roll forming, conventional stamping and tailor-rolled blanking. This approach enables frame sections, gauges, grades, processes and materials to strategically vary in order to maximize strength, durability and stiffness, without adding unnecessary scrappage, waste and mass.
hmm....
https://gmauthority.com/blog/2018/02/2019-silverado-frame-lighter-stronger-smarter/
It looks like the Trailblazer frame and is BASED on the Trailblazer frame - so must be the SAME type of steel.
The end result is that the 2019 Silverado frame is 88 pounds (40 kg) lighter than its predecessor, while offering 10 percent greater torsional rigidity.
Frames are an area where the hydroforming process has been used quite frequently. The advantage to using this process is primarily weight savings. A thinner wall material can be used without compromising the strength when compared to a welded box or C-channel. Another advantage is that a complex shape can be made with one piece of metal without having to weld multiple pieces of metal together. This enables the vehicle maker to build a frame with a modular design that is welded together.
OH I get it now - the previous "box frames" were welded together - right. Fascinating.
So that's why they were 1/8 inch thick or maybe 5 to 6 mm.
Previously, areas with a change in shape required joining pre-bent frame members together with GMA (MIG) welding. With hydroforming, this step is eliminated. Additional advantages include improved corrosion resistance due to fewer welded seams and greater predictability of how collision energy will be absorbed and transferred. When collapse zones are incorporated into the hydroformed part, engineers can better predict the rate the vehicle will collapse during a collision.
many hydroformed parts on full-frame assemblies have been made from mild steel, but applications of high-strength hydroformed steel (HSS) are becoming more common. HSS provides a stronger, more rigid vehicle while reducing the weight.
AH this is my question - I guess the Trailblazer is NOT "high-strength" steel? Just the Silverado? Or maybe they're both high-strength steel.
At the very least, the frame should be more difficult to pull, and frame parts will cost more than those used in a traditional mild steel frame because of the more advanced steel alloy.
https://www.genuinegmparts.com/pdf/techinfo/frame-repair-procedures.pdf
frame rails are pre-sleeved, mild steel, hydro-formed parts, which correlate ... Locate the two die-marks on the damaged frame rail. The die ... Utility is a mild, steel hydroformed frame assembly. A ... tool (1) square to surface to the vertical walls.
OK it's officially mild steel.
https://www.trailvoy.com/threads/06-trailblazer-rust-hole-in-frame.134353/
Was pissed gm will do nothing as this is form inside out and i looked in with inspection camera.
Oh he says it's by the catalytic converter. I will check now with the inspection camera.
They dropped the fuel tank and found severe rust-through on the frame and called me in today to discuss the situation. The service rep said I may be able to get a body shop to weld a plate over the holes, otherwise the frame will certain fail.
Yes I just treated the rust in between the fuel tank and the frame. I had the fuel tank replaced a few years ago and they never mentioned any holes...
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.
This high strength upper control arm mount comes ready to weld in with a genuine Clevite rubber bushing installed. Designed to fit all Dana axles
Full Center Frame Section w/Rear Trailing Arm Mounts
A control arm connects the wheel hub and steering knuckle to the frame of the vehicle. They are typically equipped with bushings on the frame side of the vehicle and a ball joint on the wheel side of the vehicle that allow flex and controlled movement according to road conditions and steering input from the driver. Control arms allow wheels to move up and down while preventing forward and rearward movement.
Reinforcing the front side of the axle where the upper control arms attach
where's that?
These control arms are called "trailing arms" or "rear trailing arms".
vid how to replace control arms or trailing arms
It's on the frame in the rear--- just behind the read drivers side door-
https://www.trailvoy.com/threads/help-rear-upper-control-arm-mount.93048/
Turned out both Upper Control Arms had rusted and broke completely off at the bolts allowing the axle to just float.
https://www.trailvoy.com/threads/rear-upper-control-arms.194889/
- just behind the rear drivers side door
Heard a clunking noise and it really started getting loud as I reversed out of my driveway over the curb. I saw that BOTH of the Upper control arms had snapped in half at exactly the same place! When I removed the drivers side arm, the inside of the frame looked like swiss cheese. Very rotted out. And the plastic gas tank is on the other side of the frame, so welding a patch onto the frame just got more expensive
https://gbodyforum.com/threads/rear-framerail-reinforcement.66788/
OK I'm gonna look - they must have seen my JB Weld of the steel wire brush - that I welded on as a joke - on rust. Oops. That must be why the local mechanic refused to work on the car - after he replaced the rusted out gas tank filler tube...
oops.
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.
https://forum.ih8mud.com/threads/frame-rust-opinions-requested.801210/
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.. Mine has a little bit there and a welded patch was all that was required.
The bottom spring perch is supposed to be up on the strut.
rear spring perches
I had my rear control arm's break from rust and the control arm mounts rust out and the doors will rust from the inside out
I'd check by going on the frame with a pick-hammer and see if those tiny holes aren't actually bigger. Coating the frame just on the one side may just slow it down a little as it will continue to rust from inside out.
https://gmtnation.com/forums/threads/frame-rust-weld-issue.17729/
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