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...This talk about full frame..vs integrated frame to the body pan(some suv's)...vs uni-body, takes me back many years . When I was involved in drag racing back in the 70's-80's..pony cars(Mustangs, Mopars, Camaros, AMC) for the most part had two sub frames tied together via the body pan. Cars that did not get modified with sub frame connectors and were refitted with more powerful engines often developed a slight body twist that tweaked the front and back portions of the car out of alignment with each other.
I remember reading about a modification to Chrysler intermediate bodies where the front & rear sub frames were tied together. Unfortunately, this modification went right through the rear footwells. Great for drag racing, but not so great for passenger vehicles.
Back in the Ford Crown Victoria days, police departments loved these vehicles because they were so easy to repair body damage, among other mechanical things.
Does the truck/body on frame construction style of a vehicle still result in lower body damage and less likely to get totaled by an insurance company? These days, Teslas and many expensive ICE vehicles just get totaled than trying to repair and that's even for MINOR fender benders!
There are plenty of pickups, but also SUVs that are still body on frame construction - are they better in this regard?
Your post is based on multiple inaccurate assumptions.
How about you at least touch on the inaccuracies by the OP and inform all of us rather than just making a statement and leaving? I’ve read in the past that police departments liked the Ford Crown Victoria due to the body on frame and easy to repair body panels.
I'm not going to state the obvious, but the mythology surrounding body-on-frame vehicle construction is prodigious. The old-school thinking embraced by body-on-frame advocates is almost as misguided as the thinking that leads the same geezers to proclaim that 4WD is superior to AWD.
Does the truck/body on frame construction style of a vehicle still result in lower body damage and less likely to get totaled by an insurance company? These days, Teslas and many expensive ICE vehicles just get totaled than trying to repair and that's even for MINOR fender benders!
I don't think this has to do with frame construction. It's all the electronic gizmos like cameras and various sensors that are present around the perimeter of these cars. Now, in a light collision you don't just dent a bumper or break a taillight, you break hundreds or thousands of dollars worth of electronics.
How about you at least touch on the inaccuracies by the OP and inform all of us rather than just making a statement and leaving? I’ve read in the past that police departments liked the Ford Crown Victoria due to the body on frame and easy to repair body panels.
Body on frame wasn't the reason that Police liked the CV. It was liked because the platform, known as the Panther, had been about since 1979 virtually unchanged ,making it easy to reuse equipment from year to year and it was big. Also, it was cheap to buy, cheap to operate, and cheap to repair.
I don't think this has to do with frame construction. It's all the electronic gizmos like cameras and various sensors that are present around the perimeter of these cars. Now, in a light collision you don't just dent a bumper or break a taillight, you break hundreds or thousands of dollars worth of electronics.
That's a lot of it. An airbag deploying totals many cars that don't have much other damage. Happened to me with a Taurus, the body damage was minimal but the airbag totaled the car.
A hit to a frame rig will result in more damage than to a uni-body.
Steel frames are rigid and heavy so they don't dissipate energy efficiently. A unibody is engineered to absorb the same energy and has crush zones and is much lighter than a frame rig. There's a lot of 'give' in a well designed uni-body - they're more elastic.
To give a visual:
A frame rig is like dropping a heavy wooden crate on the floor. A uni-body is more like dropping an empty milk crate.
Frame rigs are a PITA and they need heavier pulls to straighten them out. The ladder frames on pick-up trucks in particular are very 'springy' and need a lot of tension and massaging to get the stress out of them. You'll put 5,000 lbs of weight on the hydraulic pump and spend 2 hours plus beating on the frame with a sledgehammer to work the stress out. That's after you spend 2 hours chaining the thing to the frame bench so it holds still. If it isn't well anchored you'll just pull it all over the frame rack.
A lot of times a steel frame is so messed up it isn't worth fixing so a new frame will be ordered and it'll be a frame swap. Very spendy repair with 60 plus hours of labor, body shop side alone. Takes up a sh*t-ton of space in the shop too. Swapping the cab, box, drivetrain, suspension, wiring, exhaust, plumbing etc. G*d*mmit I hated those jobs! Generally, it takes a more experienced tech to get a frame vehicle back in shape.
A uni-body is much easier and doesn't take as strenuous a pull. 1500 lbs on the pump (and an untwisted chain) and some lighter taps with a smaller/lighter hammer to vibrate the stress out and it's good as new. If fact, if you go much more than that you'll start to tear stuff and damage the rocker panels at the clamping points.
It's been over 20 years since I've been on a frame rack, but I was a heavy hit guy for at least 10. My employer even sent me to Kansas Jack training in Wisconsin when we got the hot new laser measuring system, so I have thousands of hours on a frame rack.
From a repair point-of-view, I think they should outlaw steel frame rigs because they suck to work on.
Your post is based on multiple inaccurate assumptions.
how so? Id tend to agree with every word he typed.
One general thing tho "once bent, always bent" once a metal structure is bent from its state 'A' shape, the grains are changed such that unless you RE-form the structure with great heat and pressure, it will now tend to easily goto state 'B', from its repaired state "A' " or A-prime (its a mettalurgy thing)
they came up with some cool tooling in the late 90s called surprisingly - frame straighteners - that restore it close, but next time a much less energetic tap returns to the wreck condition.
Since the unibody was invented, the ENTIRE body is part of the occupant safety system and its role is to sacrifice itself in a predictable fashion to deflect energy from the people inside. That is why certain types of hits are non repairable in any economic sense and the co-part yard is full of good parts only slightly higher than retail (<-----only partially facetious)
can you cut part of the unit structure from a rear damaged car and weld it to the front of a front damaged car? sure, but my god the work, since its boxed and lipped everywhere you are never going to get all the welds in place.
AND, since cars have exactly zero corrosion protection anymore, once they get soft inside, they are oft junk, while still under the loan such that a crash is going to do some big boy damage and you cant weld to rust.
ps: rusting is oxidation, and aluminum rusts EASIER than steel, it just 'rusts' (oxidizes) differently. hence the new move to goto road acid (calcium chloride) actually leaves aluminum alone and the Al2O3 on the surface actually acts as an inhibitor. But this puts onus on the manus to completely totally isolate in any way electrical the iron, steel or copper from the AL body, which is why the ground straps disappear quickly and the electronic gizmos go batsh*** in an otherwise perfect looking AL body.
How about you at least touch on the inaccuracies by the OP and inform all of us rather than just making a statement and leaving? I’ve read in the past that police departments liked the Ford Crown Victoria due to the body on frame and easy to repair body panels.
There was real steel to mount the push bars to, so they could pit john scofflaw without totaling the cruiser.
The old-school thinking embraced by body-on-frame advocates is almost as misguided as the thinking that leads the same geezers to proclaim that 4WD is superior to AWD.
well Im a geezer and this is at best misleading. It depends on the sitch.
If the task is to encounter and survive a bad highway condition because the driver is too busy on the cell phone posting to web sites to slow the frig down, then sure, todays AWD which really ISNT, would be superior as it will react, cut power, vector torque, pump individual wheels etc.
but if you are in slippy snow or mud, AWD generally will do nothing but hum thru the torque converter as the engine wont go over 800rpm and the car wont move. whereas the 4wd is mechanically linked and all traction and therefore motion is based off the tire grip to the surface (i.e. read my old J4000 with front and rear traction lok D44s and the spicer xfer case - if you have the raw engine power - and it did, you could spin all 4 wheels free, at that point no 'anything-WD' is getting you out short of a come-a-long)
when you select a ride and its safety feature is an 'ELD' - electronically locking diff, then it means you have an open diff, just like a 1970 base model buick skylark and it will stop spinning wheels by pumping a brake and retarding engine power, which as we discussed, completely immobilizes the vehicle if both wheels are in muck. This is far preferred today to dovetail with the complete lack of driving ability the current non-geezer population has.
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