A topic for MYTH BUSTERS: Opening doors, hood, etc "to prevent damage when lifting?

[Paul Workman]

I first ran into this practice a couple years or so ago at a local Discount Tire store.

The short of it was that a corporate directive was at play, and the directive (according to the manager) required they open the hood, doors, etc before jacking or lifting the car. I was required to sign a waiver before they'd lift the car if I didn't allow them to open the panels. I signed it: of course the car didn't disintegrate before our very eyes as result:rolleyes:

As a suggestion, and maybe an article for our Club's HOTB magazine, would there be anyone who'd like to research and get to the bottom of this "precautionary procedure"?

It might be fun!

.

[secondchance]

Doors on my 79 Trans Am would get wedged and wouldn’t open after the car being lifted.

[Ccmano]

Yes! Probably the #1 C4 myth.... I have lifted many C4’s without an issue. Can’t say I have ever even heard of a problem as a result of lifting. You would think it would be in the owners manual, FSM(not in my 90’ anyway) or in a TSB, I’m not aware of any.

The only thing I have seen is damage to the hood and doors when closing the hood with the doors open.
H
:cheers:

[Paul Workman]

Doors on my 79 Trans Am would get wedged and wouldn’t open after the car being lifted.

On two occations I accidently drove my 95 LT1 car over the end of a pair of wheel ramps. The car crashes down onto the ramps, landimg on the frame just behind the front tires. If somthing was going to "pop" I'd say those were the times when it might happen...BUT DIDN'T! (After the 2nd time I left those ramps on the curb. In an hour they were someone else's problem, and good riddance!

[efnfast]

I would think the car would be stronger and stiffer with all the doors and windows closed?????

[ghlkal]

I would think the car would be stronger and stiffer with all the doors and windows closed?????


Yeah. I've often heard to make sure the hood and doors were _closed_ before lifting.



I wonder if it really makes any difference.



Good idea, Paul, someone needs to investigate this and write it up.

[32valvesftw]

I thought one of the concerns is that is that some stress / flex in the frame may get transferred to the top and crack it. That said I have jacked mine up a number of times and always keep the doors and hatch closed with no ill effects.
I think the Engineering needed to PROVE this is quite complicated and would require a Finite Element Analysis and a bunch of 3D CAD work. However if some one has some strain gauges laying around, I'd be willing to experiment by putting some strain gauges on the frame and other places to see what kind of readings you get when jacking the car up both ways doors and hatch open as well as closed.

[efnfast]

On two occations I accidently drove my 95 LT1 car over the end of a pair of wheel ramps. The car crashes down onto the ramps, landimg on the frame just behind the front tires. If somthing was going to "pop" I'd say those were the times when it might happen...BUT DIDN'T! (After the 2nd time I left those ramps on the curb. In an hour they were someone else's problem, and good riddance!
Um, twice Paul?

[32valvZ]

Well, I just dismount my wheels/tires and bring them to the shop for new skins, then bring them home and mount them myself. That said, I never open the doors, hood or anything else.... Ive not had a problem with any of the 5 C4's I've owned.

[Tripler]

Been lifting the Z up on the Quick Jack with everything closed , then open and close everything with no issues that I can see . Only creaking I hear are the wheels sliding while lifting .
If you saw our driveway grade you would see the huge twist test our car gets when backing out . I have seen no issues with the car finish .
Would the owners manual have a say in this ?

;)

[Dynomite]

I first ran into this practice a couple years or so ago at a local Discount Tire store.

The short of it was that a corporate directive was at play, and the directive (according to the manager) required they open the hood, doors, etc before jacking or lifting the car.

I suspect the thought was that closed doors and closed hoods could be damaged trying to hold the frame in position when lifting on a corner.

BUT...….It is the windshield that is the issue (with the top on) and closed hoods and closed doors help the windshield from taking stress and cracking. The key is......never lift the ZR1 on a corner only...…...Lift from the Front center plate underneath or under the cross spring in the rear and then use jackstands. If you have to lift from the corner, only lift to get the wheel off the ground.

Some guys need instructions...…...I had a tire installation once with the guy placing a jack under the rocker panel cover (fiberglass) cracking the rocker panel just before I said NO :p

[DRM500RUBYZR-1]

Back in 93 I encountered a tire shop that insisted on opening the doors just enough to clear the jamb lock, before raising the car on the lift.
Their clear and stated concern was cracking the top.
I let them do it, but observed how the rest of the car "drooped" at each end as it left the ground, and how the space at the upper door area expanded, then closed up when returned to the ground.
After observing that, I never again, to this day, raise a C-4 with doors open.
The car is far more rigid with top on and doors closed than it is otherwise, at least empirically.
I also know the change in my cars behavior when the top is removed, which also confirms my decision to keep the car as rigid as possible when raising it off of the ground.
I am no engineer, but it is very easy to visually observe how the car reacts when the designed in rigidity is reduced.
The top, while expensive, is less important to me than stressing the entire car, although I have never had a c-4 top crack during lifting.
So, myth or fact, absent factual information to the contrary, I will keep all C-4's closed when lifting.
Marty

[dredgeguy]

Back in 93 I encountered a tire shop that insisted on opening the doors just enough to clear the jamb lock, before raising the car on the lift.
Their clear and stated concern was cracking the top.
I let them do it, but observed how the rest of the car "drooped" at each end as it left the ground, and how the space at the upper door area expanded, then closed up when returned to the ground.
After observing that, I never again, to this day, raise a C-4 with doors open.
The car is far more rigid with top on and doors closed than it is otherwise, at least empirically.
I also know the change in my cars behavior when the top is removed, which also confirms my decision to keep the car as rigid as possible when raising it off of the ground.
I am no engineer, but it is very easy to visually observe how the car reacts when the designed in rigidity is reduced.
The top, while expensive, is less important to me than stressing the entire car, although I have never had a c-4 top crack during lifting.
So, myth or fact, absent factual information to the contrary, I will keep all C-4's closed when lifting.
Marty
Hi Marty and greeting from lovely Dhaka, Bangladesh (yup I'm back here until the end of the month). Tell me that was not 246!:handshak:

[Mystic ZR-1]

Charlie
I’ve said it before, you get to visit the places the rest of us can only dream about! :)

[FU]

Um, twice Paul?

Paul likes doing things twice :handshak:

[Z51JEFF]

When I have the car on a jack the door will hit the striker in the jamb not quite right and the hood won’t line up to close so I’m always mindful of these issues when the car is on a jack.

[efnfast]

I tried to reinstall my roof one day while on unlevel surface. Wouldn't go, so they twist.
Anybody know GM's take on this? Owners manual? FSM?

[Paul Workman]

Um, twice Paul?

Yeah.... I enjoyed the heart-stopping panic that ensued so much that I had to try it one more time for the thrill of it!

Once: be careful next time...

Twice!??: F'k these pieces of crap!

I went to Harbor Freight and bought a pair of floor jacks and sturdy stands - like I saw Mark Haibeck using and never looked back! (Thinking now maybe a LIFT might be the way (especially for old bones) to go. BUT! I STILL AIN'T GONNA OPEN NO DOORS, HOOD, HATCH, TOP, ASHTRAY AND CONSOLE LID to prevent cracking something! (Sheesh...)

[DRM500RUBYZR-1]

Hi Marty and greeting from lovely Dhaka, Bangladesh (yup I'm back here until the end of the month). Tell me that was not 246!:handshak:



uhmmmm, wellll,,,,,,,,,,,,,,uhhmmm,
OK
it wasn't our car...……………………….


Wait a minute, ahhhhhh………………………………. Charlie...………..


Yes, it was our car darn it!


After seeing that I never did it that way again.
That shop just did not want the liability of cracking the top.


BTW, we lifted a 78 Trans AM, and thought both front and back were going to break off from the middle so it's not only our C-4's that T Top car made ours look rigid.
Marty

[DRM500RUBYZR-1]

I tried to reinstall my roof one day while on unlevel surface. Wouldn't go, so they twist.
Anybody know GM's take on this? Owners manual? FSM?



The first time that happened to me on Ruby, I was shocked that no matter what sequence I tried, I could not get all four top bolts to start until I pulled the car back from the raised area below the one front tire.


And no, the 18,000 mile car never was in an accident as someone once theorized incorrectly.


I have always joked even on this forum how when I drive the car on the Boardwalk in Ocean City NJ for the annual show, if the top is off, I can actually see each corner moving in independent directions. it's subtle, but it is there.


So that top and the doors are integral to keeping the car rigid, or at least more so than it is if they are not all interlocked.


Marty

[secondchance]

BTW, we lifted a 78 Trans AM, and thought both front and back were going to break off from the middle so it's not only our C-4's that T Top car made ours look rigid.
Marty

Marty,

My 79 was not even a T-top car. Solid roof and it would droop like a twizzler. I believe it was the front sub-frame.
With C4, especially early C4s (I had a 84 Z51 so I know...) main concern was targa top cracking. My concern always was damage to hood latch (or jamming) and damages to door lock mechanism.
In 2012 I went to Midas to loosen and adjust OBX exhaust so the exhaust tips would be parallel and line up. The "mechanic" used "U" shaped depressed area of the sheet metal floor pan (right under the back of the seat) as rear lift point and dented the floor pan. When I ordered him to lower the car and showed him the damage he had caused, he got all upset and reported me to his manager for condescending behavior!
I had a body shop repair the damage (body work and paint) and Midas paid for it.
Since then, only time my Z goes on any lift is at WAZOO garages.

[DRM500RUBYZR-1]

Yeah.... I enjoyed the heart-stopping panic that ensued so much that I had to try it one more time for the thrill of it!

Once: be careful next time...

Twice!??: F'k these pieces of crap!

I went to Harbor Freight and bought a pair of floor jacks and sturdy stands - like I saw Mark Haibeck using and never looked back! (Thinking now maybe a LIFT might be the way (especially for old bones) to go. BUT! I STILL AIN'T GONNA OPEN NO DOORS, HOOD, HATCH, TOP, ASHTRAY AND CONSOLE LID to prevent cracking something! (Sheesh...)



Now that's funny!
Marty

[dredgeguy]

Since Marty "broke" my car in years ago, I had to find a solution. I had the no flex frame stiffener installed and it fixed most if not all the flex issues. The car feels solid with the top off or on.