Opening Door while on jackstand. Safe?
01-28-2014, 02:35 PM
#1
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Opening Door while on jackstand. Safe?
So I've been hearing conflicting opinions from people about opening up a door while a unibody is on 1 jackstand. How it can bend the frame and mess it up, etc. Is this true? and how bad can the damage be? I did some searching on the interwebz, I couldn't really find anything.
01-28-2014, 02:51 PM
#2
The RX8 chassis is rather stiff compared to other unibodies. There will of course be some minor twisting of the chassis, but it will be within the linear limits of the steel (not yielding), so the deformation is not permanent.
I open and close my doors all the time while up on stands.
I open and close my doors all the time while up on stands.
01-28-2014, 02:52 PM
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I heard it's safe when it's on 2 jackstands, which makes sense. But one is where the damage will be. I dont quite understand how it can bend the frame. I mean, putting it up on 1 jackstand already concentrates a lot of the weight to one spot. Also, is it fine to jack it up by the pinch rail?
01-28-2014, 02:55 PM
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Because the owner's manual is always ridiculously over-protective to avoid getting sued. Even if the result is barely any damage, the manual will say something like "MAY RESULT IN FAILURE! DO NOT DO THIS BY ANY MEANS!" or something.
01-28-2014, 02:57 PM
#6
You will get the most twisting of the chassis when lifting with only one stand, especially when that stand is the farthest from the center of the vehicle. The general statement that a unibody will flex when lifted with only one stand has to do with the chassis twisting under its own weight when lifted at a corner. This is true with some crappy unibodies, but this isn't the case with the RX8.
The pinch rail is an acceptable place to jack, but I would suggest modifying your jack in a way not to damage the rails. My rails look all chewed up because I have jacked on them so much. A block of wood with a slit cut in it or a hocky puck will prevent the rail from being yielded over.
Also, there are dedicated locations on the rails to jack......do not jack in the center of the car using the rails.
The pinch rail is an acceptable place to jack, but I would suggest modifying your jack in a way not to damage the rails. My rails look all chewed up because I have jacked on them so much. A block of wood with a slit cut in it or a hocky puck will prevent the rail from being yielded over.
Also, there are dedicated locations on the rails to jack......do not jack in the center of the car using the rails.
01-28-2014, 03:00 PM
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ya mine are starting to bend as well. It's taken me 2 days to change all 4 rotors lol. I can't get the piston back in using a C-Clamp, I'm finally just gonna bite the bullet and go get the tool from autozone. But from jacking the car up so much my pinch rail's starting to bend.
And ya, I was letting my buddy jack up my car the other day and I saw him starting in the center and had to correct it real quick haha.
And ya, I was letting my buddy jack up my car the other day and I saw him starting in the center and had to correct it real quick haha.
01-28-2014, 08:32 PM
#8
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Rx 8 is a full frame car not a unabody as long as you put the jack stands on the frame you golden. I did some major work this past year to my 8 and had it off the ground completely using four jack stands one at each corner of the frame opened doors sat in it no problem
01-29-2014, 01:40 AM
#9
I did my rear pads for the second time since I bought my car in May of '08 earlier this week. I didn't even need to mess with the parking brake (disengaged of course).
I popped the brake fluid lid and put it back on loose to prevent splash.
Top bolt on drivers side.
Pull caliper cover back
Pop old pads
Grease springs and back of new pads
Install new pads
Trusty caliper tool twist a little left and a little right. Grab boot while turning clockwise. I had to do a good couple full turns this time as I waited way too long (old pads had maybe 3-4 mm at most left)
Aligned piston to notch on back pad
Put caliper cover back on
Reinstalled bolt and torqued it down
Repeat on the the other side.
Ensure brake fluid lid is secure.
Ended up being about a 45 minute chore soup to nuts... just like I remembered from the last time (after reading this and other threads).
I popped the brake fluid lid and put it back on loose to prevent splash.
Top bolt on drivers side.
Pull caliper cover back
Pop old pads
Grease springs and back of new pads
Install new pads
Trusty caliper tool twist a little left and a little right. Grab boot while turning clockwise. I had to do a good couple full turns this time as I waited way too long (old pads had maybe 3-4 mm at most left)
Aligned piston to notch on back pad
Put caliper cover back on
Reinstalled bolt and torqued it down
Repeat on the the other side.
Ensure brake fluid lid is secure.
Ended up being about a 45 minute chore soup to nuts... just like I remembered from the last time (after reading this and other threads).
Compressing the rear brake caliper-piston with a G-Clamp
01-29-2014, 05:50 AM
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what's the difference between a unibody and a full frame?
and thanks for that Grace, its free to rent the tool from autozone. just gotta make a deposit and you get it back when you return the tool. Made my life so much easier. swapped all 4 rotors in about 2 hours
and thanks for that Grace, its free to rent the tool from autozone. just gotta make a deposit and you get it back when you return the tool. Made my life so much easier. swapped all 4 rotors in about 2 hours
01-29-2014, 08:22 AM
#11
Rx 8 is a full frame car not a unabody as long as you put the jack stands on the frame you golden. I did some major work this past year to my 8 and had it off the ground completely using four jack stands one at each corner of the frame opened doors sat in it no problem
Full frame cars were common up until the late 70's. Most trucks today are still full frame. Almost all crossovers or SUVs have changed to unibody.
Last edited by JCrane82; 01-29-2014 at 08:27 AM. Reason: typos
01-29-2014, 08:35 AM
#12
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Full frame is just that two peaces of steel one on ether side of the car run from the front to the back helping the car maintain rigidity and keeping body twisting to a minamum ( one of the reasons an 8 can handle in corners so well ) a unabody only has a frame where the the engine is to help support it the rest of the car is supported by stamped sheets of steel to give it some rigidity but allows body twist ( this is why most modern sports cars Like mustangs after so X amount of lunches with Y amount of power will begin to crab walk down the road because the body and unabody has been twisted so badly)
01-29-2014, 08:39 AM
#13
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Jcran I must disagree rx8 is full frame it has two box frame peaces of steel running the length of the car granted it's not the same kind of frame as a truck or the older cars but it still has two peaces of steel running the length of the car
That's also the reson the 8 can get away with no center support at the front and back doors in a unabody it would after time start to sag at the center of the car
That's also the reson the 8 can get away with no center support at the front and back doors in a unabody it would after time start to sag at the center of the car
Last edited by niteshade247; 01-29-2014 at 08:45 AM.
01-29-2014, 08:43 AM
#14
http://www.autoracing1.com/Images/20...zdaChassis.jpg
The RX-8 is a monocoque unibody with backbone frame construction and front and rear suspension subframes.
Trust me.....I'm and engineer.....
The RX-8 is a monocoque unibody with backbone frame construction and front and rear suspension subframes.
Trust me.....I'm and engineer.....
01-29-2014, 09:10 AM
#15
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That's why I don't trust you. (Engineers are fine when it comes to theory but applied theory is a very different thing just because it works on paper don't mean it will work in reality) don't get me wrong I'm not bagging on you I just argue with you guys on a daly basis and 7 out of 10 times the engineer was wrong. But ill give you this I could be wrong. I do know my 8 has two steel frames running length of the car which makes every thing els I have said true. Going to research this and if I'm wrong I will bow to your grater knowledge.
01-29-2014, 09:21 AM
#16
First of all.....not all engineers are theory based.
I happen to be a structural engineer that designs frames.....so you might want to take my word on this one.
If my word isn't enough....how about some Mazda literature claiming the unibody construction?
http://www.mazdausa.com/MusaWeb/musa.../specs_RX8.pdf
Second page, half way down:
Chassis
Body type Monocoque unibody with backbone frame construction and front and rear suspension subframes
I happen to be a structural engineer that designs frames.....so you might want to take my word on this one.
If my word isn't enough....how about some Mazda literature claiming the unibody construction?
http://www.mazdausa.com/MusaWeb/musa.../specs_RX8.pdf
Second page, half way down:
Chassis
Body type Monocoque unibody with backbone frame construction and front and rear suspension subframes
01-29-2014, 09:39 AM
#17
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If I have done this right the pics clearly show two frames running the length of the car. The illustration you have shown is just showing as added support agents torsion generated by high torque loads further preventing body twist and getting more power and torque to the road. The same reason there is a frame connecting the trans to the rear end to keep the U joints from twisting and loosing torque and maintain a straight line on the drivetrain giving you more of the power to the tiers
01-29-2014, 09:57 AM
#20
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Was not my intention to be a wise *** I just miss interpreted what I was looking at as every unabody I have seen the sub frame stop just before the front doors and nothing as substantial after that like the 8 has. I just enjoy a good battle of wits and can admit when proven wrong. I thank you for further educating me and I'm not saying that to be a smart ***.
01-29-2014, 04:19 PM
#21
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What is a FULL frame?
All I know are variations of ladder frames (trucks/proper SUVs) and superleggeras.
RX-8 is undoubtedly unibody.
BTW, isn't saying 'monocoque unibody' redundant? I thought mono-coque already means uni-body or one-shell.
All I know are variations of ladder frames (trucks/proper SUVs) and superleggeras.
RX-8 is undoubtedly unibody.
BTW, isn't saying 'monocoque unibody' redundant? I thought mono-coque already means uni-body or one-shell.
01-29-2014, 07:15 PM
#23
Rotary Evolution
no, you won't wreck your car by opening the door while it is on stands... you might however scuff some paint if you aren't careful.
the body naturally twists and the door isn't an important piece to the structural rigidity of the body. if you take off the strut brace though you may find the sag to be more pronounced.
the body naturally twists and the door isn't an important piece to the structural rigidity of the body. if you take off the strut brace though you may find the sag to be more pronounced.
Last edited by Karack; 01-29-2014 at 07:18 PM.
01-29-2014, 08:31 PM
#24
Extraordinary Engineering
Anecdotal story.
I had mine on four stands
The car was rocking diagonally on the 1/8" height difference between the four stands...
The car is plenty stiff.
I had mine on four stands
The car was rocking diagonally on the 1/8" height difference between the four stands...
The car is plenty stiff.
01-29-2014, 08:45 PM
#25
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Yes plenty stiff I had to jack bouth sides at the same time to keep the back tiers on the ground because I found that doing only one side at a time would make the back tier on the same side lift off the ground.