Because I am new to C3 Corvettes, wanted to know where the recommended locations for positioning a floor jack were. Am I correct to assume that any place on the frame is a safe floor jack location?
For instance, to work on the starter, is it a good practice to place a floor jack anywhere along the side frame? The reason I ask is that I jacked the car up using a floor jack positioned just aft of the drivers
side door to re-insert the battery compartment grommet back into the hole where it apparently popped out. So I had only one side up in the air and I noticed my door would not close correctly. This, even though
my frame is solid with no rust, So I finished what I had to do under the car and let the car down and the door now functioned properly. Is this normal?

 

https://www.corvetteforum.com/forums...968-vette.html

 

Lots of free information about your '69 Corvette here:
https://www.gmheritagecenter.com/gm-...tion-kits.html

 

✔ I hope you used jack stands also besides the floor jack if you went under the car.


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Thanks for all the replies - so it looks like:

1. Use car ramps if possible.
2. If you need to lift the front or rear ends of the car, use a 2x4 to keep the frame from flexing on the GM recommended jack points.

Does this look right? Oh, and yes I use jack stands for any work under the car - and my floor jack is a real big unit that I got from SAMS a while back (Goodyear I believe).

 

Regardkless if your farme ash rust n it or not ti is ntoa new frame nor is the cr new.

So not knowing the past history of what has happened to this car and how it has been lifted in the past can make it so when you go and follow GM recommended locations for lifting it and using jack stand may NOT be where you need to jack up and support it. Just because it has a steel frame does not make it rigid due to metal can flex and bend and is quite elastic depending on the type of steel. Because as you know...metal can dent.

The reason I say this is because I service Corvettes for a living and I have a way to raise the car and support it that does not 100% fit with what GM specified as 'their' locations to support the car. They never intended the car to last 40+ years or so.

Raising and supporting convertibles is different than a coupe and often times just simply putting floor jack under it to raise it may not work and some other component may need to be engineered to make you being able to raise the car without damage a necessity.

When not using lift. I raise the car from the front engine cradle area and from the rear at the rear spring mount area.

Like I wrote some cars I can simply drive the car up on my wood ramps to raise the front enough to get under the cradle...and on some cars...due to exhaust. I have to use an attachment that goes on the saddle of my floor jack to get to the rear spring area. If my attachment does not allow me to slide the floor jack to where it is needing to go...I have to back the car off the front ramps and get up my rear wood ramps and drive the car up on the four wood ramps so the car is up off the ground so my attachment will work.

I do not lift the car from the side ..EVER! I cannot take the chance due to what I mentioned earlier of not knowing the history of the car and it is not worth it. Even if the car only has 8000 original miles on it and it has been garage kept...I STILL would not do it.

Depending on what I am doing and if the car is a coupe or convertible I generally will place the jack stand under the lower control arm OR remove the wheel and place the jack stand under the wide section of the brake rotor AFTER making sure that IF the rotor rivets have been drilled out I might need to put the lug nuts back on to properly secure the rotor so it does not move in and out. Now the car can settle back down and is still being supported by the suspension.

The rear is the same way where I remove the wheels and carefully place and lower the jack stand and aid it moving out when it is being lowered so it does not tilt.

If I am working on the actual suspension so the jack stand is now in the way. Then I move the jack stands and will still sue the floor jack for support and that is an entirely different dynamic which will take much more writing.

DUB

 

Yeah, I should have included the fact that this is a convertible 69 in my question - my first convertible ever.
So for my case - the convertible - is front engine cradle area and from the rear at the rear spring mount area. where you place the jack or jackstands if you don't use the ramps?

 

convertibles are far more prone to body flex then coupes, another good point that you should be doing is not lifting one corner radically higher then the other 3, its best to lift evenly around the car with multiple jacks or jackstands, but regardless if raising the wheels more then an inch off the ground be sure to evenly lift the other side as well, the reason floor hoists are used in every shop is because they lift evenly and are faster then using 4 jacks. also safety blah blah, but they lift every vehicle, truck coupe, convertible, station wagon etc..

 

Do not place the jack directly under the front engine cradle/cross member, it will dent. Either place the jack on the front or rear edge or use a heavy piece of wood to straddle the center from front to back.

 

SamBrand - do you front or rear edge think it okay to raise one end of the convertible (i.e. front or rear) if both sides are evenly lifted? The reason I ask is that I do not have a 4 point lift, only a large floor jack. I could use a large piece of wood and jack up the front or rear edge as shown in the pic below. The red rectangular indicates where (under) the given points I should use a 2x8 or 4x4 to lay across the 2 given points?

 

I mean no disrespect to the op, I personally would not use a wooden support because of safety concerns, in my shop we did have multiple jacks, lift, and all the jackstands you could want. even bricks, but no wood.. I just don't trust anything that could break/dent/chip/etc
as for a do it yourself measure I would recommend that u buy a second floor jack along with at least 4 jackstands.

the op was clearly saying and correctly that the issue is uneven lifting which causes the body to flex, the reason the front end is marked jackstands is because it is assumed you will lower the front end evenly onto the jackstands, and not stress the body by jacking one of the points causing all the force to be concentrated there. think of your car as a potato chip, its a lot easier to break a corner of the chip off compared to breaking it in half, your convertible has no roof to help take the stress of any twist so like a chip it will flex a lot more at the corners then if the same force is applied evenly, that's why the jack locations as indicated are center mass, the frame can better distribute the stress along the side then it ever could if jacked form the front.

 

It has been said never never use bricks or concrete blocks. They can fracture and you would not see it until too late and also bricks can chip as you stated. I would use wood over a brick/concrete block anytime. I have used wood 2x6 and 2/4's many times and they are very safe and do not scratch anything. Just FYI
Be Safe......

 

true, however bricks do come in handy when something needs to be stored outside, and it was standing rule to not work under anything supported by bricks.

 

So Sambrand, is it OK to jack up the front or rear of the car assuming both sides (left and right) are evenly supported on jackstands or are you saying that
the front and back need to be jacked up evenly? I have a second floor jack in another garage, just haven't used it recently.

 

You do not need two floor jacks to raise your car. Worrying about raising the car level is pointless due to HOW it is being raised. Or I have been ruining Corvettes for over 30 years. Which IS NOT the case. But buy another if it makes you feel good.

If you raise the front end 10 inches and support it under your lower control arms...and then raise the rear of the car to match it and support it ....no damage will occur. The you can go back and raise the front some more than make the rear to match it till you get to the height you want.

The wood ramps I have made allow me to drive the car up onto solid wood block that raise it about 4 inches and there is no way in heck that the car will crush that wood. So making your wood ramps and blocks. ( if you choose to do so) out of 2x8 or 2x10 sections of wood will do just fine with NO FEAR of the car crushing that wood.

Professionally speaking I would not do what you are thinking like you wrote in POST#10 by running wood across the underside on the car at those two pint where the cabin is THAT is not correctly lifting the frame I WHERE it needs to be lifted so your rear clip will not sag, That is WHY you want to raise the rear clip from the center of your rear leaf spring mount area.

By lifting the car from the cradle and the rear spring area you are applying force to the frame that is better suited to how the car was built and the car will NOT collapse in on itself. If you look at the side view of the frame diagram ....hopefully you picture how the forces are working FOR YOU and not against you by using his method.

By raising the car from the cradle or a mechanism that goes across to each lower control are if that is what you want to do. You can see that when the car is being lifted the force that is wanting to raise the front end and push it to the rear is being stopped by the front clip being bonded to the cabin section which is in turn bolted to the frame where GM tells you to put jack stands. So there is no way in heck the front end is going to collapse in on itself when it is being supported by the birdcage of the car and it being bolted to the frame. BUT...IF you put jack stands UNDER the points GM states to put them. ALL of the weight of your front clip ( engine, radiator, suspension ) is hanging out past that fulcrum point and you NOW can have a problem and actually see the gap at the door widen greatly. But funny how when you raise it like I mentioned...that gap at the door and top hood surround will not close in on itself to the point of making contact. AND if it does...you have other problems to worry about.

The same holds true to the rear of the car....especially if it is a convertible. Which is why I place jack stand under the rotors on a convertible (and coupe) if I need to support it. And IF I am needing to work on the suspension. Regardless if it is only one side,. I raise up the rear of the car. And I have very tall jack stands that IF I need to hold that height I can place them on the frame just behind the rear suspension if the exhaust ill allow me to do that.

DUB

 

Thanks Dub - I like this idea for most repairs under the car that I wouldn't have to remove the wheels for. So then for removal of the wheels (which I'll have to do to
re-do the front suspension) - you seem to like jackstands under the front engine cradle area - would the areas I have in red under the front cradle be the spot you



are referring to? Don't mean to belabor the point (nor am I as thick as I look) but I just want to get this right because I'll definitely have to do some work on
my 69 convert in the future,

Now I'll assume I should jack up both points in the front at the same time, correct?

 

aye, we have differing opinions on wood/steel but both have valid sides and are more opinion then physics, takeaway on this is to do things evenly as you said, the front points are suitable for jack stands but remembering the twisting force that will be put into the frame doing it evenly "should" be fine. although every one said how to do it a bit differently the common theme is doing it evenly.

 

Thanks everyone - I think I got it now!

 

You are not THICK not belaboring the point, This is important for you to know and understand so when you raise your Corvette you do not cause problems. Where you then would have to take it to a shop and get it fixed. So ANY attachments or custom made gizmos you need to make are WELL WORTH it. Because if you don't find what works for your car. And you have a problem that developed. You then would wish you could turn back time and make those items you specifically need for your Corvette.

YES..I would jack up the front of the car where the blue is with my floor jack under the engine cradle. Then place the jack stands where you have red under the lower control arm where the lower shock absorber is mounted. I position the curved saddle of my jack stand to straddle the round end of the shock absorber.

When raising it up at the engine cradle there is no twisting of the frame due to your are picking it up in the center of the car. I have done it for so long this way without any problems.... when I see the tires come off the ground they are so close to each other that if 1/8" of difference bothers some people....well. I can not help that and that 1/8" is not a big deal.

And in many cases I have seen missing upper control arm rubber stops which will make that side take longer to come off the ground which is ALSO not a big deal to be concerned about when raising your car. Get it up in the air and then supported evenly with your jack stands and you will be fine.

DUB