Two post lift with C3 and C4

[Robert S.]

My 2 car detached garage is complete and just installed a Bendpak 2 post lift. For those of you with 2 post lifts, what are you using for front and rear lift point locations, and/or know approximate fore/aft center of gravity? Three cars going on the lift are:
1. 1969 L71 coupe
2. 1971 LT-1 convertible
3. 1994 ZR-1

[Daniel S.]

Re: Two post lift with C3 and C4

I lift my '68 via the frame inside the front and rear wheels. See attached

[Robert S.]

Re: Two post lift with C3 and C4

Daniel,
The car center of gravity(CG) should be located at the lift vertical post. So where do you position the car with respect to the post? I'm guessing the CG is close to the steering wheel.

[David M.]

Re: Two post lift with C3 and C4

Crack open the doors before lifting. Especially on the verts.

[Mark T.]

Re: Two post lift with C3 and C4

Robert if the lift you installed was new from Bendpak and it was a ALI certified lift (most models of Bendpak are certified ) You should have received with the manual a lift guide . This will show all of the correct lifting points on almost every year car
If the lift was used you can obtain a lift guide from the ALI which is in Cortland NY or Bendpak can also supply them. Every time you put a car on the 2 post lift you should raise the car just so the wheels are off the ground and then gently rock the car to make sure you have the center of gravity correct
The C6 and C7 have very specific lift points which require puck adapters
Mark

[Robert S.]

Re: Two post lift with C3 and C4

I did receive the ALI manual. It only goes back to 1995, so no info on C3.

[Mark E.]

Re: Two post lift with C3 and C4

Robert,

Help me understand the question. Daniel shows the lift points for the C3 per the service manual. Are you asking if these lift points should be changed somehow to place the CG of the car with the center of the lift?

[Robert S.]

Re: Two post lift with C3 and C4

"Help me understand the question. Daniel shows the lift points for the C3 per the service manual. Are you asking if these lift points should be changed somehow to place the CG of the car with the center of the lift?"

Not at all. The lift arm length is adjustable. Using the front and rear lift points pointed out by Daniel, the car may be rolled forward relative to the lift, and then shorten the front lift arm and lengthen the rear lift arm. Conversely, the car be rolled backward which will results in a longer front arm and a shorter rear arm. Lift points have not changed, but CG of car relative to lift has changed.

[Dick W.]

Re: Two post lift with C3 and C4

Daniel,
The car center of gravity(CG) should be located at the lift vertical post. So where do you position the car with respect to the post? I'm guessing the CG is close to the steering wheel.

Dat won't work with an Asymmetrical lift

[Robert S.]

Re: Two post lift with C3 and C4

Ain't asymmetrical lift.

[Mark E.]

Re: Two post lift with C3 and C4

"Help me understand the question. Daniel shows the lift points for the C3 per the service manual. Are you asking if these lift points should be changed somehow to place the CG of the car with the center of the lift?"

Not at all. The lift arm length is adjustable. Using the front and rear lift points pointed out by Daniel, the car may be rolled forward relative to the lift, and then shorten the front lift arm and lengthen the rear lift arm. Conversely, the car be rolled backward which will results in a longer front arm and a shorter rear arm. Lift points have not changed, but CG of car relative to lift has changed.

Understand. The C3 service manual doesn't show the CG of the car. If you knew the weight on the front and rear wheels, the CG could be calculated. On newer cars (maybe the C4 too?) the tire pressure sticker shows the weight on the front and rear wheels.

I've never seen shops that use two-post lifts worry about this. Maybe experience and eyeballing?

[David M.]

Re: Two post lift with C3 and C4

Guys your over thinking it.
Position the car evenly between the posts centered side to side with the front end extended out a bit longer from the cable troth vs the rear. Lift on the strongest(obvious) points on the frame and go...

The arms will limit you. You will see what I mean once you try to get the arms under the frame. Opening the door to egress will also default you on position.

Bias isnt as important with a short car as it is for a F350 extended cab long bed thats 8000lbs and 25' long.
A two post will only allow for so much bias due to the arm extension limits and pad adapter height.

Extend the arms out to meet the "good" spots on the frame and lift.

Practice a few times just taking the weight off the suspension, wheels still on the ground. Its always good to do this "check" to ensure the pads are in fact on the sweet spots before final lift(off).

If its not right lower it back down until arm locks allow re-positioning and retest until you are confident. By nature of the long nose short deck on vettes extending the front arm out longer automatically compensates for the bias.

It is intuitive. You will get it. Do read the safety instructions carefully, do some youtubing for some visuals and perform some practice lifts and go.

Dont forget to crack open the doors to release the striker from the latch.

[Robert S.]

Re: Two post lift with C3 and C4

Understand. The C3 service manual doesn't show the CG of the car. If you knew the weight on the front and rear wheels, the CG could be calculated. On newer cars (maybe the C4 too?) the tire pressure sticker shows the weight on the front and rear wheels.

I've never seen shops that use two-post lifts worry about this. Maybe experience and eyeballing?

I have found some front/rear weight basis info, but just don't know the source, so not reliable. I thought that someone here may have good numbers. I agree that it probably isn't that critical, but thought I would inquire what others are doing.

[Terry M.]

Re: Two post lift with C3 and C4

I have found some front/rear weight basis info, but just don't know the source, so not reliable. I thought that someone here may have good numbers. I agree that it probably isn't that critical, but thought I would inquire what others are doing.

Beginning in calendar year 1972 the front/rear and total weight is listed on a blue (changed to white later. 1974, I think) label on the driver's door. Earlier C3s you will have to guess.

An earlier post mentioned raising the car slightly and checking its stability by attempting to rock it with the wheels only slightly off the ground. That system has worked for me for 40 years for all sorts of vehicles. The lifting points from the Chassis Service Manual (also posted earlier) are also helpful. If you intend to remove major components (engine or rear differential and suspension assembly) while the car is on a 2-post lift some common sense is useful. Auxiliary support or supports (tall floor jacks) should then be employed or consider working from floor jack stands.

There is no need to overthink this. Common sense works well.