I dented my frame rail

oldass31 · 10:35 AM

Last night, I dented my frame rail while following a combination of instructions commonly found on this website and clarks-garage.com. I used my floor jack, with a block of wood, at the jacking point under the door, to lift the driver side of the car first. I then placed a 3 ton jack stand on the lowest setting under the frame rail near the front and a 2 1/4 ton stand under the torque tube in the rear. I carefully, and slowly lowered the car while repeatedly checking to make sure that the frame would rest centered on the stands. I then repeated this process on the passenger side. At some point during all this, the front driver side jack stand dented the frame rail. The dent is a little under 0.5 cm deep at it's deepest point and the entire dent is on the underside of the rail. There's no punctures and no creases. The deepest part of the dent is a little off center. The jack stand did not seem to dent either corner of the rail.

This is the design of the front jack stands I used:

Sorry, but I didn't take any pictures of the actual damage. I was a little pissed off with myself at the time. Could someone please explain to me what I did wrong?

nize · nize's Garage

are you sure you put the jack stands on the frame rail, and not on the floorboard? the markings under the car at the front are misleading, because it shows what seems to be an obvious spot for jack stands, and it's not.

oldass31 · 03-03-2010, 10:32 AM

Right of center is the driver side of the car in this picture.

As best as my now disillusioned self can tell, my jack stand was placed on the right side, green box labeled "HOIST / JACKSTAND SAFE POINTS"

There is a local Euro import shop and salvage yard I'll be sending pictures of the damage to. When I take the pictures, I'll also upload them here.

bearone2 · 03-03-2010, 02:22 PM

by the pics of the jack stands, i see a lot of sharp edges and probably the point of contact.

fwiw, i use jack stands that are flatter on the contact surface.

carlege · 03-03-2010, 02:40 PM

they also make covers that are flat to go on jack stands. i would suggest investing in those.

jkb58 · 03-03-2010, 05:04 PM

Very common for those rails to be dented if used for jack or lift points. I dont know why they are identified as lift points, as they are not hardened, and are mostly covered by the black plastic side pans. They are thin gage sheet metal, formed as a channel and spot welded to the tub. I would use the hardened points right behind the front wheels (the ones it says not to use in the above diagram).

No matter where you put the jack stands, its a good idea to use a block of wood, 2x4 or other, on the jack stand.

Grandad#3 · 03-03-2010, 07:08 PM

You have to be careful with those sharp end jack stands. If you put a block of wood on top make sure the wood grain is going across the sharp point from side to side, otherwise the points will break the wood. My stands are almost flat on the top and I use a 6" X 6" X 2" piece of oak wood on top.

Cheers,
Larry

wild man · 03-04-2010, 05:29 AM

You say the bottom corners of the rail where you placed the stands are NOT dented? Those are exactly the places where you would want the jack stand to be contacting the rail, and supporting the weight.

oldass31 · 03-04-2010, 07:22 AM

Quote:

Originally Posted by wild man

You say the bottom corners of the rail where you placed the stands are NOT dented? Those are exactly the places where you would want the jack stand to be contacting the rail, and supporting the weight.

That's the crazy part. The jack stand WAS contacting the corners of the rail. And those little bumps on either side of the jack stand's jaw? They were about 0.5 cm clear of the frame rail on either side. I lowered the car so that the frame rail rested on ONLY the two FLAT parts of the jaw. It seemed like the most perfect-fitting jack stand one could hope for. The deepest point of the dent seems to correlate with the inner edge of the flat part of the jackstand. The dent is basically on the side of the frame rail that's closer to the driveshaft. Man, do I need pictures...

I'm starting to wonder if the extreme angle I had the car at, to get a 3 ton stand under, is responsible. The inside (drive-shaft-side) corner of the frame rail would have been the only point of the rail resting on the jackstand before lifting the passenger-side. Perhaps the dent isn't so much a dent as it is a buckle?

oldass31 · 03-04-2010, 07:30 AM

Quote:

Originally Posted by carlege

they also make covers that are flat to go on jack stands. i would suggest investing in those.

I would appreciate any recommendation.

oldass31 · 07:35 AM

Quote:

Originally Posted by jkb58

Very common for those rails to be dented if used for jack or lift points. I dont know why they are identified as lift points, as they are not hardened, and are mostly covered by the black plastic side pans. They are thin gage sheet metal, formed as a channel and spot welded to the tub. I would use the hardened points right behind the front wheels (the ones it says not to use in the above diagram).

No matter where you put the jack stands, its a good idea to use a block of wood, 2x4 or other, on the jack stand.

So then what's the reason the picture says not to use the points behind the front wheels?

wild man · 03-07-2010, 06:28 AM

If you had it at enough of an angle, that probably put all of the weight onto one of the top corners of the jack stand, forcing all of that pressure onto a very small area on the rail, causing it to dent it in. I bet no one, including myself, would figure that would happen though, when putting the car on stands..

bearone2 · 03-08-2010, 06:02 AM

Quote:

Originally Posted by wild man

If you had it at enough of an angle, that probably put all of the weight onto one of the top corners of the jack stand, forcing all of that pressure onto a very small area on the rail, causing it to dent it in. I bet no one, including myself, would figure that would happen though, when putting the car on stands..

"including yourself", i mentioned sharp corners early in the thread.

carlege · 03-08-2010, 06:31 AM

Quote:

Originally Posted by oldass31

I would appreciate any recommendation.

- Harbor Freight Tools - Quality Tools at the Lowest Prices

nize · nize's Garage

Quote:

Originally Posted by jkb58

Very common for those rails to be dented if used for jack or lift points. I dont know why they are identified as lift points, as they are not hardened, and are mostly covered by the black plastic side pans. They are thin gage sheet metal, formed as a channel and spot welded to the tub. I would use the hardened points right behind the front wheels (the ones it says not to use in the above diagram).

never use this point to support the weight of the car, it is not reinforced. it looks like it's reinforced but it is misleading, and supporting by this area will push this puck right into the floorboard. i have seen many, many cars with this obvious damage.

wild man · 03-08-2010, 09:04 AM

Quote:

Originally Posted by bearone2

"including yourself", i mentioned sharp corners early in the thread.

Yea, I see it now. I must have failed to read that paragraph, the first time around. I can now say: NOT including me (now that I know about it). But it could still happen to the thousands of owners who haven't read this thread!

I need to stop getting ahead of myself though. Ah, the hell with it. Time to break out the "good" stuff. Signing off, for now.

M758 · 03-08-2010, 09:52 AM

I always use the caster block bolts to put my stands under in front. My 944 race car sees lots of time on the stands I have never damaged anything there. In the rear I used the t-bar carrier, but the flat aluminum casting and never the actual tube. I don't want bend that tube.

Now when I need to pull the front control arm off I use the frame rails. they have some dents & bends, but are fine. It does take more time to do that, but don't have any other spots.

I do use wood in between to distribute the load.

jkb58 · 03-12-2010, 10:26 AM

The big point to be made here: if you are jacking the car to work underneath, you need to be smart and very careful that the car is securely supported. Primarily for your own safety and also to avoid possible damage to the car.

There are a lot of points that can be used to lift or to support a 944, both front and rear, that will not cause structural damage to the car. But depending on how careful you are, you can cause some cosmetic damage to sheet metal, components and hardware.

A lot of the damage that you see on the front frame rails and also on the pads behind the front wheels is from careless lifting and poorly placed jack stands. Don’t drop the car onto the stands when releasing the jack. That 1-2" hard drop is what causes much of the damage in either location.

Make sure the load is properly/evenly distributed. Use a block of wood or solid block that makes even contact with the lift point. Pointed edge jack stands will cause problems. And this is very important with safety too. Uneven point contact with a poorly placed jack stand is a risk of slipping.

I’ve been working on 944s almost 20 years, and more often than not, I have used the pads behind the front wheels for a jack or support point, instead of the frame rails. For that many years of track maintenance I would conservatively estimate I have likely jacked 944s well over 500 times, and probably closer to 1000 times. My cars have more damage on the frame rails, than they do on the pads behind the front wheels (you can see the crush of the frame rail in the pic in my previous post).

And you will likely find that more often than not, p-car shops will use those points too, not the frame rails, when lifting 944s on a hoist.

If you scrape all the undercoating off the bottom of the car and the interior floor pan, as I have done, you will get a pretty good feel for the construction of the tub. The frame rails appear to be 16 gage formed u-channel spot welded to the floor pan. The hard point behind the front wheel is on a plate that is attached partially in-line with the door sill/rocker rail. This is a structural part of the tub and is perfectly capable of supporting the weight of the car.

Be aware, as others mentioned, if improperly supported or if dropped onto a jack stand, the pad can deflect the floor pan on the inboard side. And it can cause the pad to angle upward on the inboard edge, which increases the risk of the jack stand to slip.

I fabricated some caps for my jack stands years ago, that evenly center contact on the hole in the pad donut. Basically eliminates the risk of the car slipping off the stand. And it evenly distributes the load on the pad, so there is no deflection of the floor pan.

Short of caps like that, blocks of wood are best. The wood is nice in that it crushes. The jack stand cuts into it, and the hard point on the car will bite too, so it really reduces risk of the car slipping off the stand. Cut up a 2x4 into 4" blocks and use until they crack/split.

Another option is to use a block of rubber, like a hockey puck. I use these with my lift, but would also work with some jack stand applications.