C3 Frame Measurements

[David W.]

Hello All,

Is there a simple way to check the frame measurements of a C3 (1980) with the body in place? The rear end is the only suspension part still attached.
I was looking at the frame from the bottom and noticed a little more damage (floor jack or up on a curb) than I had realized. Not extreme but I still want to check. I have my assembly manual and many other books but can not find the measurements or how to do this.
Any help would be much appreciated.

Regards, David

[Joe L.]

Re: C3 Frame Measurements

Hello All,

Is there a simple way to check the frame measurements of a C3 (1980) with the body in place? The rear end is the only suspension part still attached.
I was looking at the frame from the bottom and noticed a little more damage (floor jack or up on a curb) than I had realized. Not extreme but I still want to check. I have my assembly manual and many other books but can not find the measurements or how to do this.
Any help would be much appreciated.

Regards, David

David-----


You should be able to find the frame specs and checking procedures in section 2A of the 1980 Corvette Shop Manual. If, for some strange reason, it's not in the 1980 shop manual, it can be found in the 1979 manual; I'm 100% sure of that. In the latter case, there are some frame differences between 1979 and 1980 due to the change in the differential and crossmember. However, I expect that all of the dimensions you're interested in will be the same.

[David W.]

Re: C3 Frame Measurements

Thanks Joe. I had the book but could not find the page. In the Shop Manual it looks as if the x-x, y-y and z-z measurements are the ones that are possible with the car in its present situation. Since I do not have a tram gauge, I assume the "plumb bob" method will have to suffice. My question, is this the best way to measure? Or is it possible to just measure with a tape centering each measurement hole? I figure this will get me close enough to know if there is any significant damage.

Thanks, David

[Joe L.]

Re: C3 Frame Measurements

Thanks Joe. I had the book but could not find the page. In the Shop Manual it looks as if the x-x, y-y and z-z measurements are the ones that are possible with the car in its present situation. Since I do not have a tram gauge, I assume the "plumb bob" method will have to suffice. My question, is this the best way to measure? Or is it possible to just measure with a tape centering each measurement hole? I figure this will get me close enough to know if there is any significant damage.

Thanks, David

David-----


I think you can get sufficient accuracy using the method you describe. However, another alternative is to take take the car to a frame shop and have them do it with the car on a rack. This assumes, of course, that the car is currently "rolling" and could be trailered to such a shop.

[David W.]

Re: C3 Frame Measurements

Thanks Joe for the response. I wish I could get it to a frame shop. Problem is the front end has been removed. I am going to measure tomorrow and if the frame is out more than 1/4" per the manual, then I will go ahead and lift the body. There is nothing more than the body mount bolts holding frame and body together. If this is the case then it might work for the best. Mount #1 on the drivers side does not look so good and this would give me a chance to repair.

Regards, David

[Stewart L.]

Re: C3 Frame Measurements

You do not say where you suspect the damage is but there are some initial inspections you can do. A tram would be helpful. Is there a buckle on the side where you suspect the damage that is not on the other side? Is there broken paint or undercoat where you suspect the damage? Are the body mount bolts centered in the holes? Do the doors open and shut good? Is the gas tank filler centered in the opening? You can pick a known good point on the frame such as the rear middle crossmember or torque box area and run side to side cross measurements, they should be within + or - 1\8". Let me know if you still need some specs as I think I can dig up a frame spec book.

[David W.]

Re: C3 Frame Measurements

The damage is passenger side on the bottom of the frame in the area where the #2 body mount is located. The fuel line clip (1st one past the firewall) was bent up on itself. Required hammering flat to remove clip screw. Damage looks as if the car were up on a large rock or curb. The outside of the frame in this area looks fine. No distortion of any kind. The frame in this area on the driver side has the normal "jacked-up area" look but not nearly as bad as the passenger side. There is no paint cracking, doors close very well and are centered, gas tank filler neck and gas door opening are fine. Body mount bolts look good. They appear original judging from the corrosion. Nothing appears welded, pulled or repaired. That said the frame does appear to have a little twist. Sitting on 4 jack stands in the exact same spots on a level floor, the front right stand will be in contact with the frame. The jackstand will be 1/4-3/8" from touching the frame.
I have the frame dimensions from the shop manual. Just not positive how to get an exact spot to measure from. I am trying to use a "plum bob" and I am just not sure that I am doing this correctly. Any advice is much appreciated. I am trying to find the spots to use for the "x" and "y" measurements from the shop manual.

Thanks, David

[Stewart L.]

Re: C3 Frame Measurements

[David W.]

Re: C3 Frame Measurements

Thanks Stewart. I agree that there might be a little damage Everything looks really, really good. It looks untouched until you look at this area (closely) and notice how it will not sit level on the 4 jackstands.
It would be great if you could fax or email the sheets. Fax 828-488-0958
email david@4rcc.net

[Stewart L.]

Re: C3 Frame Measurements

I will fax it over tomorrow. The datum location they give you is close to where the damage is on your right front so establish the rear and left front to diagnose the right front.