Question about 1981 Body....

[Dude...]

I have a tendency to notice little irregularities of my car, the biggest visual thing is the fact that the right rear tire is flush with the fender, whereas the left tire is tucked inside the fender about an inch or so closer than that.
Upon further investigation, I realized the fiberglass shell seems to be askew on the frame. When i measured the furthest point on the frame to the outside fender on both sides, it was an inch off.

Is this normal for these cars?

Also, I am considering putting a wheel spacer on the left wheel so it doesn't drive me crazy and both wheels are flush with the fenders.

Can someone help?

Thanks.

 

[Dude...]

...oh, and wheres a good place to get these wheel spacers?

Thanks again.

 

[pbcanney]

well, I wouldnt say its normal. I would...

swap the left rear right and left wheels (maybe someone put a 7 inch on one side to replace the 8 it should have)
nonetheless, if the scenario moves, you solved it.
then... (and only if the offset didnt change)
I would also have someone else drive it while you follow behind it. Hopefully it will drive straight down the road.

good luck

 

[Vettehead Mikey]

Is this normal for these cars?

Yes, very typical of production. Same thing on C2 cars but harder to notice. Don't worry about it.

 

[Yoda]

Yes, very typical of production. Same thing on C2 cars but harder to notice. Don't worry about it.

I can't help but ask why this would not be abnormal?? It seems to me that the factory would use a jig to set up most the body panels and other related frame/body/interior items. AND if there were out of measured tolerance it would be corrected at the factory.

It would seem to me that an inch difference between measurements of the body panel and frame, would indicate body work, or maybe frame damage and not being pulled back into GM specs

Just curious where or why you say this is normal?? To me it is a a red flag of sorts.. I would be looking for damage or replacement patching other than factory assembly...

I put a front clip on a 1974 years ago and ended up taking it to a body shop that had a frame machine and could set up the tolerance before glassing the front end on.. and that was on a front punch job accident that didn't damage the frame..

Bud

 

[Vettehead Mikey]

There was an excellent post on this subject on one of the other sites by a former F*rd employee. He described the variables involved in making a perfectly symmetrical body and frame and the likelihood of then getting a body and frame to line up perfectly.

Compare this also to the number of known 'no hit' cars (such as my own) that are off by 1/4 to 1/2". I've looked at hundreds of cars during NCRS judging and most are off by a finger or so.

 

[L82Dan]

Maybe your car's rear wheels need to be aligned?

 

[KANE]

...He described the variables involved in making a perfectly symmetrical body and frame and the likelihood of then getting a body and frame to line up perfectly.

Compare this also to the number of known 'no hit' cars (such as my own) that are off by 1/4 to 1/2". I've looked at hundreds of cars during NCRS judging and most are off by a finger or so.

Makes sense though.


No two cars were assembled with the exact same variables.:W

Which is why a fiberglass bumper must be fitted:bang as opposed to the urethane which can be massaged.

 

[KANE]

well, I wouldnt say its normal. I would...

...

I would also have someone else drive it while you follow behind it. Hopefully it will drive straight down the road.

good luck

Paul's got a good point.

Are the tie rods bent- one bent more than the other?

 

[GerryLP]

As they say, a picture is worth a throusand words...

There are perhaps a few areas that could affect this? For instance, are the rubber bushings for the differential carrier intact?

Post some pictures!

GerryLP:cool

 

[6880 Mike]

...Yes, very typical of production...

I agree. It is not uncommon for these cars to be off a little. On my '68, it's the right rear.

C3s were assembled by human beings at an average rate of about eight an hour over two nine hour shifts, usually six days a week. They were not perfect.

Personally, I would forego the wheel spacer.

 

[melsy]

Back in the day it was just common knowledge that no two Corvettes were the same. There were always variances in measurements--especially in C2 and C3 cars--as someone else also said. Just make sure all your mechanicals are correct and then don't worry about it.

 

[Yoda]

I'm not trying to here

I could see a 1/4" maybe even up to a 1/2" alignment issues, but anything larger than that I would think there would be real problems with fitting all the pieces together and keeping the car looking straight and the body lines equal

I know I'm a hard headed Irishman, but I've done some body work on C2 and C3 in years past and if it ain't close you ain't going to force it. It requires a Bubba Fix with shaving and cutting, and once you start that process it carries on and on from front to back from side to side.

So the 1" comment really seems a bit more than acceptable, at least to me

I would also think (there I go again "Thinking") St. Louis or even the early C3 production at Bowling Green would have better tolerances than "if it's within an inch, splap her together" body panels in general and esp top surrounds on the Midyears would be quite a challenge to align with the headlight buckets and side fenders, not even thinking how the doors and windshield would fit :eek

A nieghbor years ago, retired Ford worker, told me Ford would let folks tour their plant, with the exception of the area where they mounted the hoods.. he laughed and said if anyone saw what they did to make the hoods fit, they probably wouldn't sell any Ford Trucks :L

Anyway, that's my thinking and reasoning... dashed with a bit of experience around these monsters

Bud

 

[Peer81]

I would say, take a look at the frame and the inside of the body from under the car. No weird things there then no need to worry.
You can always loosen up the bodymount bolts and move the body around a little.

Greetings Peter

 

[Vettehead Mikey]

Personally, I would forego the wheel spacer.

Yes,agreed. Wheel spacers are always 'bubba', this would be an extreme example

You can always loosen up the bodymount bolts and move the body around a little.

Greetings Peter

I'm seen and heard of many people trying to do exactly this with little or no gain.

My own car (no-hit as stated before) had a 1/2" shift to one side and ended with exactly the same offset after a full frame off, despite our best efforts to 'fix' it.

 

[6880 Mike]

...I would also think...St. Louis or even the early C3 production at Bowling Green would have better tolerances than "if it's within an inch, splap her together" body panels in general and esp top surrounds on the Midyears would be quite a challenge to align with the headlight buckets and side fenders, not even thinking how the doors and windshield would fit....

As I understand his post, he is not asking about panel fit or gaps. He is talking about the alignment of the body on the frame. For the most part, bodies were fully assembled and preliminary panel fit checked before body drop.

Body Drop 1969

Body Drop 1981

Same station on the line; two different views, two different models years. Bodies are 95% complete.

 

[Yoda]

Thanks Mike

I understand the process, my point being about two things.

1. I find it rather disturbing that the factory would allow 1" of out of tolerance for fit. Also since the body is mostly assembled and dropped on the frame, it would be time consuming and a pita to force fit a body on a frame that was off by an inch or more. There has always been quality control measures setup for all aspects of assembly.

2. The result of the 1" discrepancy may have been from repair. In that case it could be identified by an inspection of the seams and looking for any glass repair and type of glass used and type of patchwork.

Like I said, it may be very true that the factory let some go through assembly and they were at the ends of the tolerance setup by the GM Engineers and Factory layout Engineers. I realize the Corvette didn't have the Iacoca badge of excellence on them until Lutz added it in 2006 or there abouts, but I would still like to think quality over mass was more the norm for Corvettes than the K-Car

Bud Dougherty
Amarillo, Texas

 

[JohnZ]

Back in those days, the dimensional tolerance on the frame and its body mount brackets was +/- 3/8"; measuring from one point to another could be up to 3/4" off and be "in spec" if one point was on the low side of spec and the other was on the high side.

The body mount bolt reinforcements riveted to the underbody weren't much better dimensionally; when you combine that kind of tolerance stack between the frame and the underbody, you'll see a good deal of variation.

Passenger car frames had a 4-way round Master Gage Hole adjacent to the bolt hole at the driver's side mount below the firewall, and a 2-way Master Gage Slot (fore-aft) adjacent to the bolt hole at the driver's side rear body mount; these two holes were used for Body Drop Gage pins that engaged two Master Gage Holes in the steel underbody to accurately align the body to the frame at Body Drop. Those two gage pins were left in place until after the body mount bolts were torqued.

The Corvette didn't use the Master Gage Hole and pin scheme - it just used a pair of pins through the bolt holes in the frame and body at the #1 and #4 locations, which were subject to the +/- 3/8" tolerance. That's why you'll see significant variation on Corvettes in terms of body-to-frame location.

Check your rear suspension alignment (camber), and make sure you have the same wheels on both sides; if that checks out, don't worry about it. Do NOT use spacers - they're dangerous, as they subject the lug studs to much higher shear loads than they're designed for.

 

[GerryLP]

All things being equal, it would seem apparent that if it is 1" difference now, does that mean that perhaps was less than that 29 years ago?
But if were talking about a very low mileage L81, then would that mean that the deviation on this vette is at the very extreme end of the tolerances? Que no?

GerryLP:cool

 

[JohnZ]

All things being equal, it would seem apparent that if it is 1" difference now, does that mean that perhaps was less than that 29 years ago?
But if were talking about a very low mileage L81, then would that mean that the deviation on this vette is at the very extreme end of the tolerances? Que no?

GerryLP:cool

Most likely. Mileage doesn't matter - they could exhibit that level of variation when they were new.