C3 bent frame ?? question

Hi,

Have a urgent question about the C3 frame. I have a 79 here which has the
complete right side (were the 4 bodymounts are) sitting on average 1/2"
higher than the left side. Cross measuring from one bodymount to the other
suggest the frame is still very much straight.
I had the frame jacked up evenly (with carpentersbubble) both on the front
and back outer tips (measurements taken from a workshop manual/engine,
transmission, rear axle, tires, still on it)

There is no evidence of an accident on this car. I checked it already for
nicks, welding etc, but have found nothing. Welds are still looking normal
on this car. Only engine crossmember and rear axle crossmember has got
damage from a jack.

Could this be normal ? Seems to much difference between the two sides to me.
There were also a lott more shims on the right than on the left side. Shims
seem to be original (already pretty much rusted).

Thanks for any input.

YT

YT wrote:
> Hi,
>
> Have a urgent question about the C3 frame. I have a 79 here which has the
> complete right side (were the 4 bodymounts are) sitting on average 1/2"
> higher than the left side. Cross measuring from one bodymount to the other
> suggest the frame is still very much straight.
> I had the frame jacked up evenly (with carpentersbubble) both on the front
> and back outer tips (measurements taken from a workshop manual/engine,
> transmission, rear axle, tires, still on it)
>
> There is no evidence of an accident on this car. I checked it already for
> nicks, welding etc, but have found nothing. Welds are still looking normal
> on this car. Only engine crossmember and rear axle crossmember has got
> damage from a jack.
>
> Could this be normal ? Seems to much difference between the two sides to me.
> There were also a lott more shims on the right than on the left side. Shims
> seem to be original (already pretty much rusted).
>
> Thanks for any input.
>
> YT
>
>
You'll have to give a better problem description than that. Are you
saying the body (and frame) "leans" to the left side when the frame
isn't propped up straight, or that the frame is bent, or that the
bodymounts on one side aren't in the right position, or what? What does
"on average 1/2" higher" mean... random, higher in back than front, or
what? You also state that there were "a lot more shims" on the body
mounts of the same side that's high. Either that's a "duuhh!" or you got
me all confused.

Wayne,

I'm going to try and give you a better discription :
This is what I did. I had a sheet here that gave the height of the frame
bodymounts (top of these mounts) from a certain datum line both on the front
and back tips of the frame ends + for each bodymount.
Since the datum line in this drawing was under the car (where my floor is
now) and it is difficult to measure the top of the mounts from this line, I
used a datum line above the car. Recalculated the difference in heigth
between the front and back tips of the frame and adjusted according it.
Frame hangs flat + level (hanging on the front and back tips of the frame)
Then I used a tube filled with water and measured the heigt difference for
the bodymounts (all 8 of them) from this datum line
What I got was (difference in height left to right) :
- difference on bodymount nr 1-2 : 0,51"
- difference on bodymount 2-3 : 0,55 "
-difference on bodymount 5-6 : 0,28"
- difference on bodymount 7-8 : 0,20"

So as far as I can see the frame has got the correct height on the tips both
front and back and thus is level, but the middle of the right side rail is
sitting high compared to the left side. This would suggest a front end
damage on the right side, but I cannot find any trace of this.

When the body is on it, there is a difference, meaning that it leans about
0,50 " (measured to the lower siderail of the birdcage) to the left.

Concerning the bodyshims : for an example : there were about 4-6 shims on
the right side (nr 4-6) and 3-3 on the left side (nr 3-5). You would expect
them to be less on the right since this side is higher...

You're not the only one puzzled by this.

Thanks again Wayne.

Yves

Yves
"WayneC" > wrote in message
...
> YT wrote:
> > Hi,
> >
> > Have a urgent question about the C3 frame. I have a 79 here which has
the
> > complete right side (were the 4 bodymounts are) sitting on average 1/2"
> > higher than the left side. Cross measuring from one bodymount to the
other
> > suggest the frame is still very much straight.
> > I had the frame jacked up evenly (with carpentersbubble) both on the
front
> > and back outer tips (measurements taken from a workshop manual/engine,
> > transmission, rear axle, tires, still on it)
> >
> > There is no evidence of an accident on this car. I checked it already
for
> > nicks, welding etc, but have found nothing. Welds are still looking
normal
> > on this car. Only engine crossmember and rear axle crossmember has got
> > damage from a jack.
> >
> > Could this be normal ? Seems to much difference between the two sides to
me.
> > There were also a lott more shims on the right than on the left side.
Shims
> > seem to be original (already pretty much rusted).
> >
> > Thanks for any input.
> >
> > YT
> >
> >
> You'll have to give a better problem description than that. Are you
> saying the body (and frame) "leans" to the left side when the frame
> isn't propped up straight, or that the frame is bent, or that the
> bodymounts on one side aren't in the right position, or what? What does
> "on average 1/2" higher" mean... random, higher in back than front, or
> what? You also state that there were "a lot more shims" on the body
> mounts of the same side that's high. Either that's a "duuhh!" or you got
> me all confused.

In article > ,
"YT" > wrote:

> When the body is on it, there is a difference, meaning that it leans about
> 0,50 " (measured to the lower siderail of the birdcage) to the left.
>
> Concerning the bodyshims : for an example : there were about 4-6 shims on
> the right side (nr 4-6) and 3-3 on the left side (nr 3-5). You would expect
> them to be less on the right since this side is higher...
>
> You're not the only one puzzled by this.

What condition does the driver's seat look like? How many miles are on
the car and how much use do you see on the interior - like the brake and
accelerator pedals?

I'm heading off in the direction that a very heavy driver used the car
on a regular basis and the left side springs are more tired than the
right. I've seen it with other cars, so I guess it could be similar on a
Corvette.

What you're saying is that when the car sits on a, for all intents and
purposes, "level" surface, the top of the arches of the wheel openings
differ from side to side by 1/2"?

Here's waving to ya - \||||

Owen
___

'67BB & '72BB

-- not affiliated with JLA forum in any way -- alt.autos.corvette is
original posting --
___

"To know the world intimately is the beginning of caring."
-- Ann Hayman Zwinger

Car is pretty clean inside and out. Body is not on it right now. It had some
fairly good use on it, but of coarse it is 25 years old.

Thanks

Yves

"Barking Rats" > wrote in message
...
> In article > ,
> "YT" > wrote:
>
> > When the body is on it, there is a difference, meaning that it leans
about
> > 0,50 " (measured to the lower siderail of the birdcage) to the left.
> >
> > Concerning the bodyshims : for an example : there were about 4-6 shims
on
> > the right side (nr 4-6) and 3-3 on the left side (nr 3-5). You would
expect
> > them to be less on the right since this side is higher...
> >
> > You're not the only one puzzled by this.
>
> What condition does the driver's seat look like? How many miles are on
> the car and how much use do you see on the interior - like the brake and
> accelerator pedals?
>
> I'm heading off in the direction that a very heavy driver used the car
> on a regular basis and the left side springs are more tired than the
> right. I've seen it with other cars, so I guess it could be similar on a
> Corvette.
>
> What you're saying is that when the car sits on a, for all intents and
> purposes, "level" surface, the top of the arches of the wheel openings
> differ from side to side by 1/2"?
>
> Here's waving to ya - \||||
>
> Owen
> ___
>
> '67BB & '72BB
>
> -- not affiliated with JLA forum in any way -- alt.autos.corvette is
> original posting --
> ___
>
> "To know the world intimately is the beginning of caring."
> -- Ann Hayman Zwinger

Barking Rats wrote:
> In article > ,
> "YT" > wrote:
>
>
>>When the body is on it, there is a difference, meaning that it leans about
>>0,50 " (measured to the lower siderail of the birdcage) to the left.
>>
>>Concerning the bodyshims : for an example : there were about 4-6 shims on
>>the right side (nr 4-6) and 3-3 on the left side (nr 3-5). You would expect
>>them to be less on the right since this side is higher...
>>
>>You're not the only one puzzled by this.
>
>
> What condition does the driver's seat look like? How many miles are on
> the car and how much use do you see on the interior - like the brake and
> accelerator pedals?
>
> I'm heading off in the direction that a very heavy driver used the car
> on a regular basis and the left side springs are more tired than the
> right. I've seen it with other cars, so I guess it could be similar on a
> Corvette.
>
> What you're saying is that when the car sits on a, for all intents and
> purposes, "level" surface, the top of the arches of the wheel openings
> differ from side to side by 1/2"?
>
> Here's waving to ya - \||||
>
> Owen
> ___
>
> '67BB & '72BB
>
> -- not affiliated with JLA forum in any way -- alt.autos.corvette is
> original posting --
> ___
>
> "To know the world intimately is the beginning of caring."
> -- Ann Hayman Zwinger

No, it appears he's saying the frame is out of spec, because when the
reference points at the front & rear of the frame, right and left, are
all leveled, the passenger compartment body mounts on the right side are
higher than those on the left side. Sounds like he needs to have a good
frame shop check it out and bend it back into proper shape, if the
distortion is noticeable when the body is on.

In article >,
WayneC > wrote:

> No, it appears he's saying the frame is out of spec, because when the
> reference points at the front & rear of the frame, right and left, are
> all leveled, the passenger compartment body mounts on the right side are
> higher than those on the left side. Sounds like he needs to have a good
> frame shop check it out and bend it back into proper shape, if the
> distortion is noticeable when the body is on.

If the body sits level does it really matter? He indicated something on
the order of twice the number of shims on the "high" side - maybe the
mounts in the body were fabricated a tad out of specs and that's why the
factory shimmed it noticeably more than the left.

Here's waving to ya - \||||

Owen
___

'67BB & '72BB

-- not affiliated with JLA forum in any way -- alt.autos.corvette is
original posting --
___

"To know the world intimately is the beginning of caring."
-- Ann Hayman Zwinger

> If the body sits level does it really matter? He indicated something on
> the order of twice the number of shims on the "high" side - maybe the
> mounts in the body were fabricated a tad out of specs and that's why the
> factory shimmed it noticeably more than the left.

> Owen
butt it would be a pretty easy fix with a bare frame.
Check it out and fix it now, with either proper body mounts or frame
straightening whatever the best frame guy around tells you to do. It's
always a good idea to start with a strait foundation

Kickstart

Hi guys,

I did some additional measuring and comparing of these values again.

As far as I can see it now, the left front of the siderail (where the
bumperbrackets mount and front suspension mounts) seems some half inch
higher than left (when I have the bodymount positions levelled out to the
right side). This could in my opinion explain for the fact, when levelled at
the front and back, the frame would try to sit lower on the left side (in
the middle where the mounts are). What do you all think ?

Of coarse I can have this corrected on a bench (pulling the front left leg
about 1/2" down), but since there is already some extensive shimming on this
frame (shimming which was still like it came from the factory), the
question arises, if these frames had this kind of deviation from the
'correct' values when new. I read info on the net that suggests that the
factory shimmed the frame because the frames where already out of specs when
built and the fact that it were not the body's that needed shimming...
(where did they make the frames anyway, this kind of deviation
considered...China ?? I always thought that frames should be as close to
specs as possible)
An accident should of coarse also be considered (hit front wheel ?), but I
didn't find any trace on the front suspension points either. I would think
that the lower suspension arms or spring towers would tear off or something.
All welds are still looking normal.

Thanks

Yves

"YT" > wrote in message
.nl...
> Hi,
>
> Have a urgent question about the C3 frame. I have a 79 here which has the
> complete right side (were the 4 bodymounts are) sitting on average 1/2"
> higher than the left side. Cross measuring from one bodymount to the
other
> suggest the frame is still very much straight.
> I had the frame jacked up evenly (with carpentersbubble) both on the front
> and back outer tips (measurements taken from a workshop manual/engine,
> transmission, rear axle, tires, still on it)
>
> There is no evidence of an accident on this car. I checked it already for
> nicks, welding etc, but have found nothing. Welds are still looking normal
> on this car. Only engine crossmember and rear axle crossmember has got
> damage from a jack.
>
> Could this be normal ? Seems to much difference between the two sides to
me.
> There were also a lott more shims on the right than on the left side.
Shims
> seem to be original (already pretty much rusted).
>
> Thanks for any input.
>
> YT
>
>

In article > ,
"YT" > wrote:

> the
> question arises, if these frames had this kind of deviation from the
> 'correct' values when new. I read info on the net that suggests that the
> factory shimmed the frame because the frames where already out of specs when
> built and the fact that it were not the body's that needed shimming...

Hmmmmmmm. Seems I read a loooong time ago it was due to the body molding
process that the shimming took up the variations in mounts on the body
assembly.

Here's waving to ya - \||||

Owen
___

'67BB & '72BB

-- not affiliated with JLA forum in any way -- alt.autos.corvette is
original posting --
___

"To know the world intimately is the beginning of caring."
-- Ann Hayman Zwinger