Frame Tweaked? - NJFBOA - Home of New Jersey's Camaros and Firebirds

BonzoHansen · 05-23-2007, 02:31 PM

OK, here is my dilemma. I got my 77 Z28 back on its feet, actually drove it around the streets a bit last night (fun with no hood). The car feels much tighter then before.

Problem: Here are the ride height measurements (from center of fender lip):
LF: 27” … RF: 26”
LR: 26 ½” … RR: 26”

Now, the car had the RH sag before I did this, but I hoped/thought the old springs were the primary culprit. No dice. I can live with the ½” difference in the back, but the difference in the front is noticeable. Plus the RF wheel has too much negative camber and I am out of adjustment room on the arm (guess I need the 5” adjuster sleeves). At this point, I am making the grand assumption the frame is tweaked. There is evidence of prior damage to some of the sheet metal. I believe the SF is back on correctly. The front sheet metal is straighter now then before I took it off. For now I am discounting a bent spindle since I had this issue before and have changed the spindles during this overhaul.

Anyone know a good place to take it for frame inspection? How much does this kind of thing run?

WildBillyT · 05-23-2007, 03:11 PM

Quote:

Originally Posted by BonzoHansen

OK, here is my dilemma. I got my 77 Z28 back on its feet, actually drove it around the streets a bit last night (fun with no hood). The car feels much tighter then before.

Problem: Here are the ride height measurements (from center of fender lip):
LF: 27” … RF: 26”
LR: 26 ½” … RR: 26”

Now, the car had the RH sag before I did this, but I hoped/thought the old springs were the primary culprit. No dice. I can live with the ½” difference in the back, but the difference in the front is noticeable. Plus the RF wheel has too much negative camber and I am out of adjustment room on the arm (guess I need the 5” adjuster sleeves). At this point, I am making the grand assumption the frame is tweaked. There is evidence of prior damage to some of the sheet metal. I believe the SF is back on correctly. The front sheet metal is straighter now then before I took it off. For now I am discounting a bent spindle since I had this issue before and have changed the spindles during this overhaul.

Anyone know a good place to take it for frame inspection? How much does this kind of thing run?

You can try jacking it in the air and dropping plumb bobs from different points on the frame, marking them on the ground. Then measure between all of the points and see if the dimensions match. This is what I did when I installed my frame rails.

Did you check and make sure that your coil springs are sitting correctly in the spring pockets of your lower control arms?

BMF · 05-24-2007, 12:08 AM

Bonzo,
Before you freak out about the frame being bent or whatnot, there are a few things to check for.

The springs, make certain they are actually seated in the pockets in the frame, they can be out of the pocket and make about a 1" difference in height.
Same if they're rotated in the pockets incorrectly.

last, if you tightened up your front suspension while the car was still in the air (on the lift or on jackstands) it wont sit level when on the ground.

If your frame was tweaked soo bad it sat high by an inch on one side, i seriously doubt the sheetmetal would line up nicely, i could be wrong....but thats my thoughts on it.

BonzoHansen · 05-24-2007, 09:04 AM

Springs are seated, torqued on the ground.

You know, I thought more about this last night. I need to look at the LCA. I never gave that any thought.

BMF · 05-25-2007, 12:28 AM

Bonzo, you know that for certain, did you look up in the frame? Its pretty easy to do when you are putting the springs in to have one that isnt seated.

BonzoHansen · 05-25-2007, 12:59 AM

Yeah, I triple checked tonight. The bottom of each is aligned witht he index holes, and the tops are sitting correctly. And right now the rear leafs are loose, and with the LCA bushings I am using (global west del-a-lum lowers), the front end has good free travel. So it isn't weird bind.

I pulled the shocks out and measured from upper mount (frame) to lower mount (LCA) on each side - same measurement each side. So I think the springs are at the same height each side. I did notice that on the low side of the car, where the rebound bumper on the LCA would contact the frame, the frame looks like the bumper came in heavy contact - there is an indentation that would match the OE bumper, and the other side does not have that. So I am guessing that side got super compressed at one time.

The LCA and spindles appear to be strait. I did a bunch of measurements on each side trying and everything was the same.

BMF · 05-25-2007, 11:39 PM

If you can, get the factory measurements for checking the alignment of the frame, and start there.

It might not be a terrible swap to just put a different subframe in the car.

NJSPEEDER · 05-26-2007, 09:25 AM

if the bump stop made that hard a contact with the frame, i would have to wonder if the control arm or the mounts are tweaked. the mounts and arms are made from far less material and i would think that would give before the subframe.

BonzoHansen · 05-26-2007, 05:48 PM

I made a bunch of side-to-side comparisons/measurements. Everything else seems ok. I spent some time talking to Marcus at SC&C, and his suggestion was to do a 3/8" spring isolator on top. That should bring it up close enough, considering about a 2:1 ratio in ride height adjustment from that point. At least for $20, it is worth a shot. For this app, it isn't worth the effort for now. He told me he has seen pristine examples be off that much and not to stress over it too much. I'll put them in Wed and let you know the outcome.

When the 67 is done, I'll use this as a reason to go aftermarket subframe shopping...

BonzoHansen · 05-30-2007, 12:18 AM

Update:

UPS truck left me a present. A 3/8" Energy Suspension coil spring isolator & a pair of 5" hex adjusters for the SPC arms. Now it is 1/4" short on the RH side, which is fine. I got the alignment eyeballed in, car drove awesome. I can't wait to get it all wrapped up.

Once the new 245/60/15 hoops are on instead of the 225/70/15, she'll drop another 1" or so. Then I am rocking, LOL. Still don't know if I will make Carlisle with it. Not sure I'll have enough shakedown time.

One step closer. Now if I could get the hood on straight.

BTK79 · 06-01-2007, 08:09 AM

cool, nice to be over that hump. if you want to put some miles on that z let me know. i'll cruise with ya .

BonzoHansen · 06-01-2007, 12:55 PM

Cool. I have to paint that tank tonight, put it in on Sunday. I just need to get the hood on right, which is proving harder then it sounds. I have a hinge giving me crap - I shouldn't hvae cleaned & painted them. LOL

bad64chevelle · 06-02-2007, 04:07 PM

Quote:

Originally Posted by BonzoHansen

Cool. I have to paint that tank tonight, put it in on Sunday. I just need to get the hood on right, which is proving harder then it sounds. I have a hinge giving me crap - I shouldn't hvae cleaned & painted them. LOL

Scott if you need me to come and get that hood right for ya let me know. We got everything else lined up, the hood shouldnt be too bad.

BonzoHansen · 06-02-2007, 07:31 PM

I almost got it today. It involved loosening up a bunch of stuff and pushing the nose to the RH side. But I think we need to re-do the LH side. I can get the hood pretty good, but I think the LF hood to nose gap is gonna be too big. The LH door has a bigger gap then the RH door, so I think the LH door and fender needs to slide back 1/8" and also come up a hair. That would even out the gaps, me thinks

What'cha doing this week?