Passenger side

Driver side

The PO installed a new 9 leaf rear spring in my 68 and it looks as though it’s badly misaligned. I was planning on putting in longer bolts to fix the ride height as it’s about 2 1/2 inches too high on each side. That’s when I started looking underneath and saw the ridiculous angle that the bolts are from the trailing arm to the spring. The passenger side is a little worse than the driver side and it looks like the spring is to far towards the rear of the car. The driver side is about the same only less so. Would loosening up the spring and trying to align it correct this? Any help with this will be greatly appreciated.

 

 

But one side seems way more than the other... it's possible the spring is off-center but the bolt that holds the stack together should center it in the differential cover.
Is the yoke sticking out a lot on the half-shaft for that side (from the diff)?
M

 

Need pictures of the center where the spring bolts to the differential cover.

 

It looks like it’s too far towards the driver side and I noticed that the spring is closer to the driver side tire than the passenger side.

 

That's pretty minor and there's more play in that plate than the diff cover, you can use a tape measure to check though. I'm still thinking the trailing arm might be out, can you see the yoke on that side?
M

 

Both half shafts at the diff look the same and neither yoke is visible.

 

So much for that idea
The amount that the bolt is off-center in the plate there hardly seems enough to create that difference on the end. Is the car jacked up in those pictures and are the TA hanging down about the same amount?
M

 

Yes

 

Seems weird, ah well,
use a tape an measure from the end of the spring to the diff housing, not that plate on the bottom but to the castings somewhere on both sides and see

If the TA are just hanging free they swing in a bit of an arc, usually that's controlled by the front bushings and the 1/2 shafts so if they are even and the yokes are good, and the front bushings are good, those two bolts, although on angles should be close to the same.
Try jacking the TA up just until the take the slop out and see if that makes a difference, careful not to take the weight off the jack stands
M

 

I’ll try measuring and see what I come up with. I did notice that with the wheels on and the car on the ground that the end of the spring is closer to the tire on the driver side. I’ll try jacking up on the trailing arm and see how it acts tomorrow. It’s 108 here right now so pretty warm in the garage. I’ll get back to you with my findings.
Thanks for your help so far.

 

Wait till it drops down to 105* before attempting any repair.
Not familiar with the steel stock and bolt above the upper bushing. Is that a rear sway bar? Is that centered correctly?

There is always the slim chance that the holes in the end of the spring was drilled off kilter.

And last but always least. I wonder if the spring mounting bracket bolts were torqued to specs before or after the weight was place on the car?

 

I measured and it’s more towards the driver side by only 1/4”. As for whether it was torqued correctly I haven’t a clue. The sway bar is centered correctly and that’s not a problem. I may just put in the longer bolts, put the wheels back on and put the car back on the ground and see what it looks like.

 

Stranger part is that it's sitting high, normally going to anything longer than the 6" bolt is for lowering the car less than the stock height or using glass springs. I wonder if they had the spring made or re-arched or something.
When the car is sitting back on it's wheels take another set of pics and post them just for future reference
M

OH, HeadsU.P. That steel strip is the "nuts" for the sway bar bracket like you think
M

 

The rear spring appears new and has a part number on the bottom. For all I know it may be wrong for the car.

This is how it sits now. The tires are 60 series and I don’t plan on using them.

 

I recall a situation like this on the forum years ago.
Owner was not happy with a brand new steel spring "stance". His solution was to lay both old and new springs on the garage floor. By carefully disassembling both springs, he modified the newest one by alternating leafs from the old & new.
Bottom leaf was new obviously. Then next was old leaf, new leaf, old leaf and so on until he had nine stacked, banded / bolted.
He claimed he had the perfect arch because the new leafs were too stiff overall.
Lots of work. Have to get the rubber liners in there just so. But if you don't have the old spring . . . . . . . . ???

I need a new rear spring myself. But after reading all the bad reviews about incorrect arch, poor ride, stiff steel, too high, too low, cracked fiberglass . . . . . . . . .

I think I would do something with the arch before swapping to longer bolts. Keep in mind, the longer the bolt, the more hazard in the event of a low tire sidewall.

 

Gas tank full of helium or something?
I see the interior is in or anything but that seem abnormally high. Did they use shorter bolts for the spring / trailing arms? (should be about 6-1/2" long stock)
M

 

The bolts are 6 1/2” stock length. I found some markings on the bottom of the spring. It has JRS and 21-309-219 on it. No other identifying marks on it. I wonder if it’s the right spring. The PO had a habit of doing things incorrectly. The interior isn’t in, and no helium in the gas tank. The gas tank is half full. It seems to be abnormally high. I’m thinking of going with a composite spring. Not sure which one would be closest to stock though.

 

So, I called the spring manufacturer in Michigan and he told me I have a 7 leaf heavy duty spring with a shim. I went to the garage and that’s what it is. Looks like I’ll be shopping around for a 9 leaf stock equivalent.

 

I have an early 1968 Corvette Convertible similar to yours and I had my Positraction acting up so I took it to a local Chevrolet dealer and let them rebuild the differential. It came back sitting much higher in the rear and when I asked about it they told me that the spring has to "settle in" after being removed. The truth was somebody changed the bolts to a shorter one and that made my rear stick up and the half-shafts started binding. The technician changed out my spring hardware as he was under the impression that they were supposed to be 6-1/2" according the a "Book" he was using.

One year at Corvettes@Carlisle I spoke to a older gentleman from VBP and he literally laughed when he heard my story. He suggested that they used the wrong length bolt for my rear spring and sold me a pair that were longer. It solved the problems and my half shafts were MUCH happier. The dealer put the 6-1/2 inch bolts where I had 8" bolts previously. Why? My rear spring is a five-leaf spring, does that make any difference?

The correct bolt length on my 1968 C3 L71 convertible with heavy duty suspension is 8" long.

The previous ones were 6-1/2" and they would not let my rear set down normally. With the wrong bolts the rear spoiler was in sight in the rear view mirror and my half-shafts were at a steeper angle. With the 8" springs the rear looks like it should and the half shafts are not making any noise. I have over 8000 miles on the longer bolts with no rubbing, bottoming out or any issues at all.

I had this Corvette to several Corvette Mechanics and even spent money getting no answers to my problem. I went through a set of half shaft u-joints before I simply put the longer bolts in it. It always surprises me to hear about this problem as it happens way too often. 6-1/2" inches would put my rear up too high and make my half shafts wear out pre-maturely. Beside a Corvette looking "jacked up" in the rear looks silly, to me at least.

If VBP knew about this problem how come nobody else is aware of it? Now with the 8" spring I have the choice of where it rides, you can tighten it up and push the rear upwards or loosen the nut to drop the rear of the Corvette.