installed tha long c4 bolts.. when all pressure from spring and axle is released (still have jack stands in front of trailing arms) i have about 2 inches of naked bolt above tha bottom bushing and nuts below tha spring itself.. guess in other words tha bushings aren't seated in tha spring and below tha cup in tha spring???.. its like tha bolt is totally way (at least 2 inches) to long???.. what am i missing???

will try ta get a pic....

 

Normal??? without a load???

 

Those look like the parts we use on our C3's. You have the wrong bolts as they are a bit too long in your application.

I had some work done and when I got the Corvette back the rear end was all jacked up and the car looked funny. I approached the mechanic and he assured me it would settle down a bit. It NEVER Settled at all. It turned out the mechanic at a Chevrolet dealership put the wrong length bolts in my rear. It was not until someone told me about it and I bought the right length bolts that my car would finally settle down. It worked and now I can lower the rear or raise it just by adjusting those long bolts.

Using those longer bolts might not work. I would bet that your bolts are shorter than what you have on the car. I will go take a peek at my C4 and see what is different. I have 2 Corvettes, a 1968 BB Convertible and a 1988 C4 Coupe.

For what it is worth I would Install the tires and wheels before making any fine adjustments to the suspension. The half-shafts should be close to horizontal with the chassis set up properly.

The young mechanic at the dealer swore they were the bolts that it called for. They listed the shorter bolts in the newer books for a 1968 427 Convertible. I would probably to a reputable Corvette Aftermarket companies like ZIP and others. My bolts were purchased at Vette Brakes and Products which sold the long ones for less than $20 (a while ago) when I bought mine. Van Steel is really good with read end chassis parts would have the shorter bolts if that is what you really need. If you have a source for Good quality hardware you could get a Grade 8 bolt the right length and use it as long as it is a Grade 8 with the right nuts.

If some chimes in with the length soon or I will go out and climb under the car and measure the bolts that I use on a 1968 C3. It was like a 6" bolts versus a 8" bolt making the huge difference in how the car sits.

I have a rebuilt Steel spring in my rear end. We dismantled it down to the individual pieces and then sand-blasted the metal parts before painting them before reassembling the spring. We used a kit which had the right rubber pieces that are part of the rear spring once assembled. Lots of grease and a messy but unique experience. The rebuilt spring has worked for three decades and has no squeaks or noises.

 

my understanding is tha longer tha bolt tha lower you can get.. seen 9 and 10" bolts advertised for tha lowering on tha c3... was told and have read that tha c4 bolts will work.. doesn't look like it to me though.. gonna drop it down on tha tires in a little bit.. will see what happens... maybe with tha stock spring but not tha composite single leaf???

tha c3 stock bolts really aren't that adjustable with tha bolt drilled for a castle nut and carter pin...

 

When you get it all down on the ground, the first thing you want to check is to make sure that the end of the bolt does not extend past the lip of the wheel. If it does, and you get a flat, the bolt will dig into the pavement and you will have a big problem on your hand, the worst part being you could loose control of the car.

 

6 3/8” is the factory bolt length. I’ve seen 8” to drop the end down a respectable amount. Those in your picture look extra long though. I would be concerned about hitting the tire, and like above, losing control of tha car.

 

Yes, 6 3/8th's is standard length. I am running 7 inch bolts with my mono spring for a ride height I am very happy with.
These bolts are not rocket science. 9/16ths or 14 mm hardened bolts is all they are.

 

understand 'bout tha bolts and length thing... very few places carry anything in that length in stock... i've got a coupla 8" and 9" but had to order from Fastenal.. had tha 8" installed prior to tha ones ya see... got these ya see from a friend.. supposed ta be stock c4's and supposed to work.. have my doubts now though.. tomorrow will tell tha tell....
thanks all........

 

They may be C4 bolts but I am not positive. They look like the long bolts on a car with no weight on the tires. That appears to be a C3 in your pictures however. They do look similar down there.

If you have a C3 then why would you try the C4 bolts? The Correct Bolts would have more threads on them and made for this application. Standard hardware Metric or S.A.E. does not normally have the threads up that far on the bolt. They sell them at ZIP Products for $74 a set for the 8" bolts if that is the right length. How long are the ones that you are using now?

Put the car on it's tires and show us the excess bolt length with the wheels and tires installed and on the ground 100%.

 

it is a c3.. tha "stock bolts are close ta 7 inches long.. i also have a set of 8 and 9 inch bolts..tha ones in tha picture are 10+ inches.. i want a lower ride height is reason i change tha bolt lengths... stock height it looks like a four wheel monster truck!!! using tha 8" looks lots better but really wanted a tad bit lower with tires and wheels i'm puttin' on it... got tha front right with a spring change.. probably have ta settle on tha 8 or 9 inch...

 

results are in!
these pictured are indeed c4's.. there are two available for tha c4, 8 3/4" and 9 3/16".. these iv'e got are tha later and are, in my opinion, too long for tha c3..
tha c3 bolts are 6 1/4" with a 8" available.. goin' with tha 8" till i get bigger dia. wheels............... but as said they are jus plain 'ole grade 8 9/16 bolts so any length is possible............

 

Are you aware of the D height measurement in setting the C3 rear ride height? It's basically the difference in height measured from the ground at the inner and outer half shaft u-joints. The half shafts with driver and full tank should be slightly higher at the differential end. Dropping the car to level with the ground or higher at the wheel end of the half shaft isn't recommended.

 

i knew there were recommendations of sort with it but didn't pursue it.. jus want it ta look (appealing) right ta me... its more or less a garage queen anyway till my grandson takes over.. sooooooooooooooooooooooooooooo.

 

This is why you don't do that. The end of that spring, and the sidewall of your tire, will occupy the same space at the same time. Guess which will win!


From this (long) thread (well worth a read!)

https://www.corvetteforum.com/forums...igh-still.html

Short answer, return those bolts, and get a Van Steel low-arch composite spring instead. The Hyperco kayak paddle spring is terrible.

 

When I lowered the back of my 81 I bought some grade 8 1/2 bolts that I planed on cutting to get the car to sit exactly where I wanted it. While I was rummaging through my tool box I happened to notice the stock rear bolts from my 91 ZR-1. Initially I was going to cut a set of bolts 8 1/2 inches but I grabbed these bolts from my Z and put them in the car. Car sits perfect with the stock rear ZR-1 spring bolts,I didn't even measure the bolts. Got lucky I guess. By the way,my Zs got 10 inches rear spring bolts. Is it safe,been like that going on 20 years and nothing hangs down past the bottom of the rim.