This might be a silly question but did you just do a complete rear end rebuild? I think a lot of people make the mistake of tightening down the snubber,trailing arms, and shock mounts before settling the suspension. Dave..

 

Yes: And despite what the people selling these types of rear springs are saying, I'm beginning to believe that load rate has alot to do with the way the rear end reacts. The spring I got is suspose to be rated at 315lbs. The stock steel spring is rated a 196lbs. I think that's the problem. So, I may be going back to the 'stocker'. Don't know if I can get my 'bread' back for this mono spring. I contacted the place I bought the spring at about all of this & they just seem to "blow me off". I guess I could get some sort of satisfaction if I pressed it. The place I bought the spring from is called "Fast Corvette". They're really helpful as long as your buying things from them. But, just start mentioning that you're unhappy about one of their products, or are having trouble with something & they seem to have a "different tune" to the whole issue. I guess they just refuse to believe that people can have trouble with their products. Their prices are good & their tech dept is OK, but I think they are uncaring to a person wanting to return something they don't like. Just my observation about "Fast Corvette" as it stands right now.

 

Let's Try That.

ttt

 

About lowering the car....

Basically what you really want for your rear suspension is to have the rear half-axles parallel to the ground. This places almost minimal stress on the U-Joints. So to adjust the rear, you have to figure that with a full tank of gas you have 6.35 pounds per US gallon in a 20 gallon tank for a early C3. You have a ??? 200 lb driver (I've picked up on the fact that we have some really tall C3 drivers. I'm 6'2".) With this weight, you make the rear half-axles parallel to the ground. Then adjust the front springs to make the car evenly horizontal.

I have 225R50/17 tires. Lowering the rear to meet my horizontal half axle criteria gets the car pretty low. I will have a pretty minimal clearance for street driving since I will be running sidepipes.

The rear adjustment is done with the bolt between the rear transverse spring and the trailing arms. The stock bolt with the stock iron spring is 6 inches. I bought VBP 360# spring which included an 8 inch bolt. This bolt was too short. I bought from VBP a 10 inch bolt and this works. I have it at the maximum length now and the differential is setting a little low. I will probably end up with an effective bolt setting of ~9.5 inches to get the half axles parallel to the ground with running weight on the rear end.

Once again...my opinion. You don't want to pick some cosmetic value for the amount to lower the car. You should lower the car so that it runs withe the rear half axles parallel to the ground. If the half axles are parallel to the ground and you think the car is too high, you need to start lowering something else.

 

Thanks 68/70vette: Yes I was aware of the fact that the proper ride height should be where the half shafts are parallel with the ground. That's where I want to be at. As it stands right now, the car's way too high. Maybe I'll try 10 inch bolts. I've got the 8 inchers in there now. I'm running those same size tires as U are, but in the front (225-50R-17). In the rear, the size is 245 50R-17. These tires are just about 27 inches tall, which fill up the wheel well pretty good. But to have about 4 inches of clearence between the top of the tire & the lip of the wheel well is way too much. I was thinking of going back to the stock steel 196lb rated spring. What's in ther now is one of those mono composite springs rated at 315lb. There seems to be way too much arch in the spring as it sits right now.

 

It seems that many forum members complaint about the fiberglass springs from Muskegon, there were also many horror stories about re-arched steel springs - the rear was reported to sit way too high and 10" bolts were needed to get it down...

I also have a re-arched spring. With 8" bolts my rear is sitting at 28.5"

From what I heard and read the fiberlass springs from VBP are great. You may want to call them....

 

ttt again

 

For what it's worth, I'm running a 360# VBP composite spring in the rear, with 8" bolts. With stock bolts, when I first put it in, the sucker sat WAAAAYY too high. It settled a bit, I put the longer bolts in, and it sits just fine.

 

Seems to me there was a discussion a month ago about Fast Corvette. Don't think I was very complimentary.

The Vette Brakes and Products Dual Mount rear spring does not seem to have issues with ride height and is adjustable for spring rate and height.

 

I would use longer bolts to acheive the desired ride height, then determine if you have clearance issues.

IMO the ideal ride height is with the half shafts angled down slightly towards the wheels. That way under heavy acceleration and the rear squats, the u-joints are straight during highest loading. Also, this will allow the rear wheels to toe-in slightly during cornering. After installing side pipes on my car, I lowered it as low as I dared (with half shafts angled up towards the tires). It looked great, but it had a tendancy towards snap oversteer at high speeds because the rear wheels would toe-out in the corners. Or you can raise the differential...which I am working on.

 

I have the 330 lb. adjust the bolts for proper ride height. VBP (supporting vendor) has them. call them if you have ?'s You can also install a front mono spring to get 4 corner ride height adjustment. It is a pretty sweet set up.

 

Torque everything down at ride height.
Aside from the cosmetic issue, ride height may also affect your cornering: I found mine got very tail happy when it was sitting too high.

 

Thanks guys (and gals?) for all of the posting on this thread. I'm the originator of this thread. What I need to know is Y I can't get the rear of my vette to ride height? Is there something that needs to be done to get it to ride height?

This is what I've done so far. I put in the longer spring bolts & have them adjusted all the way to the bottom of the threads. Still no noticable drop in ride height. Car sits up way too high & is showing way too much top of tire wheel well. So, am I missing something? I'm planning on taking out the TRW mono spring & replacing it with the OEM stock steel spring, if I don't get results. Any thoughts?

 

Sounds like the problem is with your muskegon spring. I have a vbp dual mount and with 8 inch bolts, I was able to hit 27 inch ride height in the rear.

 

Take digital pics of the half shafts, spring, etc....pictures are worth more than words...maybe we can spot something....

 

Hmmm.... another satisfied customer. I'm sorry to hear that you were unfortunate enough to buy a TRW spring. I suppose somebody should report them to the Better Business Bureau. I wonder how many thousands of dollars have been wasted on these springs by Corvette owners over the past 20 years.

Here's a link to the thread that was referred to earlier Composite Rear Springs - Why So High? . It should answer all your questions.

Here's a pic showing the proper geometry of the rear suspension:

 

Yep...That's how mine sits...good ol' 7 leafer....

 

kid vette lives for these kind of posts...

 

"Kid Vette": Thanks for the post & the pic. Yeah..that's how it's suspose to sit. Too bad mine don't look like that. To tell U the truth, you know how much arch the spring (TRW composite) has when U first take it out of the box? Well, that's what it looks like installed on the car. It hasn't flattened out one iota. So, I'm gonna go back to the stock 196lb rated spring & see what happens. My kid sez it's too bad, as the spring looks "bitchin" in the car. Much better than the stock spring.

 

Hey "Kid Vette": Where is Edwardsburg?