Hey all,

Have a 69 vette and just about 80% done with a frame up restore. I got 95% of the weight in the car and the suspension is high. Any ideas why? It does have new EVERYTHING. The spring was swapped out with a fiberglass mono-leaf. Could get more picts if you want. Also took one of the front end as well. The tires are not stock, and are smaller in dia. but wider. So that is some of it. But still she sits high...

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With the smaller diameter tires, what are the actual ride height measurements vs. what they are supposed to be?

What type of engine do you have in? What front springs are you using and what is the weight of the rear mono spring you have?

 

Here is the kit I got...

Kit

It is a 350... Would have to double check the tires, but think 145 70 15

 

Did you tighten all the suspension bolts that have bushings before getting all the weight on them? Especially front A-arm bushings, but I guess rear trailing arm and camber rods could have some affect also.

Ralph

 

Yes the frame was supported when I did that. They were tightened without weight. I see some people say it will settle some. But seems it would have to settle allot. And I have "bounced" it and she moves fine (very stiff, but they all are).

 

Hi bd,
I believe that the car should be sitting down on it's tires when the 4 (upper/lower) a-arm cross shaft bolts are tightened. That may be part of your front ride height situation.
The same is true for the 4 bolts that mount the rear leaf spring. I'm not sure about a mono spring.
In your case it looks like you've discovered what most people do when they up-grade to a mono-spring.... they need to use much longer bolts from the trailing arms to the end spring mounts.
The 'stock' ride ride height is very close to 28" when measured from the ground to the center of the wheel arch.
The height dimension depends on the height of the tires too. The original F70-15 tires (which were part of the 28" dimension) were 26.9" tall.
I hope this info is of some help to you.
Regards,
Alan

 

All final suspension torques are completed with the wheels on the ground.

 

I will be real interested in your findings/resolution on this one. I was thnking mine also looks high, and I did the same thing you did. Put a mono spring on the back and I went with the short MOOG springs on the front but those were suppose to have the same rate as the factory.

 

Did that kit come with 8" rear spring bolts and if so how far up did you tighten the nuts?

 

If you do some searches on the forum, I think a lot of guys put in 8 in bolts to lower the rear end.

Between tightening the A-Arms with weight on them and possible aluminum heads on the engine, that may get you a couple inches off in the front. The heads is just a guess.

 

What was the 'spring rate' on the monospring you purchased? I'm fairly convinced that more than 330# spring will sit excessively high in the back. Mine came with a monospring (don't know what rate) and it was sitting high [not as high as yours], so I installed 8" bolt-links from spring to T/A. Now, the front and rear wheelwells have about 2" clearance to the top of the tires (235R60-15). It sits nicely, at present.

I think you will need 8" bolts (at least) to drop the rear significantly. The problem then becomes the length of the spring could interfere with the inner sidewall of the tires. The metal hardware attached to the ends of my monospring were protruding some, so I used a powered grinding wheel to remove those protrusions and smooth them down, minimizing risk of tire damage during operation.

I'm thinking the monospring manufacturers don't do a great job of shaping and sizing those springs to fit well with the C3 application.

Also, are you certain that you got the lower end of the front springs properly installed in the A-arms? If they are, then you must have installed high spring rate springs up-front, as well. With a small block engine, those hi-rate springs may need to be cut down a bit to get the ride height correct.

 

Check this post:
http://forums.corvetteforum.com/c3-t...-car-look.html

and:


http://forums.corvetteforum.com/c3-t...esponse-2.html

TheSkunkWorks also was good enough to post a link that will be very helpful.

http://www.corvettefaq.com/c3/ChevyPower.pdf

If you look at figure 11 on page 10, you will see the “D” height. You may need longer bolts.

 

One more piece of information to add to what's already been shared here, If you haven't moved/driven the car any since it came off the jack stands, expect it to "drop" an inch or so when you do move it. The car has to settle into the suspension.

BTW, the project's looking nice!

 

Will 10'' bolts lower the rear end. Thats what i was thinking of trying.

 

10" bolts will not fit a stock C3. The rear of the car would be dragging the ground (most likely). Because of the 'leverage' involved with the distances between the rear wheel bearing (in the T/A), the T/A attachment point to the body, and the drag link [bolt] connection at the rear of the T/A, the amount of body drop is greater than any increase in bolt length. So, you want to be careful about the amount of change to the bolt length. If you need to drop the rear about 2" (+/-), increase the bolt length about 1".

 

I see a lot of post say they put 10'' bolts on there c3,to lower the rear,after reading your post iam a little confused about the 10'',i dont think it would lower the rear only a inch or so. so maybe i will hold off ordeing them.

 

Not to steel the OP's thread but I measured my ride height because I think my front end is too high, it came out to 29 5/16, I have 255/60/15's. I'm thinking that someone along the way put aftermarket front springs on so I have two choices, either cut the spring and hope I get it right or buy stock springs. Correct?

 

I put 17x8 wheels on,so maybe 10''bolts will be ok. if they dont i will just put the 8'' back on.

 

I can't speak for the front end but I just rebuilt the rear of my 76. I torqued my adjustable struts about 1/2, put the car on the ground and torqued to spec. The car looked like a 1960's hot rod - way to high in the back. I actually rolled it back and forth about 10 feet a few times and it settled almost 1 inch. Took it out for a 25 mile drive and it's almost down to wear I started. I retorqued everything one more time and am good to go.

 

Hi 7T1,
Are you sure about the relationship between bolt length and body drop?
My experience was that the body dropped 1/2 the increase in bolt length, (not twice the increase), because the center point of the spring stays mounted at the same point, and the bolt end of the spring is traveling in an arc.
Isn't that the reason some people feel they need to go beyond the 8" bolts and have problems with the even longer bolt touching the wheel or tire?
Regards,
Alan