69 Ride Height and how to "settle" the rear

[Greg L.]

So what is the most practical way to check for proper ride height and what should it be for a 69?

My original rear spring was sagged so I bought a good used one from what I was told was from a early mid-year. I cleaned it up and put new liners in, did the final torque to the diff housing with the weight on and used new rubber bushings so everything should be to original spec now. However now the rear sits about 1 7/8" higher in the rear than the front as measured at the wheel well lips.

The car was sagging in the rear before and now it looks way too high. I've read that if I drive it that it will settle but I want to do my alignment before I start to drive it and I need the right height to be at least close for this. I've check the J and K dim as per the AIM but I don't trust them as my floor isn't true enough for an accurate measurement. Regardless, J seems close and K is too high.

So for checking ride height I would think that a measurement from the wheel well lip to the floor would seem like a reasonably accurate way to check ride height. If so what would be the measurements?

Is there any way to "settle" the rear spring? I'm actually thinking of taking it out and greasing the liners or even intermixing some of my original leafs to obtain the correct ride height. There must be better way than to just drive it and wait for it to settle.

Thanks

[Larry M.]

Re: 69 Ride Height and how to "settle" the rear

Your AIM should have a "K" and a "D" dimension in the rear suspension section.

When you installed the spring and torqued everything up, the car should have been on its wheels PLUS additional weight added to the cabin to achieve these K and D dimensions. This is what the factory used.........although they used special fixtures to achieve these numbers.

So loosen up the rear suspension point bolts/nuts, add weight to achieve K and D, and then re-torque. This should/will help. You might still have issues due to the replacement spring, but try this first.

Larry

[Tom E.]

Re: 69 Ride Height and how to "settle" the rear

Greg,
this video from the Michigan NCRS Seminar may help you some.

[Ed S.]

Re: 69 Ride Height and how to "settle" the rear

With all due respect, you problem may have begun with....... "from what I was told was from a early mid-year." I my humble opinion, that irregular rear ride height is way beyond normal settling in range. Post some close up pics of the spring you installed, especially the ends of the individual leafs - there are experts on this forum that will be able to tell you right off if it is an original C2 spring or a cheap repro.

[Duke W.]

Re: 69 Ride Height and how to "settle" the rear

Your original spring may be okay. The most common cause of rear sag is compressed/hardened spring link cushions. Disassemble the original spring, clean it up and inspect for rust. Little pits are not a big deal but "craters" may be an issue. If it checks out paint with a rust preventive coating and reassemble with new liners, and install with new or serviceable spring link cushions.

I think it's clear from the photo that the used spring you installed is totally out of spec and not likely OE on any Corvette.

Duke

[Ed S.]

Re: 69 Ride Height and how to "settle" the rear

If you are able to do what Duke suggests the most important leaf to inspect is the main - large one - if it is pitted or you are the least bit concerned about its integrity you can purchase a single leaf from Eaton spring - I did just that. The issue with the main spring is if it breaks the wheels are all over the place - you can expect a lot of body damage - even if you do not crash into something. If any of the other 8 leafs break you will just get some sagging - nothing catastrophic.

[Greg L.]

Re: 69 Ride Height and how to "settle" the rear

Wow thanks for all the quick replies.

Okay so, I removed the tire tub for some more pics. Near as I can tell it is an original spring and it was bought from a reputable member here about 15 years ago and was told it should work just fine(not by him but from other members). It looked good with no issues so that's why I used it.

Now for my original spring, it has lots of very tiny pits and the ends are worn where the upper leaf has wore through each liner into the leaf below it so those issues were why I thought it was beyond repair....but maybe not.

I've tried the K and D dimension check and determined that my floor isn't true enough for the K and the D is just too awkward to get close enough for any measurement let alone an accurate one, maybe if the car was on a rack but not on the floor for me anyways.

I'm guess that a good guide to correct ride height would be if the half shafts were pretty much level and the spring had little to no arch, correct???

I also wanted to add that there was no spare tire in the tub and there is about 1/4 tank of gas in it. I'm thinking those two factors might lower it 1/8" max so it's probably a moot point.

If it might help I could post close up of one of my original leafs to show the pits and worn ends.

[Ed S.]

Re: 69 Ride Height and how to "settle" the rear

Looking at the position of your spring and axles - which are near parallel to the ground - I would not expect to see such a contorted ride height. Spring and axles look "right" - I checked the Eaton Detroit website - the recommended rear leaf for a standard ride height is an ML813 - for all C2s with SB engines and 68 & 69s. So..... there is no difference in a C2 and your original spring. Something is not right - I would begin to look elsewhere - with your axles almost straight out I don't understand how the body can sit so high.

[Greg L.]

Re: 69 Ride Height and how to "settle" the rear

Since I'm in picture taking mode, here are two of my original leafs. The one on the right is the upper most curved one so that is why there is no wear on it. The one to the left shows wear towards the end from the other spring and the remaining leafs all show similar wear. Any thoughts to the serviceability of my original spring assy?

[Ed S.]

Re: 69 Ride Height and how to "settle" the rear

You made a wise decision.

[Mark M.]

Re: 69 Ride Height and how to "settle" the rear

That looks like an original spring. You may have already done so but have you driven it or put power to the rear wheels yet. The rear of these cars will sit lower than. As mentioned the trailing arm, strut rod and sway bar nuts should be tightened at close to ride height as not not to hold a stain on the bushings. New spring cushions can be stiff or need time to compress. I need to finish a 69 soon with similar issue.

[Greg L.]

Re: 69 Ride Height and how to "settle" the rear

I've driven it about 5 miles so far and haven't noticed any reduction in height.

[Frank D.]

Re: 69 Ride Height and how to "settle" the rear

Looking at the position of your spring and axles - which are near parallel to the ground - I would not expect to see such a contorted ride height. Spring and axles look "right" - I checked the Eaton Detroit website - the recommended rear leaf for a standard ride height is an ML813 - for all C2s with SB engines and 68 & 69s. So..... there is no difference in a C2 and your original spring. Something is not right - I would begin to look elsewhere - with your axles almost straight out I don't understand how the body can sit so high.

^^^^THIS ^^^^^ It almost looks like you have air shocks in the rear.

The half-shafts and spring do look right for a weight-on-wheels "settled" car. I realize the 63s have some unique factors but here is my just rebuilt 63 coupe rear with 1/2 tank of gas and weight in the interior cargo section to simulate the spare and tub. Which is how I did the final torque on the suspension hardware.

I tightened the outboard leaf spring nuts just enough for the castle nuts to clear the hole for the cotter pin and installed it pin.

[Bob R.]

Re: 69 Ride Height and how to "settle" the rear

The new bushings will settle into position after a while and 5 miles is not enough driving to allow it. Based on my car I would think your car will drop an inch or so eventually. When you replaced the spring did you use the correct length bolts. Incorrect length bolts can effect the ride height also.

[Duke W.]

Re: 69 Ride Height and how to "settle" the rear

Too short spring link bolts will raise ride height. Did the original spring have the original link bolts? Did you replace them? Offhand I don't know the length, but measure them and post and someone with a known original '69 can measure theirs for comparison.

Duke