Completed the front suspension rebuild; new coil springs, ball joints, rubber bushings etc etc. Went just fine. Each side measures about 27" from fender tip to the ground. Right where I wanted it.

Rear end had droopy drawers so I ordered a steel 9 leaf spring and bushing kit from one of the big supply houses. New and old springs are 2.25" width.
I noticed that the old one is only a hair over 2" thick while the replacement measures 2.75". So I went and got longer bolts to mount it and put it in. I was careful to measure and make sure they won't bottom out and crack the diff when I torque them down.

Used the standard 6.25" bolts in the bushing kit - same as the ones I took out. I left the bolts on the mounting plate but not cranked all the way down and intended to do that after it's settled. The rear end is waaaay up now. Measures 31" from fender to floor. Took it for a 2 mile spin around the hilly bumpy neighborhood and no change. Rides nice anyway, like a new pair of sneakers. I can loosen them and drive it some more, but they really aren't all that tight.

So I ordered 8" bolts and have to wait a few days - couldn't get them locally. The spring is stenciled JRS 21-307 which I see is the John R Spring Co in Michigan, no doubt where the supply house gets them. I really don't want those long bolts so close to the tire and rim and am concerned about ever getting a flat - but it's easy enough to try them when they come in. If I have to I'll put the old spring back in with shorter bushing bolts.I think I'll give JRS a call after the holiday weekend and ask them what the spring rate is - I think the factory should be 196lbs.

This is one of those here we go again topics I know, but this is a global forum and I'm just fishing for ideas and would appreciate any. Maybe I missed something.

 

I did the same with my car but put a new 7 leaf in and was told it would settle in a few weeks and to keep a full tank of gas...............after 6 years it settled 1.5 or 2 inches........I bought a fiberglass spring and looked much better..........I got tired of explaining of "why do you have air shocks on your car?"

 

Thanks for the post. Please let us know if the 8 inch bolts resolves the ride height problem; I also need a new spring (9 leaf) for my 70 and have been considering the from John R spring. What size tire are you running?

Thanks JFG15

 

jfg15 - I certainly will. Those are 245/60R15 BFG T/A tires - on all four corners.

After some thought it seems to me that the standard 3.25" bolts for the center mount and the 6.25" bolts for the bushings have probably been on that car for half a friggin' century and why am I trying to overthink the GM engineers that put them there in the first place? I don't have an AIM and would like to know what the factory specs for those are, including the thickness of the original spring if anyone here knows.

The old spring may not have been ideal but it really wasn't that bad compared this new one that I am pretty certain is installed correctly and know is about 30% thicker. Longer bolts that could cause clearance issues and have the potential to create real trouble with a flat just sounds like making a second mistake to correct the first one. This isn't a Saturn V rocket hissing on the pad, we're talking about six bolts and a spring.

If it were just a bit higher I believe it would settle. Having just rebuilt the front suspension and seeing it do exactly that after a few short trips (total maybe 10 miles) before I torqued the cross shaft bushing bolts down I would never have posted this. Right now I could put a loaf of bread on top of the damned tire and it probably wouldn't touch anything, and I find it hard to believe that it will settle that much.

Next week I'll give JRS a call and see what they say, as well as the supply house. We'll see and I'll post it here.And if I screwed up somehow I'll post that too. The supplier has been cool so far and I'm not bashing them (or even naming them). All I want is to drive the damned car. To an alignment shop, and then anywhere else.

 

You will be 10 years older and that car won't settle 2 inches...............get the glass spring and you'll be down to earth.........told ya once already I went thru this 15 yrs ago........

 

Screw that. The old spring goes back on and I'll be driving it this week.Waiting years to settle is nuts.

 

I purchased a leaf spring and the back went up. I think I purchased a 10" bolt (sorry, I'm not sure from who). That brought the back end down. This discusses the importance of setting your D height.

https://www.corvetteforum.com/forums...springs-2.html

After the D height was set, I trimmed the bottom of the bolt. Looking at your half shafts clues you in. They will be parallel to the ground.

 

In my opinion: unless you are going for NCRS, there is literally ZERO reasons to replace a rear leaf spring with a metal one. The fiberglass units make for a better ride, reduce a bunch of weight from the rear, and do all this while still having the right fender gap.

 

Which fiberglass spring do y'all suggest? Where can you find the 8 and 10 inch bolts?

 

Any larger hardware company........Fastenal, and you need 10" grade 8 bolts with nyloc nuts!

 

Lots of places on the web.........Vette Brakes......etc....

 

IF you use grade 8 bolts and Nyloc nuts I suggest drilling holes in the bolts and putting a cotter pin below the nut as a safety measure. I removed mine after 7 years and the nylon was loose and the nut spun pretty easily after removing the cotter pin.

 

They are out of business.....

 

If you read the link, this will be a debate with both sides not seeing eye to eye. Getting a quality part will be key. I did a Google search: 10 inch rear spring bolts for a corvette. A few came up


https://www.corvettepacifica.com/pro...ts-pair-84-96/

https://www.ecproducts.com/products/...-pieces-84-96/

https://www.corvettemods.com/C4-Corv...in_p_7232.html

Be sure to match the spring rates to the front suspension. Do not buy a stiffer rear spring and leave the fronts the same. I always like F-41 spring rates and found Daytona too stiff.
So you may want to consider matching the new spring rate to the one in the car now.

 

I just noticed the half shaft in the first picture. Note the angle. They ideally should be parallel to the ground.

 

I noticed in your picture that the scuff pads in between each leaf are much thicker than stock,look to be 5/16(just guessing by photo)the factory style scuff pads are very thin,try willcox corvette for the correct scuff inserts,you can take your spring apart and replace them,this may drop your height a bit.as a side note,eaton/detroit spring has the factory spring specs from GM and can make you the correct spring,they made me a new 7 leaf for my car and it provides correct ride height.

 

A good spring shop might be able to re-arch the spring. I have done that in the past on my trucks when I wanted more height. Maybe they can also do it to reduce the height.

Redvette2

Edit: This likely would not work as the holes at the ends of the spring would be pushed further apart and cause other problems. Never mind.

 

Thanks to everyone who responded. Put the old spring back in and again the rear end stuck up too high. Took the car for exactly the same ride as before and it settled right down. Not hundreds of miles - only a handful. With the new shocks and bushings it's at a bit over 28" and the car seems fine. I torqued the bolts on the carrier plate to 70 ft.lbs and call it done for now. If the ride height remains unchanged I'll replace the scuff pads and clean it all up over the winter.

The scuff pads on the JRS are 1/16"as are the ones in the original spring. I called them and they confirmed the 21307 should be the standard 9 leaf spring for my '69. They had no answer as to why the thing is 3/4" thicker than the one it's replacing. They said that they are indeed made in India. So is the grate for the storm drain down the road (not Pittsburgh anymore unfortunately). I noticed that it isn't sticking up way too high. Can't control where it comes from and if it worked I'd have been happy. I boxed it up and returned it today. As for shipping costs and returns - Amazon seems to have worked out OK for me. Worth a look at least.

The supplier was Corvette Central. Wasn't going to mention the name but they've been totally cool and easy to deal with. I spoke to their product support a couple of times just for the hell of it to see if they had any advice - sometimes you just miss simple stuff. Not in this case. I can't recommend that JRS 21307. If some people got them and they worked OK then I'd wonder about quality control with the manufacturer. If my original spring were broken and I wanted another steel one I'd probably take a look at Eaton. Maybe a composite at that point. Dunno.Hopefully no need to revisit all that.

I didn't like the idea of longer bushing bolts. Three lefts do make a right but I didn't want to go that way - and a flat could make for a bad day.