Yet again.
So many spring choices, all with different load and spring rates, it's rather hard to determine what to buy,
Mine are like rubber and sit so low there are air shocks to keep it off the bumpers.
I'd be interested in info from those who have replaced theirs with new stock ride height replacements.
No everyone has the same wheel and tire combos so I'm looking for the measurement from the center of the wheel to the fender lip, and the brand/part number of the spring installed.
Thank you for any help,

I just went through this myself and found that Detroit spring offers the best quality and set up for our cars. But in the end it all comes down to personal taste. When selecting your spring, I disagree with your statement of different loads and such. For our cars, when you select springs using you specific data they should all have the came specs. The only thing that can be changed is the arching. The stock springs give a a fairly low ride height, lower than the front even. But that was stock if you look at original specs and stock photos. For my personal taste I choose rear springs with a slight higher lift. When doing this, your front ride height will change also, so you will have to compensate for it. Look at some stock photos and some of the members rides and decide what you like. Its a tedious process, but when done you have the look that you want and are proud of what you did. It really makes all the difference the way a Firebird sits!

Thanks for the reply. You are right about personal taste and the load rate, stock replacements should all be the same so the car sits at the correct height. But after reading all the posts I can find on this site it's obvious some install springs that leave their car too high and some to low. That is why I asked for some measurements. IF someone has installed a set of springs and the center of the wheel cap to the fender is the number I am looking for, that would be a good spring to consider. If someone installed another spring and their car sits lower than I want, I know that is a spring to avoid.
Now the spring rates really vary, Eaton offers three springs for the 68 Firebird coupe, DS01 - 4 leaf, ML035 - 5 leaf and ML 1925 - 4/1 leaf. [four leafs and one straight leaf on the bottom] The spring rates are 175, 90 and 119. Eaton also make a three leaf spring to replace mono leafs, it has a spring rate of 126 and the top of the center bolt is peened flush to fit in the mono leaf perches. They also offer height of +/- three inches for those who want to lower or raise their car.
Other manufacturers and suppliers sites list a wide variety of load and spring rates. not necessarily what GM used but they sell them all the same.
Do you remember what you used when you replaced yours?

Remember also that spring rate refers to the strength of the spring itself and not necessarily the ride height. So you can't really pick ride height by picking a particular spring rate. Seeing as how 69s have a different shape to the rear wheel opening I can't offer any measurements but when I was searching for springs the best deal I could find was from Classic Ind. in LA. At the time they handled Eaton springs from Detroit. Just worked out cheaper for me with shipping and all believe it or not. Also they say that gas shocks will add another 40# to your spring rate and will tend to lift your car a little bit.

The load rate is how much weight a spring will support at a certain height, spring rate is how many pounds it takes to move the spring one inch from that height. Put a couple of hundred pounds in the trunk and the car will lose one inch IF the spring rate is 100 pounds, two springs taking 100 pounds each. Springs can be made to carry the weight of our cars with a variety of ride heights and still have the same spring rate. The challenge is knowing ahead of time, what height your car is going to sit at after the springs are replaced.
A lot of guys have R&R their springs more than once to get the height they want. I've had the front springs off mine four times and really don't want to go through that with the rears.

Anyone remember if there was any measurement in the factory assembly manual? I always measured from the ground to the fender/quarter lip. My front is 26.5 I think, but I have Hotchkis springs.

Yes, the factory has the ground to rocker panel height specs:
Front- 8.4" at 33" behind the center of the front wheel:
Rear, 8.10" at 29" ahead of the center of the rear wheel.

Those numbers go out the window as soon as you replace the stock tires. Any change in tire or wheel size affects the height of the car off the ground. That's why I am asking for measurements from the center of the wheel to the lip of the fender. Most of us have an Idea what we think is just the right stance. Some like low in front high in back, some like low all the way around with huge wheels and skinny tires and some like pure stock.
I think a lot of us want the wheels and tires to fill the wheel wells just so...
Having the airshocks, which I hate, allows me to raise or lower the rear to whatever I want, once I know the wheel center to fender lip distance that looks good, I will get a spring that matches without the airshocks.

Timely topic...
I was just about to order springs from ESPO Spring & Things. And, was wondering if anyone has bought their stock height 4-leaf springs for a 69?
If so, I'd like to find out what the dimension is from the center of the wheel to the edge of the fender.

Well, I made a typo in the factory manual specs:
Front 8.40" at 33" behind front wheel center;
Rear 8.10" at 20" ahead of rear wheel center. [not 29"]
I've looked it up in the AMA specs and it differs from the service manual:
Front 7.0 at 33.1" behind front wheel center;
Rear 6,2" at 20" ahead of rear wheel center.
That is a large discrepancy.

Also found the AMA specs for the 69, that has the front at 6.6" and the rear at 5.3. You wouldn't be able to go over a speed bump without dragging the rocker panels let alone anything hanging down like a cross member or exhaust part. A Hotchkis lowering spring would have the rockers at just over 3 inches, Doesn't seem correct to me.

Rohrt,
How much are the Hotchkis springs supposed to lower the front and do you have basic stock weight under the hood? Mine sits at 27-3/4", floor to fender lip, with what is supposed to be a stock replacement coil, Moog 6312, and 26" diameter 235/60 R15 tires. I do have a bit of weight reduction with an aluminium intake and heads. Coincidentally the tires are almost the same diameter of the stock 14" Firestone Redlines, E70X14-25.76" dia and the F70X14-26,24" diameter.
That has the front rocker panel at 9.5" and the rear measurement at 10". 1.1" higher than that of the Firebird manual specs front and 1.9" at the rear.

27 3/4 seems way high! I have stock springs just put in and it was at 26 1/4, same tires as you. Wonder if your springs are seated all the way....

Yes, they are seated, I've had a lot of practice r&ring them so many times.
My front end weight is most likely near a 100 pounds or so lighter than a stock 68.
There's four of five different springs listed for a 68 Firebird as stock replacement all with different load rates.
Do you know the make and part number of the coils you put in?
Do you know how far the rocker panel is off the ground?

I have performance Springs from Hotchkiss, but they are heavy duty and put your car right at about 26" in the front. It gives you a somewhat aggressive look and the car handles awesome. I first thought I was too low and replaced the coil spring again although I put the previous springs on 2 years ago (same brand). They are identical and they normally outlast the life of the car. If you're interested I'll sell you the once I have. The are practically new, few scratches, but hey, you'll never see it once installed and put you at 26" guaranteed! Both sides where 100% equal, no leaning to one side.

I appreciate the offer but the shipping would be more than the springs and 600 pound spring rate is close to double the 337 pounds I have now. If I was road racing...

I will most likely cut 3/4" off the bottom of mine, that will drop the car an inch and a half and raise the spring rate to 366 pounds.

What about the rear do you have the Hotchkis there as well?

I have a 4 leaf HD set up in the rear, little taller than stock, like it that way.

Are they the Eaton ML1925 4+1 leaf?

I just ditched the 5 leafs I got from dr classic.... I got the hd 4 leaf from summit.. there is a HUGE difference.. I cant wait to see if this solves my traction bar issues...

This is the HD 4 leaf Eaton 126lb rate. I got them at NPD

I would have to look back, but I think that's what I am putting in mine as well, I like the stance it it creates.

That's a nice pic Harold.

What do you have on there for redlines?

https://firstgenfirebird.org/forums/ubbthreads.php?ubb=showflat&Number=303188#Post303188

Thanks 68tpls400,

Are you guys satisfied with the ride these give?

I don't even have them in my hands yet, much less on my car, but I've heard from six or seven people that T/A's are the best riding tire they have ever used.

I have no issues with the tires or the springs. Both have been great.

I haven't used TAs in probably 20 years and I know they have changed since. I've heard people say the rubber compound is hard now. Easy to spin them up but not so great for holding their grip. My son had a set of the g-force on his 5.0 and they seemed to stick pretty well.

Not sure on how much it suppose to lower. I used the BB spring on my convertible. Its all iron with no weight savings anywhere. Ops I take that back I don't have the front cocktail shavers in.

Tires are 25.5 tall so the fender lip is 1 inch taller for me.

I put new TAs on last July, they grip great compared to the tires I took off. They do get hard with age but I think most tires do. I have a buddy who complained his TAs were so hard they wouldn't even chirp when he matted it, but his were 19 years old. I quit riding with him until he put new ones on. They looked OK but who knows what the carcasses were like? 90 mph with those old tires made me nervous.

Aw cmon Al. Don't be such a sissy. ;D
Can't say I blame you. Our time left among the living is getting shorter every day. No sense pushing your luck unnecessarily. The very reason I buy the best tire I can afford.

Well I guess I am a sissy these days, I don't care if the car is a smoke spewing, oil dripping, paint blistered rust bucket, I have to have good tires, brakes, glass and lights.

Years ago I worked at Competition Corvette in Calgary. Four of the crew and I drove up to Edmonton to see the Oilers play the Flames. We only had about an hour and 45 to get there so we had to put the hammer down in the 1963 Chrysler 300 I owned at the time. We spent most of the trip just over 100MPH following a Maserati and a Mustang Mach I, fortunately neither driver had any respect for speed limits. We kept smelling what we thought was the clutch burning in the Ford. The next morning we put the Chrysler on the hoist to check out the shimmy that developed on the considerably slower ride back to Calgary. The front left tire had broken steel cords sticking out of the inner sidewall. We could have killed ourselves or even worse killed someone else.

Scary. Life lesson. Stuff like that never leaves the back of your mind.
(Not tire related but still)
I still think about the the time I was trying to get my oil pan off with the motor still in the car. It just would not clear the cross member so I loosened one side motor mount and, while I was under the car, had my wife pulling on a big 2x4 trying to lift the engine enough that I could pull it free. When I look over at the jack stands and they are teetering over as I tell her to pull. Just one of those stupid things that make you shiver a little bit when you think about it. Lesson learned.

I used some of the information in this thread so I'll add my recent spring project to this one in hopes it helps someone down the road. Yes, much can be said on the spring topic but if you are new to suspension work as I was, I think you just jump in and see what you've got when you're done.

I've been second owner on a 69 convertible since 1999. I put rally 2's and new tires on the car about a year after I bought it. Never had it aligned so I shouldn't be surprised that after 18 years the car was scary to drive and the inside of the front tires were down to the wires.

I'm after new tires but felt it wouldn't hurt to do a redo on everything made of 50 year old rubber on the front suspension. On a recommendation from a mechanic friend, I decided to replace everything up front with MOOG brand bushings, upper and lower ball joints, springs as well as steering rod ends. MOOG makes replacement parts for almost everything on the front end. Capped it off with KYB shocks. Purchased parts from RockAuto. My suggestion for this project is to get a spring puller and outsource bushing/ball joint removal and installation on the upper and lower control arms. I also had my control arms powder coated while removed. Once back on the ground with everything loose to prevent binding I felt the front was maybe a little higher than where I started but I didn't measure it.

Prior to new tires I moved to the back end suspension and the leaf springs. After reading much on the net and this forum entry I decided on the Eaton Springs. I called them and discussed the 2 major options for original ride height. I decided on the 126 spring rate 4 leaf (ML3581). I ended up ordering the springs through NPD as they had the hardware kit required as well as free shipping. For some reason ordering direct from Eaton is +20.00 per spring and full shipping on some heavy stuff. I broke at least 8 fasteners getting the rear springs off. I will echo that one should not be alarmed by spinning the fasteners holding the front spring bracket. Stay calm and cut the heads off the bolts. Replacing the clip nuts is simple once the springs are out, you have access to all of it. I blasted off rust from the front and rear spring brackets as well as the rear axle. I used POR-15 to refinish these parts. I was very impressed with the finish. Not a quick process if you follow all the steps. I got everything back together this past weekend and have put a few miles on the car to get some settling in the springs.

To recap the springs:
Front = MOOG 5246
Rear = Eaton ML5381

I'm including some pics as well for you 69 owners for reference. This sits a little higher overall but front to back is pretty much the same as it was.