Chevy Impala SS Forum banner

Wagon rear springs--close to stock heightbut stiffer?

6K views 15 replies 6 participants last post by  jasonlachapelle 
#1 ·
My new-to-me '94 wagon has lowering springs in the rear. They are at least 2" lower than stock. (I have receipts from the previous owner so I need to see exactly what they are.) They are too low and not stiff enough. I added some airlift 1000s and with the airlifts aired up to about 26psi, the back end feels a lot better, but that's unloaded and without towing anything.

I want a rear spring that has ride height that is stock or only a little lower than stock, but is stiffer than the stock rear springs. I may just switch back to stock rear springs but am hoping there is a better option. (the front is lowered with drop spindles and I'm putting it back to stock because the 18s with 225/60s that I put on rub over even mild bumps.)
 
#2 ·
The reason the fronts rub is that the drop spindles move the wheels out about 1/2 inch. The main rub point is the top bolt holding the wheelhouse to the fender. If you remove the bolt, it will probably stop 90% of the rubbing. I use 215-70-15 tires in the front. They are 27 inches in diameter, and the narrower tread gives me and extra 1/4 inch. The tires you are using are actually .6 inches taller than stock (28.6 inches). A better fit would be the 215-60-18s because they are only 28.1 inches in diameter. Your rubbing would probably stop with the 215-60-18s.

If you go back to the stock spindles in front, and put the stock springs in back with the airbags, you will find out that it is probably what you are looking for. You can even use your oversized tires without hitting the fenders. Stock tire diameter is 28 inch, so to keep your ABS and speedo happy you should run the same diameter tires front and back (not necessarily the same size).
 
#4 ·
Fred, thanks for the suggestions. If anything, I want to go with bigger tires so going back to stock spindles up front is probably the only way to go.

Scot, I've also got a '96 RMW with the tow package. Are the springs you're talking about the same as I've got on the RMW? If so, the ride height of the car with those springs is good, but the springs are a little soft. I have to keep the airlift 1000s aired up to at least 10 psi to make the back end feel sufficiently stiffly sprung. Those would be an improvement over what's on my Caprice wagon now, but I'm hoping for springs that will have similar ride height but are firmer.
 
#5 ·
There are some lift spacers on ebay right now. You can use your current springs and get the ride heigth you want. Search for "caprice wagon" in car parts. You can use them in the front as well.
 
#6 ·
Lift spacers won't help--the lowering springs are too soft. The stock springs on the rear of my '96 RMW are stiffer, but I'd like something even stiffer.
 
#7 · (Edited)
"Scot, I've also got a '96 RMW with the tow package. Are the springs you're talking about the same as I've got on the RMW?"

Yes.

"If so, the ride height of the car with those springs is good, but the springs are a little soft. I have to keep the airlift 1000s aired up to at least 10 psi to make the back end feel sufficiently stiffly sprung. Those would be an improvement over what's on my Caprice wagon now, but I'm hoping for springs that will have similar ride height but are firmer."

I wonder if firmer shocks are really what you need then for this car. The V92 springs will give you the ride height and ride quality you want. 10 psi with the airlift is resonable ( maybe 8 psi L + 10 R or whatever it takes to level the rear static height)
Moog and various others make replacement stock height springs. BUT if handling is the goal, then I would not go there. 4 wheel matched spring sets always perform better than mixing any F+R springs because the natural bounce fequency of every spring is different. Only when the bounce fequency is matched for all springs will you find handling maximized over the road. Smooth autocross courses may work for mismatched springs, but nothing else will. I'm exclusevely refering to maximized handling, not just what works or even feels good.

In a RMS I use this set up ... 1 3/8 F+R bars, Koni's set at half way to full hard and wheels of 15x8 F, 15X9 R with 275/60-15 Firehawks, DMR #5029-w frame braces, ZQ8's and AirLift#60755. This car is neutral, corners flat and rides soft enough to be my mothers favorite car.
It sits 28 1/2 in F, 21 1/2 R on a RMS.
 
#8 ·
If you want a stiffer spring, if you could measure the installed height and free height of the stock RMW springs you have, I can see if there's a possible Moog spring. I posted a spread sheet awhile ago for estimating springs for sedans. Could be altered with that info to make a wagon version.

I believe at least for chevy's, the only rate spring in the wagons was the 37nm springs. Possible in a few different right heights. Guess would be the same for buicks.

Else it won't work. That case would require a test set of springs, then exchange them for the 'right' set after measuring in the car.
 
#10 ·
If you want a stiffer spring, if you could measure the installed height and free height of the stock RMW springs you have, I can see if there's a possible Moog spring. I posted a spread sheet awhile ago for estimating springs for sedans. Could be altered with that info to make a wagon version.

I believe at least for chevy's, the only rate spring in the wagons was the 37nm springs. Possible in a few different right heights. Guess would be the same for buicks.
I'll have to remove the stock springs from my RMW to be able to check their free height, although I can check their installed height--sort of. Basically I should just be checking the distance from the top coil to the bottom coil, with the spring installed on the car, with the car unloaded?
 
#9 ·
The V92 rear spring charts as one step stiffer than the 9C1 rear spring on the GM chart. A long time ago I used the 9C1 rear spring with Koni's set at almost (9/10's) full firm. It made for a VERY stiff feeling spring. I've got to think that the V92 with Koni's set like that would feel very stiff, and be exactly the ride height you want, while matching the bounce frequency of the front V92 springs.
 
#12 ·
Rear springs

I am currently running a set of camaro 4th gen V8 front springs in the back of my 92 RMW.The ride height is the same as stock and the spring rate seems just right. I think they are 310lb./in. The body drops less than half an inch when the cargo area is full of wheels and tires. They really tighten up the body but still allow buick ride quality (think modern buick:) The price was right but i plan on finding a set of direct fit springs as they dont really fit right unless i modify the lower spring perch. For testing purposes they do fine. (They wont fall out, they just creak sometimes as the rubber isolator is not the same size). Hope this helps.
 
#13 ·
I figured I'd necro this thread since, well, it IS my thread.

Back in 2011, I ended up going with the AC Delco 45H2044 springs and Airlift 1000s. https://www.rockauto.com/en/moreinfo.php?pk=440508&jsn=3

The Airlifts eventually stopped holding air, which I traced to the hoses getting slightly cut where they rubbed as they went through the top spring mount. I replaced the hoses and all was well for a thousand miles or so, and the springs no longer hold air again. (I originally wasn't diligent about maintaining at least 5 PSI in them, but after going through the trouble to replace the hoses, I made sure at least 7-8 PSI were present.)

The main reason I use the Airlifts is that I periodically tow a trailer. Usually it's a beefy 5x8 utility trailer (full-sized 15" wheels, strong frame) hauling a couple of motorcycles. Without the Airlifts, the back of my wagon will drop at least several inches, so they are necessary evils.

Thing is, the diameter of the 45H2044 springs is so wide that it's a pain to get them completely out of the car--I can get them off of their perches, but I have to raise the opposite side of the rear axle to get the other side to drop enough where I might be able to wiggle out the spring, maybe. So, I am not really looking forward to messing with the Airlifts any more and have started researching alternatives. My goal is to run a spring that is stiff enough to not need the Airlifts when pulling a trailer.

I found this thread, which talked about using the Moog CC623s or CC625s. http://www.impalassforum.com/vBulle...ock-combo-wagon-ss-springs-2.html#post2722487 I also found this Moog spring chart. Universal Coil Spring Specifications | Moog Suspension Parts

The spring specs are as follows:
45H2044 installed height - 8.5" , constant spring rate
CC623s installed height - 11" , variable spring rate of 206 lb/in.
CC625s installed height - 10" , variable spring rate of 222 lb/in.

Since the 625s sit closer to the 45H2044's installed height AND have a higher spring rate, those seem like the springs to go with. Thing is, I don't know what spring rate the 45H2044s are and haven't had any luck with Google. I figured that the coil diameter might tell, with thicker coils being stiffer, but the 623 has a thicker coil than the 625, but is a lower spring rate, so that assumption isn't correct. I'd hate to go through the trouble of swapping out springs only to find that the CC625s aren't significantly stiffer.

You guys think the CC625s will be stiff enough to not need the Airlifts when towing my motorcycle-laden utility trailer?
 
#14 ·
Did you try Global West? Global West Suspension - American Muscle Car Parts

They manufacture springs, and other assorted suspension parts. I bought a spacer to fine tune my front drop from them. They also seem very knowledgeable about how springs work. It is good to have more than one input on what will work best.
 
#15 ·
I sent an email to their contact address--hopefully they'll have some helpful input!
 
#16 ·
from navy lifer

ACDELCO Part # 45H2044 {#88913714) = Moog 5417
Caprice wagon rear

That's a substantially softer spring than the CC623 and CC625 you're considering. I run the cc623 in the caprice and 625 in the wagon. Don't tow but they are substantially stiffer than stock. The CC623 sits higher than stock. You can approximate the additional compression of the springs generated by your loaded trailer using the stated spring rate. Should give you a good WAG. Unless you're towing AND carrying 3+ adults in the back, I think you're good.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top