What are the differences between rear springs in a Chevelle and an El Camino? I am guessing that the Chevelle springs are a bit shorter but how much shorter?

Trying to anticipate how much adaptation I am going to need to do to fit the Eibach Pro Kit springs into the Elky. After hearing Marcus sing their praise so often I picked up a set of off Ebay without really thinking about them being correct for a Chevelle rather than an El Camino. That and I get so used to thinking of the El Camino as just a long Chevelle with an long open trunk :thumbsup:

Steve , I bet there the same diameter.I have a set of springs that were in My 69 and are out at the moment they measure 13 1/4 " tall. top and bottom opening of spring at the smallest point is 2 1/2 " coil dia approx .540
hope this helps

I had 2 pairs of factory Chevelle and one pair of factory El Camino rear springs side by side... coil diameter, wire diameter, and number of coils were all the same, so the rates were no different. (my math came out to 119lb/in)

Elky springs were a little taller, about 1/2" if I remember correctly.

Derek I came out with 118.5 :D

Well Steve if your springs are really for a Velle than they will be even easier to get in place:hurray:

Thanks guys. Sounds like I will be just fine once UPS gets my address right so they can deliver the darn package.

The rear springs are not hard to get in there at all, even the "stockers" that I have now. Just have to do the side to side wiggle of the rear end with the shocks off and out they come. I say "stockers" because on a 40 year old car who knows what some PO has changed at some point.

I really was not going to go the lower/stiffer route on this thing... but I have a vibration at highway speeds to some extent. And it goes away when I have a load in the back. So I guess somebody is trying to tell me the back end needs to be dropped to optimize the driveshaft angles. And then stiffer is not entirely a bad thing for the rear end of a load carrying El Camino either. And thus we go sliding right on down the slippery slope of rationalization. I get myself into more trouble that way :D

Sometimes you just never know until you try it...

My original ride height: 26.25" left, 26.75" right so let's call it 26.5" to the top of the wheel arch.

My rear springs: free length 14.75", 6.25" diameter, 0.645" wire, and about 5.5 coils
Eibach rear springs: free length 13.75", 6.25" diameter, 0.584" wire, and about 6.5 coils

Hmmm... looks like we are going a fair bit softer here.

Lowered ride height: 23.75" left, 24.25" right, call it 24" for a drop of 2.5" or right about the difference in free length (the Chevelle affect?) plus what Eibach specifies.

Without changing front springs (that is LOTS more work!) the back is about .25" lower than the front by measurement. By Mark IV eyeball it is even lower.

BTW the front springs I have are 0.661" wire and the Eibachs are 0.691 so at least SOME of the lowering springs are stiffer.

Ewww... if I calculate this stuff right my old rear springs were about 190 lb/in and the Eibachs are about 100 lb/in. But that does not match up at all with the prior numbers mentioned for the Eibach rear springs so wazzup?

Actually I guess that starting rate of 100 lb/in does match up on the Eibach springs since they are progressive. Looks like about 2 coils bottom very soon on compression, leading to an upper rate of about 150 lb/in.

Some specs on the front springs...

My original ride height: 27.375" left, 27.875 right (same 1/2" offset as the rear) so call it 27.5" to the top of the wheel arch.

My front springs have a code number stamped into them: 34T5390. Anybody know what that maps to? They measured a free length of 17", 4.25" diameter, 0.651" wire, and 9 coils. Might be 390 lb/in springs?

Eibach Pro-Kit front springs measured a free length of 13.5", 4.25" diameter, 0.691" wire, and 7 coils. I calculated about a 500 lb/in rate.

The lowered ride height is 24.5" left, 25" right (that 1/2" offset just won't go away!) so I dropped about 2 7/8" in the front. Pretty big drop... now my floor jack will not go under the cross member without a 2x4 shim under each front tire.

Check here for the rate of your spring
http://www.hal-pc.org/~rthlc/68-72_front_springs.html
I see that as 336lb springs.
I had a similar problem. Tried calculating my front springs with the formula every way until I pulled them out to install my 650lb speedway springs. Once I found the number I was close but not real close.

Well the combination of 3" front and 2.5" rear drop was too much. Especially with Hooker headers. I was dragging the header flanges on the driveway going in/out or the garage.

I put a set of Mr. Gasket #1287 coil spring boosters in the bottom coil of the rear springs and that lifted the back up an inch. And I put a set of Mr. Gasket #1285 coil spring shims on top of the front springs and lifted back up an inch to an inch and a half in the front. No more scraping on the driveway. Looks pretty good and rides nicely.

I also added in some Energy Suspension generic bump stops to reduce the bump travel a bit. When the front end bottoms out the Hooker headers hit the ground. With the taller bump stops, it I have measured correctly, after cutting off one step from the bump stop it should stop just short of the headers making contact. That makes the bump stop about 1/4" taller than original.

With what I have in boosters and shims, if I had to buy the springs new/retail it would have been cheaper to just run the circle track springs and adjusters. As it is I am still probably pretty close with having only spent $200 on the springs.

Well the combination of 3" front and 2.5" rear drop was too much.

I don't get it. Eibach Pro Kit springs are advertised as a 1.3" drop. Are these the ones you got? http://www.jegs.com/i/Eibach/369/3856.140/10002/-1#moreDetails

Yes indeed those are what I got. I might be able to explain away the back because I am putting them in an El Camino then Eibach specifies them for a Chevelle. But I have NO explanation for how 1.3" in front turns into 3".

That's interesting. I was considering getting these springs for my Chevelle to eliminate the huge fender gap on the front with the stock height springs/suspension. I also heard good things about Eibach springs elsewhere on this board but there is no way I want to slam my front end down that much. Guess I'll keep looking for springs.

The rub here to me is that if you shop around a bit you can find the circle track springs for about $34 each plus $25 a corner on the rear for adjusters and $30 a corner on the front for adjusters. That comes out to about $250 or the same as the best prices on the Eibach springs. And you will KNOW for sure what the rates are.

I suppost there may be some advantage in the progressive rate on the rear springs in the Eiback package though. But you could also achieve the same affect using air bags with a much greater load carrying capability.

I almost get the impression that there is a price increase coming through the pipe because through Summit the Eibach springs are $280 but the same springs from Edelbrock are only $250.