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View Full Version : Leaf spring advise- 1st gen camaro



another69
05-25-2008, 11:09 AM
Are there any stock height leafs out there that are comparable to Hotchkis' rears?

I was originally set on Hotchkis, but they are only available in 1-1/2" drop, and combined with my 1-1/2" adjustable lowering blocks (I need them), it would add up to 3" drop- which is way too much for my setup.

I've been looking around at circle track springs from Afco, Landrum, etc. and would really, really appreciate advice to point me in the right direction. What rate should I choose to have a good balance between traction, handling, and ride quality?

chicane67
05-25-2008, 11:38 AM
Stock height comparable to the Hotchkis leafs... ?? I don't believe that there is anything available off the shelf, but anything can be built. Unfortunately, it becomes cost prohibitive for most.

I would seriously consider re-thinking your lowering blocks. Its cheaper to keep this as your fine tuning component to your ride height. So please explain to me why it is that you have to keep your blocks at 1.5" and adjustable ??

Rear spring rate... depends on your front spring rate. If you are looking at purchasing a spring in which you have a selection of available rates... I would do some homework before I pulled the trigger on which rate to use... as I am sure you dont want to buy springs two or three times to get the balance right.

So... to start off, we will need to know more about your entire chassis before anyone can even consider giving you an intelligent recommendation.

Lowend
05-25-2008, 12:27 PM
It should also be noted that just because the springs advertise a 1.5" drop does not mean that is exactly what they will achive. Every car sits differently, and its pretty likely that the stock springs have sagged quite a bit.
I have seen lots of people install "lowering" springs and have the car sit higher than with the original sagging stockers.

Personally I am weary of lowering blocks in general. They can do some nasty stuff to your pinion angle and tend to inspire wheel-hop.

another69
05-25-2008, 12:53 PM
My front springs are a QA1 "coilover" setup with 350# springs. I have a DSE (Hotchkis) 1-1/8" swaybar up front. I'm trying to maintain decent ride with the light springs (smallblock car) and I hoped the larger swaybar would keep it from being too lazy in corners. It handles alot better than stock now, but I may step up the front spring rate if I need to. I'm shooting for 3000# total car weight.

The reason I need to add the lowering blocks is because my rear axle is not perfectly square to the car. The adjustment in the blocks allows front to rear positioning of the axle. I'd post a picture If I knew how. I like the idea of being able to fine tune the position of the axle in the car and (finally) having perfect alignment. I've spent hours measuring the car, and even had it on a rack, and it looks like a combination of a few tolerances stacked up and my pass. wheelbase is 3/8" to 1/2" longer than the drivers- lucky me!

Anyway, it's time to upgrade the rear suspension, and my wallet tells me it's going to be leafs for now. I thought about stock replacment multileafs, but the rate seems pretty low (under 125# I think).

Your input is appreciated.

Lowend
05-25-2008, 01:18 PM
Have you yet done a front suspension geometry correction? The Guldstrand mod (or like) is really the best thing you can do for the car.
I would invest in that before new rear springs; but I would also highly recommend the Global West L2's if you are going with leafs.

another69
05-25-2008, 01:38 PM
I have not yet done the Guldstrand mod- I wish I'd known about it when the subframe was bare! I rebuilt the front suspension in '07 and added a unisteer rack, poly bushings, bigger brakes, performance alignment- pretty simple stuff. I'll admit it's no corvette, but its WAY better than before, and i'm actually pretty happy with it. The rear monoleafs and joke of a rearend are the last untouched pieces on the car, and they've gotta go.

chicane67
05-25-2008, 02:03 PM
Poor spring design is the culprit of wheel hop... not a lowering block.

FWIW... Guldstrand and many others have used lowering blocks successfully for some 40+ years without issue. Not to mention that you can machine the offset into the block to correctly set the pinion angle. Although... the lowering blocks used have only been an inch to an inch and a half... and I think anything over that, you should have the mains re-arched.

If your rear axle isnt square in the chassis... you have other problems that need to be taken care of.

The Guldstrand Mod can help... but its not an aswer to the other associated geometrical issues with the front suspension. One other thing to consider is the AFX spindle... as it addresses the other issues that the Guldstrand Mod cannot.

So for the rear leafs... the L2 or CAT5 spring would be good for something off the shelf... as would the Hotchkis. But the CAT5's... do much more than the standard L2. If you are changing rear ends... I would take all of this into consideration as it can influence spring rate. Considering your light front rate... I would look at something around 175... which is right where the Global West offerings are. But then you also have the composite springs available thru ATS as well.

Weight. 3000 lbs can be difficult to achieve without prettty much stripping the interrior and shedding some other things off the chassis. It can be done... but you will have to sacrifice.

another69
05-25-2008, 06:04 PM
The main reason the rearend is not square is that, for some reason, the torque box (@ the front leafspring mount) is off- or at least the mounting holes are off. It's weird, though- the rockers and torque boxes are original and look undamaged, and the rest of the car is straight and true. Maybe I have a lemon or maybe something happened earlier in the cars life, I don't know. In the future I hope to change to a HTH setup or something similar (a three link is a little out of reach), which will not use the stock spring pickup points, so as long as the rest of the car is straight, I'm not really concerned.

As for now, the stock rearend and monoleafs need to change, and I thought that the adjustable lowering blocks and a good set of leafs would be a good way to go. I know some of you would want to square up the torque box mounts- I agree, and I would if I was planning on staying with leafs forever- but I'm not.

I haven't found any GW or Hotchkis springs that aren't dropped already, and if I use the adj. block I'm afraid I'll be too low. Not to oversimplify, but besides the rate you suggest (175), what else do I need to look for in a spring? Front bias?

I know 3000# will probably be hard to get to, but I'll try to get close. I'm borrowing a set of scales soon.

I tend to ramble, but what i'm trying to find is a set of springs, stock height, that will work with my chassis until I change to HTH.

funbnme
05-25-2008, 07:13 PM
Not sure if this is helpful. This is a post over at camaros.net about a different multi-leaf spring.
http://www.camaros.net/forums/showthread.php?t=122050

chicane67
05-25-2008, 07:47 PM
Have you loosened up the front spring perch and re-set it's position yet ??

Why the big push to get rid of leafs ?? A properly designed and built set of leafs is damn hard to beat. The problem is... not to many people really know and understand leafs or how to properly tune the spring pack to get it to work correctly. The right leafs will still beat up on link systems without question... for much less monies.

The right leaf will have a partial wrap on the front main eye (which is the traction control portion of the spring pack)... real spring clamps to hold the spring pack together (which does more than just hold it all together, it will also control axle tramp under braking)... and you can even tune the ride height by using one of a few positions for the rear main eye... that alone is nearly two inches of adjustment when the main leaf is built. You also have the individual spring leaf lengths that modify the ride.

If you do some research over on camaros.net... you'll find that this very discussion has come up quite a few times. In fact, I designed a custom spring that was utilized in a group purchase that did what has already been discussed in leaf spring technology.

I will say... good luck... with packaging everything around the HTH system if you choose to go with it. It does not really give you very many options for everything else that needs to be under the chassis... and its just down right heavy.

If this is going to be a bandaid until you get whatever suspension under the chassis... you could always get a stock set of mulit's or even a set of Z28 springs and not brake the bank doing it.

another69
05-26-2008, 07:01 AM
Yes, I've tried repositioning the axle by pulling the D.S. spring perch toward the front subframe while pushing the pass. side away, but I got no measurable differance. I was lucky enough to over torque and strip a couple "j nuts" though!

I like the way the HTH setup ties into the front subframe. Also the pinion angle does not seem to change much, and it doesn't look like there is any chance of binding. As for packaging- I know. All that cutting and re routing won't be fun.

I'll look over at camaros.net when I'm done writing. Do you sell leafs?

This is pretty much going to be a bandaid, but one I'm wearing for at least a couple of years, so I don't want to buy leafs twice. If I can avoid wheelhop and a really harsh ride, (like my 1 ton leaf spring truck) I'll be happy.

According to NPD, the '69 Z28 multi leafs have a rate of 103, and standard multi leafs are 89. I'm guessing they're progressive?
Do you think wheelhop will be an issue with them?

Honestly, will I be wasting my time with the Z28 springs and blocks? I've never driven a 1st gen with multi leafs to compare my mono leafs to. My other option, that I'm trying to avoid, is welding, drilling, cutting, repositioning, etc. to fit Hotchkis and forget about the blocks.

chicane67
05-26-2008, 12:43 PM
According to NPD, the '69 Z28 multi leafs have a rate of 103, and standard multi leafs are 89. I'm guessing they're progressive?

Uhm... what? I take it that NPD doesn't know very much about OEM leaf springs?

The OEM mono leafs actually had a higher rate than the standard 3 leaf multi... at 132-135 lbs/in. vs. 124-127 lbs/in. The OEM 5 leaf Z28 is 142-145 lbs/in.

The stated OEM rates are from the spring study that Guldstrand did some 40 years ago (and is where I received my leaf spring education while working for him)... so, the late reproductions might be that weak... but I kind of doubt it. 89 lbs/in is almost non existent and I believe that you would have issues with the bump stops in no time.

I guess I fail to understand what exactly that you would have to cut, weld and fit to make the Hotchkis spring work ??

I have run a 720/320 set up in my 67 for 15+ years and have found no other combination that suits my chassis requirements as well. Most think that the rates are a little high for any kind of street use... but this was my daily driver for 10 years. The reason I believe that I was able to get away with it was the addition of some late model tech that made the package more compliant and in fact, it's ride quality is very good. There is a lot more of this that involves to the bushing and damper than most I believe are willing to admit or maybe even aware of.

Do I sell leafs... yes. Do I think that you are a candidate for them... no, not if you are going to be changing out the rear suspension, I dont believe that my efforts would be a cost effective solution to your current needs. Now, if you were going to run leafs for your rear suspension... then yes, there is the benifit to having properly designed leafs made for your specific chassis/application.

Here is an old and very simplified diagram of a basic performance leaf that i did years ago, but gives some insight on things that can be manipulated to change spring parameters. By changing leaf thickness and length you can imagine that the amount of tuning in a specific spring is infinite. The example below is for a chassis that makes at least 400 lbs/ft of torque and a manual transmission:

http://i90.photobucket.com/albums/k270/chicane67/reardiagram.jpg


As for traction modification... any and all springs can yield the same (and actually much better results than an under/over ridden or a j-bolt traction bar)... from a simple secondary leaf modification at the time of manufacturer, a partial main eye wrap. Basically a built in traction bar... and completely sleeper. The picture below also shows an example of which spring clamp NOT to use.

http://i90.photobucket.com/albums/k270/chicane67/Camaro-Rear-Leaf.jpg

another69
05-27-2008, 05:43 PM
I need to cut and/or weld & drill my torque boxes to square up my rearend without using the adjustable lowering blocks. They are really the only part thats not square to the rest of the car.

I'm 90% sure that I'll go w/ the Hotchkis leafs. Sounds like they're pretty good for the price. I'll probably have better luck balancing the suspension than if I throw in some questionable repro leafs. Do I need to up the front springs to 450? I'm planning on keeping the rubber front/ poly rear leaf bushings, possible poly fronts.

How the heck did you make 720/320 ride compliant? That's impressive!

Thanks for your feedback and diagrams/ pics. Love that partial wrap.

RUSSSMITH3
06-01-2008, 06:30 PM
i bought the z28 springs from ndp for my 68 with 3.73 gears 255/60r15 and zz4 pushing about 400 hp and ran it on the track with no wheel hop.

chicane67
06-01-2008, 08:39 PM
I need to cut and/or weld & drill my torque boxes to square up my rearend without using the adjustable lowering blocks. They are really the only part thats not square to the rest of the car.

I'm 90% sure that I'll go w/ the Hotchkis leafs. Sounds like they're pretty good for the price. I'll probably have better luck balancing the suspension than if I throw in some questionable repro leafs. Do I need to up the front springs to 450? I'm planning on keeping the rubber front/ poly rear leaf bushings, possible poly fronts.

How the heck did you make 720/320 ride compliant? That's impressive!

Thanks for your feedback and diagrams/ pics. Love that partial wrap.

The bushings are key. Del-a-lums do more than look pretty. Well... that and the shock type and valving... and I wasnt running rubber bands for tires. With that combination, anything over a 17" wheel and tire package... and the quality really starts to fall off.

As for the front springs... I think you could be OK if you ran the QA1 big block springs that are made for that set-up. Since they dont really have a huge selection, or any selection for that matter, concerning front rates... you are kind of limited to what is available. So with that in mind... I would limit your rear spring to 175 to 200 lbs/in.

jaybee
06-02-2008, 06:12 PM
Chicane, I enjoy your writing on the subject of leaf springs...to the extent that I always come away with more questions that I hadn't considered previously! Hopefully these questions don't get tedious, they're motivated by having a car that doesn't have a hard core track history like the Trans Am veteran models. In those cases you often don't have a lot of choices for springs and certainly nothing like the Hotchkis springs that are designed from the word go for...go. Choices consist of stock replacement or lowering springs, with different spring rates hard to come by and even the rate of a given spring kind of unknown.

All that said, on to questions. 1) In the diagram above, how is the rate varied within the same basic spring? 2) How do you determine if the spring you're considering is in the ballpark when rate information is hard to find? 3) What are the odds that a stock rate spring is reasonably close for spirited street driving with some mods like sturdier clamps and an extended second leaf? Yeah, I know that absolute best results require a custom spring, but what can be accomplished by a regular guy who's willing to do his homework?

chicane67
06-02-2008, 09:05 PM
1) The rate can be changed by the individual leaf lengths and the individual leaf thickness'.

2) There are, albiet very few, mathematical equations that can get good ballpark numbers. Other than that, you would have to build a spring fixture and actually test the rate for the individual leaf in question.

3) You could have a stock spring re-worked... and it would'nt brake the bank to do it. All you would have to do is re-make the second and possibly use better spring clamps. But, the stock rate (125-135 lbs/in) is still a litte light even for light duty use... unless it has had the second spring modification. I should say... that a stock rate would be good for lower power/less aggressive driving or in a SSBB set-up... but you will end up finding out what the bump stops are all about in no time at a lowered ride height.

I'd look up your local spring shop... and see if they can just do a re-build with a modified second leaf. You can also play with the ride height by re/de-arching the spring while your in the thick of it.

jaybee
06-03-2008, 12:44 PM
Thanks, that's very helpful!

opnwide
06-03-2008, 06:55 PM
Check out speedwaymotors.com They have leafs avail that are much stiffer than stock and for under $100. DSE uses a 175 lb spring, as opposed to a factory Z28 140-150 spring. Rates range from 175 to 250 or so.
These are stock height, I believe.

By the way, I bought the DSE 3" drop springs. Hey, Chicane, Did I get the shaft on these at $399?

6'9"Witha69
06-04-2008, 09:06 AM
By the way, I bought the DSE 3" drop springs. Hey, Chicane, Did I get the shaft on these at $399?Based on your username you are either a Dentist or accustomed to getting the shaft! lol j/k:poke:

zuess4u
06-06-2008, 01:31 PM
Based on your username you are either a Dentist or accustomed to getting the shaft! lol j/k:poke:

Off subject...but you had me rollin:rotfl:......

Im using a set of Landrums 275lbs...not sure if they still make them or not. The fronts are 650lbs Hypercoils, I purchased them about 5 years ago, they were my second item purchased for the car, and was influnced by Chicanne at that time.

I think the Landrums were 170.00 dollars, once the car is 100%, full tank of gas a couple of CDs, a Big Gulp and my 200lbs ass is in the car, we will set pinion angle, front suspension and the like. Then take the car to one of the spring shops, and have them D-arch the leafs for the rear height.

Other then having Chicanne build you a set, this would be the best way to get what you want. You wouldnt have that much invested, and you can stay away from the blocks.

I think you would be happy how leafs perform, you could give Marcus at SC&C a call as well for a second opinion.

Just my 2 cents.

6'9"Witha69
06-06-2008, 01:46 PM
Off subject...but you had me rollin:rotfl:......Thank you, I'll be here all week.

chicane67
06-06-2008, 08:26 PM
Check out speedwaymotors.com They have leafs avail that are much stiffer than stock and for under $100. DSE uses a 175 lb spring, as opposed to a factory Z28 140-150 spring. Rates range from 175 to 250 or so.
These are stock height, I believe.

By the way, I bought the DSE 3" drop springs. Hey, Chicane, Did I get the shaft on these at $399?

I dont think so... heck, when I first starting building custom leafs I thought I was doing good at $135 each. But with the price of American spring steel sky rocketing... that same spring is now $440 each.

$399... isnt too bad for what you are getting... I do however believe that the simple design that it is can be greeatly improved upon... and without impacting cost per spring very much.

opnwide
06-08-2008, 05:51 PM
I kindof like Zeuss's setup. I've got hyperco 600 lb coils up front with the DSE 175s in back. I won't know if the front are too tall or not till I've got the engine back in. The 275s would probably work better with these stiffer front springs.