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Re: Spring/Wheel rate
[Re: TC@HP2]
#36066
04/27/07 11:48 AM
04/27/07 11:48 AM
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Joined: Jan 2003
Posts: 1,692
Seattle WA
RichV
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,692
Seattle WA
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Quote:
Quote:
Have you considered something like this Street Lynx system A Body Joe just installed?
https://board.moparts.org/ubbthreads/show...part=1&vc=1
This is a very nice set up. while the coil over change allows a greater range of spring rates and the link arrangment is somewhat lighter than leaf springs, it doesn't have any adjustment in it for roll center alterations. Not that this is a big deal for most guys as once it is set, they learn to live with it and they never run it in varying track conditions that require tunability. However, with a few simpler mods than this system requires, leaf springs can be set up to have changeable roll centers which can then be used to alter the amount of rear bite you need in your set up.
A big advantage to coil springs over leaf springs is that your roll rate is 30 to 50% lower with coil springs than leaf springs for the same wheel rate. The result of the higher roll rate is that you have to optimize your leaf spring rate for roll rather than for ride. You can increase your rear roll rate from the 30%, but you can not decrease it to a coil spring level with conventional bushings. Stiffer spring bushings such as poly or nylon will increase the roll stiffness of leaf springs as will angling the rear springs. I wish the Street Lynx kit were a five link rather than a four. Even the GM suspension designers, who used four links for many years now admit they are flawed.
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Re: Spring/Wheel rate
[Re: RichV]
#36067
04/27/07 07:09 PM
04/27/07 07:09 PM
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Joined: Sep 2003
Posts: 10,645
Houston, Tx
AlexP
OP
I Live Here
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OP
I Live Here
Joined: Sep 2003
Posts: 10,645
Houston, Tx
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Here is another option that I have found for getting the proper rate leaf springs... Alltime racing leafs These guys look like they know a thing or two about going around corners in a classic mopar.
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Re: Leaf springs for a G-Machine application...
[Re: AlexP]
#36069
04/27/07 11:33 PM
04/27/07 11:33 PM
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Joined: Jun 2006
Posts: 254
Vista, CA
71Chip
enthusiast
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enthusiast
Joined: Jun 2006
Posts: 254
Vista, CA
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What made you decide to go with those huge torsion bars with 15" wheels?
Seems like the car won't be good at anything. Terrible ride, understeer, no weight transfer at the strip.
I have some tires in my backyard right now I am saving. They are 235/60 BFG Comp T/As that are unique side-to-side and were custom shaved by a road racing outfit. A lot of classic road race porsches run 15 inch wheels and huge spring rates with great success but I really think you need a expensive, well set up tire to pull it off.
71 Challenger
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Re: Leaf springs for a G-Machine application...
[Re: 71Chip]
#36070
04/27/07 11:38 PM
04/27/07 11:38 PM
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Joined: Sep 2003
Posts: 10,645
Houston, Tx
AlexP
OP
I Live Here
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OP
I Live Here
Joined: Sep 2003
Posts: 10,645
Houston, Tx
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Quote:
What made you decide to go with those huge torsion bars with 15" wheels?
Seems like the car won't be good at anything. Terrible ride, understeer, no weight transfer at the strip.
I have some tires in my backyard right now I am saving. They are 235/60 BFG Comp T/As that are unique side-to-side and were custom shaved by a road racing outfit. A lot of classic road race porsches run 15 inch wheels and huge spring rates with great success but I really think you need a expensive, well set up tire to pull it off.
I respect your opinion, but I don't totally agree to any of the above.
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Re: Leaf springs for a G-Machine application...
[Re: AlexP]
#36071
04/28/07 02:00 AM
04/28/07 02:00 AM
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Joined: Jan 2007
Posts: 2,431
SK,Canada
gregsrt
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top fuel
Joined: Jan 2007
Posts: 2,431
SK,Canada
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Thanks for the link to All Time Racing. They look like they've got some cool products for my Challenger. Why does everyone think the SS springs have so much arch? I ran a set of 3600lb auto trans ones in my 69 Bee with them mounted on the upper most hole on the front hanger and my car sat low. I don't have any pics though as I sold it 5 years ago. 
Last edited by gregsrt; 04/28/07 02:12 AM.
An association of men who will not quarrel with one another is a thing which has never yet existed, from the greatest confederacy of nations down to a town meeting or a vestry.
Thomas Jefferson
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Re: Leaf springs for a G-Machine application...
[Re: TC@HP2]
#36072
04/28/07 07:47 AM
04/28/07 07:47 AM
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Joined: Jan 2003
Posts: 5,387
Pikes Peak Country
TC@HP2
master
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master
Joined: Jan 2003
Posts: 5,387
Pikes Peak Country
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Quote:
Again, consideration of using a rear sway bar will factor into deciding the springs to get. In general I'd say go softer then add sway bar sizing to dial things in or you could go heavier and not use a bar at all. For a ball park guess, I'd say 160# if using a rear sway bar, or 200# with no bar.
Sorry. I guess I buried this in the middle of too long a response earlier.
The Alltime guys definetly know their stuff, but they do tend to be pricey.
The SS springs may not have "a lot" of arch but the point is for a handling application, the spring should be flat. Even the old DC and MP manuals say flat is mandatory for maximum cornering effort. While you can use hangers and shackles to get a SS spring to a decent ride height, it still has some arch to it which can create a lever arm against the mounting points. A flat spring reduces this leverage. Think of it this way, breaker bars are longer than ratchets to give you more leverage for breaking loose those stubborns bolts. Side loading a leaf spring with arch would work the same way.
Speaking of which, adjustable front hangers are a great way to get two inch drop from a mounting point. Another is to replace shackles with sliders. A slider is a u shapped frame with horizontal slots running down the sides. A bearing runs in two track the length of the slots on each side. The rear of the leaf spring is bolted in between these two bearings. Instead of pivoting like a shackle, the leaf slides back and forth on the bearings. This is a 2" drop in mounting point over a shackle. I've only ever used these in copetitin, so I can't say how they would work in a street application.
Another advantage to solid or bushing mounted leaf spring is the width of the spring resists twisting as well which helps increase roll resistence compared to a coil spring.
However, as mentioned in an earlier post, if you simply want to use a leaf spring as a spring and not the whole suspension locating system, you can swap out the front bushing for a spring eye pivot. This allows the spring to twist and roll with the car and not resist twisting. Once it has this freedom of movement, sway bars and panhard bar/watts link become a requirement to locate the suspension and provide roll resistence. The advantage of doing this in a track application is that the rear roll center location can be easily changed with just minor adjustments. This can have a tremendous impact on how a car will hook up exiting a corner. It also allows you to run a lower spring rate since the leaf now acts exclusively as a spring and not a roll resistor. FYI, this is how the trans am cars of 1970 were set up and they continue to use this set up in vintage racing to this day.
As an aside to drag racing with a handling set up; yes, you reduce the effeciency of weight transfer and suspension movement, and consequently, will increase you e.t. over a similarly powered car built exclusively for straight line performance. However, a handling set up will be less sensitive to track, tire, and atmospheric changes and will be deadly consistent in later rounds where cooling things down in an effort to maintain consistency becomes a factor. Not to mention that turn on the return road is a lot less scary. 
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Re: Spring/Wheel rate
[Re: Moparmatty]
#36073
04/28/07 08:21 AM
04/28/07 08:21 AM
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Joined: Nov 2005
Posts: 15,118
85086
moparpollack
Lil Herman
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Lil Herman
Joined: Nov 2005
Posts: 15,118
85086
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Nope  that's $920 a pair 
56 Plaza 63 D100 step side 67 Coronet, 68 Roadrunner, 69 Super Bees, 69 Coronet 500 convertible, 70 Roadrunner Post, 79 D150 360, and a severe case of Mopar a,d,d
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Re: Spring/Wheel rate
[Re: moparpollack]
#36074
05/01/07 10:30 AM
05/01/07 10:30 AM
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Joined: Jan 2003
Posts: 5,387
Pikes Peak Country
TC@HP2
master
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master
Joined: Jan 2003
Posts: 5,387
Pikes Peak Country
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Since a lot of members here use Summit, here is info straight from their latest catalog.
Afco oval track springs, mono leafs, $55 ea, 5" arch. Available in 34, 47, and 64 spring rates
Multi-leaf Chrysler style spring packs $130 ea
5" arch available in 142, 152, 166, 194 # ratings.
Another vendor worth checking out is Landrum. They also specialize in leaf springs.
So it isn't that tough to get specialized spring rates at a reasonable cost from a vendor who knows what they are selling you.
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Re: Spring/Wheel rate
[Re: TC@HP2]
#36075
06/12/07 05:16 AM
06/12/07 05:16 AM
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Joined: Jan 2003
Posts: 2,273
Bern, Switzerland
6o4o
top fuel
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top fuel
Joined: Jan 2003
Posts: 2,273
Bern, Switzerland
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I also got a 1.22 Tbar on the front and will reinforce my 72 Satellite BIG time in the next few months (subframe connectors, all XV motorsports reinforcement available, 10point rollbar, torque boxes etc.)
I got red konis front & rear, 83/4 3.55 SG rearend.
I got reillymotorsports tubular UCA, 11.75" spindles with alu MC manual (probably going to change to Viper brakes from Andy later this year), reinforced LCA, FF stage 2 PS box, reinforced k-member, biggest FF swaybar on front and endlinks.
On the rear I removed my stock swaybar and I bought the flex-a-form fiberglass leafsprings. So far I didn't test all of this, I just calculated for a long time and asked people. There are some good books out there that will help you get into ballpark. But I also would guess, that you need to get around 200lbs/inch on the rear with those tbars, ALTHOUGH rather having understeer than oversteer! A rear swaybar will get you more to the oversteer side.
I heard of a guy here that got problems with his flex-a-form (delaminating) but here are 3 guys in Germany that got some g-machine Mopars with those fiberglass springs (since years) and no problems so far...
To be honest, I also don't trust them yet, but I will try them and see. Corvettes did use them for many many years with success and I won't be driving over pot holes with my car. But a check from time to time is surely not a bad idea.
I got by the way 200lbs/inch at 4". Should be flat when the car sits on it. You can tell him the spring rate and arch. I wouldn't go lower with the spring rate on fiberglass, I heard they start to oscillate at high speed because they got less damping than a steel spring. The german guy here even got 250lbs/inch. The weight reduction is also massive!
They did cost 400$/pair.
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Re: Spring/Wheel rate
[Re: 6o4o]
#36078
06/14/07 12:03 AM
06/14/07 12:03 AM
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Joined: Sep 2003
Posts: 10,645
Houston, Tx
AlexP
OP
I Live Here
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OP
I Live Here
Joined: Sep 2003
Posts: 10,645
Houston, Tx
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Quote:
I will have to learn to trust them! 
I trust SS springs and I won't have to tread lightly with them, other people have shown that they can work for what I need.
You convinced me that the shocks I need are the Konis. My car will be mostly street so I don't think I could ever utilize what QA1's can offer me.
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