coil overs in back.. tortion bars up front.. YES or NO?

[hogpowr]

Guys -

I'm still researching potential suspension answers for my 70 dodge challenger. I"m running a big block and have recently purchased most everything hotchkis sells for the front end. I'm wondering.. Would it make sense to spend the money and put coil overs in the back and eliminate leafsprings.. Or do you think I'm wasting money without matching it with coilovers up front? It is kind of a money thing... Not sure I want to spend all the money to put new front end on the car. I may at some point, but for now I just want to get the car to handle and stop for the Optima street car challenge.

Don't hold back.. I would like opinions.

[hogpowr]

no mopar opinions?

[andrewb70]

The leaf springs are not just springs, they also serve to locate your rear axle, so you can't just replace them with coilovers. If you want to use coilovers in the rear, you will have to redo the whole suspension and install a 4 link, or some other type of suspension system.

Andrew

[mmosley]

The front springs won't care what type of spring you have in the back. You could run a 3 link in the rear with coil springs and a Watt's link locator.

Torsion bars, not "tortion". Let's light this thread on fire: Torsion bars are used in race cars, like Formula 1 type. Car manufacturers like coil springs and struts because they are easier to package.

[72BBSwinger]

An XV rear setup would be my choice with its swaybar setup and aluminum components. If you have or plan on high power numbers, leafs can be a wrap problem. If you don't push the car super hard I doubt your seat of the pants would much difference between c/o's and a set of Hotchkis leafs though.

[High Plains Mopars]

With the OUSCC your objective, I think you will eventually need to replace both ends of the car if you plan on challenging for the top spot. However, since you've just sprung for the whole Hotchkis catalog, you could also update the rear with fiberglass leafs and maybe a panhard bar to adjust bite, and see where you fall. These would be relatively easy updates to accomplish just to see if the Optima races are really what you think you want to do before dropping many thousands of dollars and considerable fabrication time on aftermarket suspensions.

IMO, there are a few problems with running the stock Mopar front end in an "unlimited" type of class like Optima. First, they are a bit heavy. Second, they are rear steer. Third, the torsion bars have limited rates available for them to really fine tune the spring rates. Now, it is possible to run lighter t-bars with bigger sway bars and really dial in the shock performance, but you aren't going to find t-bars in 50# increments like you will find in coils. This is simply a drawback of using a Mopar. However, for now, I think the stock front end will be a fine starting point and wouldn't compromise a coil over rear end set up. The tires don't care what kind of spring is acting on them, only that its rate is compatible with their grip.

For the rear, there are a few coil over options out there to consider when it comes time such as Alterkation, XV Racing, and a few others that slip my mind right now. I think Heidts is even working up a minimal fab IRS system. I certainly wouldn't go down the path of a traditional drag style four link.

[Nothingface5384]

http://www.magnumforce.com/magnumstore/shop/item.aspx?itemid=19
https://www.reillymotorsports.com/store/home.php?cat=263
or AME 3link/tri-4bar

[hogpowr]

Thanks guys. leaf springs or coil overs, I am planning to run a panhard bar or watts link. I will have the winter to get everything together for spring. ( I live in milwaukee). It will be a long time from now, but eventually, I would like to get rid of the traditional big block and put in new k-member, coil overs, rack/pinion, 6.1 hemi up front. Just wondering if it makes sense to go in stages and get the back half of car setup with coilovers now. May not be a noticeable different from leaf springs now, but puts me in better spot 3-4 years from now...

[hogpowr]

and yes. thanks for spelling update. torsion.. It was a late night post. Brain was fried.

[High Plains Mopars]

I'd guess that to depend on your time, talent, and budget. You just spent $3k on front suspension, it is going to take another $2-3k for the rear plus all the cutting, fabrication, and set up time to complete it plus the front changes. If you can accomplish this within the time frame before next spring and not blow your current budget, then by all means, go for it.

[MonzaRacer]

As long as the shocks match up too the car/application your good. If I remember ridetech has a Mopar suspension replacement. Honestly the tuning on torsion bars means keeping several to adjust spring rate. Coil overs are MUCH cheaper to swap springs on, and you can still bump ride height easy enough.

[hogpowr]

I'm kind of leaning towards coilovers in the rear, panhard bar etc... Might not be any better than leafsprings for now.... but it gets the car a little closer to fully ready for attacking the cones...

[High Plains Mopars]

t. Honestly the tuning on torsion bars means keeping several to adjust spring rate. Coil overs are MUCH cheaper to swap springs on, and you can still bump ride height easy enough.


This is an unfortunate truth of mopar torsion bars. There are only four or five decent sizes out there to play with and they are $300 a pop.

If you chose to stick with the original suspension systems, then ultimately it comes down to choosing a t-bar/s-bar rate for the front and then backing into a complimentary leaf spring rate to match, as it is less trouble to find custom leaf spring rates than it is to find custom torsion bar rates. However, the calculations for this are fairly complex and pretty cumbersome to deal with and most guys just swag it and get it wrong, which then leads to dis-satisfaction and a conversion to coil overs where someone else does the calcs for balance and if they are off, they can be swapped out for $50 a pair and the shocks adjusted to match

In this regard, a coil over conversion will provide a much greater range of spring choice at much better price points than the stock set up. If you are actually going to change up the suspension and not set it and forget it, the coil springs do have this advantage.

[WallaceMFG]

If I was doing a Mopar, I'd be buying Magnumforce parts. The tubular K-member system they make seems to be the best thing you can get for a Mopar, it gets rid of those torsion bars for some coilovers, rack and pinion steering, and its considerably stronger than a factory K-member.

[mmosley]

If I was doing a Mopar, I'd be buying Magnumforce parts. The tubular K-member system they make seems to be the best thing you can get for a Mopar, it gets rid of those torsion bars for some coilovers, rack and pinion steering, and its considerably stronger than a factory K-member.

OK for drag racing... not everyone in the Mopar community loves these. I do not have one, so I cannot speak from direct experience. The "Alterkation" owners seem to be a much happier group as a whole. Alterkation kit is also coil over conversion with a front steer rack and pinion. It is made by Bill Reilly of Reilly Motorsports. https://www.reillymotorsports.com/store/home.php. I did meet and talk to Bill two years ago at the Mopar Nationals. The hardware on display was impressive and Bill was very knowledgeable.

Personally I am going with a reinforced stock K-frame, bigger torsion bars, tubular control arms, and a big sway bar up front. Once that is in I will see how it does and if I need a rear bar or not and go from there. Maybe a small rear bar and a bigger front bar? We will see.

[hogpowr]

thanks guys... definitely a lot to think about.. unfortunately cold weather is on its way here in wisconsin. so I will have time to figure it out. Ultimately plan is to run coil overs on all 4 corners and will probably use alterkation front end. but that is a ways away.