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suspension question...air ride

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suspension question...air ride

Post by aronhk_md on Thu Sep 08, 2016 12:17 am

So like everyone else it seems I'm a bit leery of every leaf on the road now, and cracks that ants would have trouble squeezing through have me bracing for impact. My car has leaf springs in the rear and MII suspension up front. I have been reading the threads on owners making modifications, including the detailed suspension analysis one member has done.

Obviously there is a LOT of improvement that can be made, and I think coilover conversion would be a good way to go, and I may yet do that. I also saw some of what is posted on the cobra forum from the classic owners.

But not long ago I took a ride in a car equipped with an air ride setup. It was a full sized muscle car, but I have to admit...I had a preformed notion about air rides from watching all those hydraulic cars in california bouncing the front wheels off the ground. This car seemed to have a pretty sophisticated ride and the car handled corners well. Anyone have experience with these things? I wonder if they are another option for handling and a comfortable ride?
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Suspension

Post by DrJ on Thu Sep 08, 2016 8:55 am

When I began accumulating the suspension data that I posted, the reasons for the harsh ride on my MX (rear coil springs) became clear. Searching for components that could be fitted to the car and that would correct these issues was a little more challenging. Our cars are light and Mustang II front suspensions are a bit long in the tooth geometrically. They suffer from low levels of available suspension travel and the absence of an actual "A" lower control arm. The Mustang II LCA is a beam. Triangulated stability is generated by the use of a strut rod anchored to the frame at one end and approaching the LCA at an angle to attach to the LCA near the ball joint. As the suspension travels (what little there is) in it's vertical arch, the path of the arm and the path of the strut rod are different so they fight each other. Ford dealt with this by employing big rubber bushings that stretch and distort as they react to the forces involved. Add to this the age of these suspension components. When I disassembled the front end on mine I could barley mussel any movement in either the UCA or LCA, the bushings were so deteriorated. Another issue was the available spring rates at the time the kits were designed. Mine measured out at 300 lbs/in. My calculations came in at 175 lbs/in. So the challenge was to find aftermarket tubular Upper and Lower control arms so as to eliminate the strut rod and a 175 Lb/in spring in a fully adjustable package that would still fit a Mustang II crossmember. That was doable. At the time I was talking with Vi-King regarding their coilover shock body and Gayleco about their springs I was also working with RideTech. They offer coilovers as well as the air suspensions you were interested it. Ultimately I found the chalanges of fitting coilovers to both the front and rear something I could understand and adjust but air suspension was a viable option. You should visit RideTech's web site. They show up at all the big car shows I attend, been in business 20 years. There are other companies providing air solutions that you can search out as well. I purposely omitted discussing the issues regarding the rear suspension as yours is a leaf spring configuration. They can be removed and coilover/air installed as well, it's just a bit of fabrication and welding.

Hotrod has posted a bunch of data regarding his suspension modifications, far deeper into it that me. Read his stuff, he is extremely knowledgeable.

DrJ

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Re: suspension question...air ride

Post by Hotrod on Thu Sep 08, 2016 9:42 am

If you don't want to go to a full air ride setup, there is a system called air over leaf.  With it, you remove nearly all the leaves in the rear spring and mount a small air spring either over the axle or directly in the front or rear of the axle.  The leaves still locate the axle side to side, while the air springs actually support the weight of the car.

There are downsides to this setup, just like all the others.  You would most likely need traction bars with an AOL to keep spring wrap to under hard acceleration under control.

Also, I doubt that there would be anything off the shelf that will work.  It's going to be a do it yourself project all the way, but that's going to be true on a Sebring no matter what you choose to do.

FWIW - I had a T bucket with full air ride on the rear using Firestone 7076 springs.  This was a 1700 lb. car and T's are notorious about riding like they have no suspension.  My car rode nice until you found the bump stops (limited suspension travel).  We did several 1500 mile trips in that car with no need of chiropractic adjustment Very Happy.  Point being, air ride is the best way to get good ride in a light car IMO.
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Re: suspension question...air ride

Post by aronhk_md on Fri Sep 09, 2016 1:06 pm

All interesting stuff guys. There is NO deflection when I put my weight on any corner of the car. Therefore I dont think the suspension is really working at all.

I saw your post Dr J, and have to say you researched it thoroughly. Unlike posts on the cobra forum where they are talking about using coilovers with very high spring rates, I tend to agree that with a car this light they have to be far less, and what you said made sense.

I saw whole front end kits on ebay for the MII with tubular control arms top and bottom, I believe larger disc brakes, etc. Going to have to do some more research here. I really wouldn't mind going to larger brakes. I think the car needs them.

I'll have to look for the posts on your suspension hotrod. I'm very curious about it.
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Post by DrJ on Sat Sep 10, 2016 8:13 am

Yeh my MX was the same initially, basically a rock at all four corners. For what it is worth, and keep in mind that I am still tuning all of this and have not yet road tested it, it all looks encouraging. The Vi-King shocks are independently adjustable in both bump and droop. With the adjustments dialed down to zero I can grab either the front or rear bumper and bounce the car threw almost it's entire travel potential. I can also dial the adjustments up and reestablish the hard as a rock effect so I should be able to create any level of firmness that I want, soft to moderate for cruising and as firm as I need for the track.

I should mention that the data I published is a work in progress. When I first took all of this on I had never really turned a wrench before. I read books on the topic and went at it. Still you dunt know what you dunt know. There have been many set backs that I did not anticipate along the way but so far I have been able to engineer (with much consultation from Hotrod) solutions to them. I am in the process of building up the new fuel tank and once installed and the remaining suspension complications cleared, I hope to be on the road to beta test it within the next 4 weeks. At that time I will re document the entire process and post the results.

As an aside I too felt the brakes to be a tad lacking and am in the process of installing 11" discs (fits my 15" wheels) from SSBC. 2 additional inches of heavy rotor, larger pads and piston should help that situation. I still have drums out back but did upgrade the shoes to semi metallic and had the drums cross drilled so as to dissipate heat and the glazing potential generated from off gassing.

DrJ

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Re: suspension question...air ride

Post by aronhk_md on Sat Sep 10, 2016 11:26 pm

I have disc brakes on all 4 corners and was told its a 9" rear, but honestly I havent even had time to look under the car yet. I got what I thought was a good deal for a 5 speed with hard and soft top, and figured I can work with it from there.

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