Coil spring rear suspension?

[manimal]

I just read in Classic Trucks that CPP has now come up with a coil spring rear suspension kit with trailing arms. Just like the earlier trucks. I have been concidering taking a trailing arm crossmember from an early truck and grafting it to the '75short stepper. Has anyone else done this?
-Lance

[N2TRUX]

HMMM? I do see any advantage to the conversion. Care to share your theory?

[manimal]

The trailing arm set-up is just like ladder bars, 2 forward control arms and a panhard bar. You wont have the harsh ride known with typical leaf spring suspension,nor the axle wrap in high perf trucks. It would be a WHOLE LOT EASIER to lower. And I believe that it would handle much better too. Think HOT RODS TO HELL. They do it for ANY car and have had VERY successfull results,slalom course,drag strip, and overall handling. If you havent gotten the copy of ClassicTrucks(has green 50's FORD on cover) I suggest you do and check out the article about this. I think you might enjoy it. Thanks.
-Lance

[Malo83]

Read the article and it sounds like a big improvement over the Leafs, a lot smoother ride and stability ala Nascar style rear suspension, would love to put a kit on my 83

[moneyeater]

I haven´t read the article but i thought about that since i first saw the trailingarms from the 67-72 trucks.The ride should be much smoother and the lowering is much easier wether you take a coilspring or an airbag.My leafspringsuspension rides alot better after removing two leafs but i don´t think that carrying loads would be the same.The trailingarmsuspension should be a great improvement in ride and handling no matter if your bed is used or not!

[Pyrotechnic]

You can get decent results with Cal Trac bars and leafs springs for drag racing purposes or if you just want to hook up. This is what I'm going to do, but I've never had a problem with the ride that leaf springs gave me and $350 for good traction doesn't sound all that bad.

[manimal]

Wow, I thought this might bring a little more interest than this....
-Lance

[streetstar]

You're not completely alone. I am actually interested in this -- thats a trick setup--- but i have too many irons in the fire already. I won't be doing anything chassis related for a few months.

[killthewabbit]

Of course CPP has nothing on their site about anything over 1972. I should say that if they do, I can't find it. I would definitely consider doing that, but it would have to be relatively inexpensive.

I'm totally jealous of the 67-72 guys and their rear suspension. It looks so easy to bag and do even a static drop.

[Malo83]

I'm still waiting for their 73-87 Catalog

[N2TRUX]

I read the article. I agree that trailing arms might be an improvement over leaf springs if you are trying to get low. Nascar has proven this type of suspension works as that is what they use in the rear.

I wonder what would be the difference between this system and a 4 link.

[killthewabbit]

Seems like with triangulated trailing arms, it would stay put side-to-side a bit better than a parallel 4-link. That's just a guess, though.

[N2TRUX]

Air Ride Tech tried the triangulated theory, and it didn't work that well. We put a triangulated 4 bar system on my 82 Blazer. The lower bars were in your typical parallel placement, and the upper bars were triangulated. The problem with the system was the upper bars allowed to much lateral movement.

If you use a traditional 4 link, or triangulated trailing arms you still have to have a 5th link to locate the axle. Your going to run a panhard bar either way. The advantage I see is the longer trailing arms would give more leverage for lift at less air pressure.

[boxrodz]

I've though a bit about it, but I haven't taken any measurements with a pair of stock arms that I have. I believe a member (?wild?) was looking into this a few months ago. I finally had a chance to read the article. It didn't say how low you could set it up without the trailing arms bumping up against the frame rails during ride travel. (It looks like their set up requires about a 2" notch.) Herb Adams (Suspension Engineer/Author) favors a trailing arm setup over a 4-bar suspension. The trailing arm suspension gives you better articulation over a 4-bar. The roll center is probably better as well for street driving. I would think that with the Johnny Joint, one could obtain the same type of articulation. Although, I don't see 4-bar setups with anything other than regular bushings (or Heim joints). Even more, some of the setups use poly bushings over rubber bushings. I wonder how much the 4-bar binds during a typical articulation of the rear wheels. I suppose a 4-bar with Johnny Joints may be a more convenient setup then a trailing arm.

[87Wrangler454]

I too have been thinking about adapting the 67-72 rear suspension to my 87' 1/2 ton. The longer arms have less effect on what is called rear steer when the axle travels up and down.
Take a drawing compass and draw a long arc to represent long arms and a short arc to represent short arms, the axle follows the path of the arc during suspension travel. You will notice less of a change with longer arms, that change is in your wheelbase if both arms are equal length.
If arms are mounted parallel to the ground in both 2 and 4 link it is said to produce zero anti dive (front end dropping during hard braking)and anti squat (rear end dropping during hard acceleration).Moving the front arm mounting point up or down will change these characteristics. Some four links come with that adjustability in there front mounts. Nascar boys also move these mounting points up or down for the long trailing arms to tune their suspension.
Panhard bars locate the rear axle and also control roll oversteer (body roll during cornering), the longer the bar the less roll oversteer.
The only panhard type linkage to produce zero roll oversteer is called a Watt's linkage. It consists of 2 parallel mounted bars and a central pivot point. The pivot point can be mounted to the rear axle and the end of the bars mounted to the frame or the pivot point can be mounted on the frame and the end of the bars mounted to the axle tubes. This type used to be popular with the Trans Am crowd.

[SCOTI]

It would be a worth-while conversion if the 'kit' isn't overpriced. My 68 that's lowered 6/8 rides much better than my 5/7 dropped 74.

[85 c-10]

An older gentleman has contacted me about putting a 572 in a 2008 shortbed Chevy. One thing he is adament about is the older, coil spring setup. Early Classis Enterprises has a new boxed style that I was looking at. I would love to use this setup as it cures a lot of ailments the leaf springs cause in high horse applications.

http://www.earlyclassic.com/

Josh

[N2TRUX]

Originally Posted by SCOTI

It would be a worth-while conversion if the 'kit' isn't overpriced.....

I guess it a matter of what it compares to. I don't see a price for the 73-87 conversion kit, but the 67-72 kit is 672.00 so I will assume the 73-87 conversion kit will be around $1k or more.

[N2TRUX]

That's vs the Air Ride Tech bolt in system that is 1699.00

[87Wrangler454]

The setup posted by N2TRUX looks like it would be fairly easy to fabricate with the right tubing. Does anybody know if the distance between the frame rails of a 67-72 & 87 are the same where the crossmember bolts in.

[SCOTI]

Originally Posted by 87Wrangler454

The setup posted by N2TRUX looks like it would be fairly easy to fabricate with the right tubing. Does anybody know if the distance between the frame rails of a 67-72 & 87 are the same where the crossmember bolts in.

I believe the measurement is 34".

[Tony@AirRideTech]

When we started developement of a new rear kit for the 73-87's we originally looked at doing a trailing arm set up like our 63-72 rear kit. We ran into a couple frame framerail / arm clearance issues and the fact that to use an arm set up like that you would need to weld on new axle perches. That is why we went with a parallel with a panhard bar.
The problem with doing a triangulated four link on em is the narrow framerail width. You end up bringing your angled bars down on the rear end housing which is cast. In order to pull it off and get enough angle on the upper bars to be effective, you need to build a foward crosmember, attach the front of the bar towards the center of the truck and then run the bars outward toward the ends of the axle tubes.

[SCOTI]

Originally Posted by Tony@AirRideTech

When we started developement of a new rear kit for the 73-87's we originally looked at doing a trailing arm set up like our 63-72 rear kit. We ran into a couple frame framerail / arm clearance issues and the fact that to use an arm set up like that you would need to weld on new axle perches. That is why we went with a parallel with a panhard bar.

Or grab a 64~70 rear housing for a little less BS on the wheels (71-72 housing should keep the BS the same).

[87Wrangler454]

Thanks Scoti; I'll go and measure my 87 to-morrow and see how close it is.
I am going to replace the GM rear axle with a F**d 9" we ran them in the stock car with great success. I have broken those GM axles before and they come right out when that happens. The 9" we converted them to floater style axles and hubs, which means if you break an axle it does not come out. I am thinking about adapting adjustable coil over shocks which will save the work of having to make spring pockets.

[Bagged Nissan]

The reason why triangulated 4 links dont work too well on c10's is for the sheer fact that the frames are super narrow, not allowing you have the min of 35* of angle on the upper bars to eliminate most lateral movement, if not all. That is why the vast majority of guys with fullsizes, run parallel 4 links. With that you need a panhard. The kits out there make the panhards pretty short and in any kind of leverage setup (be it true canti, bag on upper bars in a parallel, lift bars for a 6 link setup) is the panhard pulls the rear end to 1 side, some more so then others, it depends how long you make your panhard bar.

The 'trailing arm' conversion, which isnt really a ladder bar setup, as ladder bars have both upper and lower mounting points that join into the same link later on. trailing arms like on the old trucks work fine for a non-adjustable setup. When you start bagging them, in stock locations, you might not see much of a problem, not sure as to not many ppl i know, want to go from a 1:1 over axle to like a 1.2:1 b/c the bar isnt far up on the bar in a trailing arm setup. But when you start moving the bag, you run into severe pinion problems, in a 2:1 you can easily have a change of 8-12 degrees throughout the motion.

If you are staying coil as your title suggest, then a trailing arm will work fine for you, if you plan to bag, there are far better options out there.

Good luck with the truck.