Parallel or triangulated 4 bar??

[JD'sTT55]

Trying to decide which would be better for my ride?? Building 55 chevy going w a pro touring theme. Grafted 2nd gen camaro front suspension. Plan to narrow rear frame to fit 14'' wide meats in the rear. Would like to keep 12 bolt rear end. Engine plan is a twin turbo vortec 454 mild to begin with but may pump It up later on. Plan to drive on street mostly but will autocross and drag race too. Also plan to x the frame once I figure out the rear suspension. Your thoughts and ideas would be appreciated. Thanks in advance Jeremy

[Bryce]

Jeremy,

I would go with a fully adjustable 4-link that is parallel in plan view. with a watts link.

Or yo could do a 3-link. Check out AME, I think they have a 3-link for your car.

sounds like a cool car, get some pictures posted.

[Motorcitydak]

You really would be better off with a 3 link. A parallel 4 link with a track bar or watts link is better suited for drag racing but they will not allow much in the way of articulation which you want/need in an auto cross car. A triangulated 4 link will be better because it allows articulation but then you may not end up with the best geometry. 3 link is the way to go

[monteboy84]

I'm with these guys, I'd go with a 3-link with a Watts link.

-matt

[JD'sTT55]

Thanks guys for the input. I had looked at the ame 3 bar setup but was unsure how I'd attach the top bar and watts link to my 12 bolt rear? If I was going w a 9 inch it would be easy but I have an early camaro/nova 12 bolt I was planning on using. I contacted ame about their triangulated 4 bar but they said it wouldn't work with the 12 bolt or the narrowed frame. Articulation is an important factor as I would like the car to corner well both on the track and the street. Maybe I'll just have to not be stubborn about putting ford parts in my chevy so I can get the end result I want.

[JD'sTT55]

Oh and as soon as I figure out how to post some pics I will

[JD'sTT55]

I see that bmr offers a torque arm / watts link for a 12 bolt so if I was gonna put a 3 bar and watts link on my 12 bolt I'd have to fab up something like that.

[exwestracer]

Only potential issue with a 3 link would be the amount of force going through the top link rod ends. They work great, but the 14" tires and twin turbo 454 might be cause for concern. Make sure you get top quality components to hold it all together...

[dontlifttoshift]

See if BMR will sell you the torque arm, forward links, and watts link. Bolt it all to you 12 bolt and fab everything else. You said your were going to x the fram anyways so that would make a perfect spot to mount the torque arm. We did a 56 Buick the same way except with TCI stuff and it worked out really well.

Here is a few pics...wish I had gotten more. http://frameupwheelworks.smugmug.com/Repair-Service-Upgrades/56-Buick-Chassis/11054518_jf6kQ#773667807_5VJXd

[Norm Peterson]

The single upper link carries about the same load as either lower. Not double like people tend to think because there's only one. Still, and especially with a powerful engine and decent grip, you'd want to have enough difference in the heights of the UCA and LCA pivots to keep the loads as reasonable as possible or practical.

It's probably easier to build enough anti-squat into a 3-link for dragstrip duty without screwing up the handling than it is to make either a dragstrip-based 4-link+PHB or an OE-based triangulated 4-link work very well through a slalom.

Another 4-link option is the AME triangulated 4-link, which appears to be skewed more toward turning corners.


Norm

[NickChassisworks]

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[Motorcitydak]

Typically the top link on a 3 link setup is offset to the right side to counter driveshaft torque upon acc but it may not be far enough to get it away from your cast iron center. Check into getting a steel diff cover and welding the mount to that then add a brace going to the axle tube. Also, check out the fays 2 watts link, should be able to work for you

[JD'sTT55]

Well I got a lot of good info on here and have read and studied Fred and Herb's books. I think I'm gonna go with a three link with a watts. I've measured everything out and should be able to fit this type in my frame the best. I've been looking at curries Johnny Joints and making my own control arms. I am trying to decide wether to use them on both ends or use a poly bushing on one end??? I see some companies do it both ways so am unsure which would work the best for me????

[JD'sTT55]

Typically the top link on a 3 link setup is offset to the right side to counter driveshaft torque upon acc but it may not be far enough to get it away from your cast iron center. Check into getting a steel diff cover and welding the mount to that then add a brace going to the axle tube. Also, check out the fays 2 watts link, should be able to work for you

Thanks Steve my plan is to offset it a inch to the right so hopefully I won't have the opposite when I am braking. Im actually thinking of drilling and tapping the top of the center section to bolt my uca mount on.(what do you think??) I'll look into the steel diff cover and see if that might work better. Bmr uses a plate that goes between the cover and housing for their torque arm mount I have been looking at as well. The fays watts link did catch my eye and I think that type is going to work the best too. I wanted to add a crossmember in that area for the coilovers and I think using this type will give me the most room for my exhaust as well.

[Norm Peterson]

. . . my plan is to offset it a inch to the right so hopefully I won't have the opposite when I am braking.
There will be a little asymmetry, but with the UCA at only 1" eccentricity it won't amount to much.

Some sort of arrangement using a plate between the cover and the housing sounds like a better solution than attaching directly to a casting not designed for heavy local loading at that point. Buick specifically used this sort of plate with two attachment points for the traction arm on the GNX and Kirban continued this design as an aftermarket offering at least for a while, but I don't know if it or parts of it are still available. I think the offset was a little more than 1", which might mean a little more asymmetry in a 3-link but still shouldn't be a deal-breaker.

Side benefits: gaining a little diff fluid volume can't hurt in a high powered car, and the more rearward position of the axle side UCA pivot makes it easier to get some length into your UCA without compromising the rear seat.


One further option might be to use an axle out of the current Mustang, as that car already comes with a 3-link suspension and has a properly designed ear for attaching the UCA. Watts link kits already exist for this axle (Fays2 and Steeda that I know of).


Norm