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1967 Nova coupe
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Discussion Starter · #1 ·
I am about to fabricate a triangulated 4 point suspension system for my 67 nova . Can anyone share some pro's and con's of that type of set -up? I am trying to get away from the pan hard bar .
 

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Lots of info about exactly how to set up a triangle 4 bar on line. Here are a few things I've learned setting them up. First, the upper bars must be angled out to the frame a lot. Because they are the ones that will keep the rear end from moving side to side there must be a greater angle. The top bars should also be pointed downward (back to front). This will prevent the front end from popping up on launch. Bottom bars parallel to the ground. Make SURE all your joints are tight. Any bracket to rod end loose fit will cause ill handling. If possible do not use heims joints.
 

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Discussion Starter · #4 ·
Lots of info about exactly how to set up a triangle 4 bar on line. Here are a few things I've learned setting them up. First, the upper bars must be angled out to the frame a lot. Because they are the ones that will keep the rear end from moving side to side there must be a greater angle. The top bars should also be pointed downward (back to front). This will prevent the front end from popping up on launch. Bottom bars parallel to the ground. Make SURE all your joints are tight. Any bracket to rod end loose fit will cause ill handling. If possible do not use heims joints.
I find it interesting you would not recommend Heim joints. I have read that using them eliminates the binding in case of misalignment. I purchased some high end joints from Rod End supply that they recommended for the application and plan on using 3/4" shoulder bolts for the precision fit. I own a manufacturing facility and have access to lasers, cnc mills and lathes so fabricating the components will not be an issue. I have also read that the top bar should be about 70% in length compared to the bottom bar. Do you have any experience with that ratio from top to bottom?
 

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I used heim joints on a roadster and there was a constant clicking. Joints wore out and gave a "harsher" ride. I like urethane for a smoother, quieter ride but you have all the tools necessary to provide a sharp positive rear end location. I left the suggestion of research on purpose for your education on triangle four bars. I have read lots about them and how to set them up and there is some conflicting info on setting them up and bar length. Much to much info to answer here. Appears you have the tools and knowledge necessary to make it happen. I really like the triangle 4 bar rear suspension, had it on my '33 Willys. Bite was so good the earth would rotate a couple of degrees. Had to make runs in the opposite direction just to reset sunrise! Weak link was the damn coil over shocks. Went to air bags and things were sweet after that. No more coilovers for me. How about some pictures of your setup when building?
 

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I would seriously consider a parallel setup with a watts link.

Running parallel your allowed to have the links tuck up next to the frame rails. This gives more room for exhaust, suspension, etc. It generally allows you to lower the thing further down (parking) with bags etc.

These are also easy to make adjustments on.

A triangulated setup is nice on something lifted where the suspension really needs to work and be less limited in travel while remaining straight.

For a car parallel will do most what you ask of it without issue.
 

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Discussion Starter · #8 ·
The rod ends I purchased for this application are from Rod Ends Supply which they recommended. The are called Chromoly Steel Nylafiber which have a nylon type liner cast into the body of the joint. However, I do like the way Johnny Joints are made and will take them into account in my design. If I do have issues with the heim's , I can always switch them out.
My Auto -cad model shows the lower arm at 24" and the top one at 19.75 inches. When I show the travel of the axle, it looks like there will be a slight pull towards the front of about .300". Does anyone see that as a problem?
 

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I assume you are talking about the arc travel of the rear end. Most of your suspension travel will not be to the full extent during normal driving which would produce about (guess) 1/8" travel. I see no problem with the max of .3" either. Biggest issue would be ANY side to side motion. Ask me how I know this! Seems you have this covered with quality rod ends and proper hangers.
 

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When I put the original triangle 4 bar in the handling was downright scary. Didn't have to apply much power and the rear end would jump out from under me. Let off the gas and it would do it again. Looked for broken welds and loose bolts but all was fine. Went to slide under the car and grabbed the lower bar to pull myself under and noticed a little play in the front mount. Inserted a shim washer on the forward 4 mounts and the problem when away. Amazing how that little play caused such white knuckles.
 

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Discussion Starter · #13 ·
Thanks for sharing that! I will make sure everything is solid . When I get it together I will post some pics..
Here are pics of what I have so far. Top link is 19.5" and the lower is 24" . All dimensions are ctr.-ctr. Any thoughts?
 

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Good deal of spread on the upper bars which will keep the rear end in place just fine. Only thing I can't see is the amount of down angle the upper bars have. As long as when you launch the front end doesn't pop up much and you have lots of bite then I think they are just fine. Lots written about the focal point but I really don't expect to see you on Street Outlaws.
Just me, but I hate coilovers. Note that the whole rear of the car is suspended on just two bolts. I snapped one off on a mis-matched bridge seam. Air bags are adjustable from the dashboard with a push of a button whereas crawl under the car to adjust the coils.
 

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Discussion Starter · #16 ·
Good deal of spread on the upper bars which will keep the rear end in place just fine. Only thing I can't see is the amount of down angle the upper bars have. As long as when you launch the front end doesn't pop up much and you have lots of bite then I think they are just fine. Lots written about the focal point but I really don't expect to see you on Street Outlaws.
Just me, but I hate coilovers. Note that the whole rear of the car is suspended on just two bolts. I snapped one off on a mis-matched bridge seam. Air bags are adjustable from the dashboard with a push of a button whereas crawl under the car to adjust the coils.
I have 3 degrees of forward down angle at ride height. The rear end seems to hold the three degrees through out the range of travel so I think the difference I noticed in the model is pretty accurate. As far as the shocks are concerned, I plan on using grade 8 bolts but if I have trouble the air shocks are always an option and will bolt up to the brackets I made. I do like the idea of adjusting them on the fly..
 

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I have thought about making a different lower shock mount that puts several bolts into the rear end hanger and a cross bolt for the shock. This way the bolt is supported on both ends. Hope that makes sense. Would like to have a followup when you get the car on the road regarding launch and front end lift.
 

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Discussion Starter · #18 ·
That won't happen for a couple of years! This is my retirement project and I am still working. The car was crushed by a tree in a storm so I am starting from scratch. Having 30+ employees keeps me pretty busy with very little time to work on it.
 
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