Setting up a 4 link

[PrerunnerRob]

Hey guys,
I picked up a new 4 link for my truck at the local car show, and was wondering if anyone has set one up properly with a dropmember. Any input would be greatly appreciated, especially geometric stuff!

[leftcoast66]

Originally Posted by PrerunnerRob

Hey guys,
I picked up a new 4 link for my truck at the local car show, and was wondering if anyone has set one up properly with a dropmember. Any input would be greatly appreciated, especially geometric stuff!

Is it parallel or triangulated. I'm guessing triangulated but figured I would clarify.

Triangulated, you need the triangular bars to be greater than 30 degree angle to keep it from going side to side, unequal length obviously for top and bottom will create a change in pinion angle throughout the range of travel, which can be good or bad, depending on what you want to use it for. Those are a few things that pop into my mind right now, its midnight and I've studied 6 hours for tests so might have a few more thoughts when I'm awake again haha.

[PrerunnerRob]

Originally Posted by leftcoast66

Is it parallel or triangulated. I'm guessing triangulated but figured I would clarify.

Triangulated, you need the triangular bars to be greater than 30 degree angle to keep it from going side to side, unequal length obviously for top and bottom will create a change in pinion angle throughout the range of travel, which can be good or bad, depending on what you want to use it for. Those are a few things that pop into my mind right now, its midnight and I've studied 6 hours for tests so might have a few more thoughts when I'm awake again haha.

Thanks for the info, it is triangulated.

[leftcoast66]

Originally Posted by PrerunnerRob

Thanks for the info, it is triangulated.

Sweet. Let me know if you need more details than that. One other thing is the longer the arm the better it is for the geometry. The axle will change the pinion angle a lot less with a longer arm.

[Captainfab]

I'm almost done with a Morrison Tri-4 bar in a '67.....is there something specific you need to know? What brand is yours? I had to do some fabbing to make it work. I can get you some pics if it will help.

[PrerunnerRob]

I think I may be putting more into this then I really need to. I was going to use a 4 link calculator to set up the handling perfectly, but I'm thinking that is no necessary. I.m wondering how far the lower link must be placed from the frame to keep good frame clearance, but not so far out it get near the tire. Any pictures would be greatly appreciated!

[ChiefRocka]

Sweet...does this mean the cabs are done..and your working on the chassis !?!?!?


BTW, this should be in the suspension forum....

[ElkyRacer]

Hey Rob, I had the same questions as you when I was starting to order parts for my 4 link. Heres a good thread in the suspension section.

http://67-72chevytrucks.com/vboard/s...d.php?t=270699

Hope that helps.

[PrerunnerRob]

Originally Posted by ChiefRocka

Sweet...does this mean the cabs are done..and your working on the chassis !?!?!?


BTW, this should be in the suspension forum....

Cabs are nowhere near done, but I had to pull it out the other day. It was a nightmare trying to steer the truck outdoors, and since I picked up a 4 link at the Pleasanton show on Saturday, I'm goint to try to get this done.
I thought about the suspension forum, but I was hoping for an easy answer....

[ChiefRocka]

I went to the show on Saturday too...was actually a nice turn-out...LOTS of rides there considering the weather looked crappy.

[Captainfab]

Here are a few pics of the tri-4 bar that I did on a '67.

[Captainfab]

And a couple more.....

[PrerunnerRob]

Originally Posted by Captainfab

And a couple more.....

Very nice work!

I just tried out the 4 link calculator I found at pirate4x4.com, and it works perfect. All of the technical data I could ask for, and alot I probably don't need. I think I'm going to use this to set everthing up in theory, and move stuff from there. Sweet!!!!!!!

[PrerunnerRob]

Originally Posted by ChiefRocka

I went to the show on Saturday too...was actually a nice turn-out...LOTS of rides there considering the weather looked crappy.

I know! I tried to stay away from the FBI booth, but too many good deals to pass up(especially after 2 beers)! 4 link and 4 valves for $300 cash!

[LILRED66]

Originally Posted by Captainfab

And a couple more.....

After looking at the photos...I understand why you are know as Captainfab.

Very nice work.

[PrerunnerRob]

ok, one last question. Why mount the lower links inside the frame instead of outside? I would think the truck would be less prone to chassis roll the further the bars are spread apart. Is there an issue of the tire to link clearance?

[Captainfab]

Originally Posted by PrerunnerRob

Very nice work!

I just tried out the 4 link calculator I found at pirate4x4.com, and it works perfect. All of the technical data I could ask for, and alot I probably don't need. I think I'm going to use this to set everthing up in theory, and move stuff from there. Sweet!!!!!!!

Originally Posted by LILRED66

After looking at the photos...I understand why you are know as Captainfab.

Very nice work.

Thanks Guys

Yes Dan and Greg's 4 link calculator is pretty sweet

Originally Posted by PrerunnerRob

ok, one last question. Why mount the lower links inside the frame instead of outside? I would think the truck would be less prone to chassis roll the further the bars are spread apart. Is there an issue of the tire to link clearance?

Yes it is best to have your arms as far apart as you can for better control. This one was done this way for a couple of reasons 1) this was all a kit that was purchased from Art Morrison, and in order to get everything to fit in the required space that is where they ended up. 2) There just isn't room for the lower bars outside the frame with the tire & wheel size that will be ran.

[PrerunnerRob]

Excellent info, thanks for the help!

Originally Posted by Captainfab

Thanks Guys

Yes Dan and Greg's 4 link calculator is pretty sweet



Yes it is best to have your arms as far apart as you can for better control. This one was done this way for a couple of reasons 1) this was all a kit that was purchased from Art Morrison, and in order to get everything to fit in the required space that is where they ended up. 2) There just isn't room for the lower bars outside the frame with the tire & wheel size that will be ran.

[joe231]

nice work Capt.
is that truck finished? if so how does that setup handle?

[Captainfab]

Originally Posted by joe231

nice work Capt.
is that truck finished? if so how does that setup handle?

No unfortunately it isn't done yet.....I took those pics just today. The goal is to have it finished for next summer. Should be a blast to drive with a 620hp 572 under the hood

[Captainfab]

Originally Posted by PrerunnerRob

Excellent info, thanks for the help!

No problem, Let me know if you need anything else.

[RunninLo]

cap'n,
I may be wrong here but it was always my understanding on the tri 4-link that the "longer" bars were the uppers and were longer to compensate for being mounted at angles instead of straight like on a parallel 4 bar. It was also always my understanding that it was done that way to keep the pivot points on the frame the same distance from the axle and to minimize pinion change.

I see by looking at your pics you went with the short bars up top and have a pretty good distance between your pivot points.

I'm not saying right or wrong just curious why you chose that way and what the benefits are?
TIA,
Josh

[scotts62]

Originally Posted by Captainfab

No unfortunately it isn't done yet.....I took those pics just today. The goal is to have it finished for next summer. Should be a blast to drive with a 620hp 572 under the hood

Yeah i can see how that would be fun to drive!!!
Setup looks good

[Captainfab]

Originally Posted by RunninLo

cap'n,
I may be wrong here but it was always my understanding on the tri 4-link that the "longer" bars were the uppers and were longer to compensate for being mounted at angles instead of straight like on a parallel 4 bar. It was also always my understanding that it was done that way to keep the pivot points on the frame the same distance from the axle and to minimize pinion change.

I see by looking at your pics you went with the short bars up top and have a pretty good distance between your pivot points.

I'm not saying right or wrong just curious why you chose that way and what the benefits are?
TIA,
Josh

I'm far from an expert on link suspensions, but I think what you're thinking would definitely be the direction to go with a vehicle that needs substantial suspension travel, like in offroad, but could be used on the street as well. On a street driven vehicle with a more limited travel suspension, you can get away with a little more. The principals and design of link suspensions is quite complex and involved. The 4 link calculator that Rob already used is a very useful tool and can certainly be applied to street use.

The '67 that I'm building is for a good customer, and with my limited link suspension experience, I decided to play it safe and just order the kit from Art Morrison. The Tri-4 bar suspension was designed by the engineers at AME and is a proven setup, which is one of the reasons I went with it. The bars come already welded and the kit comes with instructions giving parameters for installation. Here is the kit that I ordered
http://artmorrison.com/layout.php?y=...i4bar/&x=index

I am by no means saying that this is the best triangulated 4 link for the street, it is just one that is proven and was the 'safe' way for me to go at the time. If it was my own truck I probably would have built one from scratch.

Let me know if I can be of any help Josh

John

[Captainfab]

Originally Posted by scotts62

Yeah i can see how that would be fun to drive!!!
Setup looks good

Thanks for the compliment Scott