Don't worry, this isn't a debate on which is better. My 3-link project is coming together very nicely, picts here
http://www.chevelles.com/showroom/showgallery.php?cat=500&ppuser=26133
There still is some finish work to do, but it is working out nicely. There is quite a difference between the 3-link and the original suspension. First was with the original arms/bushings. I could lift one side and you could hear the bushing squeak/bind. The rear end didn't move freely. Second was with heim-joint lower arms, motion was much better. I almost stopped here since the rear end moved pretty good. The upper arms did have alot of slop in the bushings on the axle, though. Last, with the 3rd link, the rear end moves so easily it is amazing. Worlds better than the stock setup.
I originally wanted to do an upper mount like this one http://members.webpathway.com/dougnsteph@webpathway.com/mustang/rear-suspension.html but, the mounts are closer together and up higher on the 10 & 12-bolts. So I came up with my mount which bolts onto the upper mounts with 4 bolts each side. Works pretty well, and I can transfer to a 12-bolt when I find one I can afford. 10-bolt will have to do for now.

Don't worry, this isn't a debate on which is better.I'm pretty sure there would be no argument. 3-links rock :thumbsup:

That's awesome! What's the length of the upper link?

Derek, the upper link is 12.5", adjustable 12-13" in length approx. If I was willing to cut into the floor, It could have easily been longer. Of course then I would probably have extended the lower control arms and then... well I didn't want to get that snowball rolling downhill. :clonk: I want to keep the car closer to stock, no full tilt race car.

Derek, the upper link is 12.5", adjustable 12-13" in length approx. If I was willing to cut into the floor, It could have easily been longer. Of course then I would probably have extended the lower control arms and then... well I didn't want to get that snowball rolling downhill. :clonk: I want to keep the car closer to stock, no full tilt race car.

That's awesome. I like how you went through the frame to get a little extra length but only far enough that you wouldn't need to cut the body.

With the body on, is there enough room to get wrenches in there to unbolt the upper link? It's a little late now, but I wish I would have done this on mine.

It will be tight on the front mount getting the bolt off. Before I took the body off, it looked like there will be enough room. The mufflers and driveshaft will make it harder. The rear is not too bad, since I can unbolt the bracket from the ears on the rear end.

Randy,

Nice job! I just finished a lot of this myself. Have you started on the panhard bar yet? My setup ended up being bolt-in but I had to compromise with a ~10" 3rd link. Good luck!

Ryan

The corners on that square hole would make me worry about cracks. Are you going to reinforce the frame crossmember?

Ryan, the panhard is next on the list. I will probably use one like Dennis68 has on the axle side, but will have to make the frame side one. I can't find one that suits my needs.

Steve, the angle on the front goes up higher than the square opening in the crossmember and is welded at the corner, so I hope cracking won't happen. I still might do some more bracing yet. I haven't decided how to do it yet.

Ryan, the panhard is next on the list. I will probably use one like Dennis68 has on the axle side, but will have to make the frame side one. I can't find one that suits my needs.

Steve, the angle on the front goes up higher than the square opening in the crossmember and is welded at the corner, so I hope cracking won't happen. I still might do some more bracing yet. I haven't decided how to do it yet.

For my panhard bar, I ended up making my own brackets on both ends because I couldn't find one that would clear a full-length tailpipe. I think Dennis just runs exhaust dumps on his. I think I have pics in my forum gallery-thingie, but let me know if you'd like me to email you some more.

I'd be careful with that crossmember, too. I'd imagine that there's a good bit of stress in it. I think I saw some braces welded in, but you may want to find a way to help reinforce it across your new opening.

Ryan

Ryan, yep I seen your picts, thats where I got some of my ideas from. I have a couple rough ideas to brace the crossmember more. Just got to hammer them out to see what will work.

...I'd be careful with that crossmember, too. I'd imagine that there's a good bit of stress in it. I think I saw some braces welded in, but you may want to find a way to help reinforce it across your new opening.
I've been watching these projects and contemplating my own. The strength and stress on the cross member has been one of those things to puzzle over. GM did add braces on the BB cars suggesting there is some design weakness there.

But what I always wonder is if there really is a problem in the 3-link configuration? We have concentrated the force further along the crossmember making it worse. But we have also completely removed the loading from lateral axle location. So are we really left with a problem or not?

Well, I braced the crossmember better. Check out my showroom. Notice that the frame is now black, looks alot better than before. :hurray:

I've been watching these projects and contemplating my own. The strength and stress on the cross member has been one of those things to puzzle over. GM did add braces on the BB cars suggesting there is some design weakness there.

But what I always wonder is if there really is a problem in the 3-link configuration? We have concentrated the force further along the crossmember making it worse. But we have also completely removed the loading from lateral axle location. So are we really left with a problem or not?

I don't think it's a problem as long as you're careful. The load from the center link can be spread out pretty easily, so the center of the crossmember isn't hit too hard and the twisting forces from the upper arms (the lateral location) are gone, so it's a wash. I would think that it basically makes the control arm braces (either stock, Hotchkis, or Edelbrock) mandatory, though, since those also help spread the load in the crossmember.

Randy - looks good! Let us know how it works out. How long until you get to try it out?

Ryan

Ryan, If I am lucky, it may be moving by December :sad:

Ryan, If I am lucky, it may be moving by December :sad:

Nothing to be sad about there. It took me almost 3 years to restore mine. I did the 3-link after I already had everything together - trust me, you're doing it the right way! Nothing like knealing on the bed support beams for 3 weeks!

Ryan

Ryan, you got me beat then, I am going on my 5th year of owning this car and never having driven it yet (rolling chassis only when I got it). I do know it wouldn't be much fun to do this with the body on the frame still. That would be rough. At least you had the bed floor out, that had to help.

Ryan where do i go to se your pics of your 3-link.I was looking through some threads and found this one.Thanks for any info

I don't think it's a problem as long as you're careful. The load from the center link can be spread out pretty easily, so the center of the crossmember isn't hit too hard and the twisting forces from the upper arms (the lateral location) are gone, so it's a wash. I would think that it basically makes the control arm braces (either stock, Hotchkis, or Edelbrock) mandatory, though, since those also help spread the load in the crossmember.

Randy - looks good! Let us know how it works out. How long until you get to try it out?

Ryan

How much power can a 3 link handle?:rolleyes:

Ryan where do i go to se your pics of your 3-link.I was looking through some threads and found this one.Thanks for any info

Click on the link in my signature! There are a few pictures on page 3. I think there may also be a few in my gallery on the site here.

How much power can a 3 link handle?:rolleyes:

That depends on the design....mine right now won't tolerate much more than ~400hp if you're looking for a number. You have to remember that there is only one link to counteract the torque.

Elusive r,
how well does your 3-link work.are your lowers in the stock location.are runnimg coilovers i couldnt really see in the pics.Thanks for the input.

Using 450 ft lbs engine torque and 10 inches from the center of your rear to the upper mounting point I am calculating close to 1700 pounds force on the upper link. As you move the upper mount further from the center, force on the pull bar is reduced. The moral is the higher you mount your upper link on the rear axle, the less force exerted on the cross member. Also with any supension with angled lower control arms in plan view, the panhard bar needs to be as long as possible to reduce rear steer tendencies. As the panhard moves up and down it moves the axle side to side slightly. As the rear moves side to side with angled lower arms, one side will move forward, while the other moves back. This will produce different handling in different direction turns. The panhard needs to be as long as possible and level at ride height to minimize this effect. Try it in the garage. Move your rear side to side and measure the amount it steers. You will be shocked. Just some things I learned the hard way circle burning.

I think your estimate is too low. For one you have to factor in the gear ratios of both differential and transmission. With a simple 4.11 rear end and 2.5 1st gear that provides a 10X multiplier putting you up to 4500 ft lbs. Then you have to factor in the impulse loads of dumped clutches and flywheel inertia. And finally add in margin for fatigue and safety factors.

And of course there are limits to how high you can go with the upper link before you run into bodywork.

As to PHB lengths... what you say is true if you run ridiculous short PHBs like a lot of the regular stock car parts. But if you run a bar that actually goes across the car (not just to the center) then you are looking at 40" or more. At which point you are looking at a +/- .1" sideways displacement of the axle. Work that through a 22" long LCA as we have on the A-body chassis and you get nil steering.

Elusive r,
how well does your 3-link work.are your lowers in the stock location.are runnimg coilovers i couldnt really see in the pics.Thanks for the input.

It works well. It rides like stock but is very predictable. I don't really like how my panhard bar is mounted, but I'll take what I can get. I'm using stock lower arm, spring, and shock locations - no coilovers.

And finally add in margin for fatigue and safety factors.

It's amazing how big the forces can get once you factor in fatigue, particularly for an aluminum link :eek:

As to PHB lengths... what you say is true if you run ridiculous short PHBs like a lot of the regular stock car parts. But if you run a bar that actually goes across the car (not just to the center) then you are looking at 40" or more. At which point you are looking at a +/- .1" sideways displacement of the axle. Work that through a 22" long LCA as we have on the A-body chassis and you get nil steering.

Actually, my panhard is only 36" long. The reason it is this short is because of the angle of the rear shock, I couldn't make it any longer because the shock interferes with the panhard mount. Otherwise I could have made it 40-42" long.

Actually, my panhard is only 36" long. The reason it is this short is because of the angle of the rear shock, I couldn't make it any longer because the shock interferes with the panhard mount. Otherwise I could have made it 40-42" long.
Oh horrors, that means you have a +/- 0.125" lateral swing of the axle, presuming of course a full 6" of suspension movement. Your LCAs move 0.33* to accomodate that wide variance of motion. I don't have the measurements to calculate what that does to the axle, but I seriously expect it to have too many leading zeros to care. :beers:

Obviously you needed to put the PHB lower where the shocks are further apart so you can make it longer :thumbsup:

And just so you don't all threaten to come lock me up... these type of questions come up often enough that I created a Excel spreadsheet one day to to the trig calculations for me. Makes it trivial to figure this stuff out.

Oh horrors, that means you have a +/- 0.125" lateral swing of the axle, presuming of course a full 6" of suspension movement. Your LCAs move 0.33* to accomodate that wide variance of motion. I don't have the measurements to calculate what that does to the axle, but I seriously expect it to have too many leading zeros to care. :beers:

Darn, I hoped I had removed that pesky 0.025" lateral swing. :p

Obviously you needed to put the PHB lower where the shocks are further apart so you can make it longer :thumbsup:

It would be easier to just move the lower shock mounting point up than lower the panhard mount. Short shocks anyone?

And just so you don't all threaten to come lock me up... these type of questions come up often enough that I created a Excel spreadsheet one day to to the trig calculations for me. Makes it trivial to figure this stuff out.
Me hears Styx song playing Too much time on my hands... :wacko:

thanks guys,
Now for the one question that might get me thrown out of here.It seems that every one doesnt want to talk about lengths and angles of a 3-link.I know that ever car is different,a camaro 3-link geometry wont figuritivly work in an a-body,but isnt there a formula that can be applied.Just asking because i dont know.I know there is a lot that goes into a 3-link as mark from sc&c and others on here have stated.But it seems they say the lowers are ok where they are located,so that only leaves the upper link to get the geometry right.I know i'm looking at this from a simple piont of view and there is a lot more i'm probably not seeing.I am in the process of reading herb adams chassis book and planing on taking some engineering classes to help understand all of this.Suspension design to me is like psuedaphedrine and anhydrous ammonia to a meth head.I love learning what i can and appling it to my car(s).Any insight would be appreciated.Thanks Greg