3 link rear suspension

[marty69212]

any of you guys ever design your own 3 link with a watts link that doesnt interfer with the rear seat ? also , if i do design my own using the lfront leak spring mounting points for my lower arms,like des or many others , does it matter how long or what angle my upper would need to be?

[andrewb70]

I think the reason that this 3 link:

http://www.lateral-dynamics.com/

interferes with the seat because it is the optimal way to do it. I am not suspension expert, but from what I understand if the upper link is not long enough, bad things happen. Who needs a back seat man?

Andrew

[marty69212]

my 2 kids!!!

[parsonsj]

I did my own, and have a back seat. I used a panhard though.

jp

[andrewb70]

I did my own, and have a back seat. I used a panhard though.

jp

Yes John, but you also made your own floor pans and have a custom rear seat.

Andrew

[marty69212]

john, does the upper bar length or angle matter? i imagine the longer it is the better... did you have it designed or did you just build it yourself/???? thats pretty nice stuff!!!

[parsonsj]

True ... but with some reasonable fabrication of the factory floor and upper link frame bracket, something similar could be done, I'd think.

You will need to think in terms of bucket seats in the back, rather than a bench seat. The upper link comes in over the top of the driveshaft.

jp

[parsonsj]

Marty,

I'm the welder/fabricator. Katz Tsubai designed the geometry. And yes, the length and angles most definitely matter.

The hardest part was getting something strong enough for the upper link since the link is in "space" in most cabins. I made the bracketry that triangulated into the Morrison crossmember for mine.

jp

[marty69212]

i dont think fabing an upper link mount would be very hard.. i just dont know how to go about getting someone to design something like this

[silver69camaro]

i dont think fabing an upper link mount would be very hard.. i just dont know how to go about getting someone to design something like this

The best thing you can do is pick up a copy of Herb Adam's Chassis Engineering book, as well as Milliken's RCVD bible. Then purchase a suspension simulation software package and a couple cases of Red Bull...then go at it.

[andrewb70]

What do you plan to do with the car Marty?

Andrew

[marty69212]

i think thats the plan... u know if someone like art morrison or someone would design somethin like that , it would sell like hotcakes!!!lol ...

[marty69212]

i plan to beat the crap out of the car.. i live fairly close to road atlanta and commerce dragway !!!

[Damn True]

Do you plan on running a 5-point harness?

[parsonsj]

art morrison or someone would design somethin like thatMark and Matt at Lateral-dynamics have something like that. My understanding is that Katz did the design. I also understand that Morrison has a 3 link design on its way too. Perhaps Matt Jones can provide more data on it.

jp

[marty69212]

both lateral dynamics and art morrisons intrude into the interior terribly !!

[hotrdblder]

so lets see, you do not know how to design a susp, but your saying both companies invaid the interior too much???
maybe just maybe thats the way it has to be?? just a guess:slap:

you could easily fabricate a camaro for use of 2 rear seats with lateral dynamics or ame

[Mean 69]

Just a point of clarification, Katz did NOT do the design of our 3-Link, I did. Katz was on the team after the design had already been completed, and worked to help out primarily with CAD drawings, and some refinement to the various brackets, etc, but the geometry of the system came from me (good or bad!).

The biggest issue you face when you try to do a 3-Link, or a 4-Link for that matter is that the packing space on these cars is pretty bad: it'd force you to run really short links on the uppers, and this can cause some issues in terms of high performance handling that most folks wouldn't be happy with at all. If you are just going to cruise car shows, or on the streets, then basically any rear suspension design is about good enough. Some are clearly light years ahead of others, but most setups will allow you to "drive" the car. You noted Road Atlanta, that is a complex, high speed course, and if you intend to develop a link rear setup to run on that or similar tracks, I'd highly, highly, highly recommend consulting a true professional that understands what the car needs to do, and how the suspension makes it happen. A ton of folks will give you advise, but few really understand all of the things that happen simultaneously, and that's where the hard work comes in to play. It is not a trivial exercise by any means.

And by the way, you CAN run a back seat with our setup, and others as well I'm sure. It will need to be a custom deal, but nothing any capable interior shop can't do with one hand tied behind their back, it's not a big deal at all for them.

And the question about the five point harness is a good one, and to play on that a bit more, what else do you plan to do for safety, knowing you intend to run high speed road courses? Things can happen out there that are completely beyond your control, and when bad stuff happens, you'd better have the right safety equipment. I haven't driven RA, but Willow Springs out here is a fast (very fast) track. Last year, during the first session, a World Challenge Ferrari broke an oil line and dowsed the whole track. I wasn't the first to arrive, luckily, as I saw a bunch of cars deep into the dirt at turn one. I had a chance to slow way down, turn one is at the end of a long straight, 140 MPH is no sweat for a modestly prep'd car. The dudes that went off were white as ghosts during the de-brief, one guy thought for sure it was all over. It happens, don't think it can't.

Sorry to be dramatic, but we get a lot of calls from folks that are hesistant to cut up the car to install a good setup in the rear. Funny thing is, when you ask them about the rest of the car, they are usually tubbed (seat mod's needed here, thank you), and "sometimes" have a cage (our strong opinion is that anyone running hard on a road course should have a appropriately done cage). It's just a bit ironic.

Mark

[silver69camaro]

I also understand that Morrison has a 3 link design on its way too. Perhaps Matt Jones can provide more data on it.

jp

We do have a 3-link setup, just like the one pictured with our Camaro Max-G photo that's been floating around. I have set up a couple different versions with varying geometry to accomodate different cars and overall packages (dimensional constraints). The ride height and tire diameter play a big role on how much the interior must be cut. Some cars may need the rear set removed, some may just need to trim the seat frame.

We've had quite a few go our the door lately, and it's terrible you have to hide most of the suspension with sheetmetal. It looks killer! :headbang:

[marty69212]

ok.. im wondering about 3 links like ive seen on some mustangs... the upper link is not more than 12inches long... how is this ? lateral dynamics is like 2 feet long... also does anyone have any pics of art morrison tri link install?? i really like their stuff and plan on using their corvette front ..

[parsonsj]

Hey Mark! Sorry I had the genesis of your 3 link wrong.

My thinking is the same as yours. The only real reason to go to a 3 link is to go all out on a road racing course. And if you're gonna do that, then you need the right seats, harness, and cage. A back seat can be worked into the equation, but it necessarily should be a secondary consideration.

jp

[parsonsj]

lateral dynamics is like 2 feet long... As is mine.

jp

[Mean 69]

My thinking is the same as yours. The only real reason to go to a 3 link is to go all out on a road racing course.

Well, yes, and no. As you know now, the 3-Link setup (again, assuming it's done correctly) is just as much at home on the street, or any environment for that matter. Ride quality is terrific, looks killer, the only real downside is installation, and in relative terms, cost (and I stress relative, when you consider all factors, it's very competitive).

Yes, the upper link on our setup is very long, and there's a very good reason for that. And yes, the upper link on the late Mustangs is very, very short. And there's a reason for that too, but it's not performance oriented. The engineers that designed this 3-Link (i.e. 05 Mustang setup) did so on an incredibly short schedule, with virtually no liberty at all to develop it as well as their capabilities would have allowed. Why? Because in Ford's infinite wisdom, they decided VERY late into the car's development, that using the IRS that they HAD been developing for the car would have been too expensive for production, and would have eaten into margins. They gave the engineers almost no time, and wouldn't allow them to delve into the already finalized body/packaging envelope. And that is a true story, not self serving, and the design has issues. So much so, in fact, that a popular late model Mustang aftermarket suspension company has actually adapted a torque arm setup instead of using the 3-Link, which speaks volumes to not only the design approach (i.e. 3-Link versus Torque Arm), but more importantly to the design execution.

M

[marty69212]

thanks , thats what i wanted to know

[parsonsj]

the 3-Link setup (again, assuming it's done correctly) is just as much at home on the street, or any environment for that matter. Ride quality is terrific, looks killer, the only real downside is installation, and in relative terms, cost (and I stress relative, when you consider all factors, it's very competitive). Yes, I sure can't argue with that. I completely agree. I was approaching the issue from a different POV: if you already have a working rear suspension, then the only good reason to need the 3 link's kinematics is for real road racing. Most existing OEM designs are fine for street use.

If, for whatever reason, one decides to replace the rear suspension, then the 3 link ought to be on the top of their list of candidates.

jp

[novanutcase]

Marty,

I'm probably the least knowlegeable person on this subject but what I will tell you is that if your going to be beating the snot out of the car, using it to transport your kids is not a good idea. It sounds like you are trying to setup a hybrid and, ultimately, I think you'll not be satisfied with either setup you do in the end. The car won't perform to your satisfaction and transporting your kids will not be very comfortable. I think you need to decide either one or the other!

John

[marty69212]

dont get me wrong.. im no pro racer or anything.. but i want to get in turn the key and go wherever i want, race a day and drive home !!!

[Damn True]

One thing to consider. If you are planning on tracking the car you really ought to have harnesses. If you run harnesses you really ought to mount them correctly. To mount them correctly you need a harness bar. If you have a harness bar the back seat is pretty much off-limits to anyone you care about.

[parsonsj]

One other neat thing about a 3 link is that it also works for drag racing. Adjustable anti-squat is the same thing as adjustable "bite". The only thing to keep in mind is that the single upper link is doing what two links do in a drag racing 4 link. Be sure and size the link bars accordingly.

jp

[Mean 69]

If you are planning on tracking the car you really ought to have harnesses. If you run harnesses you really ought to mount them correctly. To mount them correctly you need a harness bar. If you have a harness bar the back seat is pretty much off-limits to anyone you care about.

Bingo.

To reiterate though, this doesn't mean that a 3-Link and a back seat are mutually exclusive, they aren't necessarily.
M

[Damn True]

Absolutely right. If somone planned only to auto-x the car a harness setup would not be as big of a deal. Though it would help keep you in the seat better which enhances the drivers ability to like.....drive. But on the track one must consider the very real possibility of wadding the thing up and prepare for that.

[zuess4u]

But,

If anyone gets time check out www.jimfays2.com (http://www.jimfays2.com) he has designed a nice Watts link that works well, and has been race tested.

Currently Jim Fay and Marcus from www.scandc.com (http://www.scandc.com) are working on a package for A bodies as well.

Take a look at Jims product....I think youll be suprised, good guy to deal with quality product.

If you call him let him know Bob halt from Phoenix refered you, he may hang up on you...lol

[olds87]

The link you have for Jim Fay dose not work. Here is the correct address http://fays2.net/

[marty69212]

i just ran acrosss this !! check out www.gmachineracing.com (http://www.gmachineracing.com) ! thats almost exactly what i want only with a watts link and for a camaro!!! does or can anyone make this !!!

[James OLC]

...and pass along a couple of opinions (and facts) based upon my experiences with the LD 3-Link and what you have described as bing your intended use for your car.

I totally respect your desire to have a street legal car that has the ability to be at home on any race track on any given Saturday and I think that a majority of the members on this forum share that desire to some extent or another. That you are looking at retrofitting a 3-link into your car suggests that your desire is for more than having the ability to take your car to the track, you want to be ... competitive (?) ...faster than the other guy (?) ...able to put down some impressive lap times (?) over and above what (you perceive) you can achieve with a modified leaf spring set up. That is great. The issue that I see, however, is that you want all that and the ability to throw your kids in the back seat and go for ice cream when you are done. While the two things are not entirely mutually exclusive, they (at the very least) may require some compromise from both sides.

If it is an absolute requirement that your kids are able to ride in the back seat of your Camaro then the trackability (?) of your can has to suffer. Not because of the packaging of the LD 3-link but because of the other things that you will not be able to incorporate in your car for the track. As has been pointed out, the LD 3-link in no way compromises the ability to have a back seat. In fact when I was mocking my back seat up I found that a near stock mid-80's camaro back seat fit nearly perfectly and required only a bit of modication to fit. The compromise is with the roll bar or roll cage which certainly reduces the usefulness and safety of the rear seat. Even with a removably harness bar (if you go that route) the rear down tubes encroach more on the rear seat than the LD 3-link.

From a performance point of view I am confident that you would be happier with a modified leaf spring set up (see David P. or Carl C. as examples) than with a poorly designed 3-link that sacrifices geometry for packaging. The LD 3-link encroaches on the interior because the suspesion was designed first and foremost to work.

Anyway, take that for what it is worth. I hope that I did not come off like I was posting on cc.com, I just wanted to provide some food for thought. The problem with compromise is that once you have done, you always think "what if".

Just my 2 bits.

[James OLC]

A couple of pics of the cage in the OLC Camaro and how it ties to the LD 3-link:

https://static1.pt-content.com/images/noimg.gif

https://static1.pt-content.com/images/noimg.gif

[marty69212]

so what about www.gmachineracing.com (http://www.gmachineracing.com) /????????

[James OLC]

If you go back to the last time you asked about 3-links (thread: https://www.pro-touring.com/forum/showthread.php?t=30180) Jason from g-machine addresses the Mustang upper link that you are refering to. Jason would probably be the best person to talk to about this so maybe an email or pm is in order. There is are several threads on other boards regarding that upper link so finding more information shouldn't be difficult.

[jason@gmachine]

hello guys, how is everyone?

I think this is the upper link you guys are talking about. I fabricated it, and Louie was the designer. It is made with 3/6" 4130 for the sides and 1/8" 4130 for the top and bottom. The receivers are 4140 Light Racing pinch units that have the highest strength rating in the industry (if you dont believe me then check out lightracing.com). Then we used our Chromoly Heims with the liner to top it off.

Here are some shots of the link.

https://static1.pt-content.com/images/noimg.gif

https://static1.pt-content.com/images/noimg.gif


You can call us at the shop anytime if you have any questions, we always make time to answer any question about any of our products.

Jason

[1971novaSS]

Yes John, but you also made your own floor pans and have a custom rear seat.

Andrew

It is possible to keep a stock rear seat with modification to the floor pans and tranny tunnel. I did it to my nova. But you will have to Modify the metal seat frame work.

I also fit in a mini-tub as well while keeping the stock seat.

If you need some pics/specs then let me know.

[marty69212]

id like to see pics!!! hows the geometry?have you driven it? does it work well???

[1971novaSS]

Geometry is pretty decent. All links are adjustable through hiems. Eventually i will be switching to johny joints.

I haven't got it on the road yet, i have to finish the fuel lines and brake lines.

I will post pics when i get home. At work slacking...

[ProBell]

I ran the 3 link up between the back seats. I used a fire proof shifter boot to seal off the 3
link . Both rear seats are very functional. Take a look at my Car-Domain link in my signature to see more pictures.
The 3 ink works great on the street and the road course. I have gotten some wheel hop in a drag race type launch a few times but have not try ed to tune this out yet.

[marty69212]

yeah, thats what im talkin about.... finally someone thinkin about this dillema !!!! looks good !!!!i keep askin and usually u just keep gettin: thats just the way it is!!! guys , there is a way to have a decent back seat with a three link. I think most of the guys on here must have so much money on there hands that they just have 2 cars..one for racing and one for street abuse!!!! must be nice !!! cant wait to get my car done and blow your doors off!!!

[Mean 69]

err, you originally asked for a "stock" rear seat, and this is anything but that. If you don't have issues with this approach, then the LD setup shouldn't even make you blink or think twice? I must have severly overlooked your requirements, or misunderstood what you really mean to do with the car.

Best of luck,
M

[796spdbu]

Hey just my two cents worth...
1. probell nice car.
2. to me the way the upper link comes through the floor,with the bracing and all.I dont think that would be safe for any young and curious child( i speak from experience,i have a 3 year old daughter)
3. worry about the seat last, as was already said any good upholstery shop could knock out a back seat in no time..even if they had to start with a plywood base and work the foam and cloth from there.
4. if you really want a 3-link,go for it.Build it and learn to tune it..hands on is the best way to learn..just know your limits of both driving and fabrication...so you dont get your self and the kids hurt