Pro Street 4 link for a daily driver?

[bgreen776]

I've built many different styles of 4 link suspension, for front and rear suspensions, but never a "parallel" 4 link with a watts or panhard. I am trying to get into the high 10's without making any more HP, (ran an 11.04 backed up by and 11.06 this year) and traction and launch/chassis/suspension tuning is the way to get this done.

Caltracs would be easy. Thats not my style. Though if time runs out, this is the way I will go.

My inclination is to go with a double triangulated 4 link, but I realize there is likely a reason nobody uses this on the track. A standard parallel 4 link with a panhard bar will likely provide me the strength and handling needed for my application, and be simple to fabricate. I'm not sure if I want to go with some sort of OEM coil, air bags, coilovers, or some combination of the above.

Any input, advice, or experience would be greatly appreciated. There is literally ZERO snow here, and I am getting cabin fever.

[jlibert]

since it's a dd, I'll assume you aren't going to back half it too. The new 1/2 ton rams are 4 link, and I've heard the HD's are too. No problem daily driving those. For the track, you'll probably want a good set of double adjustables, but they would wear quickly on the street. You'd probably need two sets (track/street). What was your race weight, and can you throw up a timeslip?

[bgreen776]

Originally Posted by jlibert

since it's a dd, I'll assume you aren't going to back half it too. The new 1/2 ton rams are 4 link, and I've heard the HD's are too. No problem daily driving those. For the track, you'll probably want a good set of double adjustables, but they would wear quickly on the street. You'd probably need two sets (track/street). What was your race weight, and can you throw up a timeslip?

Im at about 7200 lbs. The truck is a "DD" only in the sense that I drive it on the street for tuning purposes, sh!ts and giggles, and the wife drives it when we get a big dump of snow and her car cant get out of the driveway. Neither of us actually drives it daily. I like that I can fill the bed with trash and take it to the dump, or go to town and get groceries, or maybe tow a two place snowmobile trailer, then go thrash the track all weekend and crush a few egos and hurt a few feelings. I can put up with some inconveniences, like the door bar on my roll bar, not having a back seat or a headliner. But it needs to be safe and comfortable to drive on the road. Shock life shouldn't be an issue with the low number of miles that the truck sees. Probably less than 2000 a year.

I'd back half the truck in a heartbeat if/when I talk the wife into it. I really enjoy fabrication work. I attached a couple pictures of the last one I did.

[shortbusdriver]

My street driven truck is double triangulated. Havent gotten to the point of suspension adjustments however besides a wheel alignment. Cant say if its better or worse then other 4 links, but I wanted something beefy that could be used for sled pulling and this is the ticket.

I believe most just build what others have done before so that's why no one runs it. Monkey see monkey do. Of course I'm an idiot and don't know enough about suspension to say its worse or better.

[Beat68CST]

http://performancetrends.com/4link.htm

http://www.etcracingprograms.com/ima...kwiz/4link.htm

Read until you're steamin out the ears.

[DieselheaD]

I say go for it, thinking of doing the same thing myself. I'd like to drop weight and have it hook much better at the strip.

[jlibert]

Originally Posted by bgreen776

Im at about 7200 lbs. The truck is a "DD" only in the sense that I drive it on the street for tuning purposes, sh!ts and giggles, and the wife drives it when we get a big dump of snow and her car cant get out of the driveway. Neither of us actually drives it daily. I like that I can fill the bed with trash and take it to the dump, or go to town and get groceries, or maybe tow a two place snowmobile trailer, then go thrash the track all weekend and crush a few egos and hurt a few feelings. I can put up with some inconveniences, like the door bar on my roll bar, not having a back seat or a headliner. But it needs to be safe and comfortable to drive on the road. Shock life shouldn't be an issue with the low number of miles that the truck sees. Probably less than 2000 a year.

I'd back half the truck in a heartbeat if/when I talk the wife into it. I really enjoy fabrication work. I attached a couple pictures of the last one I did.

Well, from the pictures, you definitely have the skills to do the back half. From what you'd lose in weight alone, you should be in the 10's. Talk to the shock manufacturer about expected life. On a drag only car, many shock builders recommend dynoing the shock after every season.

[bgreen776]

I wonder if i could just rebuild it myself once a year? Do they come apart like a regular rebuildable shock, and do the big names sell rebuild and or tuning kits?

[dvst8r]

Looking at that time slip, just playing with a few things: Tire pressure, clamping springs, leaving with different amounts of boost, where you hit lock up, ect... That you can run a 10 without changing anything.

[WUnderwood]

dumb question:
would you a) install 4 link, or b) run 10's or c) both A and B

from what dvst8r said, I think you could run in the 10's with your current setup.

[bgreen776]

Option C. Run mid to low 10's with a 4 link, drag radials, more practice and tuning, better shocks, and a little nitrous. If I don't run a 10.8X this summer....

Launches

Launches

I'm confident I can get into the 10's with transmission tuning alone. I ran the 11.04 backed up by an 11.06 with one exhaust gasket about half missing and another leaking badly. I should have fixed it that day, pulled my passenger seat, dropped the tailgate, and raised my lockup point. But I didn't.

I actually bought spring clamps the day before the last race weekend, figuring I would get my best time without, clamp, then run again and see how much they helped. Too bad they didn't fit around the leaves.

I like building suspensions, its winter and there is no snow to ride, and traction bars are half a 4 link, so why not. Well... thats how my mind works anyway.

[WUnderwood]

Your truck runs very clean for making that kind of power!

[bgreen776]

Fuel only. Thanks to AH64ID at Coffman Customs!

[DieselLance]

i would do a wishbone before drag link

[bgreen776]

Drag link on a rear suspension? I am assuming you are talking about a panhard bar.

Why do you feel this way? Please explain.

[DieselLance]

i couldnt think of that word, same difference

[bgreen776]

A drag link is a steering component. You must have been thinking track bar, but ya, I think I knew what you meant. I am still curious why you would do a wishbone over a panhard to locate the axle side to side in a street vehicle. I'm a big fan of the double triangulated 4 link, is this what you are calling a wishbone?

This is the "double triangulated (top and bottom links are triangulated)" suspension I built for the front of my offroad truck. I run the same style suspension in the rear of that truck but I don't have a good picture of it.

[dvst8r]

A wish bone is often called a three link, and is like a dual triangulated 4 link, but the top links converge before they reach the diff or the frame (depending which way it faces).

So sorta like this: /Y\

The reason for it vs a standard pan hard is that obviously with a panhard or diagonal link as the suspension cycles the axle moves side to side. While this isn't noticed much on a street vehicle, when you are trying for every last ounce of traction it is.

I see no reason that a dual triangulated rear setup wouldn't work great as long as you get the numbers right, though it may weigh a bit more than a wishbone setup.

[bgreen776]

Okay. We are on the same page.

The three link style we are talking about offers simplicity in design but lacks the strength and adjustability of a 4 link. I'm a little rusty on my suspension geometry, but I do know that even a triangulated 4 link can offer substantial side to side movement depending on design. One of the benefits of a panhard rod is that all the side to side movement is applied to the locating link in a manner in which it is most able to resist. IE: no additional loading on the main link ends. The other main advantage, as I see it, is that you can easily adjust the roll center by using long panhard brackets. The panhard can be mounted perfectly parallel to the contact patches of both tires, then raised or lowered to change the roll height. On a street vehicle, the length of the panhard bar can be quite long, therefore reducing the side to side movement of the axle under the chassis as the suspension moves.

On a drag car/truck, I believe that anti squat percentage is probably the most important factor, and the ability to counteract torque steer is a close second. The former I am curious what other drag racers find appropriate, the latter I believe to be subjective though I am open to input.

I think I could design and build either style and achieve similar results, but in actual application, it seems the panhard style parallel 4 link would be easier to tune, especially if one built it to have an infinite instance center and other options readily available.

[Tate]

You could put a Watt's link in place of the panhard bar and eliminate all side to side movement.