4-link design & tuning: 2wd trucks

[PSDPlayer]

Originally Posted by SMOKIN93

Just set the record over the weekend for the fastest converter driven pro mod, 6.04 242, never been on a set of scales.

I thought Coby Rabon was in the 5s on an automatic?

[diesel junkie02]

Subscribing...

[they all break]

They make a computer program to figure out roll center. We use it to help us set up are super late model and pro late model. Another thing that is help full is a shock dyno are someone that has one. Having the proper shock set up is just as important. Most of the time people just buy shocks of the shelf but if you want that edge shocks are it.

P.S If you say shocks aren't important then go hide in a hole.

[bmarlatt]

How about some pictures? or maybe even some drawings, for those of us who will probably never build one but wanna learn anyway.

[Hurley]

Here is mine, uppers are triangulated 40deg for lateral support.





(mine may be an example of what not to do haha. At some point the lower control arms and the coilovers may be mounted inboard for a narrowed axle)

[12vriviera]

you wont need to. but if they arent triangulated, you could add a panhard bar or watts linkage to keep axle located

[they all break]

I would make your uppers adjustables and move the shocks to the inside. Looks clean though

[sstockton]

This is very interesting and I would love to learn about this. How much do you think you saved in weight by back halfing your truck and going to the 4 link? My buddy and I were just throwing this idea around for his race truck, seems like it could shave a lot of weight since he is a long bed.

Sean

[1lowdiesel]

Originally Posted by they all break

I would make your uppers adjustables and move the shocks to the inside. Looks clean though

x2 just get some adjustable ends from Suicide Doors.

I wonder if putting the coilovers inboard of the frame and angle them towards the center would make it handle a little better.

I know with my parallel link, panhard and shocks on rear lift bars i will get a little roll around turns.

[morkable]

I would imagine the science would be the same for a 4wd truck also? I plan on doing a 4 link on my truck this coming winter.

[Hurley]

^it is, for the rear suspension haha.

1lowdiesel, i remember us talking way back when- Positioning the coilovers farther from the centerline of the axle gear housing will decrease the amount of body roll with a given spring rate. For anyone that is curious why my coils are where they are, this is the reason. I am running 150#/inch springs and have pretty minimal body roll compared to a truck that is a twin to mine originally

here's mine at launch:


A$$ down, and yes, the launch was soft - i was barely making 7psi when i left the line...the next time i blew through the tires after about 50ft

[Diesel_Weasel]

From my limited understanding... all from Pirate4x4 reading... Triaged, ErikB, and Booger_Weldz are the guys to talk to...

I think you are going to want to bring your AS down in the 50-60% range and then play with it from there.

A good rule of thumb for finding quick CQ without measuring too much is to use the top bellhousing bolt as a reference.

Also, get your RA down in the -1*to -2* range to make it handle better at speed. Roll Oversteer can get SCARY quickly...

Personally, I would triangulate both uppers and lowers for more lateral stability, or run a 3 link with a panhard. 4 links with panhard have inherent binding qualities if you run joints with little deflection.

... but really, if you want to get spot on, you are going to need corner weights and also more numbers with your coilover inclination and mounting in respect to your links and axle.

...or you can just stab at it in the dark until it "feels right", the more information you get yourself the less you have to "stab"

[24VChevy]

I just took my truck over to a fabrication shop to help set up my suspension and adjust the 4 links. I thought that I had it all figured out, man not a hope. I had it all wrong, problably the main reason I got out of shape and hit the wall. They are going to square the truck up and then scale it. Hopefully it will launch better and drive a little better down the 1/4.

Weather permitting I will be testing this weekend.

Malcolm

[joefarmer]

Originally Posted by 24VChevy

I just took my truck over to a fabrication shop to help set up my suspension and adjust the 4 links. I thought that I had it all figured out, man not a hope. I had it all wrong, problably the main reason I got out of shape and hit the wall. They are going to square the truck up and then scale it. Hopefully it will launch better and drive a little better down the 1/4.

Weather permitting I will be testing this weekend.

Malcolm

Did they say what they changed up on your links? Instant Center?

[24VChevy]

They changed alot, move the four links down 3 holes on the upper, changed the rear track bar from a lateral bar to one that bolts to the lower four link brackets and is now a diagonal track bar. Changed the shock mounts preloaded the four link set up the springs on all four corners. They made a list that they would change further but that will happen later on. I was really supprized to see my weight distrubution. I am heaver on the rear of the truck than the front. total weight for the truck is just a hair under 4500 lbs. with a 51% of the weight on the rear tires. I have bolt on weight in the back of the truck they want me to move them to just in front of the rear tires.

Now the truck does a straight burn out and launches straight and drives great. Another thing that I noticed is how easy it rolls now when we push it.

Guess it was pretty bad....

Malcolm

Thanks to A & A performance.

[joefarmer]

I wonder what caused the rolling resistance change? I know mine pushes way harder than I think it should. Maybe my preload is messed up again.

[24VChevy]

I forgot to mention that they also fixed the front suspension camber, caster and toe, I would imagine that the toe had alot to do with it. My truck was not set up at all. I did take it to someone else a year ago but I guess they did not set it up.

Malcolm

[joefarmer]

Originally Posted by stock600

Front to rear 4 bar adjustment will cause that faster than anything. With a spool or locked rear diff., if one side is even as much as 1/8" forward of the other is will be very noticable hard to push, the fronts are steering it to go str8 and the rear is tring to crab.

Ah, that's the case. I'm 107 13/16 driver wheelbase and 107 15/16 passenger wheelbase. My leaf springs are showing quite a bit of movement. I should probably just backhalf it and be done. Wouldn't be the first time you're right, Ryan.

[Signature600]

Originally Posted by joefarmer

Ah, that's the case. I'm 107 13/16 driver wheelbase and 107 15/16 passenger wheelbase. My leaf springs are showing quite a bit of movement. I should probably just backhalf it and be done. Wouldn't be the first time you're right, Ryan.

WHOA....nice torque Brandon

Chris