4 Linked Duramax Thread

[TheBac]

You know what I love about threads like this? Look how many guys are offering help, advice and know-how. :thumb:

If you think about it, we could make one hell of a hotrod performance company with the combined talents of the individuals here.

 

[RENODMAX]

So when you put all this power to the ground how is it going to be distributed? Just kind of confused because I thought the whole point of a 4 link is to place force exactly where you want it? Just curious as I've obviously never built one.

 

[paint94979]

this truck squats 4x4 4 link


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[TrentNell]

So when you put all this power to the ground how is it going to be distributed? Just kind of confused because I thought the whole point of a 4 link is to place force exactly where you want it? Just curious as I've obviously never built one.

My first goal /plan is to treat it as i always have, the front tires being the primary drive , and the rear secondary , the way the bars are configured in the picture is what i think is going to work , the bottom bar is angled high for alot of hit/ bite on the rear tire to maximize the grip they can offer , the top bar being angled down puts the instant center height very low and far back , low meaning the weight transfer should be very minimal . The rest of holes going up on the top frame brackets holes are for if my theory is wrong, i can switch back to traditional thinking of weight transfer and the rear tires being the primary drive with the front being the assist.

this truck squats 4x4 4 link


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Solid front axle had that freedom , when our front end comes up our tires lean out because of the IFS , and this leaves up with only using the outer edge of the tire instead of the full contact patch . the dodges are a prime example of still being able to hook with using weight transfer type thinking because the front tires may have less weight on them but the tire stays flat and has full contact patch .

 

[paint94979]

My first goal /plan is to treat it as i always have, the front tires being the primary drive , and the rear secondary , the way the bars are configured in the picture is what i think is going to work , the bottom bar is angled high for alot of hit/ bite on the rear tire to maximize the grip they can offer , the top bar being angled down puts the instant center height very low and far back , low meaning the weight transfer should be very minimal . The rest of holes going up on the top frame brackets holes are for if my theory is wrong, i can switch back to traditional thinking of weight transfer and the rear tires being the primary drive with the front being the assist.


Solid front axle had that freedom , when our front end comes up our tires lean out because of the IFS , and this leaves up with only using the outer edge of the tire instead of the full contact patch . the dodges are a prime example of still being able to hook with using weight transfer type thinking because the front tires may have less weight on them but the tire stays flat and has full contact patch .

Thank you for the explanation that makes perfect sense

 

[RENODMAX]

What about all that force though? If the rear does provide all the drive won't you need something to distribute force away from the 4 link? The ones I have seen in high hp builds use stuff to keep the 4 link in one piece when you unleash the beast sorry for all the questions. Just wondering your reasoning as this 4 link duramax stuff is pretty new stuff

 

[TrentNell]

What about all that force though? If the rear does provide all the drive won't you need something to distribute force away from the 4 link? The ones I have seen in high hp builds use stuff to keep the 4 link in one piece when you unleash the beast sorry for all the questions. Just wondering your reasoning as this 4 link duramax stuff is pretty new stuff

part of the goal in 4link design is to transfer that "force" into forward momentum , it is actually possible from what i have heard that if the geomitry is way wrong the car can hook and still not 60ft well because the energy is being miss directed . i dont see what force needs to be re-directed unless i am mis-understanding what you are saying ? are guys breaking parts or what ? I do know there is alot of force involved but that is why the whole this is being built so heavy duty , once its finished you will se alot more boxed in stuff and it will be pretty stout , the axle brackets are 3/8" thick and the bars are twice as big as most use .

 

[Fingers]

What was said about keeping the panhard parallel with the ground is very true. Otherwise it will kick the rear end badly. Since you really don't know your final setup yet, you might want to make one or both the frame and axle mounts adjustable.

 

[Fingers]

part of the goal in 4link design is to transfer that "force" into forward momentum , it is actually possible from what i have heard that if the geomitry is way wrong the car can hook and still not 60ft well because the energy is being miss directed . i dont see what force needs to be re-directed unless i am mis-understanding what you are saying ? are guys breaking parts or what ? I do know there is alot of force involved but that is why the whole this is being built so heavy duty , once its finished you will se alot more boxed in stuff and it will be pretty stout , the axle brackets are 3/8" thick and the bars are twice as big as most use .

4 links are all about dealing with the axle torque. By adjusting your geometry, you can control how much of that torque is used to push the car forward and how much is used to push the tire into the ground. The goal is just enough to keep the rear from spinning.

A squatting car is not using a lot a torque to plant the rear tires. Those that seem to jump up off the line are.

Weight shift is more about the relative positions of the car/truck's center of gravity and the center of front-back roll point.

Regardless, you're well on your way with your setup.

But, what do I know?

 

[TrentNell]

4 links are all about dealing with the axle torque. By adjusting your geometry, you can control how much of that torque is used to push the car forward and how much is used to push the tire into the ground. The goal is just enough to keep the rear from spinning.

A squatting car is not using a lot a torque to plant the rear tires. Those that seem to jump up off the line are.

Weight shift is more about the relative positions of the car/truck's center of gravity and the center of front-back roll point.

Regardless, you're well on your way with your setup.

But, what do I know?

thanks Jon , I am trying . There isnt excactly a book on what a 4x4 is going to like . Any idea's or theroys ? The red section above is what i feel is going to be the biggest bennifit is having the ability to adjust the weight shift along with the bite of the rear tire .

 

[bullfrogjohnson]

Looks great Trent

 

[JoshH]

Trent, maybe I missed it, but what is the length on your upper and lower suspension links?

 

[mytmousemalibu]

If your worried about the panhard being if your unsure of final placment. Could go the ultimate route and use a watt's linkage instead. Then your rear will stay in a perfect lateral movment VS the panhard moving it some. Another alternative is a diagonal bar that triangulates the lower 4-link bars and holds them parallel. More a track only stetup there. Our Pro-mod had a wishbone to locate it but also a track only setup as there is a telescoping piece.

 

[TrentNell]

Trent, maybe I missed it, but what is the length on your upper and lower suspension links?

29" long lower bars , 26" long upper's

If your worried about the panhard being if your unsure of final placment. Could go the ultimate route and use a watt's linkage instead. Then your rear will stay in a perfect lateral movment VS the panhard moving it some. Another alternative is a diagonal bar that triangulates the lower 4-link bars and holds them parallel. More a track only stetup there. Our Pro-mod had a wishbone to locate it but also a track only setup as there is a telescoping piece.

Pan hard bar is working just fine .

here is an updated pic of its placement , the truck is a few inches under what ride height will be this pic though .

 

[RPM Motorsports]

Jmo! I would put the extra support in the green areas (not the ?), just incase you accidently touch the wall. It would give you better odds of keeping the rear somewhat in place. I would also triangulate the bottom half of the front mounts.

 

[TrentNell]

Jmo! I would put the extra support in the green areas (not the ?), just incase you accidently touch the wall. It would give you better odds of keeping the rear somewhat in place.

thats a good idea Russ , I am still not finished with it , have some boxing in to do and some braces that need to go in still . and yes the ? mark area will be notched and a drive shaft loop with hang from that cross member along with one on the rear axle itself .

 

[Fingers]

Getting better all the time.

 

[D-Maxx]

Got my bars and Pan hard bar today ..................... finally ! They do look great , especially for what they cost .

here are a few pics , put a soda can next to one to show the size .

Man... I wish I could weld like that!

 

[TrentNell]

Man... I wish I could weld like that!

Me too , i wouldnt have had to pay to have them made :rofl:

 

[RENODMAX]

In the past pictures it looks like your diff is pointed very downward. Im assuming thats just my perception