RCCrawler Forums

davidmcox · 07-31-2011, 09:33 PM

I tried using the search but nothing really stood out to answer my questions or my situation I had in mind....

Compared to the y style 3 link a stock comes with, what does the 4 link add to the equation? How mathmatically does it work " better " and in theory would it work just to remove the "y" and have the lower links and shocks hold the axles in place.. who has tried it and what will explode?... I understand this will put more strain on the shocks from rotating but will they hold up to the stress with the lowers???

Dogbreath · 07-31-2011, 09:46 PM

You have to have links top and bottom to control the axle movement, shocks control the up and down, the links control the side to side

four links have better articulation then three and are stronger

DRV KRAWLER · 07-31-2011, 10:10 PM

I would like to add to the better articulation comment. It creates a better CONTROLLED articulation, with a stabilization of the axles movement. Thus controlling torque twist at the axle.

davidmcox · 07-31-2011, 10:12 PM

Now just in theory wouldn't the lower links and the shocks keep them together and "square" or would it just flop around like a loose fish..

So a 4link is just stronger and allows more articulation.. I also notice most do the rears and some never do the front is that just lazyness or cheapness? Or does it not really offer anything?

davidmcox · 07-31-2011, 10:14 PM

So the biggest thing without them and shock mounting it as mentioned above would be to much torque twist on axles which would kill the shock rod?... it makes sense. I definetly see how the y limits its movement...

Motor also would have a play in how much torque is applied correct.. faster turn compared to slower turned with more torque?...

DRV KRAWLER · 07-31-2011, 10:17 PM

Without the upper links it will just flop around. You are correct some people only do the rear. But, the benefit is for bothe front and rear. Stabilizing the roll of the axle is beneficial on both axles.

davidmcox · 07-31-2011, 10:20 PM

Sounds great.. my dad is tweaking his ax10.. I suggested not to reinvent the wheel but he wants to try... I kept saying there is a reason for it and their is alot of research that gets put into these by the companies... but hey what ever floats his boat hopefully that 27 turn motor wont snap his brand new lcc shocks

TSK · 07-31-2011, 10:22 PM

On a crawler, as the suspension cycles, the axle swings around a pivot (called roll center). On the stock 3 link setup, the pivot is where the 3 link mounts to the axle. This results in the axle swinging like pendulum around that pivot, which can result in axle steer. On a properly designed 4 link suspension, the pivot would be ideally be dead center of the differential. This would result in a pendulum effect during suspension articulation, and thus no axle steer.

Other, more obvious benefits are increased tuning options as the 3 link is fixed with only tuning being done to the upper link via the chassis side mount points. Most all 4 link mounts allow for vertical and horizontal placement. These can affect your roll center, squat/anti squat, axle clock angles, etc.

Meatwad · 07-31-2011, 10:23 PM

Durability was the main selling point for me. That weak ball joint at the y link would rip out when looked at wrong.

davidmcox · 07-31-2011, 10:31 PM

That's what I had brought up to him without them the angle (ill assume the squat) would be able to do what ever it wants, putting tension on the outdrives and shafts.. I told him I think he'd have a ton of articulation and swing but to much play on the degree the axle sits at....

rdcobra · 08-07-2011, 07:23 PM

I have heard that alot of guys run the 3-link in the front and a 4 link in the rear, particularly when running the BTA steering setup. is that advisable?

DRV KRAWLER · 08-07-2011, 08:19 PM

It is not necessary to run three link on the front w/ BTA . It does not make any difference either way. I personally suggest running 4 link front and rear regardless. That is my own opinion.

Mud Puppy · 08-07-2011, 08:27 PM

I run 3-link front and 4-link rear.
I did the rear to control torque twist.
I will pobably do the front eventually, but for now it is working great.

TSK · 08-07-2011, 08:51 PM

If you could only afford to 4 link one axle, it's wiser to 4 link the rear. You'd get more benefit from it as the changes you make for anti squat and torque twist would seem more significant.

jessejoe23 · 08-07-2011, 09:21 PM

I run a 4 link front and rear. I like the adjustability of the set up. It allows you to really fine tune your suspension.

Trubble · 08-09-2011, 11:52 AM

I was recently relocating some components in my AX-10, and wondered about the 4 link up front. For doing the fronts, did you just buy the extended servo mount, and put the upper links on the back of that?

And at the other end of the upper links..... I put my receiver and ESC on the chassis side plates, and at full compression, the upper links contact my receiver. If I upgrade to aluminum tube upper links, can I use the offset ball ends (say from the steering tie rod) and drop that upper link down just a hair or two?

07-31-2011, 09:33 PM	#1
davidmcox Rock Stacker Join Date: May 2011 Location: san diego Posts: 60	ok explain 4 link???? I tried using the search but nothing really stood out to answer my questions or my situation I had in mind.... Compared to the y style 3 link a stock comes with, what does the 4 link add to the equation? How mathmatically does it work " better " and in theory would it work just to remove the "y" and have the lower links and shocks hold the axles in place.. who has tried it and what will explode?... I understand this will put more strain on the shocks from rotating but will they hold up to the stress with the lowers??? Last edited by davidmcox; 07-31-2011 at 11:25 PM.

07-31-2011, 10:14 PM	#5
davidmcox Rock Stacker Join Date: May 2011 Location: san diego Posts: 60	So the biggest thing without them and shock mounting it as mentioned above would be to much torque twist on axles which would kill the shock rod?... it makes sense. I definetly see how the y limits its movement... Motor also would have a play in how much torque is applied correct.. faster turn compared to slower turned with more torque?... Last edited by davidmcox; 07-31-2011 at 11:26 PM.

07-31-2011, 10:31 PM	#10
davidmcox Rock Stacker Join Date: May 2011 Location: san diego Posts: 60	That's what I had brought up to him without them the angle (ill assume the squat) would be able to do what ever it wants, putting tension on the outdrives and shafts.. I told him I think he'd have a ton of articulation and swing but to much play on the degree the axle sits at.... Last edited by davidmcox; 07-31-2011 at 11:27 PM.

07-31-2011, 09:46 PM	#2
Dogbreath Rock Crawler Join Date: Aug 2009 Location: Sandy Oregon Posts: 517	You have to have links top and bottom to control the axle movement, shocks control the up and down, the links control the side to side four links have better articulation then three and are stronger

07-31-2011, 10:10 PM	#3
DRV KRAWLER RCC Addict Join Date: Dec 2008 Location: Sonora, CA Posts: 1,664	I would like to add to the better articulation comment. It creates a better CONTROLLED articulation, with a stabilization of the axles movement. Thus controlling torque twist at the axle.

07-31-2011, 10:12 PM	#4
davidmcox Rock Stacker Join Date: May 2011 Location: san diego Posts: 60	Now just in theory wouldn't the lower links and the shocks keep them together and "square" or would it just flop around like a loose fish.. So a 4link is just stronger and allows more articulation.. I also notice most do the rears and some never do the front is that just lazyness or cheapness? Or does it not really offer anything?

07-31-2011, 10:17 PM	#6
DRV KRAWLER RCC Addict Join Date: Dec 2008 Location: Sonora, CA Posts: 1,664	Without the upper links it will just flop around. You are correct some people only do the rear. But, the benefit is for bothe front and rear. Stabilizing the roll of the axle is beneficial on both axles.

07-31-2011, 10:20 PM	#7
davidmcox Rock Stacker Join Date: May 2011 Location: san diego Posts: 60	Sounds great.. my dad is tweaking his ax10.. I suggested not to reinvent the wheel but he wants to try... I kept saying there is a reason for it and their is alot of research that gets put into these by the companies... but hey what ever floats his boat hopefully that 27 turn motor wont snap his brand new lcc shocks

07-31-2011, 10:22 PM	#8
TSK Shelf queen Join Date: Aug 2008 Location: Internet Posts: 5,857	On a crawler, as the suspension cycles, the axle swings around a pivot (called roll center). On the stock 3 link setup, the pivot is where the 3 link mounts to the axle. This results in the axle swinging like pendulum around that pivot, which can result in axle steer. On a properly designed 4 link suspension, the pivot would be ideally be dead center of the differential. This would result in a pendulum effect during suspension articulation, and thus no axle steer. Other, more obvious benefits are increased tuning options as the 3 link is fixed with only tuning being done to the upper link via the chassis side mount points. Most all 4 link mounts allow for vertical and horizontal placement. These can affect your roll center, squat/anti squat, axle clock angles, etc.

07-31-2011, 10:23 PM	#9
Meatwad I wanna be Dave Join Date: Jul 2009 Location: Rancho Relaxo. California. USA. Earth. Posts: 3,292	Durability was the main selling point for me. That weak ball joint at the y link would rip out when looked at wrong.

08-07-2011, 07:23 PM	#11
rdcobra Rock Stacker Join Date: Jul 2011 Location: Chesterfield, VA Posts: 50	I have heard that alot of guys run the 3-link in the front and a 4 link in the rear, particularly when running the BTA steering setup. is that advisable?

08-07-2011, 08:19 PM	#12
DRV KRAWLER RCC Addict Join Date: Dec 2008 Location: Sonora, CA Posts: 1,664	It is not necessary to run three link on the front w/ BTA . It does not make any difference either way. I personally suggest running 4 link front and rear regardless. That is my own opinion.

08-07-2011, 08:27 PM	#13
Mud Puppy Rock Crawler Join Date: Oct 2010 Location: Abbotsford BC Posts: 522	I run 3-link front and 4-link rear. I did the rear to control torque twist. I will pobably do the front eventually, but for now it is working great.

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08-07-2011, 08:51 PM	#14
TSK Shelf queen Join Date: Aug 2008 Location: Internet Posts: 5,857	If you could only afford to 4 link one axle, it's wiser to 4 link the rear. You'd get more benefit from it as the changes you make for anti squat and torque twist would seem more significant.

08-07-2011, 09:21 PM	#15
jessejoe23 Rock Stacker Join Date: Mar 2007 Location: Bethpage,TN Posts: 94	I run a 4 link front and rear. I like the adjustability of the set up. It allows you to really fine tune your suspension.

08-09-2011, 11:52 AM	#16
Trubble Proverbial threadkiller Join Date: Feb 2011 Location: Central Wisconsin Posts: 1,453	I was recently relocating some components in my AX-10, and wondered about the 4 link up front. For doing the fronts, did you just buy the extended servo mount, and put the upper links on the back of that? And at the other end of the upper links..... I put my receiver and ESC on the chassis side plates, and at full compression, the upper links contact my receiver. If I upgrade to aluminum tube upper links, can I use the offset ball ends (say from the steering tie rod) and drop that upper link down just a hair or two?

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