Getting ready to complete the new four link and had a quick question before we cut and weld. Is longer better? Are 55" lower links too long?

55", holy long links batman. rudezuk is trying to talk me out of 48"ers. i dunno:confused: .

i've read somewhere that links around 35- 47 work well .. can anyone back this up?

The length of the links are not so important as to their geometry.

I wouldn't go over 40" personally...unless it was a link going from the side of the frame to the axle, like MrTwstr on the board.

If 55" links give you an acceptable Anti-Squat/ roll Axis then I don't see a problem, but that sound awful long to me. If its all drawn out and the figures look good run with it.. But I would think the wheelbase would need to be in the 120 range!!

Good Luck

Originally posted by TPIJeep
But I would think the wheelbase would need to be in the 120 range!!

Good Luck

Sounds like Dima to me:flipoff2:

You got those suckers forward of the rear output with that configuration?

IMO links should be determined by wheelbase, center of gravity and lastly adaptibility.

Dan

with a link that long there are 2 things I would be asking myself:

1: What the hell am I gaining with a link so damn long?

2: How am I going to keep these things from being a rock magnets?

Originally posted by NE-RokToy
with a link that long there are 2 things I would be asking myself:

1: What the hell am I gaining with a link so damn long?

2: How am I going to keep these things from being a rock magnets?

for #2, I had an idea on how to deal with that. let them be rock magnets.. but make your lowers capable of sliding.


(if this turns out to be a good idea... I'll be pissed cause I won't get to use it before someone else does and claims it as theirs. LOL)

Take your standard round tube for a link. lets' just say 1.5" .250 wall. Then, take some 3/16-1/4" thick bar stock, using 3 lengths to form a triangle around the tube. weld the bar stock together, then plug weld the hell out of the bar stock to the tube.

What I was figuring... the tube alone could handle the compression being applied by the suspension. by having a triangle shaped link, I figured that would be the best design for sliding over something or hitting something on it side, without bending, for the least amount of weight. So.. combine the two.. the cylinder inside takes care of compression, the triangle gussets on the outside would take care of bending problems.

ok.. now.. tell me how thats a bad idea.:D

Both my front and rear links are around 44" long. Depending on your style of suspension and the location of the axle in relation to your CG, the long links may be necessary. (im using a radius arm front suspension, so had I used shorter links it would have had more negative impact on my anti dive.)

Originally posted by Jason R
The length of the links are not so important as to their geometry.


There you go.

A longer link will bend easier while under pressure. That can be compensated by a sturdier link but both will add to weight.

Originally posted by Travis Waldher

.....(if this turns out to be a good idea... I'll be pissed cause I won't get to use it before someone else does and claims it as theirs. LOL)

Take your standard round tube for a link. lets' just say 1.5" .250 wall. Then, take some 3/16-1/4" thick bar stock, using 3 lengths to form a triangle around the tube. weld the bar stock together, then plug weld the hell out of the bar stock to the tube.

What I was figuring... the tube alone could handle the compression being applied by the suspension. by having a triangle shaped link, I figured that would be the best design for sliding over something or hitting something on it side, without bending, for the least amount of weight. So.. combine the two.. the cylinder inside takes care of compression, the triangle gussets on the outside would take care of bending problems.

ok.. now.. tell me how thats a bad idea.:D

Yah mean like this?? :flipoff2:

http://www.solidaxle.net/durango_conversion/images/control_arm_pass_side_lg.jpg

They aren't quite as long as you describe, but the design is similar.

I take no credit for the design. Credit goes to Mike Duncan.

actually... I was thinking like this....

Lets pretend the steel mills make 2"x.250 triangular tube. ou take some 1.5"x.250" round tube and usse the triangular stuff to sleeve it.

then plug weld the hell out of the two pieces.

or.do I need to pull out mspaint and try to draw a pic?

Originally posted by Travis Waldher
actually... I was thinking like this....

Lets pretend the steel mills make 2"x.250 triangular tube. ou take some 1.5"x.250" round tube and usse the triangular stuff to sleeve it.

then plug weld the hell out of the two pieces.

or.do I need to pull out mspaint and try to draw a pic?

I see what you're saying. I was just pointing out a similar design that is working VERY well. 2-1/2 years under a rig that weighs 5820 lbs.

I'd be interested to see how large those arms you desrcribe end up beiing.. Sounds huge.

a) my lower links are 44", and my uppers are 36"

b) you dont want your lowers as a slider when hitting ledges it will keep your tires from ever getting to the ledge.

c) geometry is the answer

Originally posted by SolidAxleDurango


I see what you're saying. I was just pointing out a similar design that is working VERY well. 2-1/2 years under a rig that weighs 5820 lbs.

I'd be interested to see how large those arms you desrcribe end up beiing.. Sounds huge.

Could be... I just figured that... while everyone works to keep the link arms out of the way of rocks.. I figured.. why not design them to handle a few rocks.

Now.. redruM pointed out something in "b" I hadn't thought about.. so link arm length has to be thought about there.


Even if my idea didn't pan out for strength against rocks.. maybe keep the arms out of the way and be able to thinner/lighter material than what most currently use today for link arms.

Originally posted by Travis Waldher


Could be... I just figured that... while everyone works to keep the link arms out of the way of rocks.. I figured.. why not design them to handle a few rocks.

Now.. redruM pointed out something in "b" I hadn't thought about.. so link arm length has to be thought about there.


Even if my idea didn't pan out for strength against rocks.. maybe keep the arms out of the way and be able to thinner/lighter material than what most currently use today for link arms.

I'm too lazy to go back and find out what rig you want to put these long arms on.. But I agree with the other poster that (outside of geometry) wheelbase and lift amount does have something to do with it... I mean, in an extreme example, you wouldn't want 55" arms on a TJ with a 94" wheelbase and enough lift to only clear 31" tires.

For reference, my arms on the Durango are 32" long (IIRC) and my wb is 116". I almost never catch rocks with them. At ride heigth they're nearly level.. Road ride is great and flex/travel works wonders. I attribute that to a great geometry setup - thanks 4xDoc.

About the only time I've dragged them, was when I was a dumbass and drove right off a ledge that was bigger than I thought. Landed right on both of them. They're strong enough to take that. Short enough to not get in the way.. And long enough to work well for me.

My advice (from a gimp - take it with grain of salt).. Find out what geometry and length works for your rig.. THEN work on making it strong as necessary.

I used tire OD = approx LCA length

Of course as was mentioned adjust the link length from there to correct geometry.

Originally posted by redruM
[

b) you dont want your lowers as a slider when hitting ledges it will keep your tires from ever getting to the ledge.

[/B]

What he said!

Sliders on the frame or body are OK. Your suspention can still make up for it and streach for traction. Sliders on the lower links just lift the axel.
But I do agree with making them stout enough to take a hard hit, or suport the weight of the vehical.

You're making the triangle slider part too complicated. If that's the way you wanna go then just weld a piece of angle iron to the bottom the length of the link.

OK, this sounds good to me, but the question I am wondering is what length? I have a CJ5 with a 100" wheelbase. The links are gonna be triangulated the way Desert Toy built his I think. The top links go from the top of the axle out, and the bottom links go from the center of a crossmember to the outside of the axle. It is not going to be a traiditional 4 link.

My question is, do all the links have to be the same length, or shoudl the top ones be shorter than the bottom ones. I had mine figured in to be in the 40-45" range just like I did last time on the Flatty.

Thanks
Dimitri

flatty

i am going to e-mail you some pics of mine it is like what you said you want to do

my uppers are 6" - 8" shorter than my lowers uppers and lowers are all triangulated

Originally posted by Flatty
OK, this sounds good to me, but the question I am wondering is what length? I have a CJ5 with a 100" wheelbase. The links are gonna be triangulated the way Desert Toy built his I think. The top links go from the top of the axle out, and the bottom links go from the center of a crossmember to the outside of the axle. It is not going to be a traiditional 4 link.

My question is, do all the links have to be the same length, or shoudl the top ones be shorter than the bottom ones. I had mine figured in to be in the 40-45" range just like I did last time on the Flatty.

Thanks
Dimitri

My setup is double triangulated, all 4 links are 39" eye to eye, it's much easier for carrying spares. It works great too.

Why would you carry a spare upper link?

Originally posted by Rock Toy
Why would you carry a spare upper link?

Bwahahahah Sergei, remember our top ones? They were BENT to hell!!!!! that is why you carry spare upper ones.

Dima

They still worked fine. I would only swap out a link if it was WAY bent (as in an L shape) or if it actually broke. Besides, that was the first time I have ever seen bent uppers before and I assumed it was because of all the jumping Eric was doing with the Jeep.

True that. Oh well, I am gonna build them SUPER stout. What time you gonna be home today? I gotta see the dentist today, and then I will shoot over. I should be there by 5:30 at the latest.

Dima

Pick up a bottle of CO2 at the Dentist's. The Keg is full and I'm ready to drink... Let's build some short_ass links :flipoff2:

I made my lower arms from round, and bent them on the first test run. (I got a bit carried away with "Testing", but they still bent.) Then I went back and added a piece of 3/16" by 1.5" angle to the bottom of them as shown in the pic. Holding up good now....

D-toys links are 44" and his wheelbase is around 108" I think.
its cool if you can make the upper mounts of the lower link close to the out put, easyer on the drive line. other than that its all about what ever make the geometry work. 40" to 45" is what works best for me most of the time.

Originally posted by Flatty
Getting ready to complete the new four link and had a quick question before we cut and weld. Is longer better? Are 55" lower links too long?


There's no such thing as too long. You have to think about how the angles change as the suspension moves. The arms swing in an arc as they move up and down, which means the axle moves fore and aft as well as up and down. A longer arm moves fore and aft less for a given vertical movement than a shorter arm. This means less bump steer and other problems with changing angles. Build them as long as you can fit, beef them to handle the rocks.

Longer LCAs on a crawler is not always better. On a road race machine sure, but not always on a crawler. The fact that the axle moves for and aft actually helps in some instances. Some people like to build in rear steer and such.

Example: you are approching a ledge, you walk the two front tires onto the ledge and you have to set-up for the next approach so you straighten up and the rear axle hit both wheels flush to the ledge. the rear compresses with the hit but because the axle has to swing back a touch as it compresses the wheels don't bounce and you keep traction. Up you go and the chassis doesn't get up set for the next obsical.

Of course this is just one example of MANY. With the above set-up you will have at least some anti-squat.

Oh well, just spewing info.

Pertaining to the thread: Tire OD is a great starting point for lenght. If your roll center isn't correct then ajust lenght to make it work. You can also move the frameside mounting points to help bring the roll center where you want to LCA length is only part of the issue. If you are building the LCAs to help you get over stuff like sliders do then that is a specific function the you are looking for. But the downfalls of this have been addressed all ready.

You might just want to sit down and figurte out what you want to do with your rig first and then try and come up with what you need to do to get it. Rigs are like beautiful women, each has specific traits that turn each person on but they all look great to everyone. :flipoff2: :D

Tim

Originally posted by Tim Smith
Example: you are approching a ledge, you walk the two front tires onto the ledge and you have to set-up for the next approach so you straighten up and the rear axle hit both wheels flush to the ledge. the rear compresses with the hit but because the axle has to swing back a touch as it compresses the wheels don't bounce and you keep traction. Up you go and the chassis doesn't get up set for the next obsical.



Good example. I don't think that's a valid reason for short arms though. First, that only works if the arc of the tire follows the obstacle. Even "short" arms could be too long to provide that effect on some obstacles. Second, the axtra arc of short arms can just as easily lift a tire off an obstacle and cost valuable traction. Third, using fore-aft motion of the axle to provide rear-steer is ineffective due to it's randomness. You can't predict in the design phase how the axle will need to move to help you on different obstacles. And every obstacle will require different steering. The steering effect, though small, could easily force you off the line you're trying to take.
There are a few reasons to build short arms, it's cheaper, the arms don't have to be as strong or heavy, it's easier to fit to the chassis, lateral control can be easier....... All valid. If one of these concerns outweighs the benefit of longer arms, then build the shorter ones. Me, if I could figure out how to run the arms all the way to the other end of the frame, I'd do it.

Well I made my links last night. Running bushings on one side, and heims on the other. Running the "x" setup under the rig. The links are all about 40-48" long. Should have it all in this weekend and then I get to move it around in the garage and see how it works.

Dimitri

on all my projects more length has meant more travel. without binding up but all my rigs normaly have a longer wheelbase
and depending what you are doing with it. haul ass desert racing
and sand the longer the links the better but they dont have big
rocks to slide over.