I have gotten the triangulated 4 link under the front of my stretched CJ5, and have a question on control arm placement.

In using a TJ as a general reference for the placement of the control arms, it would appear that I need to separate the upper and lower arms mounting points to prevent lifting upon braking and acceleration. Does it matter if the separation is vertical (the TJ has about 7" of vertical separation at the frame end of the control arms and 4" of horizontal separation) or can I just move the lower control arm back substantially on the frame (about 12 inched behind the upper and only have the lower arm attach about an inch or two below the upper?

Thanks in advance.

Ed

Originally posted by Rock Taxi
or can I just move the lower control arm back substantially on the frame (about 12 inched behind the upper and only have the lower arm attach about an inch or two below the upper?
Ed

i understand your question untill this point

BTT for ya

Brian

Sorry, I may not have worded it as well as I could have.


My question is, do I have to spread the frame side mounts apart in the vertical plane (hood to ground) or can I accomplish the same thing by seperating them horizontally (from the front to back of the Jeep)?

Is that clear as mud?

Ed

after researching and building with lots of conduit i think you can mount all the frame mounts in the same plane (horizontally) then have them seperate as you go to the axle i am going to shoot for 8" seperation (top to bottom) and spread them out as far as i can on the axle more like XX than |\/| on the por baord if you look at desertoy's he has his set up like this only he has seperation on the frame side (about 1/2 as much as the axle side) my problem with his is when the front (or Rear) drops it will try to rotate the pinion parallel to the frame..........if you line up the mounts on the frame (theoretically in the same plane below the CV joint) the pinion will always point at the t-case

Brian

Exactly, that was what I was thinking, and in building models, it does seem to work, but I just wanted to find someone who has employed this mounting method to try to determine the handling characteristics. It helps that someone else has seen the same apparent result of doing it that way.

Thanks Brian.

Ed

well i havnt tried it yet but that is my plan ........ do it and let me know GINNEY PIG

guinney pig? find just as long as you don't ask me to squeal like one.....:flipoff2: :flipoff2:

Thanks man!

Ed

I don't completely understand what your asking but I think I see where you are going.

If your concerned about diving on braking with the front end, it's called anti-dive. Looking at the suspension from the side, extend the lower and upper arms back until they intersect. I set my Jeep up with the intersection about 32-40" back from axle centerline. This ended up working out really well. In terms of vertical separation between the mounting points, that was pretty much determined by where I wanted them to intersect. I mounted my lowers at axle centerline and the upper is raised about 6-8" above. On the frame there is only 3-6" of separation if I remember correctly.

In terms of looking at the links from above, the placement is too critical, although the further out on the axle and futher away from centerline will mean they can control the axle better.

Hope this is sorta what you were after,
CJ

Yes, that kind of answers my question. I actually stay flat, or slighty rise on braking. Really a strange feeling. I think I built an Alice in Wonderland Jeep where down is up and up is down! The strangest part is that merely holding the brake and putting the Jeep in gear at idle causes the front end to raise about 4"! No bueno on hill climbs! It drops about the same if I put it in reverse.

Am I correct in assuming then that if I have a yard or so of the anti dive angle (where the imaginary lines intersect) that is good enough regardless of where the arms are mounted, so long as the lower mounts below the upper? My axle is setup almost exactly like yours.

I actually seem to have nailed the width and upper triangulation angle pretty well. It is MUCH better at locating the axle left to right than the leaf spring setup was.

Thanks,

Ed

so if i am reading CJ Lagos correctly we do not want the upper and lower control arms in the same plane we want them (uppers up and lowers down) ??? isnt this going to force the pinion to parallel to the frame instead of always pointing at the t-case ?

Ya just can't stop makin' changes on the 'Taxi', can ya Ed?:D

this comming from CUTTER....

2 weeks cutter i will be ready to cut mine.... u wanna volenteer ?????

yes I do! hehehe.....

just a little off the front and back OK ???

Nope, it's never done. That is what makes it an obsession ya know. :p

Ed

Sounds like (similar to rear 4 links) for our uses you want the control arms to be almost parallel to each other (when looking from the side) or your front end will want to lift when you're climbing steep grades and that will shift the weight to the rear and you will not be able to climb as well as others.

Rock, a yard is a good guess...I don't like to use the terms plane because it is hard to convey your references over the internet without a picture...

Generally what I've done is to mount the lower arm under the frame and then run it to centerline of the axle. I then build the upper arm to put the intersection point or instant center where I want it.

When the scorpion just started coming around he was having issues with the instant center being way to close to the axle. It was causing the rear axle to actually rise on acceleration...that's because he had way too much anti-squat. This is from word of mouth though.

I didn't read the suspension god thread because i have better things to do with my time :P, but the impression I got was that people don't quite understand the anti-squat setup. It isn't like an on/off switch. In my opinon a properly designed suspension will have anti-squat in it, you don't want an ungodly amount...but generally it really can't hinder you until you start getting into just way too much, put your instant centers 30-36" from the axle and it will work great.

Good luck,

CJ

CJ...... can you please explain "instant center" ?

This was a very informative thread... it's long, but has a lot of good information.http://www.pirate4x4.com/forum/showthread.php?s=&threadid=29920&highlight=dive+vs+antidive

:beer:

Originally posted by redruM
CJ...... can you please explain "instant center" ?

I'll feel dumb if I am wrong, but I think he meant "moment". And I am going to have to reread all this thread to make sure I understand what everybody is saying. In general, you want the arms pretty flat to the ground, you need a pretty good angle between them laterally to stabilize without a track bar, and want them close to the same length (uppers and lowers).

-Bart

Originally posted by redruM
CJ...... can you please explain "instant center" ?
you just add hot water.....:D
How about a LOT off the front and rear?

OK cutter alot off the front and back ............ and a little off the sides

Ha Cutter, I actually heat mine also.

Instant center is this....It is the location out in space where if you only had one arm...it would act the same as your upper and lower together...it's a fairly important measurememnt but it isn't always something physical. I think one of the tech books said this was hard to overcome for some people.

For instance, the instant center on the long arm Rubicon Express TJ kit on the front is the lower control arm bolt on the frame. I guess this is a bad example since this is actually a physical point...same thing witht he Ford Radius arm design.

This is generally why you always see the upper control arm mounts raised, its to get the mounting point further up so it brings the instant-center in.

There was a guy on Jeeps Unlimited that had a shop install a triangulated rear uppers while leaving his tera long lowers. The mounts on the axle were raised up a whole lot over the diff. This really leveled out the upper control arm, which really moved his instant center closer to the axle. Well, after the kit he noticed his jeep was squatting a whole lot less acceleration. It's because the instant center was moved forward a whole lot during the conversion to the triangulated 4link(raising the rear upper axle mount leveled the upper arm which made the intersection point much closer).

He then figured out why his front wad diving. With long flatish lowers and really steep short uppers, they never intersect so it has no-anti dive. Just watch how monster trucks dive and squat at their shows, no anti-dive or anti-squat, all parallel arms.

CJ

Ok, this is cool...really damn cool.

I went from an 18.5" lower control arm length to a 35.5" LCA attached 1.5" below the upper control arm's frame mounting point, and 21" behind the upper. The current angles place the instant center behind the LCA mount some, not sure how much because they quickly hit the floor pan, cross members etc.... Before I welded it all on, it looked like it would be about 2.5' back.

With no shocks at all, I get maybe an inch of nose dive on normal back street speeds braking.

On medium acceleration I get an inch or so of lift, it actually feels similar to the front lift I get in my diesel Superduty. No biggie. This is all with no shocks at all!

Thanks folks, and especially CJLagos, this worked very, very well.

Ed