Will a single 2.5 inch johnny joint be strong enough for the axle end of an upper A-arm suspension?

The frame ends are just bushings, the lower links will be angled in towards the center of the frame , but not all the way.

Also does is it better if the johny joint bolt runs paralell or perpendicular to the axle tubes? Which and why?

Thanks, I searched but couldn't find an answer, if someone knows a link can you send me there?

when you say a arm do you mean control arm ?

I think he means an upper triangulated link, where it would mount on the top of the pumpkin or whatever.

he means an upper A arm and if you don't know what that is don't reply to the post :p

I don't know if a johny joint is strong enough but I do know the bolt should run perpendicular to the ground because the main forces it is there to deal with are axle torque and side loads.

thanks ne-rock-toy
and yes I mean "A"-arm

anyone have an idea on strength?

my yj has a tri 3 link in the rear with three attachment points at the rear axle and 4 at the frame. all johnny joints. unfortunately, we are waiting for some more parts to come in before its driveable. the joints seem pretty beefy though, and i'm not worried about them at all. we also have another jeep in the shop at outback with the same config with 44 inch boggers, i think it will be fine to. its halfway through its corvette engine swap.

I am not sure about JJ's but I have run some calc's on RE joints. The difference between the two is that JJ use polyurethane (? durometer) and RE's use UHMW. From my figures they were looking at about 26,000 lbs. radial load. If your are set on running those type of joints I would run it so that the bolt is perpendicular to the ground as someone else said. It is that upper link that will be keeping the axle from moving side to side. Obviously it will take a lot less force to pop the ball out of the joint if you run it the other way.

I just got done with my front 60. I am going to utilize 3-links front and rear and plan on abusing my shiat like it's yours. I came up with my own version of the JJ(mines very simple), only I think it's beefier and is a LOT cheaper. Now would be a good time to get thoughts on it.
The worst problem with the JJ's and the RE joints is that they do not have enough misalignment to allow for lotsaflex. If you run the threaded type and leave the jamnut looses, you WILL rip it right out of the sleave. My idea is a 1/4 inch walled tube milled out for Wrangler spring bushings(I even spiral cut it to spread grease better:D ) welded to a 1" bolt. The bolt slips through a sleave so it can rotate freely. The sleeve is threaded, and just to be on the safe side, I tacked another not onto the end of the bolt to prevent it from stripping the threads and sending the axle rolling. Ever see that happen? It's ugly.

i dont think a rubber j-joint will last on the end of an arm. a typical a-arm suspensions carry the weight of the vehicle. steel ball joints dont last. unless your using an a-arm in place of a control arm, i wouldnt attempt it.

the A-arm is the upper link of a 3 link. It will not support the weight but rather help locate the axle laterally. The springs will do the lifting.
I guess the real question is how small of a bolt would you use?

go look at a stock truck with link style suspension,
small bolts
so a 3/4 or 5/8 should be plenty big

Originally posted by fcfred
the A-arm is the upper link of a 3 link. It will not support the weight but rather help locate the axle laterally. The springs will do the lifting.
I guess the real question is how small of a bolt would you use?

1 1/4" Aurora with misc spacer. It uses a 5/8" bolt and allows for deflection up to 35 degrees.
http://www.polyperformance.com/spacers.jpg

Here is one mounted with the bolt perpendicular as suggested above.

http://www.polyperformance.com/a003.jpg

Originally posted by PIG


Here is one mounted with the bolt perpendicular as suggested above.



you have a side shot of that?

Originally posted by BornInAJeep


you have a side shot of that?
I don't have a good one showing the mount, if thats what you are looking for. This is GOAT1's rig. I'll see if I can get one this week.

Thats wierd that the 5/8 reducer spacer on the 1 1/4 hiem only goes to 35 degrees because I have the same setup except I have the 3/4 inch reducer instead of the 5/8 and it still goes to 35 degrees. I just measured it today.

Can someone tell me why one would mount the top link this way?:confused: :confused:

It just seems as though your selling yourself short. I mean your limited to the misalignment on all plains of movement in the susp. If you mount it upright (bolt parallel with axle) then at least you have the bolt working for you during the travel of the axle. I'm I missing something?:confused:

Originally posted by twistedmetal
I came up with my own version of the JJ(mines very simple),

Got anymore pics I'm intrigued:p

Originally posted by Bill4rest
Can someone tell me why one would mount the top link this way?:confused: :confused:




actually that is the proper way to mount a heim. i can't tell you why because i am not an engineer. and of course the do work the other way but from an engineering stand point this is the correct way.

I don't know if this is a go fast chassi or a rock buggy but if it's a rock buggy, mounting the rod end vertical is ok because the center line of the diff(area over the pinion) doesn't move up and down very much, only twist. all the up and down is out wide.

The best suspensions I've seen are the ones where the center of the diff doesn't move at all and there is equal travel on the ends. For every 1" of left down there is and equal 1" of up on the right.

Use a good quality rod end and it will last, use junk and, well....

I love the pivot bushing idea, cheap, rebuildable, tons of surface area on the bushing....sounds like a new part number.

thanks,

tony k

Originally posted by Bill4rest


Got anymore pics I'm intrigued:p

Not yet, I want to get it together and test it to make sure I'm not just kidding myself:( . The way I figure it, someone has already tried everything I can think of, so now I just need to find out for myself why it doesn't work, or what I can do differently. There are two things I am worried about on my "joint." First I am a little paranoid about my welding skills where the bolt is welded to the tube, and also I am worried about the bushings simply crushing and providing no location of the axle.
BUT, then again, I am hopefully just worried over nothing and it will work out fine:D .
I'll keep you posted and I'll supply pics when my POS is in one large piece!

I had that same set up on my 4-link. One J.J. at the end of the wishbone (A-arms are on independent front suspensions). Worked great used it fore two years of hard core rock crawling with no sign of wear. They also make a 3'' version. If your rig is over 3000lbs I would go that way.

Originally posted by Bill4rest
[B]Can someone tell me why one would mount the top link this way?:confused: :confused:

The rod end is mounted this way because like camo said, it is the correct way to mount it. Someone was right in that you are limited in both vertical travel and in articulation to the misalignment of the rod end. That is way we use those himiss spacers that PIG showed above. It is a 1 1/4" rod end redused to use a 3/4" bolt, it has 30+ degrees of misalignment and is plenty for this vehicle with 16" of travel and we use them that way on trophy trucks with 30" of travel.

On a upper triangulated suspension link as shown, the rod end is subjected to radial loads from acceleration and braking and also a side load from turning or cornering, which still loads the rod end radially. When you mount the rod end so the bolt is horizontal, the acceleration and braking loads load the rod end the same, but the loads due to cornering are putting an axial load on the rod end, it wants pop the ball out of the rod end housing. I have seen many vehicles mount the rod end this way with no problems, but a rod ends axial strength is only about 15% of their radial strength.

Sup, Goat? You seem(or at least act like:D ) a knowledgable gent. What are your opinions on my "Codyjoint?"
I've been expecting a bunch of flameage, but I am getting a little frustrated!

Originally posted by GOAT1


The rod end is mounted this way because like camo said, it is the correct way to mount it. Someone was right in that you are limited in both vertical travel and in articulation to the misalignment of the rod end. That is way we use those himiss spacers that PIG showed above. It is a 1 1/4" rod end redused to use a 3/4" bolt, it has 30+ degrees of misalignment and is plenty for this vehicle with 16" of travel and we use them that way on trophy trucks with 30" of travel.

On a upper triangulated suspension link as shown, the rod end is subjected to radial loads from acceleration and braking and also a side load from turning or cornering, which still loads the rod end radially. When you mount the rod end so the bolt is horizontal, the acceleration and braking loads load the rod end the same, but the loads due to cornering are putting an axial load on the rod end, it wants pop the ball out of the rod end housing. I have seen many vehicles mount the rod end this way with no problems, but a rod ends axial strength is only about 15% of their radial strength.

Ok I get it, so by mounting this way you get a little give and take while side loading the axle. Right? I guess If it where mounted the way I said, the rod end might shear? I remember watching a stadium race and seeing the axle shift to side to side while landing side ways and such, are we on the same page? Or Am I still lost?
For a trail truck is it really that big of an issue? Thanks for the imput:D

Originally posted by Bill4rest


Ok I get it, so by mounting this way you get a little give and take while side loading the axle. Right? I guess If it where mounted the way I said, the rod end might shear? I remember watching a stadium race and seeing the axle shift to side to side while landing side ways and such, are we on the same page? Or Am I still lost?
For a trail truck is it really that big of an issue? Thanks for the imput:D

Yeah, I think you are on the right track, I dont think you will shear the rod end, you might just pop the ball out of the body of the rod end. For a trail truck you probably will be just fine, like I said I have seen many people do it like that with no major problems. I would just advise someone to use a good quality rod end, and it wouldnt hurt to go oversize since you are loosing strength of the rod end by loading it axially.