A-arm fab discussion

Milner · **Posted:** Sat Sep 30, 2006 12:26 pm

Wanted to start a thread about A-arms. There have been a few threads about this lately. It really has me thinking. So lets through out some ideas.

My thinking: Fab new upper and lower arms 1-2" longer than stock. Get a wider stance and decreased cv angle for a given amount of lift. (easy to ad spacers to the rear to match, but I would mind the front being a little wider than the rear. I was thinking 2" each side on the front and add 1.5" spacers on the back) Prerunners fab and widen the a-arm set ups all the time. I am not even opposed to looking at fabbing knukles. It would be nice to have some big uni-balls and get rid of those ball joints.
CV's what about porche 930's? Sand guys beat them to death, and there are tons of upgrades! Even 300m versions.

I a not very familar with the KJ front end (only had one a month) but I am not afraid to fab/r&d, infact I LOVE to do it

So lets get some ideas flowing....post up some pics of various components. As has been mentioned, what about adapting Toyota parts? What about the Ranger long travel kits?

So lets here it!!

kjhawaii · **Posted:** Sat Sep 30, 2006 1:33 pm

1 thought I had if the arms were longer, one would be able to keep the stock rims due as some have had contact problems, larger tires hitting waterbottle, sway etc. Im interested KjHawaii

auggy · **Posted:** Sat Sep 30, 2006 5:23 pm

Jeepin Al did this exact project already .. you can buy his arms from his website http://www.jeepinbyal.com :wink:

Milner · **Posted:** Sat Sep 30, 2006 8:15 pm

I am aware of those....What I am talking about is longer uppers and lowers, to widen the track width, increase travel, decrease cv angle, and address the steering issues.

Yes, it would call for new cv's/axle, and steering links, but....

Jeger · **Posted:** Sat Sep 30, 2006 8:40 pm

Would longer Upper and Lower Control arms, call for some fender/fender flair modifications? Or would 2 inches still fit in there?

swyszomirski · **Joined:** Sat Oct 01, 2005 2:59 am **Posts:** 286

I was thinking of carving some longer lowers out of wood and then casting them at the metal shop. Then possibly have Al make some uppers to fit. I was thinking of using the same clevis, only with the tabs of the lower arm tall so as not to have contant issues. This way there aren't spacers to deal with, and the lift could be greater than 3"

Milner · **Posted:** Thu Oct 26, 2006 11:55 pm

My thoughts.....

May or may not still fit without flare mods, depending on back spacing....can be addressed as needed....
I would fab a new clevis to allow for coilover mounting with standard config.
Casting would be cool, but not as easy for me, the fabbing lowers from tube/plate is not too bad, and easier to mod to get a prototype right.
Not really looking at a production sort of thing, just for me and who ever else my want to play, not a full on kit, and not for those looking for bolt and go. I know plent of you are skilled enough to be interested.

My biggest hold up is not being able to tear apart our KJ as it is a DD.

pokey555 · **Joined:** Fri Jun 09, 2006 2:47 pm **Posts:** 50

Milner,

The problems I have with a uniball mounted on the upper control arm is the radial vs. axial loading of the joint. When using to control a steering spindle it is placed on axial load direction, the joints secondary strength axis. It could be overcome by correctly sizing the joint to the load but resulting in a large joint. This is equivalent to using the steel I beam in your house and rotating it 90 degrees to create an H. Now the load is on the secondary strength axis and you just lowered the critical load by 2-5x. An exaggerated translation: if your kid(s) jump in the right spot of your house, it will look like a dozer hit it.

Another problem will be the wheel motion ratio, by extending the track width a stiffer spring will be required to have the same effect on vehicle performance, if the same spring damper location is utilized.

Without knowing your background, I would at a minimum read Fundamentals of Vehicle Dynamics by Thomas Gillespie.

Rob

OzLtd · **Posted:** Sun Oct 29, 2006 6:40 pm

Good post pokey555, very sensible.

To keep the IFS arrangement you would have to go down the lines of this kit. It is possible and would be good, but feasible ? To go to a shop like these guys it would cost a fortune for a '1 off' kit.......

Milner · **Posted:** Sun Oct 29, 2006 7:44 pm

My thoughts are very similar to the pics OZLtd has posted. While I am not an engineer, I have a fair amount of practicle experience. As in the pics shown, the uniballs have held up in race rigs running 30"+ of travel, 37" tires, and 5000lb+ trucks. I figure if it holds together for them, the libby will be fine.

pokey555 · **Joined:** Fri Jun 09, 2006 2:47 pm **Posts:** 50

Key words: Race truck, meaning suspension parts are considered consumable.

I also thought about using uniballs on the upper control arm, but I am not sold yet, due to my above statement of the axial loads. I checked with Rubicon express on their joints, and they have not been tested. Another vendor poly performance has 1" uniballs rated at 104,000 lb in the radial direction, axial is not listed, and I did not call them yet. The problem I have with the poly performance joint is that there is no bushing. Why is it a problem, friction, the tolerance will eventually increase causing undesired vehicle movement. For a track vehicle it is fine, due to they will be replaced/inspected periodically, and are necessary for the last reduction in milli-seconds. For a daily driven vehicle, I would prefer a joint with a bushing. To each his own, I use solid rod ends on my other car's panhard bar and replace the ends ~8k or 0.010" of play.

If you want some more information check out this forum, search rod ends: www.corner-carvers.com. Even if it is focused on paved track motorsports it is still applicable.

Rob

A-arm fab discussion

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