Track bar Help

Larrythedog

Larrythedog

NAXJA Forum User
Location
Covina CA
I have started my Jeepspeed build. It's my first time working on or building a jeep. Although I have built several other types of off-road racers, the Jeep thing is new to me. I'm currently building an XJ for the 2010 season. I'm using a Full Traction long arm kit on a 2wd axle. I'm setting up the front end and i ran across a few issues that have stopped my build.
1. I'm cycling the front end with the Full Traction track bar and track bar mount in place, and it seems the front axle will shift from side to side as it goes through the full 9-10 inches of travel. The axle will actually move about 2.5-3 inches. Is this right? Did I miss somthing here? I know the track bar will travel in an arc as it rises, so it must move some, right? What can I do to reduce the amount of side movement?
2. The caster angle I'm starting with is 6-7 degrees at ride height. This also increases to about 12-13 dergrees as the suspension cycles. Is this excessive? What caster angle are most of you using? Its a 2wd axle so i dont have to worry about the pinon angle.

IMG_1119.jpg
 
everything sounds good and normal to me! sure, the axle will move side to side, but you won't notice in the dirt. that's kinda the only way to keep the axle under the jeep.
 
The rules on that are open, as are the rules for steering. At the Baja 1000 this year, that full traction track bar was bent and replaced twice during the race on the Filarski Rig. You do not want a bent track bar on a race car...it tends to make the bump stops stick through the coil springs.... If you can get your draglink/track bar angles as level as you can, it will minimize the side to side movement a lot and not bind on droop. I prefer the cross over steering to the stock design also, because your toe-in won't chage throughout the travel.

-Dan
 
There's wasn't exactly the Full Traction track bar. You can also gusset the bend to make it stronger and not bend, which is pretty simple to do.

The sideways motion can be reduced by decreasing the angle of the track bar at ride height, but then the drag link angle also needs to be decreased to match the track bar to avoid bump steer. The sideways movement isn't bad, you'll never feel it, as long as you set the bump stop locations to hit in the right spot when the suspension is compressed.

Raising and lowering the height of the track bar mounts effects the roll center, which effects the handling. On a rock crawler you want it high, but on most road racers you want it low. I don't know about a desert racer and what would be better. A higher roll center creates more stability, less leaning in turns, but it also produces less predictability, less feel for the driver. Since the overall center of gravity is raised on a lifted XJ, I'd bet the handling would be better with the roll center raised as well.......the roll center and the center of gravity would be closer together. But, raising the steering to match on a D30 presents it's own issues.
 
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Two out of three of them were the FT ones, the third one, we made at the shop, and the RE one was never used, I believe. The one we made was sleeved, bent, then plug welded, and then the ends put on. I think it was probably stronger than the FT one but the problem is in the "Z" shape or the FT design. But that's just my $.02.

-Dan
 
I bought FOA 2.5 bumps for the front and rear, it sound like the 2.5 bumps are to big and will hit the coils. Are most using 2" bumps in the front?
 
You'll probably have a hard time getting the coil over the bump can, as it will be 2-3/4" OD. You'll probably have to trim the top end of the coil spring where it wraps around to a smaller diameter on the top. Also with your track bar at such an angle, it'll be tough to keep the bumps from hitting the springs. To hit the center of the bump pad at full bump, the bump stops are going to be pretty close to the driver's side of both of the springs at ride height, and probably bouncing off the springs at droop.
 
Loose_Nuts_Enterprises said:
Two out of three of them were the FT ones, the third one, we made at the shop, and the RE one was never used, I believe. The one we made was sleeved, bent, then plug welded, and then the ends put on. I think it was probably stronger than the FT one but the problem is in the "Z" shape or the FT design. But that's just my $.02.

-Dan
Click to expand...

I didn't know which ones were made, and which were original. I know one that was made bent. The RE one never got used, we were carrying it and put it in the car at one of the stops.



Interesting that track bars and steering are open. It's pretty simple to make a setup that will work well if you have options other than off the shelf parts.
 
I think I'm going to ditch the FT track bar, and move the mount on the axle a little higher then make my own track bar and drag link.
 
Just an update. I had to rebuild the axle side track bar mount. I used r1 1/4 DOM tubing .281 wall for the steering and track bar.

IMG_1205-1.jpg


I just mocked up the TB bracket to test. It has less than 1 inch of side to side movent. I moved the axle mounting hole up about 1/4" after that (not shown yet).
IMG_1204.jpg


Finished the axle TB mount. I still plan to weld a short picie 1" DOM 1/4 wall tubing on either side of the bolt hole for a little extra sheer.

IMG_1209.jpg
 
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