Rubicon Owners Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
478 Posts
Discussion Starter #1
I work at a Dodge/Jeep dealer in Canada and I own an 03 Rubicon that is mostly stock. I am currently saving for a 4'' lift and 33'' tires. I've seen lots of jeeps but today is the first time ever that I saw front upper control arms ripped in half. It was an 03 rubicon (not mine!!) and both upper control arms broke when the guy had both diffs locked and he climbed done into a creek bed and backed up to take another hit at the bank on the other side. Ever heard of this before!?!
 

·
Registered
Joined
·
478 Posts
Discussion Starter #3
The Rubicon was/is bone stock, both front upper control arms were torn in half. i've never seen anything like it, wish i had a digital camera.
 
G

·
Guest
Joined
·
0 Posts
I've seen it, but not on a Rubi. A friend pretzled both his front upper arms on a 2002 climbing up a sandy hill out of a gulley . We don't know if they were going before, but we know that they definately bent on this hill. He had to rock it a couple of times to get unstuck and finish the hill climb. His is set up very similar to the Rubi's 4:1 t-case with 4.88's. Remember the front upper control arms are under compression when you drive forward, and under extension when you back up, so the tearing action could have happened the same way as bending a piece of steel back and forth, it will eventually rip. They may have been bent earlier, and the attempt to get back and forth out of the creek did the final damage. Especially if he was getting on it.

Ron
 

·
Premium Member
Joined
·
2,160 Posts
Stock Jeep control arms are crap. I have seen that twice before. I am sure that with the added help from the lockers, it was even easier to destroy them. I am not the least bit surprised that this happened to someone. I don't think it will be the last time.

Justin
 

·
Premium Member
Joined
·
3,745 Posts
PBR Stitch said:
... Remember the front upper control arms are under compression when you drive forward, and under extension when you back up, so the tearing action could have happened the same way as bending a piece of steel back and forth, it will eventually rip....
Ron
Far be it from me to doubt a Rubicus Maximus :bowing: , but isn't it the other way around Ron? Given a flat surface, front uppers are in tension moving forward, and in compression in reverse, yes? Whatever the answer is, the stock CAs are crap.

What am I missing here?

Jerry
 
G

·
Guest
Joined
·
0 Posts
JerryC said:
Far be it from me to doubt a Rubicus Maximus :bowing: , but isn't it the other way around Ron? Given a flat surface, front uppers are in tension moving forward, and in compression in reverse, yes? Whatever the answer is, the stock CAs are crap.

What am I missing here?

Jerry
Kinda cool title for 400 posts. Okay what are you missing. Thats easy. Remember the axle wants to rotate in the inverse direction of wheel rotation. The axle absorbs the force from the tires, so the reaction has to be equal and opposite. Easy example is take a look at the rear. When you drive forward the pinion wants to go up. so hence in the front the pinion wants to drive down when you go forward. Now remeber the rear will be exactly opposite the front.

Front axle
Forward = UCA (compression) LCA (extension) Pinion (down)
Reverse = UCA (Extension) LCA (Compression) Pinion (up)

Rear axle
Forward = UCA (Extension) LCA (Compression) Pinion (up)
Reverse = UCA (compression) LCA (extension) Pinion (down)

We straightend the front UCA's by attaching a strap to the tow hooks around a telephone pole and backed up, they straightened out far enough to be able to drive it home.

Ron
 

·
Premium Member
Joined
·
3,745 Posts
PBR Stitch said:
JerryC said:
Far be it from me to doubt a Rubicus Maximus :bowing: , but isn't it the other way around Ron? Given a flat surface, front uppers are in tension moving forward, and in compression in reverse, yes? Whatever the answer is, the stock CAs are crap.

What am I missing here?

Jerry
Kinda cool title for 400 posts. Okay what are you missing. Thats easy. Remember the axle wants to rotate in the inverse direction of wheel rotation. The axle absorbs the force from the tires, so the reaction has to be equal and opposite.

Ron
Duooh! Of course. I am humbled. :bowing:

Never had a problem with the front and rear being opposite. Time to go review Jeep Suspension 101. Wait, that was supposed to be in Chapter 3 or 4. Whew. Still time to get smart before I write that.

Jerry
 
1 - 10 of 10 Posts
Top