HELP - Rock Krawler DS Pinion Angles
10-20-2013, 02:24 PM
#1
JK Junkie
Thread Starter
HELP - Rock Krawler DS Pinion Angles
Have the 2.5 rock krawler max travel lift on my 07 2 door JK and have Adams front and rear driveshafts. My kit includes adjustable front and rear lower control arms which are set to the spec lengths that rock krawler suggested. The first time I went out with my Adams shafts, I broke the rear shaft due to incorrect pinion angle when crawling a ledge. The great folks at Adams replaced my shaft for me, but I need to correct my pinion angle so it does not happen again.
I looked at pulling the control arms again and shortening the length and realized that I only have a very small margin (about 1/4" if that) to shorten the arms to gain more pinion. I understand that I may have to go with upper adjustable to correct this, but I have seen tons of people running the same lift on their 2 door with no issues. Has anyone else run into this problem? I'm trying not to spend the extra coin right now on the uppers and have a competition coming up that I will be competing in with my JK. Can anyone help?!
Here are a couple pictures of my angles (not the best pictures, but it will give you and idea....):
I looked at pulling the control arms again and shortening the length and realized that I only have a very small margin (about 1/4" if that) to shorten the arms to gain more pinion. I understand that I may have to go with upper adjustable to correct this, but I have seen tons of people running the same lift on their 2 door with no issues. Has anyone else run into this problem? I'm trying not to spend the extra coin right now on the uppers and have a competition coming up that I will be competing in with my JK. Can anyone help?!
Here are a couple pictures of my angles (not the best pictures, but it will give you and idea....):
10-20-2013, 06:16 PM
#4
JK Jedi Master
Join Date: Jan 2008
Location: Austin <--> Colorado Springs
Posts: 11,463
Likes: 0
Received 162 Likes
on
154 Posts
The first time I went out with my Adams shafts, I broke the rear shaft due to incorrect pinion angle when crawling a ledge.
10-21-2013, 03:17 PM
#5
JK Junkie
Thread Starter
I thought it was close but according to Adams, it is not correct and is the reason why I broke it. This is what the angle is supposed to be, either 0 degrees or +1 at the axle.
Last edited by GreenJK07; 10-21-2013 at 03:19 PM.
10-21-2013, 03:19 PM
#6
JK Junkie
Thread Starter
Apparently when I was crawling the ledge and my rear coils were loaded, it caused too much of a negative pinion which caused the u joint to break and as the shaft spun, it broke the ear off of the flange. Here are some pics of the carnage:
10-21-2013, 03:50 PM
#7
JK Freak
Join Date: Apr 2011
Location: Lakeland, Florida
Posts: 719
Likes: 0
Received 0 Likes
on
0 Posts
You got a Hemi in that thing? 
I can't see how being off 3 degrees when low-speed crawling can cause that kind of break. Slamming against a rock might do it.
If you have to be perfectly aligned, what's the point of a U-joint? Sure, because the other end is a double cardan that approximates a CV you don't get the velocity balance of having a single cardan at both ends but geeze... that shouldn't fall apart like that. If it was just the yoke or just the cross I would chalk it up to bad material but both? Was the U-joint ever over-heated or not greased (assuming not sealed)?
I can't see how being off 3 degrees when low-speed crawling can cause that kind of break. Slamming against a rock might do it.
If you have to be perfectly aligned, what's the point of a U-joint? Sure, because the other end is a double cardan that approximates a CV you don't get the velocity balance of having a single cardan at both ends but geeze... that shouldn't fall apart like that. If it was just the yoke or just the cross I would chalk it up to bad material but both? Was the U-joint ever over-heated or not greased (assuming not sealed)?
Trending Topics
10-21-2013, 04:59 PM
#9
JK Junkie
Thread Starter
You got a Hemi in that thing? I can't see how being off 3 degrees when low-speed crawling can cause that kind of break. Slamming against a rock might do it. If you have to be perfectly aligned, what's the point of a U-joint? Sure, because the other end is a double cardan that approximates a CV you don't get the velocity balance of having a single cardan at both ends but geeze... that shouldn't fall apart like that. If it was just the yoke or just the cross I would chalk it up to bad material but both? Was the U-joint ever over-heated or not greased (assuming not sealed)?
I can't see how being off 3 degrees when low-speed crawling can cause that kind of break. Slamming against a rock might do it. If you have to be perfectly aligned, what's the point of a U-joint? Sure, because the other end is a double cardan that approximates a CV you don't get the velocity balance of having a single cardan at both ends but geeze... that shouldn't fall apart like that. If it was just the yoke or just the cross I would chalk it up to bad material but both? Was the U-joint ever over-heated or not greased (assuming not sealed)?