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Old 08-08-2011, 05:36 PM   #1
Join Date: Jan 2011
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Pinion angle problems

Hey there jeep forumers. I'm having a small issue that is becoming more and more of a problem. I installed one of UCF's ultra-high clearance skids about 4 months ago. I currently have 1.25" bl, 4" suspension lift, Ford 8.8 rear end, SYE w/ CV driveshaft, adjustable upper and lower rear control arms, a 1" mml and have lowered the skid plate 1" with spacers.

When I first put on the skid plate w/ the 1" spacers and mml, the pinion angle was okay. It was not vibrating and I could not hear the d-shaft clicking. After I did some offroading, it starts making a clicking noise, I figured the springs had maybe settled some so I adjusted the angle to be higher. Went off roading again, it starts up again. After working on it last week, it stopped the driveshaft clicking but started with some vibes from 0-15 mph. Again, I go off road for a few hours and come out and now the vibes were from 0-35 mph. Which leads to yesterday when the driveshaft breaks. What's the deal? I can not adjust the pinion angle up any higher because the brackets on the rear end are almost touching the gas tank skid plate and the spring perches are up against the shocks. What is making the pinion angle more severe each time I get into some mud and rocks? How can I correct this without breaking more stuff? lol Any advice is always appreciated.
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Old 08-08-2011, 09:11 PM   #2
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Anyone have any advice for me?

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Old 08-08-2011, 09:33 PM   #3
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might want a longer driveshaft..not sure but you could be pushin the limits of the short-arm...the only thing i can think of is to extend your wheelbase with a long-arm upgrade...could be wrong..
You can lock it..even put a different t/c in it..but its still not a RUBICON!
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Old 08-08-2011, 09:50 PM   #4
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The only problem with that is the gas tank. I would need to get a fuel cell or something and put it in the back of the jeep. I have contemplated that for a while now. That would be an expensive venture. If I move the axle back, I'll also have to move the shock upper mounts back I think...
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Old 08-08-2011, 09:59 PM   #5
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where did the shaft break. sounds like you had a shaft problem and not the pinon angle. you said it was a CV style shaft but was the slip part of the shaft moving? also lose the spacers on the belly skid pointless to run a tummy tuck skid then drop it.

photos will help
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Old 08-08-2011, 10:07 PM   #6
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The spacers are on the tummy tuck because without them, the pinion angle is too severe and the driveshaft is too angled. I know it's ridiculous, it bugs the hell out of me lol. The part that broke was where the slip yoke piece connects to the flange that connects to the rear end. It is certainly possible that the u-joint failed. That is where the driveshaft itself broke. I was able to just purchase the slip yoke piece from a driveline store. I will get some pictures up on here tomorrow first thing.
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Old 08-08-2011, 10:09 PM   #7
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And I'm pretty sure that the cv part was moving. When I examined it, it seemed to move freely in and out on the splines
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Old 08-09-2011, 01:27 AM   #8
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I also do not understand the need for t-case drop spacers with a CV style d-shaft on only 4" of suspension lift. Do your angles look similar to this? I pulled this diagram from Tom Wood's site. A lot of good info on there. You may have to consider relocating your spring perches and shock brackets to gain the proper geometry.
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Old 08-09-2011, 08:57 AM   #9
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As long as the slip part of your shaft has enough room you can bring in your lowers to make more room as well. That also slightly changes the angle of the shaft so make sure to check before you take off if you do that. I've got a tummy tuck on top of a 3" suspension so mine is probably even worse than yours and I have no issues.
2000 Jeep Wrangler Sport
4.0L / 5spd
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Old 10-11-2011, 08:34 PM   #10
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Ive recently been considering an 8.8 swap myself.
someone else here done it and is having issues with vibes also,its been stated that its something to do with the pinion shaft being too far over too one side and the shaft isnt right down the center,so the shaft binds up.

Im still researching it,so check the angles....from diffrent angles
Pincho De Lapiz
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Old 10-12-2011, 12:27 AM   #11
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What was the original pinion angle set at on the 8.8? Did you order it from ECGS?
You pinion angle should be around 17 degrees for the lift and TT with a SYE and DC DS.
33" BFG A/T's, 2.5" RC w/ 1.25" BL, MORE MML, Custom Bumpers, Home made disconnects, 8.8 LSD and D44 Rubicon Locker 4.10 gears.
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Old 10-12-2011, 01:44 AM   #12
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I am running the same setup as you. 4" lift UCF ultra high clearance skid (not dropped), SYE/CV and an 8.8. I have the 8.8set at 18 degrees with no vibes what so ever.
If you upper control arms arm out of adjustment or you are hitting the gas tank try putting on some adjustable lowers and shorten them. You will be able to increase the angle and get the rear away from the gas tank.

Favorite quote, Thanks GoldenSahara00 "not many people do it. most of the guys who do do it, don't sit on the computer and talk/write about it, they do it then go wheel"
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