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Unread 04-09-2014, 02:15 PM   #1
01blackout
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rear pinion angle

ive got a 2000 xj 4.5 zone lift, tcase drop, and 33s ive got 3 degrees at the pinion and 9 degrees at the tcase how many degree shim should i use?

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Unread 04-09-2014, 10:18 PM   #2
Timo_90xj
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With a normal DS, you need the pinion and tc outputs to be at same angle. With leaf springs, you want the pinion very slightly above t-case output to counter pinion angle change under load.

However, your real issue is the tc drop. Get rid of it, gain back your lift height under the belly, install SYE + double cardan joint rear driveshaft.
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Unread 04-10-2014, 02:00 AM   #3
sAe23
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Um... Doesn't the pinion move UPwards under load?
And really, a 1" or so drop isn't going to cause the belly to hang up very much.
YES, a SYE is the better way to go, but as long as there are skid plates installed, and the motor mounts are in good condition, there is nothing wrong with a drop kit...
(IMHO, YMMV)
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Unread 04-10-2014, 02:20 PM   #4
Timo_90xj
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Yeap, it goes up - my bad with that one. You want the pinion to point slightly below, not above TC output.

As for the drop kit, it is a band-aid not a fix. If you get no vibes in the rear with a TC drop and don't want to install a SYE, why not go with one inch less lift. It really is pretty much the same deal, with better driveline angles and better CA angles and only one inch less uptravel (dependikg on the tire size). I really don't see the point in first lifting a Jeep, then dropping the belly down with a TC drop - unless it's purely a street-driven Jeep.
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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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Unread 04-11-2014, 08:14 AM   #5
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The PURPOSE of lifting is to clear the TIRES and gain flexibility.. Extra clearance for obstacles is a side effect or bonus. Taller tires add ground clearance lifts DO NOT. A stock height XJ on stock 215 tire has the same ground clearance as a 4" lifted XJ running 215 tires
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Unread 04-11-2014, 08:55 AM   #6
jeepster383
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Lifting it obvious makes clearance in other places. Like dropping off a rock and smashing ur lower quarter panel. I would not lift a vehicle and lower the t case. In the future i will get rid of the low hanging factory crossmember.
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Unread 04-11-2014, 08:59 AM   #7
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Quote:
Originally Posted by jeepster383 View Post
Lifting it obvious makes clearance in other places. Like dropping off a rock and smashing ur lower quarter panel. I would not lift a vehicle and lower the t case. In the future i will get rid of the low hanging factory crossmember.
This. Clocking the TC for a flat belly is one of the best mods anyone could do on any Jeep that has the TC hanging under the frame rails. That's most of the Jeeps ever built

Quote:
Originally Posted by 93gc40 View Post
The PURPOSE of lifting is to clear the TIRES and gain flexibility.. Extra clearance for obstacles is a side effect or bonus. Taller tires add ground clearance lifts DO NOT. A stock height XJ on stock 215 tire has the same ground clearance as a 4" lifted XJ running 215 tires
If you only measure ground clearance from under the axles, yes. But that's not all there is to lift and/ or larger tires. I do know exactly what you're talking about here, but you're seeing things a bit different than I do. Same idea, different method of achieving it.
IMO, low COG is the way to go. Keep the lift height low, run as large tires as possible. Angle grinder and a welder are the keys to it! Saves one from a lot of driveline-angle, CA angle and steering linkage issues too..

But I'm not gonna go any deeper into it because it is way off-topic already on this thread..
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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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Unread 04-11-2014, 09:16 AM   #8
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Get rid of t case drop and re measure ur angles.
Generally want the axle 1 degree lower.
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Unread 04-11-2014, 01:47 PM   #9
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Quote:
Originally Posted by 01blackout View Post
ive got a 2000 xj 4.5 zone lift, tcase drop, and 33s ive got 3 degrees at the pinion and 9 degrees at the tcase how many degree shim should i use?
So, um, back to your question...
But first some questions of my own:
1: Are you experiencing drive line vibrations?
2: Do you have a "stock" ("single-Cardan") drive shaft?
3: How much drop does the T-case have?

You could try using a smaller drop to reduce the angle at the T-case...
You could try a 4 degree shim. When you change the angle at one end, you affect the other end as well, so this might get you there.

You can read up on this stuff here:
http://www.4crawler.com/4x4/CheapTri...l#Introduction
and here:
http://www.4xshaft.com/techinfo.html (geometry 101 and slopes vs angles)

HTH
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Unread 04-13-2014, 03:43 PM   #10
01blackout
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just did tc drop becuase it came with the lift if i had the money to do a sye i would but for now this is what i got and i have a little bit of vibes on acceleration
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Unread 04-13-2014, 03:43 PM   #11
01blackout
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its a 1" drop
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Unread 04-14-2014, 12:53 AM   #12
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Your vibes are most likely caused by the difference in angles. As mentioned above, you need the angles to be almost parallel, pinion pointing about 1* lower than TC output angle is.

You could try removing the TC drop altogether and see if you get less vibes, or more. Single joint DS can operate on up to about 10* angles without vibes, but the less angle the better. On the other hand, a difference of only a couple of degrees between the input and output angles can cause severe vibes. Depends on your luck really
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1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...

http://www.jeepforum.com/forum/f13/d...s-etc-1222317/


1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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Unread 04-14-2014, 01:29 AM   #13
Renix
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also try changing out your u joints, they were worn into a a specific angle prior to lift.
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Unread 04-15-2014, 10:25 AM   #14
01blackout
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I ran it without the tc drop for a while vibes were pretty bad I tried running some 6° shims that where given to me didn't change vibes i'm gonna try replacing ujoints
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BLACK OUT 2001 60th anniversery TJ*4.0*soft 8's*33x12.5 dunlap mudrovers* kc daylighters*3.25 rough country suspension lift*d30*d44* BUILT NOT BOUGHT!!!!! (sold)
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Unread 04-15-2014, 05:08 PM   #15
sAe23
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OK, with a standard ujoint drive shaft, and a 4.5" lift, the T-case has to be dropped to reduce the operating angle to make the ujoint happy.
You then need to shim the pinion to get the ujoint at THAT end happy.
You can't do one OR the other.
Did you read the links I posted earlier?
Not saying your ujoints don't need replacing, but you need to do the setup properly (which most will say is a SYE and Dbl Cardan shaft...).
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