front XJ ds out back... vibes...

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Date: Oct 23, 2009

front XJ ds out back... vibes...	Permalink

SO I have a 3.5 RE lift on my XJ, new leaf packs and coils. No tcase drop on the NP 231 4* shims SYE with front XJ driveshaft, rebuilt with all new u-joints. Dana 35 rear No vibes for a couple weeks under normal driving (with a little moderate throttle testing), until the other day I was feeling confident and ran WOT from a stop just because. Since then anything over an indicated 45 (on 31" BFG A/Ts) it starts to vibrate... increasingly worse as speeds go up. Vibes get really bad under heavier acceleration. any ideas? I know it's' something to do with driveline angles and stuff, but it seems so weird that it would start after a little wot to 45 (speed limit) run. I wonder if something 'settled' in the wrong way under the torque, but it doesn't seem to me the 4.0 is that powerful. Thanks, Matt __________________ My Fleet 1996 XJ "Snowball"- 3.5" lift, bunch of little mods. I hate pegleg rear axles! 1974 AMC Javelin "Jade Grenade"- 360v8, 4sp, green inside and out. Underfunded Project. 2009 Kawsaki Vulan 900 "Rocket III"- Summer DD

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Date: Oct 23, 2009

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With a SYE you do NOT want shims... You want the pinion yoke and the TC yoke to be parallel (ish) to each other. __________________ '93 XJ Cherokee Sport - build thread '89 XJ Cherokee Laredo - build thread '88 MJ Comanche Pioneer SWB - build thread '87 MJ Comanche LWB '94 YJ Wrangler - build thread

ChevelleSSLS6

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Date: Oct 25, 2009

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I'll pull the shims out then :)

I also ordered an angle finder so I can see what angles I'm running for you guys... I don't think it's really important with the CV (isn't that a double cardan on the ds now as a CV is a 'sealed grease boot' with a 'metal donut' and ball bearings?)

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My Fleet
1996 XJ "Snowball"- 3.5" lift, bunch of little mods. I hate pegleg rear axles!
1974 AMC Javelin "Jade Grenade"- 360v8, 4sp, green inside and out. Underfunded Project.
2009 Kawsaki Vulan 900 "Rocket III"- Summer DD

tjhawk

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Date: Oct 27, 2009

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I have a 3/4 inch pinion shim with the front shaft on the back conversion and I have no vibs. The pinion angle is fairly close to the the t case but still has a bit of angle on it. Did you say you changed the double cardone joints as well? I know quite a few guys who have had their XJ's front shaft DC joints redone because the salt eats them up. One guy I know had one so bad it barely had any movement in it. I am surprised it didn't grenade. The only difference between you and me is I have a NP 231 and a Chrysler 8.25.
Also check your motor mounts/trans mounts. You seem to have problems under acceleration which is when things will "wind up" so to speak. You say you have a vib at 45 and up. Did you try putting it in neutral at that speed and see if the vib goes away? This way you can see if its a driveline problem or a misalignment of some sort problem as with the vehicle in neutral you have nothing being driven but the driveshaft in a "freewheel" mode. (if you were in gear you would be under decelleration.)

-- Edited by tjhawk on Tuesday 27th of October 2009 01:47:59 AM

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ChevelleSSLS6

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MiniBeast came by today to drop off a wrangler air intake tube and he was looking at my Jeep, and with a quick twist of the front DS the pass. side u-joint had TONS of play, and the DS had a little, but me being me, I'll be replacing both, and hub/bearings while its apart.

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My Fleet
1996 XJ "Snowball"- 3.5" lift, bunch of little mods. I hate pegleg rear axles!
1974 AMC Javelin "Jade Grenade"- 360v8, 4sp, green inside and out. Underfunded Project.
2009 Kawsaki Vulan 900 "Rocket III"- Summer DD

MiNi Beast

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Date: Oct 30, 2009

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no forget your antiseize on the hub bolts and surround. __________________ Wheel it, Break it, Fix it, Repeat!

ChevelleSSLS6

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Date: Oct 31, 2009

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MiNi Beast wrote: no forget your antiseize on the hub bolts and surround. especially here in the rust belt! __________________ My Fleet 1996 XJ "Snowball"- 3.5" lift, bunch of little mods. I hate pegleg rear axles! 1974 AMC Javelin "Jade Grenade"- 360v8, 4sp, green inside and out. Underfunded Project. 2009 Kawsaki Vulan 900 "Rocket III"- Summer DD

Topic: front XJ ds out back... vibes...