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Unread 04-26-2014, 11:32 AM   #1
Skeelo
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another 242 swap with a vibration

I know this has been discussed on here quite a bit. However I have not quite found an answer to the problem. About 3 years ago I put a 242 into my 1998 ZJ with a 5.2. The old 249 was toast. I got the 242 from a 1996 zj with the 4.0 with 100k miles on it. I had 1 inch cut off the driveshaft, balanced, new u-joints with the correct slip yoke for a 242. After that it had a vibration at 65mph. Its not an axle or tire. It seems to be in harmony with the speed of the driveshaft. I am at stock height. For 3 years I just delt with it. However, it finally took out the the pinion bearings on the rear diff. As I noticed the diff get louder, the vibration became less and less. Now I am back trying to solve the vibration. I tried a new trans mount, took the diff apart again just to recheck. took the 242 apart and everything is good. Ran it on the lift in 2wd and 4wd, vibration still there. took out the rear ds, vibration was gone. Had it balanced again, new u-joints again. Vibration is still there. If I had a lift I would just do the SYE on it. But since it has no lift, i don't want to believe that's the problem. Checked TC and diff angles. They are both right at 6.5 degrees. Next I guess is to just replace the output shaft bearing on the TC see what happens. Replace the driveshaft, see what happens. I am tired of just throwing money and time at it to not fix the problem.

Does anyone have any ideas???

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Unread 04-26-2014, 01:53 PM   #2
localfiend
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Start playing with the t-case height. Use some washers and try going up or down a half inch or so. If that doesn't work, try 3/4".

I had a similar issue with my TJ. Couldn't solve the problem, balanced and rebalanced, tried 10 different pinion angles.

It went away after I did the tummy tuck and lifted the case.

I tried lowering it back down and the vibration came back. Go figure. Completely counter intuitive, but I musta found the sweet spot.

Anyway, it's a cheap thing to try.
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Unread 04-27-2014, 01:52 PM   #3
Skeelo
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Thank you

Thanks for the input on the t case height. I thought about that but disregarded it after the angles were all ok. But it never hurts to try. I will let you know how it goes.
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Unread 06-05-2014, 03:00 PM   #4
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Sorry it has taken me so long. School is a pain. I played with the T-case height both up and down by 5 washers stacked and there was no change still vibrates at 65. Any other ideas anyone? I have more free time now so i can work on it again. Thanks for the help!
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Unread 06-05-2014, 03:13 PM   #5
MurdaJs
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Quote:
Originally Posted by Skeelo View Post
I know this has been discussed on here quite a bit. However I have not quite found an answer to the problem. About 3 years ago I put a 242 into my 1998 ZJ with a 5.2. The old 249 was toast. I got the 242 from a 1996 zj with the 4.0 with 100k miles on it. I had 1 inch cut off the driveshaft, balanced, new u-joints with the correct slip yoke for a 242. After that it had a vibration at 65mph. Its not an axle or tire. It seems to be in harmony with the speed of the driveshaft. I am at stock height. For 3 years I just delt with it. However, it finally took out the the pinion bearings on the rear diff. As I noticed the diff get louder, the vibration became less and less. Now I am back trying to solve the vibration. I tried a new trans mount, took the diff apart again just to recheck. took the 242 apart and everything is good. Ran it on the lift in 2wd and 4wd, vibration still there. took out the rear ds, vibration was gone. Had it balanced again, new u-joints again. Vibration is still there. If I had a lift I would just do the SYE on it. But since it has no lift, i don't want to believe that's the problem. Checked TC and diff angles. They are both right at 6.5 degrees. Next I guess is to just replace the output shaft bearing on the TC see what happens. Replace the driveshaft, see what happens. I am tired of just throwing money and time at it to not fix the problem.

Does anyone have any ideas???
How much spline engagement on the slip yoke at ride height?
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Unread 07-11-2014, 11:14 PM   #6
Skeelo
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Ok. t-case height did nothing for me. Bought a custom driveshaft that has the original slip yoke to a double cardan U-joint and a single on the differential. Still vibrates at 65. However, now, under deceleration it vibrates so violently it feels and sounds like the driveshaft wants to snap off. So that was a bust. Back at square one again with no idea what do to do except use the driveshaft to beat the thing!

I will see about the spline engagement tomorrow.
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Unread 07-12-2014, 05:17 AM   #7
Snowfan2
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TC Output shaft bearings and bushing. Waaa waaa waaa noise and vibe. Varies with coast and accelerate and speed. Mine goes mostly away above 80
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Unread 07-12-2014, 06:25 AM   #8
Timo_90xj
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Quote:
Originally Posted by Skeelo View Post
Bought a custom driveshaft that has the original slip yoke to a double cardan U-joint and a single on the differential. Still vibrates at 65. However, now, under deceleration it vibrates so violently it feels and sounds like the driveshaft wants to snap off.
That setup will never work properly with a slip yoke at the TC output, and without properly adjusting the pinion angle for the double cardan joint- style DS. With a double cardan joint DS you MUST have zero degree angle at the pinion. The more angle there, the more you get vibes.

You also want the double cardan joint as close to the rear output as possible, and preferrably a fixed yoke TC output and the slip joint built into the driveshaft. No wonder you're getting bad vibes.



Quote:
Back at square one again with no idea what do to do except use the driveshaft to beat the thing!

I will see about the spline engagement tomorrow.
Measure the spline engagement. I had DS vibes at around 60-65mph with the extended rear WB and not enough spline engagement. Once I got the rear DS extended and fine-tuned my pinion angle, vibes went away completely.
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Unread 07-12-2014, 05:29 PM   #9
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Ever start wondering if replacing the VC might have been the right thing to do?
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Unread 07-12-2014, 05:56 PM   #10
Skeelo
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So I took out the driveshaft to check the rear diff pinion angle. It is sitting right at 6.5 degrees. Installed the driveshaft and lowered the transfer case till the driveshaft sat at 6.5 degrees to zero out any angle there. It is lowered just shy of 3/4 of an inch. Took it for a drive and still vibrating like no other. Took out the new driveshaft, put in the old, took it out and still vibrates but no where near what the new driveshaft did. It could be better than before, but I could be off because the new one was so bad.
By the way spline engagement is 3" with the t-case lowered 3/4'' on the old and 3" with the new. With the drivshaft out, put it 2wd and listened to the t-case with a stethoscope at idle, 25, 35, 45, 55, 60-70, and reverse at 15 ish and got grease splattered on my face because I didn't wipe of the output shaft. It all sounds normal and no Waaa Waaa Waaa sound.
Even if I solve it with lowering the t-case even more, it does throw off the geometry of the motor mounts too, so it cannot be a permanent solution. Pinion angle is not easily adjustable without cutting out the spring perches and re-welding. Someone please correct me if I am wrong, but that's not something I really feel like doing. So..... what are some other options?
Thank you all for your help and input.
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Unread 07-12-2014, 05:58 PM   #11
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Quote:
Originally Posted by Technohead View Post
Ever start wondering if replacing the VC might have been the right thing to do?
I dono, i am beginning to wonder
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Unread 07-12-2014, 11:58 PM   #12
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Properly operating viscous coupling will cause zero issues with vibes. VC does not cause vibrations and has got nothing to do with it. Incorrect DS angles, worn DS U- joints, not enough spline engagement, worn TC output or pinion bearings WILL cause vibes. Thoroughly check all components mentioned for wear, if worn replace.


Did you read my post about the DS angles at all? If you are using the double cardan joint in the rear, you CANNOT have equal TC output and pinion angles. It will NOT work - ever.


Also, get rid of that TC drop. It's not gonna do you any good. Keep the TC & tranny tucked up where they're supposed to be by the factory, and invest in at least adjustable UCAs to adjust rear pinion angle. If you are lifted or plan on doing so, I strongly suggest investing in a full set of adjustable LCAs and UCAs. It will make your life a lot easier. You do not need to cut & reweld spring perches for pinion angle adjustment, at least not because of a couple of degrees.
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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 07-13-2014, 09:00 AM   #13
Zjrookie
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I run 3 inch lift with 98 5.2 zj 242 swap out of a 98 4.0 and have zero vibe my drive shaft was shortened and sitting on the ground the back of tc to front of the slip on splines is 1.5 inches
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Unread 07-13-2014, 06:34 PM   #14
Skeelo
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Originally Posted by Timo_90xj View Post
Properly operating viscous coupling will cause zero issues with vibes. VC does not cause vibrations and has got nothing to do with it. Incorrect DS angles, worn DS U- joints, not enough spline engagement, worn TC output or pinion bearings WILL cause vibes. Thoroughly check all components mentioned for wear, if worn replace.


Did you read my post about the DS angles at all? If you are using the double cardan joint in the rear, you CANNOT have equal TC output and pinion angles. It will NOT work - ever.


Also, get rid of that TC drop. It's not gonna do you any good. Keep the TC & tranny tucked up where they're supposed to be by the factory, and invest in at least adjustable UCAs to adjust rear pinion angle. If you are lifted or plan on doing so, I strongly suggest investing in a full set of adjustable LCAs and UCAs. It will make your life a lot easier. You do not need to cut & reweld spring perches for pinion angle adjustment, at least not because of a couple of degrees.
If i had never replaced the 249 with the 242, I could have no vib problems right now. Ran smooth as glass with the 249 and as soon as I installed the 242 it started vibing. Rear diff was just rebuilt with all new bearings, took apart the tc to inspect those bearings and everything and all are good. Output shafts and input shaft have zero runout. Original drivshaft was cut and balanced at a reputable shop with new u-joints. Replaced u-joints again, had it ballanced again and new u-joints again... highly doubt its u-joint and driveshaft related. Has to be angles. As far as I can tell, tc sits at 6.5 degrees down and pinion sits at 6.5 degrees up. It has 3 inches of spline engagement so I would imagine I have enough engagement.

I did read your post about the double cardan DS. So I lowered the TC till the DRIVESHAFT sat right at 6.5 degrees so it matched the 6.5 degrees of the PINION angle. Still had the nasty vib that only came from the new DS.

I put the old back in with the TC lowered almost 1'' now. Took my wife for a drive and she says its not as loud. So maybe it is angles after all but i can guarantee that the TC is sitting at a different angle than the pinion since before I lowered it, they were both at 6.5.

So I should, #1 raise me TC to stock height. #2 get a real SYE with a double cardan. #3 at least install adjustable UCA's and maybe LCA's too and #4 adjust the pinion angle to zero any angle between the pinion and DS. Yes???
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Unread 07-14-2014, 02:28 AM   #15
Timo_90xj
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So I should, #1 raise me TC to stock height. #2 get a real SYE with a double cardan. #3 at least install adjustable UCA's and maybe LCA's too and #4 adjust the pinion angle to zero any angle between the pinion and DS. Yes???
This.

Then again, ZJ has a long enough rear DS that it shouldn't need a SYE + double cardan joint rear DS at lift heights about 5"-6" or lower. It never hurts though, so if you want to go that route, why not.

If you wheel your Jeep, I'd replace the CAs with aftermarket ones anyway. Stock ones are pretty weak, and they don't offer you with good flex, nor adjustability (apart from the small amount of caster/ pinion adjsutment with the cam bolts up front).


I had pretty bad vibes with my 249 and slightly extended WB before I got the rear DS extended and balanced, and adjusting the rear pinion angle spot-on. I later on swapped to a 242 that already had a SYE, so I had to take my DS to a shop again to have them rebuild it with a slip joint on the DS. No issues with that either Since you mentioned you're 100% sure there are no DS issues, and no bearing isses, and you certainly have enough spline engagement with the 3" (btw., you have checked no play on the slip joint?) - it has got to be TC output/ DS/ pinion angle- related.



Not to disappoint you, I have a friend who swapped in a Checy LS1 into his '73 Nova, with a rebuilt tranny and rebuilt GM 10-bolt rear axle. He has done absolutely everything ever possible to get rid of DS vibes, but it is still there. He has literally spent a grand on trying to get rid of the vibes
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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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