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Discussion Starter · #1 ·
Ok folks did the zone 4.25 lift and have a slight vibe on take off so I think I am going ahead and do the SYE (thanks Rockridge 4wd for a great price) the 2000 Tj has 170,000 miles on it so while I have it off I am going to do a new trans. mount, What is everybody replacing the stock one with? Thanks.
 

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Ok folks did the zone 4.25 lift and have a slight vibe on take off so I think I am going ahead and do the SYE (thanks Rockridge 4wd for a great price) the 2000 Tj has 170,000 miles on it so while I have it off I am going to do a new trans. mount, What is everybody replacing the stock one with? Thanks.
If your vibe is just on take off, i suggest you replace the transmission mount first and see if that doesn't take care of it before spending $'s on the sye
 

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The transmission mount material needs to match whatever the motor mounts are or you'll pick up extra vibrations. What method did you use counteract the excessively steep driveshaft u-joint angles caused by the lift that causes vibrations? Dropped tcase skidplate? Taller motor mounts? Their cambolt kit which seldom works as advertised?

If you used the cam bolt kit, what does the rear pinion angle look like? A pic of where the pinion shaft connects to the driveshaft would be helpful, taken from far enough that we can see at least half of the driveshaft and the axle so the angular relationship between the two can be seen.
 

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Discussion Starter · #4 ·
The transmission mount material needs to match whatever the motor mounts are or you'll pick up extra vibrations. What method did you use counteract the excessively steep driveshaft u-joint angles caused by the lift that causes vibrations? Dropped tcase skidplate? Taller motor mounts? Their cambolt kit which seldom works as advertised?

If you used the cam bolt kit, what does the rear pinion angle look like? A pic of where the pinion shaft connects to the driveshaft would be helpful, taken from far enough that we can see at least half of the driveshaft and the axle so the angular relationship between the two can be seen.
I did the full kit so I did the 1 inch MM and the pinion cams( it will be tomorrow before I can get a picture) but I can tell you the pinion is tipped up toward the transfer case.
 

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... I can tell you the pinion is tipped up toward the transfer case.
That's the problem right there, your pinion angle is too high and is causing the vibrations. The pinion shaft should only point at the transfer case if you had installed an aftermarket CV driveshaft.

With the factory non-CV driveshaft, the pinion shaft must be parallel to the transfer case output shaft.

Yours should look exactly like this...
 

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Discussion Starter · #7 ·
If your vibe is just on take off, i suggest you replace the transmission mount first and see if that doesn't take care of it before spending $'s on the sye
I don't doubt it isn't a combo of several things, I ran by a well known large chain brand 4 wheel parts store this afternoon and they looked at my problem and said the pinion pitch is close but might need a little bit more So next week I plan on changing mount and possibly dropping transfer case .25 inch. This is only temp. till I can get my sye here So back to my original question where are you getting your replacement mount for a stock transfer case?
 

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I spent much of my time when I worked for 4Wheel Parts' parent company trying to educate some of their techs on correct pinion angles. Not many were anxious to learn much about the subject. Just sayin'.

Take another look at that drawing above... it's the gospel for the driveshaft you're running. Pointing the pinion shaft towards the tcase is completely incorrect for the factory driveshaft and doing so WILL cause drivetrain vibrations.
 

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Discussion Starter · #9 ·
I spent much of my time when I worked for 4Wheel Parts' parent company trying to educate some of their techs on correct pinion angles. Not many were anxious to learn much about the subject. Just sayin'.

Take another look at that drawing above... it's the gospel for the driveshaft you're running. Pointing the pinion shaft towards the tcase is completely incorrect for the factory driveshaft and doing so WILL cause drivetrain vibrations.
I am sure it is the pinion angle. The problem is I really don't have a level place to make the adjustment myself, all the big box store wants to do is sell me a SYE and the shop I had put on the lift was so incompetent ( 14 days and 4 different (mechanics) who didn't speak to each other worked on the lift. I am still straightening things out ) they are not getting a chance to touch my jeep again. if I put on a SYE will that make Pinion Angle less critical?
 

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If you did the zone 4.25 combo lift, it is a 3" suspension lift using your stock control arms plus a 1" motor mount lift. Your pinion anle is likely okay if that is the case.

Change the trans mount first...about $30 at napa, and if that doesn't get rid of your vibe, add a couple of washers between your frame and t-case skid at each bolt location.

Btw, if you want to do a little test, park your jeep where you have a straight area in front of you, put it in 4wd high, and take off normally. If the vibe is absent, it is almost surely the transmission mount. The load on the front drive shaft will counteract the force on the rear.

You can do an sye if you want to, but it will also involve at minimum adjustable upper control arms, rear angled track bar bracket, sye, and dc drive shaft. An sye shouldn't be needed with the combo lift....it isn't on the thousands of other jeeps running around with it.
 

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if I put on a SYE will that make Pinion Angle less critical?
No, but that doesn't mean it's any more or less difficult to set the pinion angle with a CV driveshaft that it is with the OE factory non-CV driveshaft.

It's not difficult to get the pinion angle set correctly, you don't even really need an angle finder. I set my pinion angles visually. Just set it like the above drawing, parallel to the tcase output shaft, and it will be fine.
 

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Discussion Starter · #12 ·
If you did the zone 4.25 combo lift, it is a 3" suspension lift using your stock control arms plus a 1" motor mount lift. Your pinion anle is likely okay if that is the case.

Change the trans mount first...about $30 at napa, and if that doesn't get rid of your vibe, add a couple of washers between your frame and t-case skid at each bolt location.

Btw, if you want to do a little test, park your jeep where you have a straight area in front of you, put it in 4wd high, and take off normally. If the vibe is absent, it is almost surely the transmission mount. The load on the front drive shaft will counteract the force on the rear.

You can do an sye if you want to, but it will also involve at minimum adjustable upper control arms, rear angled track bar bracket, sye, and dc drive shaft. An sye shouldn't be needed with the combo lift....it isn't on the thousands of other jeeps running around with it.
Thank yoU Water Dog you both answered my side question (where to go to get the trans. mount ) and may have solved my problem. In 4 W high there are no vibes so I have already ran to NAPA and got a tranny mount and will change it out tomorrow, Today has already been spent fixing things the shop either did incorrectly or not at all when they did my lift. I am going to use my motorcycle jack to drop the skid plate, do I need to support the tranny while I am changing the mount?
 

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Discussion Starter · #14 ·
Jerry and Water dog Thank you both for all the info. I replaced the tranny mount and when I finely got a chance to get on level ground I looked at my pinion angle and replaced the (zone) pinion adjustment cams the installer had put in with some we made at the shop I work at that brought the pinion back to 0 ( we have these programed into the laser now so if anyone needs a set PM me) Most of the vibes are gone and as soon as it quits raining here in Ga. I am pulling the drive shaft and changing the U joints and having it balanced. Thank you again for all the info.
 

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Hello jerry or water dog. I'm currently saving up to order this same kit. My question is do I need to order both the cam bolt kit and rear pinion cam lock? I'm confused at if I need both or what they do
They will slightly adjust pinion angle, and no, you shouldn't need them. Your pinion angle will rise slightly with the installation of 3" coils using stock control arms, but you are also installing a 1" motor mount lift as part of the combo package. Those two will work together to keep the angles about where they need to be.

Some have minor vibes after installing this lift that can be cured by placing a few flat washers between the frame and t-case skid. From what I've read, this appears to happen more with Jeeps that have the D44 rear dif. Probably because the drive shaft is about an inch shorter with the D44.

If you live in the rust belt, it's probably a good idea to have a little space between the frame and skid anyway.
 

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They will slightly adjust pinion angle, and no, you shouldn't need them. Your pinion angle will rise slightly with the installation of 3" coils using stock control arms, but you are also installing a 1" motor mount lift as part of the combo package. Those two will work together to keep the angles about where they need to be.

Some have minor vibes after installing this lift that can be cured by placing a few flat washers between the frame and t-case skid. From what I've read, this appears to happen more with Jeeps that have the D44 rear dif. Probably because the drive shaft is about an inch shorter with the D44.

If you live in the rust belt, it's probably a good idea to have a little space between the frame and skid anyway.
Thank you very much for clearing that up for me.
 

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One thing about installing a rear cam bolt kit to adjust the rear pinion angle... don't!

First, the rear pinion angle is supposed to be parallel to the transfer case output shaft. With the stock rear driveshaft, any vibrations caused by a new suspension lift are caused by excessive angles at both driveshaft u-joints, not that the pinion angle is no longer parallel to the tcase output shaft which it normally is anyway. Adjusting the pinion angle is not the fix for that type of problem when you have the OE single-cardan driveshaft. Second, those cam bolts won't typically hold the pinion angle reliably. Many end up welding them in place out of frustration since they can't get them tight enough to hold the angle for long.
 
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