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Old 05-07-2012, 03:37 AM   #1
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Help with TC drop and associated problems

Recently I blew my rear yoke, I replaced the uni and yoke, however I still had some vibration (I understood I was still going to have vibes, as it was not a fix, just a band-aid)

I have been looking into SYE/control arms, and I will be purchasing them, just waiting on some more funds!

Today I decided to have a decent look under the jeep and try and see what was going on. I was going to drop the transfer case in the mean time, however I believe the PO has already done this? (with some soft-ish pucks, see below)



Now this is what my rear shaft angles look like; to me, that doesn't look right at all! I am thinking that the TC drop is too much, and is actually impacting negatively on the drive-line? Your thoughts? Solutions?

I was thinking (bare in mind, I WILL be getting a SYE) in the meantime, removing/reducing the drop, and/or possibly adjustable upper control arms (seen as I will need these anyway when I SYE) to get the angle back where it is supposed to be.



Any comments/solutions would be very welcome.

'05 TJ 6sp Man
Tough Dog 2" shocks/springs.

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Old 05-07-2012, 07:24 AM   #2
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Yes... the PO has spaced your bellypan down for a t-case drop.



Even though it may not look right... it is close... a single ujoint application runs differently than a double cardan joint....

The outputs of the tcase and diff should be parallel and the angles within certain degrees.... this cancels vibes in a single ujoint application

here is a standard single ujoint application




Tom Wood's site is down right now... (would have linked his pics and literature ) but you need to read DRIVESHAFT101 on his site to fully get and understand the angles involved, and the differences between a single ujoint application and a double cardan ( CV) application

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Old 05-07-2012, 12:51 PM   #3
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Thanks, I will keep reading once I get home from work.

The reason that I said it looked wrong is its opposite to every picture describing angles of the drive shaft.

Green: what every pic I have seen says it should look like.

Red:what mine is doing


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Old 05-07-2012, 12:58 PM   #4
Knows a couple things...

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The key thing to keep in mind is with the factory driveshaft, as said above, the rear pinion shaft simply needs to be parallel to the tcase output shaft.
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Old 05-07-2012, 01:14 PM   #5
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Quote:
Originally Posted by Jerry Bransford
The key thing to keep in mind is with the factory driveshaft, as said above, the rear pinion shaft simply needs to be parallel to the tcase output shaft.

Thanks for your input, do you have any suggestions on how to achieve this while I wait to SYE? Do any of my ideas in post #1 have any merit?
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Old 05-07-2012, 01:37 PM   #6
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do you have a body lift? If so, a motor mount lift?
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Old 05-07-2012, 01:42 PM   #7
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Quote:
Originally Posted by Rumdog
do you have a body lift? If so, a motor mount lift?
No BL yet, it is on my list.
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Old 05-09-2012, 01:31 PM   #8
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Im am going to try and raise the skid plate up in a few hours.

Any other suggestions?
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Old 05-09-2012, 01:36 PM   #9
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Raising the skid plate will make the vibes worse. You need to put some washers in to shim down the skidplate. Put one or two in each skidplate mount until the vibe goes away.

When you do finally go with a SYE and a CV driveshaft you can then remove your TC drop. Please keep in mind that you will also need adjustable rear upper control arms. This will allow you to adjust your pinion angle.
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Old 05-09-2012, 02:42 PM   #10
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Quote:
Originally Posted by nick50471 View Post
Raising the skid plate will make the vibes worse. You need to put some washers in to shim down the skidplate. Put one or two in each skidplate mount until the vibe goes away.

When you do finally go with a SYE and a CV driveshaft you can then remove your TC drop. Please keep in mind that you will also need adjustable rear upper control arms. This will allow you to adjust your pinion angle.

Looking at the picture in the first post, wont dropping the TC more, increase the operating angle? as the output shaft will be lower than the pinion yoke?
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Old 05-09-2012, 03:41 PM   #11
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Quote:
Originally Posted by carlosprite View Post
Looking at the picture in the first post, wont dropping the TC more, increase the operating angle? as the output shaft will be lower than the pinion yoke?
Yes.... although the pic can be deceiving to some degree.

I would bet that there is a MML installed that he may not know about..... OR ....a completely wiped out transmission mount and the t-case is resting on the bellypan... which could be why the angle looks so steep off the t-case...
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Old 05-09-2012, 04:12 PM   #12
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checking both motor and trans mounts is on the list for the morning :P
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Old 05-09-2012, 05:14 PM   #13
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Look for a 1" block between the motor mount and frame.
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Hella Lighting: Driving, Fogs and H4 E-Codes
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Old 05-09-2012, 06:16 PM   #14
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Go to Home Depot and buy the cheap magnetic angle gauge. You will find it in the tool section near the levels and measuring tapes. It is bright yellow and pretty inexpensive. On my lifted TJ with a T-Case drop my Driveshaft angle is 11 degrees and my pinion angle is 10 degrees. The pinion angle always needs to be the same or a degree or 2 lower than the Driveshaft. Yours looks to me like the pinion angle is higher than the Driveshaft which is not good. I put a socket on the pinion and then put the angle finder on the socket. You will see what I mean when you go to measure the pinion angle, not enough flat space to get the angle finder in there and measure. Then you will know for sure what is going on. If your pinion angle is higher than the Driveshaft angle remove spacers from your t case drop and find something thinner to replace them like stainless washers or something until you get the angle adjustment correct.
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Old 05-09-2012, 07:28 PM   #15
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Quote:
Originally Posted by yoopone View Post
....The pinion angle always needs to be the same or a degree or 2 lower than the Driveshaft.
This is ONLY the case with a Double Cardan shaft (aka CV shaft) which is coupled ( in our TJ's) with the SYE.... his pic clearly shows a stock shaft and single u-joints at both ends.... T-case output and pinion angles should be the same or parallel, which means the angle of the drive shaft off either the t-case or the pinon end will be ( should be ) the same.

Conventional 2 u-joint application.... which he has




Double Cardan ( aka CV shaft ) application....



Carlosprite,

Do me (and the rest of us) a favor.... snap a pic of your upper control arms connecting the rear axle to the frame.... the upper arms. I am curious to see if you have aftermarket/adjust control arms installed. This could account for your pinion angle being so high.
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Hella Lighting: Driving, Fogs and H4 E-Codes
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Old 05-10-2012, 10:34 AM   #16
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Quote:
Originally Posted by yoopone
Go to Home Depot and buy the cheap magnetic angle gauge. You will find it in the tool section near the levels and measuring tapes. It is bright yellow and pretty inexpensive. On my lifted TJ with a T-Case drop my Driveshaft angle is 11 degrees and my pinion angle is 10 degrees. The pinion angle always needs to be the same or a degree or 2 lower than the Driveshaft. Yours looks to me like the pinion angle is higher than the Driveshaft which is not good. I put a socket on the pinion and then put the angle finder on the socket. You will see what I mean when you go to measure the pinion angle, not enough flat space to get the angle finder in there and measure. Then you will know for sure what is going on. If your pinion angle is higher than the Driveshaft angle remove spacers from your t case drop and find something thinner to replace them like stainless washers or something until you get the angle adjustment correct.
I wish we had home deport or harbor freight in Australia! I have to order everything from the US plus freight haha

Quote:
Originally Posted by TnDz TJ

This is ONLY the case with a Double Cardan shaft (aka CV shaft) which is coupled ( in our TJ's) with the SYE.... his pic clearly shows a stock shaft and single u-joints at both ends.... T-case output and pinion angles should be the same or parallel, which means the angle of the drive shaft off either the t-case or the pinon end will be ( should be ) the same.

Conventional 2 u-joint application.... which he has

Double Cardan ( aka CV shaft ) application....

Carlosprite,

Do me (and the rest of us) a favor.... snap a pic of your upper control arms connecting the rear axle to the frame.... the upper arms. I am curious to see if you have aftermarket/adjust control arms installed. This could account for your pinion angle being so high.
I have no aftermarket control arm, which is why I couldn't understand why my pinion angle was so bloody high!

Today I removed the TC drop completely, this almost removed all vibrations; I ended up putting 3 washers (less than a 1/4") which gave it a [/i]very[i] close to stock feel. I will have to get another test drive of a stock TJ too double check


Thanks to all that gave their opinions, they were taken onboard, and I appreciated it and all your help.
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Old 05-10-2012, 12:48 PM   #17
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Good to hear.. Have you checked your trans mount? T could be wiped out and causing the tcase to ride low on the belly pan. It's the 4 bolts in the middle of the pan. Get under there and apply upward pressure to the rear output. If you can push it up, chances are your mount is shredded.
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Old 05-10-2012, 08:23 PM   #18
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Quote:
Originally Posted by TnDz TJ
Good to hear.. Have you checked your trans mount? T could be wiped out and causing the tcase to ride low on the belly pan. It's the 4 bolts in the middle of the pan. Get under there and apply upward pressure to the rear output. If you can push it up, chances are your mount is shredded.
It looked ok, but I am going to replace it anyway. Was going to do it yesterday; however when I went to the dealer, they wanted $240 for a stock mount! My jaw dropped, they are $22 of quadratec!

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