acceleration vibration

[bigred95]

Heres my situation. i got 95 xj with an RE 5.5 short arm lift. i got a high angle cv driveshaft with a slip yoke on it. After i put the driveshaft in, i took measurements with an angle finder. i put the angle finder on the driveshaft and got a measurement of 20 degrees, i then put it on the axle on those flat spots next to the diff cover and got 10 degrees. From those measurements i figured i needed a 5 degree shim, but i must be wrong somewhere. Because after installing my 5 degree shims i took it for a test drive and i am getting a humming sound when i accelerate. i hope someone can tell me what im doing wrong and how to fix this problem, any help would be greatly appreciated.

 

[bigred95]

i just measured it today in the same spots and now im getting 20 on the driveshaft and 15 next to the diff cover. hopefully that will tell someone what is going on.

 

[outlander]

by those measurements sounds like you need a 2* shim which would put you at 3* under.The reason your were getting vibes/noise on acceleration is because the 5* shim was too much

 

[bigred95]

so are you saying i should take the 5 degree shims out and throw in 2 degree shims, and that should make me good.

 

[Deadman 94 xj]

Your transfer case yoke should be at zero degrees. If it's angles up at all, double the measurement and add it to your ds angle.

Most DS are only equipped to handle 22* max. If you're already at 20*, add axle wrap to it and it's easily exceeding it's range.

Whats the angle rating of the DS you have? Adding shims to the pinion won't do anything to help this. All you're doing is messing with the pinion angle. What you want to do is mess with the t-case/DS angle.

I had the same problem and had to get a 32* DS to fix it.

 

[bigred95]

i have a high angle cv driveshaft with a slip yoke. i am pretty sure it said 40 degrees. I was told to point the pinion up at the transfer case when you have a cv driveshaft, isnt that the whole idea behind putting in axle pad shims.

 

[PapaGeno21]

Im having the same problem, but mines a pretty bad vibe.

The Pinion is like 1 degree down from poiting at the t-case, so i ordered 2 degree shims to angle it down, so when Im driving it torques up the pinion correctly.

 

[Deadman 94 xj]

i have a high angle cv driveshaft with a slip yoke. i am pretty sure it said 40 degrees. I was told to point the pinion up at the transfer case when you have a cv driveshaft, isnt that the whole idea behind putting in axle pad shims.

Yes, that's the point. You want the pinion in line with the drive shaft and pointing at the transfercase. You should have 0-2 degree difference between the pinion and drive shaft.

But, this does nothing if you have too much of an angle at the transfer case. You could angle the pinion up but your pnion angles will be off.

Where did you get your drive shaft from? 40* really?

The noise you're hearing is like a plastic on tin type of clicking sound, it is the cv joint binding up. A 40* drive shaft would be perfectly fine, no matter what the pinion was set at. I'd call who ever you got it from and complain.

 

[Goatman]

i have a high angle cv driveshaft with a slip yoke. i am pretty sure it said 40 degrees. I was told to point the pinion up at the transfer case when you have a cv driveshaft, isnt that the whole idea behind putting in axle pad shims.

Slip yoke meaning in the driveshaft? At first I thought you had a slip yoke at the t-case. So you have an SYE? Do you have a double carden joint at the t-case or a single u-joint? Saying that would make it more clear what you have.

If you have a slip yoke eliminator and CV at the t-case, the angle of the pinion u-joint should be down about 1*, basically you want it straight but it will torque up slightly under power so start with it slightly down. However, you say that you have a vibe only on accleration, correct? Nothing at highway speed? That would tend to show that you have too little u-joint angle at the pinion, meaning you should shim the pinion down a couple of degrees.

If you don't have a CV at the t-case, then you need to know the angle of the u-joint at the t-case as well as at the pinion, and they should be within 3* of each other.

 

[bigred95]

yes slip yoke in the driveshaft with a high angle cv on the t- case end. i got it from driveshaft superstore and yes im pretty sure its 40* if not 40* than its 35*, but i know for sure it is a high angle cv. would it cause a problem if the drive shaft was a little short? i realized that when i measured for a driveshaft i had a t-case lowering kit on that came with the lift. then i think i heard that i should take it off, so i did. which in turn messed up my length for the driveshaft when i put the driveshaft in. Should i put that lowering kit back in, or what should i do besides trying to get ahold of driveshaft superstore on monday? There is about an 1 3/4 inch gap between the cv and the seal at the t-case. How do i measure the angle of the u- joint at the t- case end?

 

[Yucca-Man]

The Pinion is like 1 degree down from poiting at the t-case, so i ordered 2 degree shims to angle it down, so when Im driving it torques up the pinion correctly.

Don't put those shims in. Optimally, you're looking for 1-2* down from the driveshaft, and you're there now.

Your transfer case yoke should be at zero degrees. If it's angles up at all, double the measurement and add it to your ds angle.

Most DS are only equipped to handle 22* max. If you're already at 20*, add axle wrap to it and it's easily exceeding it's range.

You assume that the engine/t-case combo is horizontal, and that the rear face of the t-case is vertical then. That's not the case, so you can take several degrees off the operating angle of the driveshaft.

How do i measure the angle of the u- joint at the t- case end?

Measure off a machined surface. You can drop the driveshaft temporarily and measure the flat faces of the yoke (rotate it 180* and check both sides to ensure it's not running on a bent output shaft).

Jim www.yuccaman.com

 

[dinorl007]

with a cv shaft at the t case end, i dont think u need the u joint angle, check th eangle of the drive shaft, and on the pinion like u did, then correct until the pinion is 1 to 2* degrees below, wether it be with shims or by lowering the t case, as far as the lenght of the driveshaft, how much is still engaged in the splines whre it goes together? i theink it will be ok when i added my lift and sye with the cv shaft it took a couple of days to get athe angle right i ended using a 2
8 shim and lowering the t case 1/4 inch to make it right hth

 

[bigred95]

so maybe i should consider putting the t-case lowering kit back in and take another measurement?

 

[Yucca-Man]

No, because lowering the front end (t-case) will make your pinion angle higher relative to the driveshaft. You want the pinion to be 1-2* below the driveshaft angle to account for axlewrap on acceleration.

You say "humming" on acceleration - that's not vibration. Although it's a pain to do on the 'net, can you describe the hum?

Jim

 

[Deadman 94 xj]

yes slip yoke in the driveshaft with a high angle cv on the t- case end. i got it from driveshaft superstore and yes im pretty sure its 40* if not 40* than its 35*, but i know for sure it is a high angle cv. would it cause a problem if the drive shaft was a little short? i realized that when i measured for a driveshaft i had a t-case lowering kit on that came with the lift. then i think i heard that i should take it off, so i did. which in turn messed up my length for the driveshaft when i put the driveshaft in. Should i put that lowering kit back in, or what should i do besides trying to get ahold of driveshaft superstore on monday? There is about an 1 3/4 inch gap between the cv and the seal at the t-case. How do i measure the angle of the u- joint at the t- case end?

Does it make the noise at highway speeds? Mine would increase as speed increased, as long as I was accelerating.

If your pinion is in spec and it's still doing it than your options are to put the tcase drop back in or return the DS for one that is rated for the correct angle. 5.5" lift doesn't seem right to run into this type of problem but if the shaft is off than it's off.

Length will not cause this type of problem.

You can measure the tcase angle by putting the angle finder on the flat edge on the outer side of the case. You'll know what I mean when you look at it.

I'm not sure what the F the other posts here are talking about but the only other one you should pay attention to is Goatman's.

 

[bigred95]

ok i just measured everything one more time before i mess with any thing.
taking into consideration that there are 5* axle pad shims in and NO t-case drop.

heres what i came up with-
5* on the t-case (measured on side of extension housing)
19* on the driveshaft
15* on the pinion
Is the T-case supposed to be level? if it is, how do i go about making it level? does that have anything to do with this situation?
Can anyone give me any other advice with all this information?

 

[Deadman 94 xj]

ok i just measured everything one more time before i mess with any thing.
taking into consideration that there are 5* axle pad shims in and NO t-case drop.

heres what i came up with-
5* on the t-case (measured on side of extension housing)
19* on the driveshaft
15* on the pinion
Is the T-case supposed to be level? if it is, how do i go about making it level? does that have anything to do with this situation?
Can anyone give me any other advice with all this information?

Is the T-case angled 5* up or down? If it's down than you're fine. Put a 3-4* shim in at the pinion and see what happens.

If you still get the noise, even at hghyway speeds, and it increases and decreases with speed, than your DS is bad. CV joint is bad.

I can't imagine that it would be 5* up.

 

[outlander]

yea....like I said before all this talk about t-case angle.....you had too much shim.

 

[Deadman 94 xj]

LOL