I installed the chevy shackles on my XJ this morning. I have read that the shackle will help with driveline angles and not cause vibes. I drove her away and had some nice vibes. So was what I read wrong? Where can I get a driveshaft for a good price? I dont know how long I can live with that vibe.
shackles hurt or help???
- Thread starter MoulderXJ
- Start date
That's kind of a dangerous blanket statement there.
Shackles, in and of themselves don't make vibrations.
What I suspect you've done is to rotate the pinion up. This will make the lower u-joint operating angle different than the upper u-joint operating angle. Normally, these phase-cancel each other out because they're the same. When they're different, you get vibes because one u-joint isn't fulling cancelling out the rotational speed differences created by the other.
Okay..... that's probably clear as mud.
Take a single u-joint, and keep the input shaft and output shaft parallel. If you turn the input shaft at a constant speed, the output shaft will also turn at the same constant speed. Now, keep the input turning. Move the output shaft so that it starts to put an angle on the u-joint. The output speed will no longer be constant, but will vary slightly above and below the input shaft speed in a sine wave related to the angle of operation. This is a vibration.
Add a second u-joint at the end of the output shaft so you now have an input shaft, u-joint, intermediate shaft, u-joint, output shaft. The u-joints do need to be phased, and for the moment, I don't remember what the phasing is (hint: look at a stock rear driveshaft for an XJ.) In any event, as long as the output shaft is parallel to the input shaft, you'll get smooth power transmission. You'll get a sine wave in the output speed when the input and output shafts aren't parallel. Again, vibration.
Back to your situation........you've lowered the operating angle (made it closer to parallel) at the axle u-joint, while the tcase u-joint hasn't changed. Possible fixes? Lose the Chevy shackles, put a reversed degree shim under the springs, or put in an SYE kit (which will probably also require degree shims.)
Shackles, in and of themselves don't make vibrations.
What I suspect you've done is to rotate the pinion up. This will make the lower u-joint operating angle different than the upper u-joint operating angle. Normally, these phase-cancel each other out because they're the same. When they're different, you get vibes because one u-joint isn't fulling cancelling out the rotational speed differences created by the other.
Okay..... that's probably clear as mud.
Take a single u-joint, and keep the input shaft and output shaft parallel. If you turn the input shaft at a constant speed, the output shaft will also turn at the same constant speed. Now, keep the input turning. Move the output shaft so that it starts to put an angle on the u-joint. The output speed will no longer be constant, but will vary slightly above and below the input shaft speed in a sine wave related to the angle of operation. This is a vibration.
Add a second u-joint at the end of the output shaft so you now have an input shaft, u-joint, intermediate shaft, u-joint, output shaft. The u-joints do need to be phased, and for the moment, I don't remember what the phasing is (hint: look at a stock rear driveshaft for an XJ.) In any event, as long as the output shaft is parallel to the input shaft, you'll get smooth power transmission. You'll get a sine wave in the output speed when the input and output shafts aren't parallel. Again, vibration.
Back to your situation........you've lowered the operating angle (made it closer to parallel) at the axle u-joint, while the tcase u-joint hasn't changed. Possible fixes? Lose the Chevy shackles, put a reversed degree shim under the springs, or put in an SYE kit (which will probably also require degree shims.)
BLKXJ33
NAXJA Forum User
- Location
- Cumming, Ga
Not trying to diss your statement w/ the shackles ChiXJeff (very knowledgeable info), but that kind of made things more confusing than they should have been. I understand what your saying, but why did'nt you just ask him these questions...ChiXJeff said:
Moulder:
1. What year Cherokee do you have?
2. How much lift total are you adding up to now?
3. Do you have stock shaft, transfer case drop? any shims, or angled blocks?
If you have a newer style cherokee, all i will say is SYE and CV Shaft. You can't really fix the vibes in newer cherokees with cheap solutions. If you have an older cherokee you could possibly fix it with 1" transfer case drop, shims, etc...
I got a 99 cherokee
5 inches in rear, 4 in front
stock driveline, no shims, no nothin
I read the statement on SYE, now where can I get one with a good price?
I plan on getting new leave packs for the rear, which will take me to about 6.5 or 7 inches in the rear. I will have 6 inches in the front.
5 inches in rear, 4 in front
stock driveline, no shims, no nothin
I read the statement on SYE, now where can I get one with a good price?
I plan on getting new leave packs for the rear, which will take me to about 6.5 or 7 inches in the rear. I will have 6 inches in the front.
Check the vendors forum...... or http://www.4xshaft.com, Tom is one of the club sponsors.
BLKXJ33
NAXJA Forum User
- Location
- Cumming, Ga
If your getting new spring packs for the rear your definately in need of an SYE/CV Shaft. www.rustysoffroad.com has the SYE for $200 alone or $480 for the shaft and SYE. The SYE alone is a hell of a deal in my opinion. I would wait to get the new spring packs in before measureing for a d-shaft though.
Barger
NAXJA Forum User
- Location
- DelaWhere?
Tom woods all the way! :roll:
I got the heavy duty Advance adapters SYE and his drive shaft. Everything fit perfect and they were there for me to answer any questions I had, and I had a few as it was my first SYE install.
I got the heavy duty Advance adapters SYE and his drive shaft. Everything fit perfect and they were there for me to answer any questions I had, and I had a few as it was my first SYE install.
xjhm
NAXJA Forum User
- Location
- pikeville,ky
another vote for woods the turnaround and shipping is very fast, product looks awesome and i went with his sye and driveshft $370.00 shipped!
that was with the feburary rebate... you can't beat that with a stick
i am installing it this weekend
that was with the feburary rebate... you can't beat that with a stick
i am installing it this weekend
sarvermr
NAXJA Forum User
- Location
- Little Rock, AR
JB conversions has there HD SYE on sale for $199. its hard to beat that.
http://www.jbconversions.com/pages/products/np231/np231j_std_sye.html
throw in an xj front cv shaft and you're out the door for less than $250!
matthew
http://www.jbconversions.com/pages/products/np231/np231j_std_sye.html
throw in an xj front cv shaft and you're out the door for less than $250!
matthew
