SYE install degree shim calculations
#1
Seasoned Member
Thread Starter
Join Date: Jan 2013
Location: SoCal
Posts: 447
Likes: 0
Received 1 Like
on
1 Post
Year: 1994
Model: Cherokee
Engine: 4.0
SYE install degree shim calculations
I know this has been talked about but my numbers seems way different than others are getting.
1994 2dr sport, AX15 (5-speed), C8.25 axle, 4.5" RC lift yielding 6" measured at the rear axle.
This is a full pack spring lift with stock shackles.
Pinion angle measures 3.6 degrees.
Drive shaft fitted into place measures 19.6 degrees.
So I need to reduce the angle by 19.6 - 3.6 = 16 degrees.
Drive shaft length is ~3x the pinion length so every degree I rotate the axle should raise the drive shaft end enough to reduce that drive shaft angle by ~1/3 degree.
16 / 1.33 = 12 degree required shim.
The biggest shims I see are on the market are 8 degrees.
These would improve my angle by 8 * 1.33 or about 11 degrees leaving me about 5 degrees out.
Is this reasonable?
1994 2dr sport, AX15 (5-speed), C8.25 axle, 4.5" RC lift yielding 6" measured at the rear axle.
This is a full pack spring lift with stock shackles.
Pinion angle measures 3.6 degrees.
Drive shaft fitted into place measures 19.6 degrees.
So I need to reduce the angle by 19.6 - 3.6 = 16 degrees.
Drive shaft length is ~3x the pinion length so every degree I rotate the axle should raise the drive shaft end enough to reduce that drive shaft angle by ~1/3 degree.
16 / 1.33 = 12 degree required shim.
The biggest shims I see are on the market are 8 degrees.
These would improve my angle by 8 * 1.33 or about 11 degrees leaving me about 5 degrees out.
Is this reasonable?
#7
Junior Member
Join Date: Jul 2011
Location: WI
Posts: 69
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1996
Model: Cherokee
Engine: I6 4.0 high output!
shim
if you run a slip yoke elimantor on it you technically wont need a shim but if u decideto u should look around 3 degrees
Trending Topics
#8
Senior Member
Join Date: Jul 2010
Location: Long Island NY
Posts: 997
Likes: 0
Received 1 Like
on
1 Post
Year: 2000
Model: Cherokee
Not true. if the U-joint on the axle end is out of alignment with the DS then you will get vibration and shorten the life of the u-joint.
#9
Seasoned Member
Thread Starter
Join Date: Jan 2013
Location: SoCal
Posts: 447
Likes: 0
Received 1 Like
on
1 Post
Year: 1994
Model: Cherokee
Engine: 4.0
Driving can cause the suspension to settle a bit and may improve the angle. I put shackles in the rear and it was a 1/2" higher when i put it on the ground before driving a lil.
Not true. if the U-joint on the axle end is out of alignment with the DS then you will get vibration and shorten the life of the u-joint.
Not true. if the U-joint on the axle end is out of alignment with the DS then you will get vibration and shorten the life of the u-joint.
I just removed the transfer case drop and installed the sye.
I have the factory shackles. Longer shackles would improve the pinion angle.
#10
Senior Member
Join Date: Jul 2010
Location: Long Island NY
Posts: 997
Likes: 0
Received 1 Like
on
1 Post
Year: 2000
Model: Cherokee
The suspension was installed by the previous owner along with a transfer case drop. It doesn't have many miles on it but it isn't new either.
I just removed the transfer case drop and installed the sye.
I have the factory shackles. Longer shackles would improve the pinion angle.
I just removed the transfer case drop and installed the sye.
I have the factory shackles. Longer shackles would improve the pinion angle.
#11
Seasoned Member
Thread Starter
Join Date: Jan 2013
Location: SoCal
Posts: 447
Likes: 0
Received 1 Like
on
1 Post
Year: 1994
Model: Cherokee
Engine: 4.0
It is at "normal" ride height.
I plan on doing some work on the rear suspension to fix the shackle angles and hopefully lower it a bit but for now, it is what it is.
#13
CF Veteran
Join Date: Oct 2012
Location: Orlando/Winter Garden
Posts: 1,277
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1998
Model: Cherokee
Engine: I6
are you supposed to measure the degree that your ds is slanted from perfectly horizontal to find out what degree of shim you need or am i completely wrong??..
#14
CF Veteran
Join Date: Nov 2008
Location: mass
Posts: 1,021
Likes: 0
Received 3 Likes
on
2 Posts
Year: 1992
Model: Cherokee
Engine: 4.0 high output
I don't think you are measuring the pinion angle properly....
the best way to do it is to stick a degree finder underneath the yolk or on a flat spot of the pumpkin. basically you want the rear axle to point straight up with the driveshaft towards the transfer case. 4 degree shim would probably be fine
the best way to do it is to stick a degree finder underneath the yolk or on a flat spot of the pumpkin. basically you want the rear axle to point straight up with the driveshaft towards the transfer case. 4 degree shim would probably be fine