DS angle? Too much or too little shim?

Headwithwings · Mar 13, 2014

99, Sport, 4.0, AW4, NP231 C8.25. Have a Zone 3 inch lift with new springs all around. IRO ALCA and Dbbl shear track bar. Ran the jeep for about 5 months with a one inch t-case drop with only a little vibration at 35-45 mph. Then the front drive shaft went out at the center ball and i ordered a new front and rear Tatton drive shafts and a Tera flex SYE.

Rear Pinon was at 5* and the rear DS was at 15* So I ordered a 6* shim from IRO thinking this would get me to 1-2* less then the ds angle. After the install i still have vibration but now only on acceleration (bad) and cruse. (not so bad)
Pulled the front ds and the vibration is still there so it's not the front shaft.

Re measured the rear ds angle and got 13* pinon and 14* ds

So, too much shim or too little?
Thanks.

Tony_SS · Mar 13, 2014

A -1º working angle is where you should be.. I think you have some axle wrap going... how are your leaf springs?

Headwithwings · Mar 13, 2014

Leaf springs are new Zone 3 inch lift springs that are a part of the kit i bought. I would hope that they are still good. Thay look good
No sag. Still stiff as all get out.

Tony_SS · Mar 13, 2014

If you have vibes on take off, I think that the pinion is climbing too far up. I might try a 4º shim and see what happens?

Headwithwings · Mar 13, 2014

Vibes seem the worst when hard on the gas. Like when going up a hill or passing but still have a little vibes at all speeds. Oddly it is better in the mornings when it's cold out and worse on the way home when it's warm.

MoparManiac · Mar 13, 2014

Check your pinion bearings in the rear end.

If there's any play in the yoke at all, check them out.

Headwithwings · Mar 13, 2014

Ugh... Don't say that. Thats the last thing i want to deal with now. I'll check it after work.

blondejoncherokee · Mar 13, 2014

Post pics. Also try getting to 11 or 12 if your ds is at 14. Could have axle wrap.

Headwithwings · Mar 15, 2014

So after looking at the jeep today I am starting to agree with tony that i need to switch to a 4º shim. The pinon and drive shaft are almost in line. The rear pinon is nice and tight with no discernible play.

Headwithwings · Mar 15, 2014

Sorry for the crap photo. Has anyone seen a decrease in the drive shaft angle after installing shackle relocation brackets? I have read that installing longer shackles lowers the pinon angle by about 1º per inch of added lift. I would guess that the eye of the leaf spring stays at about the same place and just the top side of the shackle moves forward and down and the D/S angle would not change. I need to fix my shackle angle and would like to avoid buying shims a third time!

blondejoncherokee · Mar 17, 2014

ya we need a better photo than dude. I cant really make out the pinion vs DS u joint angles in that mess.

Tony_SS · Mar 17, 2014

I have read that a lift using a shackle will mess with the pinion angle.

Also dont judge an angle just by looks... mine looks like 0 but is -3º. I'm going to try and get to -2º with a 5º shim. I have a 4º now.

blondejoncherokee · Mar 17, 2014

in that terrible pic the pinion looks a little high. but its too hard too tell.

Tony_SS · Mar 17, 2014

Just to be clear, you want it lower than the ds angle... as the pinion will climb up under acceleration.

DS angle? Too much or too little shim?

Headwithwings

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