Anyone? I ask because once I get to 65 or so, it gets flighty and I have a slight vibration.

 

I think you may be confusing driveline angle with caster. Changing caster on a Jeep CAN cause a vibration, but not from the change in caster. Only because as you are changing caster, you are also changing the driveshaft working angle. THAT'S where the vibration comes from. No, I have never known camber to contribute one iota to vibration, either.

 

To me it was already clear from previous posts that people meant driveline vibration caused by the extreme driveline angle you may get (depending on your lift also) by a 4.5+ positive caster. I don't think anybody was confusing driveline angle with caster. The only confusing post was yours...

 

I've never been confused about it since it's what Ive done for a living most of my life. My response was simply in reply to Jack's post, which did seem to indicate caster was responsible for vibration, and also implied camber as well.

 

I put my Old Man Emu 3" lift with 35's on about a month ago...just returned from getting an allignment about an hour ago....I had him set my caster to 5.5...HUGE difference...it handles much better, also had him set the toe in to about 1/8. It isn't perfect but pretty close and feels much safer. I'm going to drive it for awhile and think about adding a high steer kit.

 

i have a 4dr. w/ a tf 2.5" coil lift and plan on 35's very soon. just had an alignment and they set it at 4 degrees. dw seemed to go away but it bump steers now. lots of potholes as the govt has no $ to fix em!!! seems to handle ok w/ no bumps around.... would 5 or 6 make it better? esp. for the bump steer??

 

I'm at 4-5" of lift with 3.8 degrees of caster. No vibes and feels ok at highway speeds, but changing lanes is a bit of challenge. It's a little touchy in that regard. Have to be careful not to over commit. I'm getting my caster up to 4.5 as I'm typing. I thought about 5 degrees, but it sounds like from this thread that I might get front driveline vibes.

 

Hi Dr.McNinja,

I am not as experienced with alignment as many of the other posters here; but, I have been trying to understand what exactly how to set up the alignment on my OME LT kit from Northridge.

When I installed the upper adjustable control arms from Northridge, I shortened them by 1/4" relative to the stock eye-to-eye length. Based upon information that was posted in this forurm, and some calculations, I expected my caster would go from approximately 4.2 +/- 0.5 degrees (OEM specs) to between 5.5 and 6 degrees.

I tried meassure the angle at the hub using a couple of different tool (a magnetic angle finder and a digital level). I never could come up with measurements that made sense.

I took my JK in for an alignment. The printout that was generated showed the caster angle at 4.2 (L) and 4.1 (R). The shortening of the upper control arms really just offset the height increase and its affect on the suspension geometry to put the caster right back at OEM specs.

Although I haven't done it yet, I need to remeasure the angles at the hub. At least knowing the caster measured at the alignment shop, and the angles I measure with simple tools, I can come up with some correlation. (I know there are others here who have little confidence in the hub measurement technique for caster measurement, and I am inclined to agree with them. When in doubt, have the caster measured by a shop with the proper equipment... at least then you'll know for sure.)

I have driven the JK around town and experienced no problem with vibration or DW/flightiness. I have had it up to 80+ mph on the interstate, also with no handling problems. I also experience nothing other than an almost unnoticeable vibration above 70 mph.

According to David at Northridge (and others), there is a balance between enough caster to prevent flightiness and too much which may result in driveline vibration. I had planned to increase my caster to between 5.5 and 6 degrees; but, David suggested that I drive it for a while, and if there are no handling issues, that I should leave the caster set where it is (4.2/4.1).

As I said earlier, I think the hub measurement technique is a good tool for each individual JK; but, I think that it is hard to view the numbers as absolutes when comparing setups with others online. I think hard numbers from a good shop alignment would keep things in perspective.

I hope my opinion is worth something.

Jeff

 

Go to 4.5, if you don't get vibrations, go to 5. If you don't get vibrations there, go to 5.5. Keep doing this until you get vibrations then go back down until you don't. Driving in PR where at 1 AM red can mean DO NOT STOP! Or having a tourist cut across your bow, I would want as much caster as I could possibly get. I don't want it to feel OK, I want it to feel firm and safe.

 

jajaja! You are 100% right! You must be from around here. What town?