Unlimited04's LJ Build - Page 11

**spyder6** · 10-03-2009, 10:20 PM

i cant believe that such a minor adjustment in caster made such a big difference. i might roll my front end back a little bit.

theoretically, if there isnt any input torque on the driveshaft - i wont get any vibes right?

**Unlimited04** · 10-03-2009, 10:26 PM

Quote:

Originally Posted by spyder6

i cant believe that such a minor adjustment in caster made such a big difference. i might roll my front end back a little bit.

theoretically, if there isnt any input torque on the driveshaft - i wont get any vibes right?

Well stock is 7* caster, at least according to Firestone's computer it is, so the closer you can get to that the better, but gotta remember pinion angle.

and you can still get vibes (and u-joint destruction) from a driveshaft even if there is no torque input. It all depends where the u-joints bind, torque just makes it worse. The single cardan u-joint style is pretty bad when it comes to angle of operation. The more bend in the single cardan shaft the more friction in the system, and the larger the difference in the rotation speeds between the driven and drive side....it isn't true constant velocity.

**spyder6** · 10-03-2009, 10:30 PM

i thought TJ's front driveshafts were double cardan from the factory? i know mines got 3 u-joints in it

**Unlimited04** · 10-03-2009, 10:31 PM

Quote:

Originally Posted by spyder6

i thought TJ's front driveshafts were double cardan from the factory? i know mines got 3 u-joints in it

yea double cardan on the t-case side, single cardan on the pinion side. vibes will most likely come from the pinion side when correcting caster with a lift. I suppose you could even bind the DC side of the front shaft if you're pointing the rear down a lot for a tall lift.

**Unlimited04** · 10-03-2009, 10:42 PM

watch this YouTube Video at 3:15 and 6:48

YouTube - the Thompson Coupling in action

Its a sales pitch for the Thompson Coupling, but the demos pretty much explain why you break u-joints in the front axle with throttle + turning and where you get driveshaft vibes from.

**glockster** · 10-03-2009, 10:45 PM

my latest alignment numbers:

camber - .07 (left) .07 (right)
x camber 0.0

caster - 5.9 (left) 6.9 (right)
x caster 1.0

toe - 0.15 (left) 0.15 (right
total toe - 0.30

Here is the response to the question I posed about pinion angles and caster from flatlanded757 in his end all alignment thread:

"Caster is more important than pinion angle. Unless you are getting vibrations from your front driveshaft don't even mess with it, you're gaining nothing.

As for the 1 degree difference, a lot of vehicles actually specify that, higher caster on the right side isn't bad unless it's WAY out. Go back to the section explaining "road crown." You probably don't experience pulling because of that, they are basically cancelling each other out.

Your Jeep is fine. Enjoy it."

Phone calls confirmed this sentiment was shared by Tom Woods, Rubicon Express and the shop that did the alignment. As the FSM states, Pinion angle trumps Caster on a stock jeep. Set the caster and the pinion angle is what it is. I have run up to 90 mph without a vibe anywhere. I'll check pinion angles just so I can post a number. I ain't changing it. I'm happy. Just my .02 cents worth.

**spyder6** · 10-03-2009, 10:49 PM

incredible. Spicer was an idiot?

friday is going to be a long day

**glockster** · 10-03-2009, 11:22 PM

hmm....I didn't call anybody an idiot. Merely stated what was working for my Jeep.

What's friday got to do with anything?

**spyder6** · 10-04-2009, 12:05 AM

Quote:

Originally Posted by glockster

hmm....I didn't call anybody an idiot. Merely stated what was working for my Jeep.

What's friday got to do with anything?

i was talking to Unlimited. friday is the day im going to roll my front axle back. that is if i have time after putting my beadlocks together

**glockster** · 10-04-2009, 12:28 AM

ahhh.......gotcha.

What is it your not happy with? vibes?

**Unlimited04** · 10-04-2009, 07:12 AM

Quote:

Originally Posted by glockster

ahhh.......gotcha.

What is it your not happy with? vibes?

I think he's worried about getting vibes from the front driveshaft by putting too much caster in since he's got such a tall lift. Spyder, post pics of the pinion angle - will be interesting to the result vs caster. It will definitely drive better

Side note - on a trip to Rokmen in south denver with a friend, We saw a guy in SWB TJ w/ what looked like 4.5-5.5" springs on a SA RE lift, with 35s. He was so squirrely it was ridiculous, wandering all over in the ruts in the road...looked like he was wrestling an alligator in the drivers seat.

I couldn't deal with that....

**Unlimited04** · 10-07-2009, 09:13 AM

This might be useful to some concerned about thrust angle. Tjosh97 asked about it, and here's an explanation on how an adjustable track bar helps:
http://www.jeepforum.com/forum/f9/cam-bolts-adjust-caster-496304/index3.html#post8060770

**Unlimited04** · 10-15-2009, 08:21 PM

Update!

Quick Disconnect Stow-Away Cams

So when I drilled and tapped my frame for the JKS disconnect attachments, I didn't measure anything I just kinda marked it with a sharpie, eyeballed and started drilling in my haste. Well they were not lined up on each side and were just a massive pain to force into place for off-roading. So I invented some cam bolts basically to fix the issue. I figured the arc of both sides has to intersect someplace!! So, a little bit of time in front of the Bridgeport and bingo the result is awesome. I dialed in both sides, now I can effortlessly disconnect, stow, and then reconnect the sway bar. No spitting grease out the bushing, no grunting, no cussing, they slide on and off stupid easy. Why didn't JKS think of this!?

They're basically a 1/2" thick billet of aluminum about 0.65" wide and 1.2" long with two holes in it. One hole is tapped for 5/16-18 UNC, and one is a thru hole. Very simple to make. I used a Bridgeport mill, but all you really need is a hand saw to cut the pieces, a vise to hold them, a 5/16-18 tap, a power drill, and most importantly Q and F size drill bits. The Q is the oversize free fit bit for one hole, the F size is the tap drill bit for the other. I countersunk the thru hole for a stainless socket head cap screw, but you could use a button head or hex head for clearance, or just make the cams bigger. The stub is held on by the bolt included by JKS.

Spin both sides till the discos fit perfectly, tighten when done.

With the sway bar disco'ed:

This is one of those simple things that makes life a little bit easier

**Unlimited04** · 10-17-2009, 04:11 PM

went to the junkyard today....

$40-
XJ front spring retainer clips
ZJ V8 tie-rod from a 5.9L
XJ roof rack

Found a HP D30, but it was ABS and non-UpCountry, so it had 3.55s or worse. Decided to wait until I find a 96-99 HP D30 w/ 3.73s & no ABS. All the other XJ's were 00-01, LP's. Got a set of sagging XJ leaf springs from "COLOUXJ", hope to make a camping/off-road trailer out of those some day.

What a shame on CFC - so many XJ's and ZJ's in pristine condition - the ZJ I pulled the tie-rod from was a 5.9L

Most of the seats in vehicles were still in great condition. Its gangbusters at the junkyards, they're loving it.

Jebussaves0 · 10-17-2009, 04:38 PM

Quote:

Originally Posted by Unlimited04

Update!

Quick Disconnect Stow-Away Cams

So when I drilled and tapped my frame for the JKS disconnect attachments, I didn't measure anything I just kinda marked it with a sharpie, eyeballed and started drilling in my haste. Well they were not lined up on each side and were just a massive pain to force into place for off-roading. So I invented some cam bolts basically to fix the issue. I figured the arc of both sides has to intersect someplace!! So, a little bit of time in front of the Bridgeport and bingo the result is awesome. I dialed in both sides, now I can effortlessly disconnect, stow, and then reconnect the sway bar. No spitting grease out the bushing, no grunting, no cussing, they slide on and off stupid easy. Why didn't JKS think of this!?

They're basically a 1/2" thick billet of aluminum about 0.65" wide and 1.2" long with two holes in it. One hole is tapped for 5/16-18 UNC, and one is a thru hole. Very simple to make. I used a Bridgeport mill, but all you really need is a hand saw to cut the pieces, a vise to hold them, a 5/16-18 tap, a power drill, and most importantly Q and F size drill bits. The Q is the oversize free fit bit for one hole, the F size is the tap drill bit for the other. I countersunk the thru hole for a stainless socket head cap screw, but you could use a button head or hex head for clearance, or just make the cams bigger. The stub is held on by the bolt included by JKS.

Spin both sides till the discos fit perfectly, tighten when done.

With the sway bar disco'ed:

This is one of those simple things that makes life a little bit easier

That's bloody brilliant! I've been having this same issue with my JKS storage pines... definitely added this to the list!