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Round #2
 

The info on this page is just a summary of various numbers and measurements that I took while working on the TJ.  They are only provided as a comparison point if you get to wondering how long something might be.  If you have any questions or want some other numbers, just drop me a note and I'll include them here.

 

Shock Mount Measurements

Front axle

Extended

25 1/4"

 

Static

21 3/4"

 

Compressed

17 1/2"

     

Rear axle

Extended

24"

 

Static

20"

 

Compressed
(will cause coil bind)

14"

 

Shock Absorber Measurements

Front axle

Extended 26"

Rancho RS-9017

Compressed 16"
     

Rear axle

Extended 26"

Rancho RS-9112

Compressed 16"

 

Update 07/26/2001

Since the above measurements were taken, I replaced the front stock lower control arms with a pair of RE adjustables.  Where as the factory arms would bind in the control arm bracket and thus limit droop, that is no longer the case with this new configuration.  The limiting factor now is my RS-9000 front shocks.  I took the opportunity to "ramp" the TJ on my favorite rock on Raw Deal, right after I had put the new arms in place.  I found that the axle will droop more than the shock will allow.  However, I must also state that at configuration, the spring is starting to get loose in the spring perch so there is very little pressure being applied by now extended spring.  Given all of the variables involved, I think I am satisfied with the shock length, axle droop, etc.  I am sure it could be "tweaked" for a bit more suspension performance, but I do not need it nor do I care to pay for it either.

Measurements to the Ground

Bottom of factory bumper (front) 26 1/8"
Bottom of frame under door 20 5/8"
Bottom of rock crawler bumper (rear) 23"
Bottom of 35" spare tire 32"

 

Front End Alignment -

Lady has been on the trail twice now, as I write this, since the lift was installed.  She has had a chance to flex the springs a bit and I am assuming that everything has gotten into its "settled in" position.  I had made an appointment last week with the alignment shop down the road and stopped in this morning to have them check the front end out.

I spoke with the tech that would be doing the work.  Told him the lift was about a month old, wanted the front end checked, the handling was rather twitchy on the highway (I suspected not enough positive caster)....and told him the torque specs for the adjustable control arms.

The work took right at 3 hours.  Lady was on the alignment ramp three different times (the initial checkout and twice to check the control arm adjustments).  

As I had suspected, the caster was quite a bit off.  The tech informed me that Lady was sitting at 1.5� positive caster.  The TJ factory specs is 7� +/- 1�.  I knew there was no way we were going to get to those numbers.  I was sitting at about 5.5� when I had the Tera lift on.  The toe-in was almost 1" off as well.  I was not expecting this, but since I was there for an alignment, it cost no more to have this fixed as well.

We discussed my options on the caster problem.  The shop has a policy concerning after market parts (ie., lift kits).....you pay more if you want them to adjust a lift Jeep.  At first I decided to do it myself, but that would require scheduling yet another visit to the shop.  The tech offered to check it for free if I did the work (he would adjust the toe-in and center my steering wheel) and wanted to bring it back in.  After thinking it over, I decided that my bones were too tired to play "guess the caster angle" so I told them to do the work.

Lady was taken off of the alignment rack and moved over to another lift where the lesser techs (I think they have some kind of pecking order because they were a lot dirtier than the guy that I was talking to) worked on the upper arms.  Some time later, an opening on one of the two racks was caught and Lady was once again hoisted up and the alignment hardware attached to all four rims.

The tech reported that they had shortened the upper RE arms by 2 1/2 full turns.  It brought the caster up to about 2.5�.  There was 2 or 3 threads showing on the arms and we had the factory adjustment that could be tweaked up as well.  They took it off the alignment rack and sent Lady back to the dirty guys.  

Once again she returned and was put on the alignment rack and fitting with the alignment fixtures.  (She reminded me of Forrest Gump with his leg braces!)  The tech cranked the factory caster cams to their most positive position and locked it back down (that reminds me, I need to torque all of those front arms again).  The readout on the alignment computer showed Lady right at 4.0� positive caster.  That was as good as it was going to get.  Now the only question left in my mind was the front pinion angle.....would be cause vibrations or not?

So....I did a number of drives around town today while attempting to find a shipping store to UPS my old lift and shocks.  While driving around, I noticed a bit more vibration than I had prior to the alignment.  OK....so I got a much improved steering configuration (it was no longer twitchy at speed), but I got a little front drive shaft vibration.

While writing this, I decided I would play with the factory caster cam bolt (lower control arm, axle end).  This was the one that the tech cranked to the maximum positive position.  Since it was rather easy to see which way it was at the max position, I opted to back it off two alignment marks....going towards the 12 o'clock position.  I snugged the bolts back to spec (I still had Alan's torque wrench from Sunday morning's episode) and took Lady for a ride.  It was a bit better in the vibration department (still could feel them) and the steering still felt just fine.

I decided yet another adjustment was in order, so I decreased the positive caster to the 12 o'clock position (which is where it was when I took it to the shop this morning, albeit, the control arms were in a much different configuration).  I torqued the bolts down one more time, put the tools away, and took it for another ride.  

Not too bad....the steering still feels good (I get good return to center after turning a corner) and the vibes seem no worse than when I woke up this morning.

I don't know how the exact amount of adjustment the factory cam bolts have, but the tech at the alignment shop thought it was in the neighborhood of +/- .5�.  So, if this is somewhere near correct, I have my caster sitting at about 3.5� positive, give or take a little bit.

I think that is where it is going to stay.  I may get adjustable front lower arms some day, but then again, maybe I won't.  If I have good handling and the front drive shaft is not giving me trouble, life isn't so bad now, is it?.

 

More of Round #2

 

 

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