Trying to fix "first-build" mistakes

fortuso

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Sep 4, 2019
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32
Location
Catanzaro, Italy
Hi all,

after reading several interesting treads here, I decided to make some upgrade to my '05 Sport 4.0l TJ.
The jeep was basically equipped with: 2.5' complete lift kit by Rough Country (panhard, control arms, springs and shocks) Rugged ridge crossover steering link, RANCHO RS7000 steering stabilizer, Teraflex Belly up skid plate, JKS rear adjustable panhard with angled support, rugged ridge SYE, DC rear driveshaft, 1' MORE bomb-prof lifted motor mount, 1' MORE aluminium body lift and Cooper STT PRO 33'.
The driveability wasn't decent so I replaced the RC shocks with RANCHO XL 9000. Some improvement was achieved. After few months, RC control arms flexible joints worn out... I have replaced them with original Currie Johnny Joints and the driveability was much better than before (maybe also because springs started to seat so the overall lift was close to 2').
Then I went on 35' tires (Cooper STT pro again) on 15'x8 ion ally aluminium wheels. Maybe because new wheels have a smaller offset (-25 against previous -19) but with new tires I started to feel some bumpsteer. I tried to balance wheels and tires three times with no appreciable improvement. Finally, I used internal ceramic beads and tuned tire pressure at about 25 psi (on road pressure) obtaining a decent driveability. Anyway, in off road, my setup didn't allow sufficient clearance to the new tires so, after reading several tread, I decided to with Currie 4' springs (CE-9130H) ,Currie bumpstops (CE-9122R and CE-9122F) and RANCHO 5000x shocks. Due to belly up skid plate, taking into account the new lift amount, the SYE was replace by an extra-short SYE by teraflex and a new Tom Wood DC shaft was installed. All suspension geometries have been modified according to the new lift (some degree of caster angle was lost, I suppose).

That's the story, now my problems:

1) the on road driveability is poor due to a lot of bumpsteer and front vibrations;
2) steering wheel tremendously lost precision (the Jeep follows all street junctions)

and now my help requests:

1) is it normal that a TJ, with 35' tires and 4' lift, drives so poorly at 70-80 mph?
2) how many caster angle degrees are reasonable with my setup (all my control arms can be modified in length)? I guess the shop that installed the lift looked at the pinion angle only....
3) now, after reading a lot here, I know the crossover steering link could be involved. Could a Currie (RockJock) Currectlink kit be the way to go to improve driveability?
4) should I replace the RANCHO RS7000 steering stabilizer? Actually, it makes some pressure on the steering links. If yes what I should looking for?

Sorry for this long message, I really thank all of you for the patience and for the suggestions.
 
Post up pictures of the entire front end showing all of the steering components. In particular, directly from the front showing the entire tie rod, drag link and track bar.

It is certainly possible to have a good riding rig on 35s with the proper lift. It is very easy to screw it up.

Crossover steering is extremely difficult to get right on a TJ. It is completely impossible to get right with bolt on components. Since this does sound like a bolt on bonanza, my guess is the track bar is still in the stock location, which will definitely cause bump steer on a crossover. Pictures will help us guide you there, but expect to be told to go back to the stock steering configuration. And yes, the Currie steering setup is very good.
 
All I would add to @NashvilleTJ excellent post is, no you don’t need a different steering stabilizer, and I’d want more than 5* caster (I personally have 7-8*). Lengthen the front lowers and/or shorten the front uppers to achieve maximum caster without binding at full droop. Afterwards, re-check your rear driveline angles.
 
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Thank you for your replies. Please have a look at these 3 pictures showing my geometries. For sure it is not good even if it seems to be not too bad.
About caster, it was 7 with the previous shorter lift kit. With the new one (4' vs 2-2.5') the front axle has been moved forward (to re-establish wheel base) e rotated looking and front pinion angle (that's what the shop told me).
Thank you again, I'll wait for your suggestions

IMG_0087.JPG


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IMG_0089.JPG
 
I agree with @NashvilleTJ and @JMT. Going back to stock steering geometry (like the Currie/RockJock) Currectlink) will likely help the bump steer. Additionally, proper caster (7 degrees-ish?) may also help the steering be less twitchy. The vibration solution is less clear. Many possibilities. I might start by driving without the front driveshaft. If that fixes it, its the shaft balance or pinion angle. The pinion and shaft angles should be close (0-1.5 degrees works well on mine) but rotating the pinion up takes away caster which makes the steering twitchy. Its a balance. A front hub kit which can be unlocked is some people's solution to this. If the driveshaft removal doesn't help, I'd look at tire balance. Big tires like 35" can be tough to get well balanced.

Edit: Your front track bar location looks stock so assuming good joints, that should be fine once the tie rod and drag link are back to stock geometry. And your steering stabilizer shouldn't matter much.
 
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on the bright side, it looks like that inverted T steering wouldn't have required the knuckles to be drilled out so switching back to an inverted Y will be an easy bolt-on fix.
 
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1) is it normal that a TJ, with 35' tires and 4' lift, drives so poorly at 70-80 mph?

Do you really expect a TJ with thirty five foot tires to drive great?

🤣

In all seriousness, my TJU on 35s with ~5.25" of lift drives better than it did OE stock. Poor drivability can be due to poor parts or parts in poor condition but IMO it is mostly due to poor set up.
 
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Thank you for your replies. Please have a look at these 3 pictures showing my geometries. For sure it is not good even if it seems to be not too bad.
About caster, it was 7 with the previous shorter lift kit. With the new one (4' vs 2-2.5') the front axle has been moved forward (to re-establish wheel base) e rotated looking and front pinion angle (that's what the shop told me).
Thank you again, I'll wait for your suggestions

View attachment 340941

View attachment 340942

View attachment 340943

What a mess. Spring is not in the lower seat.
Inverted T is crap, dump it for conventional style even if it is just stock stuff.
Upper control arm mount on axle is bent and flexing as well as not retaining the bushing very well, fix it.
There is no "re-establishing wheelbase" on a lifted TJ. There is adjusting the wheelbase to be correct for the clearances needed when the axles travel throughout the range of motion.
The shop is likely setting the arms to the same length without adjusting to what the axle mounts tell them they need to be, stop doing that.
Stabilizer bolt is suspect as to the direction it points. Should generally point slightly up and rearward.

Get all that fixed and report back.
 
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Good eye! Especially the passenger, axle side UCA mount (y)

Given the condition and splayed angle of the u-bolts holding on the stabilizer bolt mount, I'm not convinced they are actually doing anything and they will be a real bitch to remove. Just because you have an impact, doesn't mean everything gets hammered with it.
 
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All I would add to @NashvilleTJ excellent post is, no you don’t need a different steering stabilizer, and I’d want more than 5* caster (I personally have 7-8*). Shorten the front lowers and/or lengthen the front uppers to achieve maximum caster without binding at full droop. Afterwards, re-check your rear driveline angles.

I think you have that backwards.
 
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What a mess. Spring is not in the lower seat.
Inverted T is crap, dump it for conventional style even if it is just stock stuff.
Upper control arm mount on axle is bent and flexing as well as not retaining the bushing very well, fix it.
There is no "re-establishing wheelbase" on a lifted TJ. There is adjusting the wheelbase to be correct for the clearances needed when the axles travel throughout the range of motion.
The shop is likely setting the arms to the same length without adjusting to what the axle mounts tell them they need to be, stop doing that.
Stabilizer bolt is suspect as to the direction it points. Should generally point slightly up and rearward.

Get all that fixed and report back.

Thank all of you for your suggestions.

First of all, I'm going to buy a Currie/RJ Currectlync kit. Switch back to the inverted Y can be done easily because the actual inverted T was bolt on.
I'll personally check geometries (I already done it before, when the TJ was running better, using laser, wire and tape meter), then I'll rotate the driver site spring (is there some reference mark on the spring plate?), then I'll relocate steering stabilizer.

Unfortunately, I'm not the first owner of this TJ (and it is not popular in my place) so the upper control arm mount has always been in the present shape (rubber bushings are not worn). Please @mrblaine when you say "Upper control arm mount on axle is bent and flexing" are you referring to this?

IMG_0090.JPG


Actually, looking better, I do not remember such a shape....
 
Thank all of you for your suggestions.

First of all, I'm going to buy a Currie/RJ Currectlync kit. Switch back to the inverted Y can be done easily because the actual inverted T was bolt on.
I'll personally check geometries (I already done it before, when the TJ was running better, using laser, wire and tape meter), then I'll rotate the driver site spring (is there some reference mark on the spring plate?),
Yes, the shape of the spring seat tells you where it sits.
then I'll relocate steering stabilizer.
You'll need to fix the mount and bolts or get a new one for the draglink which is included in the Rock Jock kit.
Unfortunately, I'm not the first owner of this TJ (and it is not popular in my place) so the upper control arm mount has always been in the present shape (rubber bushings are not worn). Please @mrblaine when you say "Upper control arm mount on axle is bent and flexing" are you referring to this?

View attachment 340949

Actually, looking better, I do not remember such a shape....
The rubber bushing shell is not tight to the side of the mount. That doesn't happen unless there is loss of press fit and the two sides are supposed to be parallel, not bent inwards.
 
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