Weird front end behavior...since lift (1 Viewer)

[100sExp]

Hey group, looking for some help here. Ever since I've lifted my truck it's had some strange things happening in the front end. When I accelerate (worse at slow speeds or from a stop) the front end wanders/shimmies significantly. I can feel power alternating from one side to the other in the front and it makes it difficult to steer straight. The harder I accelerate the more noticeable it gets and seems to be worse going uphill then down. Not really a problem when at speed but getting up to speed it is. I've also noticed that my new KO2's are wearing significantly faster up front then in the rear and when turning onto a cross street (especially if there's a dip) I can easily spin the inside front tire. Has anyone else experienced something like this? What do you think it is and how can I fix it?

The truck has the 2.5" lift OME heavy load springs/torsion bars, Nitro UCA's, Slee diff drop and Icon stage II RR shocks, stock wheels, 295/75/16 BFG's on spacers (1.5"front, 1.25"rear). Thank you for the help.

Hello sun

• 100sExp
• Nov 11, 2016

 

[Dwight S]

You may not want to.... drop your front end. Put about 1.5" of rake in it.

 

[shanester]

You may not want to.... drop your front end. Put about 1.5" of rake in it.

This or aftermarket UCA's based off the research I've done.

 

[TomEf]

drop your front end. Put about 1.5" of rake in it.

Something about the front suspension makes them act weird without the right rake.

 

[Sandroad]

Rake is needed if that's a photo of your setup. It looks way too high in front for tracking stability. Also, why did you choose wider spacers for the front than the rear. Would that affect tracking?

 

[abuck99]

Post lift alignment specs?

 

[Roadhouse1]

Presume a wheel alignment was done after the lift?

 

[brando1]

I have a similar set up but replaced the upper control arms and cranked up the tbars all the way. She crashes a little bit on slow hard bumps but overall handles well.

 

[100sExp]

Rake is needed if that's a photo of your setup. It looks way too high in front for tracking stability. Also, why did you choose wider spacers for the front than the rear. Would that affect tracking?

Yes, this is a photo of my truck. Sorry I forgot to mention that it also has Nitro UCA's and was aligned post lift. I do not know the post lift alignment specs. The reason the spacers a wider in the front is by the recommendation of someone (can't remember who) at Nitro Gear & Axle as the "magic formula". It looks correct with this spacing and doubt the issue is related to the spacers.

Can someone give me more information of what exactly you think is happening and why you think "rake is needed" or lowering the front? Will I need to replace the torsion bars to lower it slightly or is it a simple adjustment?

Thanks again

 

[Manhattan]

Simple adjustment. Do a test - take 4 full/360 turns out of each bolt and take it for a drive.

 

[Batlowboy]

There's a couple of good threads on IH8MUD about torsion bars, UCA's and alignment etc. I had the same problem as you, could spin the wheels on take off, poor handling as well on tight corners. I had lifted my front end on the oem upper control arms, however I changed these yesterday with some SPC UCA's, had the wheel alignment done and it made a world of difference.

You should also aim to have a 50mm rake (front end low), and check that you have a minimum of 70mm droop.

I'd probably say your alignment is out, maybe not enough camber since lifting it? Are your UCA's adjustable?

 

[jLB]

Can someone give me more information of what exactly you think is happening and why you think "rake is needed" or lowering the front?

There is really not that much travel available in the 100 series IFS. There is a tendency to over crank the torsion bars, which looks real good when sitting still, but tends to cause issues when going down the road. "Lifting" by cranking on the torsion bars, is really just changing the point in suspension travel that the vehicle sits at rest. The bad behavior is usually due to lack of droop or down travel. You can gain a little extra travel with aftermarket UCAs and longer shocks, but it is not a huge amount.

As an example, Slee's "fancy jumping shocks" for the front of the 100 series advertise 5.5" of travel:
Slee Off-Road - Reservoir Shocks

We fought this type of issue on my son's 2000 LC (OME suspension, and SPC UCAs), and found the "sweet spot" for us was at ~21.5" from the center of the hub to the bottom of the fender.

The typical recommendation is to have 2-2.75" (50-70mm) of "droop" after your "lift" is installed.
http://www.sleeoffroad.com/installation/torsionbar_adjustment.pdf

Just to give a feel for the travel in a stock 100 series, here are the approximate fender to center of hub measurements for an AHC vehicle:
~17.5 Low
~19.5 Normal
~21.0 High
~22.3 Extra High

As a very rough guesstimate, assuming that 17.5" of the AHC is on the bump stops, adding the 5.5" of Slee's "fancy jumping shocks" would total about 23", backing off for the minimum 2" of droop, 21", maybe your aftermarket UCAs and shocks add a little bit back to that, so let's add.5-1.0, so ~21.5-22", but you should really be measuring how much droop you have left and not how much lift you have dialed in.

Echoing some of the previous posters above...

You can probably fix most of the bad behavior by backing off on the torsion bars.
What is your center of hub to fender measurement in front?
How much droop do you have left?
Are you in spec for caster after your alignment?​

(On my son's vehicle, we also had steering rack bushing issues that seemed amplified by the lift)

 

[Rusty62]

Mine did the same with lift and power upgrade. Changed the upper arms with SPC UCA and running 3 deg caster. Worked a treat.

 

[jerryb]

your caster angle is bad, that's why people say you need to maintain the stock rake.
Toe and camber is wearing your tires.
All that stability/wandering/return to center you talk about in steering is a caster angle issue. With the front end up like that you have less weight there.
drop the front and inch and a half and go drive. Or maybe take it back to the alignment place. They didn't do you any favors with that set up. Good luck man.

 

[sleeoffroad]

Why is everyone saying it should have rake? That has nothing to do with it. They issue is the total height of the front end and also the associated alignment numbers.

 

[bwell]

Based off of the driving feedback you are describing I would search on here about diagnosing steering rack issues and see if your steering rack bushing are worn out. This combined with not ideal alignment as many have described. If you are on an ideal flat, straight Hwy with only enough throttle input to maintain speed and or no throttle input at all does the vehicle track straight with no hands on the steering wheel? Not sure of your mileage and what else you have all had to do. But the lifting/ride height, and wheel spacers can cause exponential wear on what was once a perfectly driving vehicle if old enough.

 

[slider35]

I noticed in my 2004 LC same as you describe in first post after I installed Slee shocks and OME torsion bars. My alignment specs at the time are attached. I adjusted my lift according to Slee's manual, give or take 1/4" between sides and front and back specs.

What I had to do to settle the front end down was back off on the torsion bars a few rotations. That had the effect of lowering the front end a fraction of an inch, but allowed the front end to stay down during acceleration and the chatter, wandering, and torque steer went away after that.

 

[taco47001]

Yes you can increase or decrease your CASTER angles with TB adjustments but if you want to maintain ride height that you have you need adjustable UPPER CONTROL ARMS with adjustable caster. SPC makes a good set. I ran them in my previous rig (Double Cab Tacoma) and they worked flawlessly. When you think of caster, think of the front wheel on a shopping cart. The further out in front of the wheel and the more pressure placed upon the mounting stud of that shopping cart wheel, the less it wobbles and the truer it tracks. It's the same thing. Right now with the lift, your upper ball joint is too far outside the design angle with the lower ball joint creating either not enough positive, or a negative caster. With the adjustable uppers you can rotate that joint forward or backwards, thus reducing or increasing caster angle and getting the wheels to track straight again on their own without sacrificing toe or camber angles. The design and recommended caster setting for our trucks is a positive angle (upper BJ behind the lower) but you are way past acceptable limits if your swaying at speed and experiencing bump steer.

 

[100sExp]

Thank you everyone for the help, what an amazing resource this group is for owners of these vehicles. As per the multiple recommendations, I had the front torsion bars cranked down a bit (lowering ride height and allowing more droop), rebalanced tires and realigned suspension (spec sheet below). This all made a HUGE improvement in ride, handling and cornering. It also made the problems with the wandering go away, although on a steep 13% grade I could still feel it slightly.

Alignment Specs

• 100sExp
• Feb 15, 2017