2.5" lift - Too much bump steer! Not enough caster. 1.5" better?

[RL4x4]

I have a 2001 LC with the OME/Slee 2.5" Medium lift + diff drop.

The front center to fender measurement is approx 22" and the rear is approx 22.75"

Coming from a high-performance car background I am particularly sensitive to bump steer and torque steer and I find both of these traits unacceptably bad with the 2.5" lift! Every time the front suspension moves through it's travel the bump steer is really bad and the truck also pulls to one side under acceleration at lower speeds. Two wheel alignments later (everything except for the caster is within spec) both traits remain, which isn't surprising due to the altered front suspension geometry from the lift.

Some people have suggested lowering the front more but this will cause an even greater caster loss, plus the truck will look silly with the ass way up in the air relative to the front.

My next move will likely be to install the OME 1.5" rear springs in combination with lowering the front ~1".

Can anyone comment on the driving characteristics of the OME 1.5" front lift vs the 2.5" lift?

I am surprised that there aren't more complaints about the poor road manners post-lift install, but maybe most 100 owners are willing to put up with it as a trade-off for great off-road performance or maybe lots of 100 owners are moving up from older, lesser vehicles and even a lifted LC drives better than their old rig did

 

[pfran42]

Very interested in what the veterans will have to say...subbed

 

[spressomon]

The OP's experience matches mine; its the nature of the IFS beast. Yes Carl's upper control arms certainly helped get some caster back but IMO at 2.5" front lift height it doesn't steer and track like it did at stock height or even 1.5" lift height (on highway). So for me the trade-off is to get better off-road performance and handling.

If you don't actually need 2.5" of increased lift height I'd back it down an inch to about 1.5" and you'll be amazed at the difference. You might find through your experimentation 2" might be a good compromise.

 

[jgray]

If you aren't running much additional weight in the back (basically stock bumper, etc. as you look now) try some 2" OME 865 coils in the rear. What OME rear coils did you get?

 

[Griffin]

you just articulated my exact experience after installing the same lift two weeks ago. I, too, get the pull to the right when accelerating at low speeds and was planning on having it aligned again. Think I still will (I can as many times as i want for free for 6k miles) but it sounds like i shouldn't be too optimistic about the outcome.

I'm more worried about excessive tire wear, damn tires don't come cheap, than I am road handling. I'm satisfied with my rigs appearance and the extra ground clearance while off road. I plan on adding sliders soon, then eventually front and rear ARB bumpers....I wonder if the added weight will settle down the squirrrelyness.

 

[spressomon]

Yes...having it aligned post lift is a must; thanks for pointing it out. The weight per se won't make a difference...but the effective (settled) ride height will.

 

[RL4x4]

If you aren't running much additional weight in the back (basically stock bumper, etc. as you look now) try some 2" OME 865 coils in the rear. What OME rear coils did you get?

Zero added weight and my 100 doesn't even have the 3rd row seating. I think they are 860 coils...will confirm ASAP.

 

[petrotk40]

those 860's are the tallest you can get for the 100 w/o add'l weight, the 865s or 866s might work better?

 

[OregonLC]

the 866s with OME bars work great for me. It's a stiff ride with E tires at 44, but I like a 'truck' ride.

 

[ShottsUZJ100]

I just don't get it. I was at 1.5" then 2.5 inches then 2.75F/3.00R and each setup works great on my 100. OK...speed bumps in parking lots suck but the on-road ride is great. It tracks straight, smooth on the freeway, great handling...it drives superbly...OK...the KM2's wrecked the ride some.

 

[RL4x4]

I just don't get it. I was at 1.5" then 2.5 inches then 2.75F/3.00R and each setup works great on my 100. OK...speed bumps in parking lots suck but the on-road ride is great. It tracks straight, smooth on the freeway, great handling...it drives superbly...OK...the KM2's wrecked the ride some.

It isn't the ride per se, it is the dynamics/feel from the front end as the suspension moves through it's travel. Some owners notice it and others don't.

At the end of the day every IFS is subject to these issues - lifting a 100 series 2" or lowering a 911 turbo 2"....both changes screw up the front geometry and introduce bump steer. The problem is even worse on the 100 series vs a RWD car because the 100 is also powering the front wheels and lifting the rear higher than the front (aka "rake") reduces the amount of caster which in turn reduces the on-center feel of the steering and reduces the straight line stability. These are facts - but some owners don't care or don't notice.

I am definately sold on buying new, lower lift rear springs and adjusting the OME torsion bars down to ~1.5" above stock.

 

[ShottsUZJ100]

It isn't the ride per se, it is the dynamics/feel from the front end as the suspension moves through it's travel. Some owners notice it and others don't.

At the end of the day every IFS is subject to these issues - lifting a 100 series 2" or lowering a 911 turbo 2"....both changes screw up the front geometry and introduce bump steer. The problem is even worse on the 100 series vs a RWD car because the 100 is also powering the front wheels and lifting the rear higher than the front (aka "rake") reduces the amount of caster which in turn reduces the on-center feel of the steering and reduces the straight line stability. These are facts - but some owners don't care or don't notice.

I am definately sold on buying new, lower lift rear springs and adjusting the OME torsion bars down to ~1.5" above stock.

I care and notice. My 80-series SUCKS. My 100's ride is well within the mode of being excellent despite the changes.

 

[RL4x4]

My 100's ride is well within the mode of being excellent despite the changes.

Lifting an 80 series has zero effect on bump steer, but it does lose caster (as you know ) so in essence lifting an 80 is less 'bad' than lifting a 100 series.

There is no doubt that mod-for-mod a 100 series "rides" far better than an 80 series does!

My standard for "excellent" ride quality, road manners, steering feel and chassis dynamics might be somewhat more demanding than others, hence the relative lack of complaints on this board, despite the huge number of lifted 100s present.

 

[Manhattan]

My FJ Cruiser (IFS) with the OME 3" list experienced this and SHREDDED the BFG ATs in about 25,000 miles - the outside edges. This was post-alignment

Looking to do 1.5" on the 100.

 

[dclee]

Lifting an 80 series has zero effect on bump steer, but it does lose caster (as you know ) so in essence lifting an 80 is less 'bad' than lifting a 100 series.

There is no doubt that mod-for-mod a 100 series "rides" far better than an 80 series does!

My standard for "excellent" ride quality, road manners, steering feel and chassis dynamics might be somewhat more demanding than others, hence the relative lack of complaints on this board, despite the huge number of lifted 100s present.

I wouldn't assume that "standards" are lower here (otherwise we'd all be driving Heeps), rather "intended use" may be different...

 

[RL4x4]

I wouldn't assume that "standards" are lower here (otherwise we'd all be driving Heeps), rather "intended use" may be different...

Hence this comment in my original post...

"maybe most 100 owners are willing to put up with it as a trade-off for great off-road performance"

Let's try to keep this a technical discussion.


Thanks

 

[SupraTuRD]

Looking at the tie rod angles of a lifted 100, bump steer is a given.

Tie rod ends should look like __ __ instead of / \ . Unfortunately, that's the nature of the beast. I will most likely keep my lift under 1.5". Currently, it's at stock height with 33's and I'm quite pleased with the road manners.

 

[dclee]

Hence this comment in my original post...

"maybe most 100 owners are willing to put up with it as a trade-off for great off-road performance"

Let's try to keep this a technical discussion.


Thanks

You answered your own question (with the correct answer)! These trucks are not Porsche 911 GT3s screaming around the Armco. They were engineered, and hopefully purchased for, a much different purpose (hence my comment about "intended use").

I think it is a given that you will introduce bump-steer due to such a large static suspension change. As noted previously, on an IFS vehicle it does not seem that this is caused by caster change (since the steering pivot angle should not change significantly as the truck is lifted, or, conversely, as the axle is lowered from the chassis) unlike what would happen on a live-front-axle vehicle with trailing links. You mention rake as possibly affecting caster, but I do not think most lifted 100s have enough rake to significantly affect this (or at least they shouldn't; I believe a 1" rake back to front is the accepted norm, which I would think would be effectively soaked up over the length of a 112" wheelbase given that the steering pivot angle is a rotational/angular measurement). However, I'm thinking that the lift itself introduces some inherent toe changes which would contribute to effects like bump-steer. Assuming this is the case, you would be inherently less stable at static ride height, and more susceptible to effects like bump-steer and roll-steer. Sending power through the front wheels only exacerbates this (add torque-steer to the list). It would be an interesting experiment to disconnect your front driveshaft, lock your t-case, and take it out on the road to see if the torque-steer effect is reduced/eliminated (it should be).

 

[no-pistons]

I don't see the point to go with a 2.5" lift unless you want to squeeze 35's on there. The 1.5" lift is more than enough for 33" tires. Unless doing major suspension modification for extreme conditions, I think its best to set the suspension geometry as close to stock as possible, no matter what type of vehicle.

 

[ShottsUZJ100]

I don't see the point to go with a 2.5" lift unless you want to squeeze 35's on there. The 1.5" lift is more than enough for 33" tires. Unless doing major suspension modification for extreme conditions, I think its best to set the suspension geometry as close to stock as possible, no matter what type of vehicle.

Depending on the intended use for the vehicle. My 100 would be worthless to ME at 1.5" lift and 33's.