How will Positive Caster effect ride quality? (2" lift w/ UCA's)

[Endle55_5earch]

I will be installing heavier springs on my front TRD PRO shocks (FJ Pro Front Springs 14" and 600lbs) and using JBA UCA's. This is temporary while waiting for my Eibach coil-overs to come in...

SCS F5's 17x9-38 with 285/70/17 Falken Wildpeaks is the wheel and tire combo.

I expect a 2" lift with my winch and steel lo-pro bumper.

I understand I'll need +3 to +4 caster in order to fit the wheels and tires (I have a BMC already)

The question: What should I expect the extra positive caster do to affect my ride quality? Will I notice a huge difference?

Thanks for your help!

 

[honda250xtitan]

less wandering on the highway. wont feel as twitchy.

 

[2021nightshade4x4]

It’ll drive how 4Runners should have felt from the beginning. Night and day positive improvement.


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[Endle55_5earch]

less wandering on the highway. wont feel as twitchy.

It’ll drive how 4Runners should have felt from the beginning. Night and day positive improvement.

Cool, thanks guys. Just trying to get a heads up on the changes I will feel (both positive or negative) on road or off.

Appreciate ya.

 

[repo]

I like it. Feels more heavy and planted. Personal preference I suppose, I don't like the vague stock steering that much.

 

[Jetboy]

In the 1.5-2" lift range there's a little bit of trickyness in alignments. The problem is that the UCAs add about 4 degrees of caster. At 3" of lift that's what you want. Half way in the middle, it's maybe too much - and by that I mean you can get great alignment, but at 4* caster you won't be maxing out the caster available on the lower control arm tabs - so you won't be pushing the tires as far forward away from the body mount as you would with stock arms.

I recently lowered my suspension back to around 1.5" lift and put the stock UCAs back on. (I have some JBA arms I used at higher lift). The reason was what I explained above. At 1.5" lift front I had to either run 6-7* caster to max the body clearance or pull it back to 4*. Not a problem with 33" tires, but with 34" tires it can rub a little. So I swapped back to stock UCAs and set around 3* caster, but better body clearance. The stock UCA locates the upper ball joint further forward as well. So the net of the lower height is that - oddly - at the lower height I think I might even be able to squeeze 35's. If I had a set I'd bolt em on and see if they fit.

I'm doing a lot of highway miles lately that prompted the lowering. The ride is noticeably better at 1.5" than 3" lift on long road trips.

Overall though - I'd say no question the higher caster is nicer all around for driving. Once you get below about 2* the steering wheel feedback sucks and it doesn't want to track very well. After messing around a lot with mine - I think 3* is okay, but around 4-4.5* is close to ideal.

 

[Endle55_5earch]

In the 1.5-2" lift range there's a little bit of trickyness in alignments. The problem is that the UCAs add about 4 degrees of caster. At 3" of lift that's what you want. Half way in the middle, it's maybe too much - and by that I mean you can get great alignment, but at 4* caster you won't be maxing out the caster available on the lower control arm tabs - so you won't be pushing the tires as far forward away from the body mount as you would with stock arms.

I recently lowered my suspension back to around 1.5" lift and put the stock UCAs back on. (I have some JBA arms I used at higher lift). The reason was what I explained above. At 1.5" lift front I had to either run 6-7* caster to max the body clearance or pull it back to 4*. Not a problem with 33" tires, but with 34" tires it can rub a little. So I swapped back to stock UCAs and set around 3* caster, but better body clearance. The stock UCA locates the upper ball joint further forward as well. So the net of the lower height is that - oddly - at the lower height I think I might even be able to squeeze 35's. If I had a set I'd bolt em on and see if they fit.

I'm doing a lot of highway miles lately that prompted the lowering. The ride is noticeably better at 1.5" than 3" lift on long road trips.

Overall though - I'd say no question the higher caster is nicer all around for driving. Once you get below about 2* the steering wheel feedback sucks and it doesn't want to track very well. After messing around a lot with mine - I think 3* is okay, but around 4-4.5* is close to ideal.

So, If I'm understanding correctly, at a 2" lift (and higher) I'm good to put on the JBA UCA's but if its under 2" lift I should keep the stock UCA's?

The FJ PRO Springs (14" long @ 600lbs) is supposed to give a 5th Gen T4R a 2.5" lift stock front and a 2" lift with Lo-Pro bumper + Winch. I've gathered this info from the forum and have the FJ PRO Springs and JBA UCAs in the garage waiting for install.

I daily drive my T4R but travel to the mountains (Just recently did Alpine Loop in the San Juan Mountans, CO) so I wanted a "modest" lift that's good for highway driving and the week-long off-roading vacation.

I appreciate the nuance in your response. Thank you for your help!

 

[Jetboy]

So, If I'm understanding correctly, at a 2" lift (and higher) I'm good to put on the JBA UCA's but if its under 2" lift I should keep the stock UCA's?

The FJ PRO Springs (14" long @ 600lbs) is supposed to give a 5th Gen T4R a 2.5" lift stock front and a 2" lift with Lo-Pro bumper + Winch. I've gathered this info from the forum and have the FJ PRO Springs and JBA UCAs in the garage waiting for install.

I daily drive my T4R but travel to the mountains (Just recently did Alpine Loop in the San Juan Mountans, CO) so I wanted a "modest" lift that's good for highway driving and the week-long off-roading vacation.

I appreciate the nuance in your response. Thank you for your help!

I would probably put them on. You'll want them if you go any higher for sure. Just be aware that you won't probably end up with quite as much body mount clearance, but you'll have better alignment than the stock UCAs. For 285/70/17's (32.6ish height) it should clear jus fine on the mount and you'll like the driving experience a lot better with better alignment.

I didn't have the clearance issues until I jumped up to 285/75/17 (34" height). At 3" lift up front I definitely wanted the JBA UCAs. Overall they worked great. At stock height you'd move the LCA back far enough you might have body mount clearance issues, so I wouldn't want the JBA arms at stock or near stock height.

I'm keeping them in case I end up keeping the 4R and lifting it higher again. I mess around with it a lot - it only takes me a maybe 2-3 hrs to re-adjust the front to 3", swap UCAs, swap rear springs to some 2.5" lift Dobinson ones I have, and then re-adjust alignment pretty close to where I want it. Keep track of your alignment cam locations at each height and it's an easy re-adjust back to proper alignment when you want to switch around. For now with a 2yr old - my trips are more Yellowstone and Glacier with my camper, and less Moab and Rubicon.

 

[Endle55_5earch]

I would probably put them on. You'll want them if you go any higher for sure. Just be aware that you won't probably end up with quite as much body mount clearance, but you'll have better alignment than the stock UCAs. For 285/70/17's (32.6ish height) it should clear jus fine on the mount and you'll like the driving experience a lot better with better alignment.

I didn't have the clearance issues until I jumped up to 285/75/17 (34" height). At 3" lift up front I definitely wanted the JBA UCAs. Overall they worked great. At stock height you'd move the LCA back far enough you might have body mount clearance issues, so I wouldn't want the JBA arms at stock or near stock height.

I'm keeping them in case I end up keeping the 4R and lifting it higher again. I mess around with it a lot - it only takes me a maybe 2-3 hrs to re-adjust the front to 3", swap UCAs, swap rear springs to some 2.5" lift Dobinson ones I have, and then re-adjust alignment pretty close to where I want it. Keep track of your alignment cam locations at each height and it's an easy re-adjust back to proper alignment when you want to switch around. For now with a 2yr old - my trips are more Yellowstone and Glacier with my camper, and less Moab and Rubicon.

Everything makes sense. I used to want to go 34's but I decided I'm not going to re-gear. The 33's do what I need them to do.

I miss the "terrible 2's" but I certainly didn't feel that way when I was going through it! Thanks again for your time.

 

[Mo's TE]

Question to guru's, should the caster be equal on both sides? Some shops told me that there should a degree or so difference between right and left (right being higher).... I'm not convinced this is actually correct, what do you guys think?

 

[patkelly4370]

Question to guru's, should the caster be equal on both sides? Some shops told me that there should a degree or so difference between right and left (right being higher).... I'm not convinced this is actually correct, what do you guys think?

Compensate for the crown of the road.
When I was doing alignments I would go ½ to ¾°.

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[2021nightshade4x4]

Question to guru's, should the caster be equal on both sides? Some shops told me that there should a degree or so difference between right and left (right being higher).... I'm not convinced this is actually correct, what do you guys think?

If your vehicle supports barely any positive caster from factory, I could see how one would want a compensated alignment. If you can get 4 degrees positive caster, you shouldn’t need to compensate for road crown.

Keep in mind, if you do mostly highway driving and you camp out in the left lane most of the time, the compensated alignment may not produce the desired results. Interstate highways sometimes crown in the middle of each direction’s lanes, not just in the median.


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