Seeking suspension advice -- unique case (2 Viewers)

[KLF]

One more basic question for folks with more experience than me: can I have different tires and pressures at the front than at the rear? It occurs to me that my main issue right now is at the front. The camera in question is almost over the front axle, and the seated passengers (who will be in the front row) are not far behind. So what if I went with more of an all-season tire setup at the front and air that down while keeping KO2s aired up at the back? Is that a recipe for disaster, or could that be a feasible compromise in terms of tires?

Yes, not a good idea. You want to do as much as possible to keep all the tire circumference the same on all 4 wheels. If you reduce the pressure on one axle, then they will not spin at the same speed, and this will make the transfer case work harder to put "slip" in the drivetrain.

I suppose it wouldn't be a big deal if you only did it off-road for short distances and low speed.

 

[WrongWayDave]

U4ZJ100 & KLF are correct.

The LC is AWD all the time, so it is important (some might say critical) to keep all four wheels w/i equal rolling specs, even to the point of even tire wear for long term longevity.

I would strongly consider taller, all season highway tires (and make sure your spare matches). Go for ride comfort, and off-road air down and familiarize yourself with the off-road systems that make this machine great even with average tires. You will not have "the look" but it will depend on how important ride vs traction in a 90% road, 10% off-road situation (where of that 10%, only a small percentage might get you stuck, and even smaller percentage REALLY stuck).

 

[linuxgod]

One more basic question for folks with more experience than me: can I have different tires and pressures at the front than at the rear? It occurs to me that my main issue right now is at the front. The camera in question is almost over the front axle, and the seated passengers (who will be in the front row) are not far behind. So what if I went with more of an all-season tire setup at the front and air that down while keeping KO2s aired up at the back? Is that a recipe for disaster, or could that be a feasible compromise in terms of tires?

It's probably not great to run different pressures between front and rear due to the full-time 4WD system which expects all of your tires to be rotating at the same speed. Different tire PSI means different tire diameters, which means your transfer case will be running hotter from internal slippage as it's always allowing for slightly different driveshaft rotational speeds between the front and rear diffs

4WD system aside, if you're running at a high rate of speed (40mph+) then you're also going to generate a lot more heat in the front tires, which can cause them to fail (remember the Firestone/Ford Explorer debacle?)

Aside from all of the above, you *could* do it, though lower PSI affects handling characteristics (in this case increasing understeer). That said if you're at a low-ish rate of speed offroad you should really be aired down on all 4 tires anyway.

 

[bloc]

Again, I would strongly advise talking to an expert on suspensions about your unique needs and see what they suggest. Even if they don’t know the details with regard to videography their knowledge on handling and vehicle dynamics should make up for it.
Yes it would seem that someone selling expensive parts has incentive to sell those parts, but I’d point out Ben talked me out of $300/axle compression adjusters as not necessary for my use case.

 

[BloggerL]

U4ZJ100 & KLF are correct.

The LC is AWD all the time, so it is important (some might say critical) to keep all four wheels w/i equal rolling specs, even to the point of even tire wear for long term longevity.

I would strongly consider taller, all season highway tires (and make sure your spare matches). Go for ride comfort, and off-road air down and familiarize yourself with the off-road systems that make this machine great even with average tires. You will not have "the look" but it will depend on how important ride vs traction in a 90% road, 10% off-road situation (where of that 10%, only a small percentage might get you stuck, and even smaller percentage REALLY stuck).

I hear that. And that generally makes sense. But in my particular case, the 10% is critical since this is a work vehicle. I've got people who depend on me to get home, and if we can't get where we're going in the first place, I lose a lot of money and time. Got to have the traction. But yeah, I"m dropping the different tires on different axles idea. I appreciate everyone's cautions there.

 

[BloggerL]

Again, I would strongly advise talking to an expert on suspensions about your unique needs and see what they suggest. Even if they don’t know the details with regard to videography their knowledge on handling and vehicle dynamics should make up for it.
Yes it would seem that someone selling expensive parts has incentive to sell those parts, but I’d point out Ben talked me out of $300/axle compression adjusters as not necessary for my use case.

Reaching out to Ben! I appreciate everyone suggesting him.

 

[BloggerL]

Another question for @gaijin , @bloc, @TeCKis300 , @KLF , and others--since you guys all know much more than me about these matters:

I'm learning here that increased tire flex and heat at higher speeds is what causes issues when you air down tires below the recommended pressure. However, I wonder if anyone has any insights on how time intervals come into play. There's clear consensus that you don't want to be driving around the highway on KO2s at 35PSI forever. But what about 30 minutes twice a day? Or 90 minutes every 2 days?

Is the safety factor here an incremental thing over time, like X-rays, where the more you get, the higher your risk as you age? Or is the safety factor here more of an each-time thing, like playing Russian Roulette? The camera I mentioned won't be in use all the time and doesn't even have to stay on its mount. So I wonder if, as part of the overall solution, I could air down for short periods of driving on paved roads.

 

[gaijin]

Another question for @gaijin , @bloc, @TeCKis300 , @KLF , and others--since you guys all know much more than me about these matters:

I'm learning here that increased tire flex and heat at higher speeds is what causes issues when you air down tires below the recommended pressure. However, I wonder if anyone has any insights on how time intervals come into play. There's clear consensus that you don't want to be driving around the highway on KO2s at 35PSI forever. But what about 30 minutes twice a day? Or 90 minutes every 2 days?

Is the safety factor here an incremental thing over time, like X-rays, where the more you get, the higher your risk as you age? Or is the safety factor here more of an each-time thing, like playing Russian Roulette? The camera I mentioned won't be in use all the time and doesn't even have to stay on its mount. So I wonder if, as part of the overall solution, I could air down for short periods of driving on paved roads.

If you are driving on paved roads with other cars on the road, i.e. traffic, then you should be inflated to the RCTIP for your tires. Main concerns here are you ability to safely perform an emergency maneuver (e.g. hard braking, avoidance maneuver, etc.) and durability against common road hazards (potholes, debris, etc.). Pressures lower than the RCTIP will compromise your safety under those conditions.

Tire damage caused by heat and flex are cumulative - the longer you drive at pressures below RCTIP, the shorter the safe life of your tires. In other words, tires do not recover from heat and flex damage after a period of time driving at RCTIP. Heat and flex damage at low speeds, i.e. off road speeds, is less than heat and flex damage at on road speeds.

There is no convenient formula one can apply, just the generally accepted rule of thumb that pressures lower than the RCTIP should be limited to low speeds off road.

HTH

 

[bloc]

Another question for @gaijin , @bloc, @TeCKis300 , @KLF , and others--since you guys all know much more than me about these matters:

I'm learning here that increased tire flex and heat at higher speeds is what causes issues when you air down tires below the recommended pressure. However, I wonder if anyone has any insights on how time intervals come into play. There's clear consensus that you don't want to be driving around the highway on KO2s at 35PSI forever. But what about 30 minutes twice a day? Or 90 minutes every 2 days?

Is the safety factor here an incremental thing over time, like X-rays, where the more you get, the higher your risk as you age? Or is the safety factor here more of an each-time thing, like playing Russian Roulette? The camera I mentioned won't be in use all the time and doesn't even have to stay on its mount. So I wonder if, as part of the overall solution, I could air down for short periods of driving on paved roads.

I doubt you will find a concrete/quantified answer to this, other than it not being a good idea. Plus, for it to make a significant enough difference to NVH levels such that it could improve filming, I suspect the pressures would need to be so low that it would be very clearly not healthy for the tires, not even in the short term.

 

[TeCKis300]

Another question for @gaijin , @bloc, @TeCKis300 , @KLF , and others--since you guys all know much more than me about these matters:

I'm learning here that increased tire flex and heat at higher speeds is what causes issues when you air down tires below the recommended pressure. However, I wonder if anyone has any insights on how time intervals come into play. There's clear consensus that you don't want to be driving around the highway on KO2s at 35PSI forever. But what about 30 minutes twice a day? Or 90 minutes every 2 days?

Is the safety factor here an incremental thing over time, like X-rays, where the more you get, the higher your risk as you age? Or is the safety factor here more of an each-time thing, like playing Russian Roulette? The camera I mentioned won't be in use all the time and doesn't even have to stay on its mount. So I wonder if, as part of the overall solution, I could air down for short periods of driving on paved roads.

This is gray area that doesn't have firm guidelines or objective data on how best to tailor tire pressures. There's some other strategies to cross check.

That said, tire pressures have lots of opportunity for tailoring and it's not the rigid interpretation some make it out to be. Within reason and understanding, tire pressures can be situationally lowered. Just as it's been done forever for off-roading.

As mentioned, not exceeding temperature which plies start delaminating and separating is the operating ceiling. Generally considered to be 200*F. RCTIP (use LX) pressures are established for max speed, max load, but there's some other major contributors.

1) Lower than max speed (112 mph) - largest opportunity to lower pressures
2) Lower than max stock loads - opportunity to lower pressure, but if you're heavier that should be considered
3) Low ambient temp - opportunity to lower
4) Stop and go, i.e. not continuous highway running - opportunity to lower as tires have more opportunity to dissipate heat
5) Performance driving - may need to increase pressures

I would have no hesitation situationally going to 35 PSI, or even far less. Assuming you're not operating anywhere near max speeds.

If you want a way to sanity check, get a non-contact thermometer, and check sidewall temps against that 200*F ceiling. That's generally considered a safe operating ceiling and there's margin above that before sidewalls begin failing.


In regards to the earlier 4WD discussion - absolutely one can use different pressures between axles, again, if done within reason and understanding. Axle loads are not always even anyways which causes rotational differences in tires that the driveline has to deal with. When towing, I know my rear axle may be upwards of 1200-1800 lbs over the fronts. I adjust my rears ~4PSI higher than fronts. I know you're talking about lowering pressures, which I would use the above paragraphs as basis to lower.

 

[BloggerL]

This is gray area that doesn't have firm guidelines or objective data on how best to tailor tire pressures. There's some other strategies to cross check.

That said, tire pressures have lots of opportunity for tailoring and it's not the rigid interpretation some make it out to be. Within reason and understanding, tire pressures can be situationally lowered. Just as it's been done forever for off-roading.

As mentioned, not exceeding temperature which plies start delaminating and separating is the operating ceiling. Generally considered to be 200*F. RCTIP (use LX) pressures are established for max speed, max load, but there's some other major contributors.

1) If the situation calls for less than max speed (112 mph) - largest opportunity to lower pressures
2) Lower than max stock loads - opportunity to lower pressure, but if you're heavier that should be considered
3) Ambient temp - opportunity to lower
4) Stop and go, i.e. not continuous highway running - opportunity to lower as tires have more opportunity to dissipate heat
5) Performance driving - may need to increase pressures

I would have no hesitation situationally going to 35 PSI, or even far less, on occasion. Assuming you're not operating anywhere near max speeds.

If you want a way to sanity check, get a non-contact thermometer, and check sidewall temps against that 200*F ceiling. That's generally considered a safe operating ceiling and there's margin above that before sidewalls begin failing.


In regards to the earlier 4WD discussion - absolutely one can use different pressures between axles, again, if done within reason and understanding. Axle loads are not always even anyways which causes rotational differences in tires that the driveline has to deal with. When towing, I know my rear axle may be upwards of 1200-1800 lbs over the fronts. I adjust my rears ~4PSI higher than fronts. I know you're talking about lowering pressures, which I would use the above paragraphs as basis to lower.

Thank you for these thoughts. Yes, for filming I would max out at 65 on the highway. But I'd only lower the pressures a little there. I'd be more interested in lowering pressures substantially on rough urban roads, where I'd maxing out at 50.

 

[BloggerL]

Thanks, everyone who recommended Ben. Spoke with him today by phone, and his expertise was obvious.

He echoed a lot of advice here and also added some things. He pointed out that the Kings have 7 points of change [I forget the technical term used] vs 2 in other products, which helps make them progressive in a way that can suit on-road and off-road use. So he thought the Kings would be a good choice for me. Of course, he's biased as a dealer, but I found the pitch credible.

Second, he pointed out that the speed of the suspension response is important for my use. If the suspension responds slowly to a bump, it will still be handling that bump when the next bump comes along. This helps create vibrations in the chassis while driving. A faster suspension, he said, will have less vibration, as well as more control for other driving purposes. I hadn't mentioned it here, but those vibrations (as opposed to series of single bumps) have been the worst aspect of what I've been wrestling with.

I'm probably going to go with the Kings. But I'm still wrestling with tires. Going to try to find something a little larger in diameter than stock that has full all-terrain ability but runs at lower pressure. Tough to find...

 

[bloc]

Thanks, everyone who recommended Ben. Spoke with him today by phone, and his expertise was obvious.

He echoed a lot of advice here and also added some things. He pointed out that the Kings have 7 points of change [I forget the technical term used] vs 2 in other products, which helps make them progressive in a way that can suit on-road and off-road use. So he thought the Kings would be a good choice for me. Of course, he's biased as a dealer, but I found the pitch credible.

Second, he pointed out that the speed of the suspension response is important for my use. If the suspension responds slowly to a bump, it will still be handling that bump when the next bump comes along. This helps create vibrations in the chassis while driving. A faster suspension, he said, will have less vibration, as well as more control for other driving purposes. I hadn't mentioned it here, but those vibrations (as opposed to series of single bumps) have been the worst aspect of what I've been wrestling with.

I'm probably going to go with the Kings. But I'm still wrestling with tires. Going to try to find something a little larger in diameter than stock that has full all-terrain ability but runs at lower pressure. Tough to find...

Those are called compression adjusters. This video is pretty long but covers every relevant detail.




Edit: and another video from them specifically on ride quality. Hour long, but really good info.

 

[rlynch356]

I hear that. And that generally makes sense. But in my particular case, the 10% is critical since this is a work vehicle. I've got people who depend on me to get home, and if we can't get where we're going in the first place, I lose a lot of money and time. Got to have the traction. But yeah, I"m dropping the different tires on different axles idea. I appreciate everyone's cautions there.

I would suggest Off road drivers training before doing anything if the above is the case.

What you are getting into is common in the racing and rally world, which is adjustable High and low speed compression and high and low speed rebound adjustability. Of course you are going to pay substantially more than kings for that, and you are going to need to tune the suspension to your needs.

Automotive, Motorcycle, & Off Road Shocks - Penske Racing Shocks

These are not an off the shelf item and would require all the other bits (UCA's etc) as well extra.

 

[BloggerL]

Well, I've decided after a few hours thought to proceed with the Kings. Throwing in a little lift while I'm at it. Don't want to raise COG, but sounds like the Kings will add back some stability.

 

[KLF]

Who will you have do the work? Just curious.

Would like to see it when it's done, and get your impressions. I'm also leaning this way.

 

[BloggerL]

Ben surprisingly recommended just any normal shop. He said they bolt on easily, and it's actually better sometimes to go somewhere basic than to someplace more specialized that could start tinkering too much.

Gonna be a wait of many weeks, as Kings builds in batches.

 

[bloc]

Ben surprisingly recommended just any normal shop. He said they bolt on easily, and it's actually better sometimes to go somewhere basic than to someplace more specialized that could start tinkering too much.

Gonna be a wait of many weeks, as Kings builds in batches.

My only concern would be that a fair amount of material will need to be taken off the front bump stops and brackets for clearance, and I'd want a shop I could trust doing that work. Some would tend to take off a big chunk and be sure they got it right, vs take a little, try to fit, take a little, try it, etc. I had my front right shock in and out probably four times to get it correct. With that intel the left one was only in and out twice. Many shops won't have that patience.

Also I had to modify the passenger side reservoir bracket to not touch the power steering hose. The contact is somewhat hidden, and if they aren't paying attention that could turn into an issue eventually.

The notes from King didn't say anything about turning the reservoir hoses if they don't sit correctly, which neither of the fronts did. Filthy quickly got me the info I needed to address that. It is a little tricky because they are pressurized and the DS especially has limited room for wrenches.

Otherwise yes, they bolt right in.

Are you going with aftermarket upper control arms? I got everything aligned just fine on stock arms with the preload adjusters backed all the way out, and the tech said the adjusting cams still had room to go. I still may go with upper arms eventually to put the adjusters back in the middle of their range.

 

[BloggerL]

He made it sound easier than all that. So I'll ask him in our next exchange about these details.

We haven't discussed the UCAs, but I'm assuming that I will be getting those too.

 

[bloc]

I did the install about a month ago so I’d say my perception is pretty realistic. Yes a good shop can handle it, but due to past experiences I don’t trust just “any” shop to have the attention to detail required to do this right. It isn’t just removing stock parts and replacing.. and frankly many shops aren’t great about that work either. Very few even torque the LCA bolts to spec, leading to alignment drift and other problems.

And if I made it sound difficult, it isn’t, I’m just trying to list all the details I can think of.