Question for V8 owners with Rear Air Suspension

[AlexJet]

I have a question to V8 owners. I, personally, have V6, so I can't do this experiment. My question is how the vehicle rides over speed bumps with Rear Air Suspension when it is in "High" position compare to "Normal" position? This would means when you're extending rear shocks in "High". I've 2" rear lift which is approximately the same as you guys have when raising your rear, but my rear is very stiff and jumps like basketball over each speed bump and very hard in road holes. So if someone with rear Air Suspension can make this experiment, I'd appreciate any details of his ride experience. Could you put your rear in "High" position and try to go over speed bumps on a parking lot with approximately 10-15mph (normal speed on parking lots) and do the same in "Normal" position, and compare it? This should take not more then 5 minutes. The reason of it that looks like Toyota has different rear shocks and/or setups for V6 and V8. If you have "comfort" ride over speed bumps compare to "normal" position, this means that V8 shocks have longer travel.

 

[brettc34]

I will as soon as I get mine in a few weeks, at least the dealer says it will be just a couple more weeks, we will see

 

[diverdriver]

I have never noticed any difference in ride between the low, netural, and high settings on my 05. However, After the spacer lift on my 3rd gen. the rear had more bounce to it. Next time you are down on Spring Garden, Just knock(#15). I'll pull the truck out of the garage, and we can compare them back to back. The ride on my snowtires should be compairable to your Revo's.
Mark

 

[4x4v8]

i will try it out tomorrow and report back tomorrow night. i dont think ive ever drivn over a speed up in high. but ill try both out tomorrow.

4x4v8

 

[Koz]

You are comparing apples and oranges. The OEM rear air suspension has air bags instead of coil springs (which are on all non-rear air suspension 4Runners). There is no difference in the ride quality at any rear air setting. The only time the ride changes is with a lot of added weight. The rear air set at high is equal to a 4" rear lift.

When you add a lift to the rear coil springs you are changing the spring rate and the shock dampening rate.

Koz

 

[AlexJet]

You are comparing apples and oranges. The OEM rear air suspension has air bags instead of coil springs (which are on all non-rear air suspension 4Runners). There is no difference in the ride quality at any rear air setting. The only time the ride changes is with a lot of added weight. The rear air set at high is equal to a 4" rear lift.

When you add a lift to the rear coil springs you are changing the spring rate and the shock dampening rate.

Koz

As far as I know the problem is not in the coil. It rides fine with 2 people on the back or with some load. Second thing is that I know that V8 has Air Bags. But still airbags or coils are making the ride comfortable in long term. I'm talking about short term (~1/10 of a second). I'll try to explain. When I'm going over speed bump, at first half I'm going to upper point of this speed bump and coil and shock is compressing, then after I passed the top point I'm going "down the hill" on the speed bump. At this particular moment my rear axle is slower going down that speed bump surface. This means that I have something like that. I'm going on the speed bump and then jumping from it, like it has perpendicular to the road rear side. I hope you understanding what I'm talking about. I've many years of automotive experience and all this means that shock is too slow to let axle going down. I also know that rear shocks are progressive, so extended shock is in stiff position. This position was designed for high speed turns where shocks should have big resistance against rolling the vehicle. I thought that if V8 can be lifted from the factory, Toyota changed shock travel and it's parameters to avoid this. The only question is I need to test it.

 

[4x4v8]

ok, so i tried it. i found a parking lot near york that had speed bumps and huge pot holes. i went through them on normal and on high. from what i could tell, they felt exactly the same.

 

[AlexJet]

ok, so i tried it. i found a parking lot near york that had speed bumps and huge pot holes. i went through them on normal and on high. from what i could tell, they felt exactly the same.

4x4v8, if you would have some time, could you drive through Keele/Finch North East plaza? I'm working at that plaza, so if you can pass by at anytime during business hours or after work, I can show some places where I mentioned this problem and we can try to go through together and see what actually is happening. There is series of speed bumps and road holes there, which I'm passing at least twice a day.
I PM you my office number, so you can call or email me.

 

[4x4v8]

LOL. i was actually talking about the plaza right at keele and finch. there are HUGE pot holes there. the plaza right behind the esso gas station!

 

[khaug]

You should be aware that the air suspension option is (or was, when we got our truck) bundled with the XREAS shock package. This is utterly different from any conventional shock, so I'd be very cautious about drawing any conclusions about shock travel based on air suspension performance.

Regards.

 

[Koz]

AlexJet,

From what I can get out of your explanation, the problem you are experiencing is the suspension rebound is not fast enough after compression.

If someone could check the part numbers on the rear XREAS shocks for the Sport and the Limited's rear air bag suspension, to see if they are the same. Then you may want to take a picture of the two different set-ups and take a good look at the differences, if any. Things like spring/bag/shock mounting locations and distances between mounts. If they are the same, I think your problem is caused by changing the angle of the suspension (by adding the spacer) and using coil springs that were designed to provide compression/rebound at the OEM angle. I think that the air bag suspension has a wider range of working angle. If you think about it, the rear air bag suspension would have to be designed to work from the low height setting to the high setting.

Koz

 

[AlexJet]

AlexJet,

From what I can get out of your explanation, the problem you are experiencing is the suspension rebound is not fast enough after compression.

If someone could check the part numbers on the rear XREAS shocks for the Sport and the Limited's rear air bag suspension, to see if they are the same. Then you may want to take a picture of the two different set-ups and take a good look at the differences, if any. Things like spring/bag/shock mounting locations and distances between mounts. If they are the same, I think your problem is caused by changing the angle of the suspension (by adding the spacer) and using coil springs that were designed to provide compression/rebound at the OEM angle. I think that the air bag suspension has a wider range of working angle. If you think about it, the rear air bag suspension would have to be designed to work from the low height setting to the high setting.

Koz

Koz, that was one of my points. Actually I called dealer and was told that V8 sport and V8 Limited with Air have different part numbers for shocks, the same as V6 Limited and V8 Limited. I'd have to go to the dealer to get those part numbers.

 

[M3_962]

It sounds to me like the problem is just droop travel and the loss of it using a spacer lift. I don't think shocks are generally progressive with respect to position, only speed. The rebound damping on trucks is usually soft to allow the wheels to extend to the surface (off-road traction) so I'm not surprised that one could use up all the remaining droop travel with a spacer lift and when the suspension is asked to extend quickly (driving over a speed bump or off a curb).

furthermore

 

[AlexJet]

It sounds to me like the problem is just droop travel and the loss of it using a spacer lift. I don't think shocks are generally progressive with respect to position, only speed. The rebound damping on trucks is usually soft to allow the wheels to extend to the surface (off-road traction) so I'm not surprised that one could use up all the remaining droop travel with a spacer lift.

furthermore

 

[M3_962]

I know we've been talking about rear suspensions but here's what I've been thinking would be nice in a spacer lift kit (particularly with XREAS if you want to keep the shocks).

These are some pics of Nissan Titan kits and front suspension. The circled parts are spacers for the whole coilover assembly that move the whole thing and don't decrease the droop travel. The rears seem to come with new shocks (presumably longer) but I'm thinking a simple spacer to move the shock mount down, for the rear shocks, would be good.

In another thread someone mentioned that adding such a spacer would introduce bending loads on the shock shaft, but I wonder if this could be avoided somehow.

 

[M3_962]

other pic

 

[M3_962]

i just noticed...that guy is just hanging his brake caliper off the brake line. not so good...

 

[Koz]

The OEM rear air system can be driven on the low or high setting up to 22mph, then it automatically reverts back to the normal auto leveling setting. I do believe that because the rear XREAS shocks for the Sport and the Limited's air susp have different part numbers there could be a difference in the valveing and stroke length that could help with the lifted rear coil spring set-up. The question is, is it worth changing when you could get aftermarket shocks that would be less expensive?

Koz

 

[AlexJet]

... but I'm thinking a simple spacer to move the shock mount down, for the rear shocks, would be good...

That's what I'm working on right now. Tried couple of them, didn't work so far, but I'm still in a mood to find one.

 

[AlexJet]

The OEM rear air system can be driven on the low or high setting up to 22mph, then it automatically reverts back to the normal auto leveling setting. I do believe that because the rear XREAS shocks for the Sport and the Limited's air susp have different part numbers there could be a difference in the valveing and stroke length that could help with the lifted rear coil spring set-up. The question is, is it worth changing when you could get aftermarket shocks that would be less expensive?

Koz

But with OEM ones you will be able to remain the XREAS.