Pros & Cons of IRS for Off-Roading

[MrTom]

Have a suspicion that there is a good chance the 2010 4Runner will have an Independent Rear Suspension (IRS). I personally prefer the highway ride and handling characteristics of IRS with coil springs at all 4 corners.
But I didn't get my runner for highway cruisin'. Would like to hear some of the Pros and Cons of IRS for off-roading.
Thanks,Tom

 

[Thai]

Have a suspicion that there is a good chance the 2010 4Runner will have an Independent Rear Suspension (IRS). I personally prefer the highway ride and handling characteristics of IRS with coil springs at all 4 corners.
But I didn't get my runner for highway cruisin'. Would like to hear some of the Pros and Cons of IRS for off-roading.
Thanks,Tom

Cons: weaker overall (strength wise), less wheel travel, variable ground clearance, and because it's weaker, adding a locker may not be a workable option.

Pros: on-road ride, handling, and comfort, allows for fold-flat 3rd row seating, lower cargo loading height, and less component weight.

 

[CJ3Flyr]

Re: Re: Pros & Cons of IRS for Off-Roading

Cons: weaker overall (strength wise), less wheel travel, variable ground clearance, and because it's weaker, adding a locker may not be a workable option.

Pros: on-road ride, handling, and comfort, allows for fold-flat 3rd row seating, lower cargo loading height, and less component weight.

Thai, I have a question for you. What was the logic when the H1 Hummer chose to use an IRS.

I don't disagree with your characterization you stated above I am just curious why no top load (Rockwell style) axle on H1's. You are quite the enthusiast and maybe remember having read something...

Thanks and sorry for the thread hijack


:cheers:

 

[Thai]

Re: Re: Re: Pros & Cons of IRS for Off-Roading

Thai, I have a question for you. What was the logic when the H1 Hummer chose to use an IRS.

I don't disagree with your characterization you stated above I am just curious why no top load (Rockwell style) axle on H1's. You are quite the enthusiast and maybe remember having read something...

Thanks and sorry for the thread hijack


:cheers:

Just remember why the H1 was made and where it was designed to function. H1 was never made to rockcrawl...there is plenty of video of it sucking at that on the net. So, wheel travel was NOT H1's strength nor it's purpose.

H1 has the full independent setup because it was made to travel fast over washboards and desert driving. Independent suspension is good for these terrains...as you can also see in Rally car racing. Independent setup also allows for the portal brake system (or whatever it's called) to be incorporated i think. And as such, it allows for the H1 to have 16" of ground clearance. Many people use the H1 as an example of independent suspension superiority. Yeah, over a few terrains, it is true. However, over most terrains here in the USA, solid axle is far superior (for reasons mentioned above). In addition, when was the last time that you saw a suspension design like H1 on a civilian vehicle? None exist because there are waaayyyy too many compromises in the H1 design. (Hint: just sit in one and you will see!)

 

[Falls]

Have a suspicion that there is a good chance the 2010 4Runner will have an Independent Rear Suspension (IRS).

I highly doubt that will happen. Especially if the FJ goes by the way side.

 

[CJ3Flyr]

Re: Re: Re: Re: Pros & Cons of IRS for Off-Roading

Just remember why the H1 was made and where it was designed to function. H1 was never made to rockcrawl...there is plenty of video of it sucking at that on the net. So, wheel travel was NOT H1's strength nor it's purpose.

H1 has the full independent setup because it was made to travel fast over washboards and desert driving. Independent suspension is good for these terrains...as you can also see in Rally car racing. Independent setup also allows for the portal brake system (or whatever it's called) to be incorporated i think. And as such, it allows for the H1 to have 16" of ground clearance. Many people use the H1 as an example of independent suspension superiority. Yeah, over a few terrains, it is true. However, over most terrains here in the USA, solid axle is far superior (for reasons mentioned above). In addition, when was the last time that you saw a suspension design like H1 on a civilian vehicle? None exist because there are waaayyyy too many compromises in the H1 design. (Hint: just sit in one and you will see!)

Thanks, that makes perfect sense. I guess the military would just bomb it flat or use armoured earth movers rather than crawl over rocks There's no doubt about the ride/handling in desert envir and no doubt about the ground clearance.

I'd really like to see a Land Rover system designed with off-road as priority 1 rather than a bunch of added on tricks to make IFS/IRS tolerable off-road (that's how I see the Land Rover system). Does the H1 use that type of system to simulate axle articulation?

The ground clearance is definately an attractive feature. All the reasons you listed offset that in most places though...

:cheers:

 

[Thai]

Re: Re: Re: Re: Re: Pros & Cons of IRS for Off-Roading

Does the H1 use that type of system to simulate axle articulation?

No...H1 has horrible articulation. Thus, it really needs its lockers.

 

[techno]

Re: Re: Re: Re: Re: Pros & Cons of IRS for Off-Roading

I'd really like to see a Land Rover system designed with off-road as priority 1 rather than a bunch of added on tricks to make IFS/IRS tolerable off-road (that's how I see the Land Rover system).

They do... we just live in the wrong country.
http://www.landrover.com.au/au/en/Vehicles/New_Defender/Defender_overview.htm

 

[CJ3Flyr]

Re: Re: Re: Re: Re: Re: Pros & Cons of IRS for Off-Roading

They do... we just live in the wrong country.
http://www.landrover.com.au/au/en/Vehicles/New_Defender/Defender_overview.htm

That's cool :bigok: I knew that existed, I was referring to the independent suspension system. The Defender uses a solid axle F&R. We all know that works off-road

:cheers:

 

[fourwd1]

Re: Re: Re: Re: Pros & Cons of IRS for Off-Roading

Just remember why the H1 was made and where it was designed to function. ... Independent setup also allows for the portal brake system (or whatever it's called) to be incorporated i think. And as such, it allows for the H1 to have 16" of ground clearance. ...

Portal axles, like those used in Uni-Mogs and Volvo heavy trucks, provide additional gearing (reduction) at the wheels, and increased clearance as a dividend.

 

[Thai]

Re: Re: Re: Re: Re: Pros & Cons of IRS for Off-Roading

Portal axles, like those used in Uni-Mogs and Volvo heavy trucks, provide additional gearing (reduction) at the wheels, and increased clearance as a dividend.

Very true. In the H1's case, the gear reduction is not that much. In fact, the crawl ratio on the h1 is very average. Of course, with it's torquey diesel engine, this is not a problem.