Straight rear axle or IRS?

[Dave]

I thought this would make good discussion since we've touched on it in another thread.

I haven't measured details but, most unloaded rear straight axle ATVs have lower ground clearance than an independent rear axle, at the tow hitch area.

Some say the IRS rear squats too low when the ATV is towing or carrying a heavy load.

I believe the IRS rear still has about the same ground clearance as a straight axle ATV.

What do you think and why?

[Eric Wettschreck]

I have a Yamaha big bear 400. It's a straight axle. The tow hitch is about the only thing I don't like about this wheeler. The chunk of steel that the ball screws into is welded right off of the rear axle, and it's way low. I havn't measured it, but it's too low to tow my fish house. I had to Mcgyver an adaptor so I could tow trailers and my fish house.

[Benny]

My cousin from Shevlin claims the straight axle machines will actualy go through more mud than an IRS machine.His thought on this is the SRA machines can be leaned from side to side even if high centered over the ruts, where as the IRS machines are stuck if they get high centered.

When I say leaned from side to side I mean they can lift one tire up while driving the other down into the rut further to get to the solid ground.Or they can get one tire up against the wall of the rut to gain forward traction.

The IRS just hangs its tires down off the center , so you can't get the machine to dig in.

Now I don't promote mud bogging on public lands, there are ATV parks to do this and it is legal there.Or if you have private land that is not a clasified wet land.

Benny

[Sod Farmer]

I did a little test on this not to long ago. I loaded 250# on the rear rack of my 2004.5 Sportsman 500HO. With the rear shocks set on the lightest setting, the rear suspension (with me on board @ 192#)squated 2.75". The Sportsman is rated @ 11.25" of clearance which is not measured at the rear wheels. There is over 13" of ground clearance between the rear wheels. The low point is on the skid plate farther forward. If the suspension squats 2.75" with me and a 250# load, the ground clearance loss is approximately half of the amount of squat (2.75") because of the geometry. The actual ground clearance loss with 2.75" of squat is about 1.5" which gives a ground clearance of 9.75", which is still about 2" more than most of the straight axle machines. If you load the rear suspension with an EXTREME load, ground clearance could become less than a straight axle machine. In deciding which suspension is best for you, you should consider how often, if ever, you would put such an extreme load on the rear suspension.
Sod

[Fisher Dave]

On my Kodiak the trailer ball is right off the rear axle ... there is no suspension squat ... only the tires being depressed.

I prefer this over another machine getting *pre-loaded* (squating)with the weight of a trailer because I still have my full range of suspension with a solid axle, where the IRS suspension will be altered due to the tongue weight depressing the rear. The tongue weight does not affect my suspension.

If I am hauling excess weight on my racks, I can adjust the preloads on the shocks for desired performance .. within the boundaries of the shocks.

One last factor that I like about the solid rear axle .. is less moving parts.. or less things to break in the long run. If I want a smoother ride I will decrease the amount of air in my tires.

The machine I have is a Kodiak 450 (03' model).