I can already tell you what happens, I weigh 300 lbs and I've done that to a lot of quads, that's how I check the suspention before I buy them. The Honda Rincon squats about 6 inches or more, My Brute Force squats about 2 inches, the Polaris 700 EFI doesn't squat at all. All of those have IRS and react completely different to my dropping weight on the back of the rear rack. The Prairie 700 squatted about 2 inches, that one doesn't have IRS. I don't see any connection to IRS and squatting.

 

I have rode them both quite a bit last week, The Brute Force is unbelievable! Go with Brute Force

 

I don't know about a 46 year old man, but this 44 year old man recommends the Brute Force!!!

 

HEllo, I just bought the brute force 650. I didnt want the IRS. I like the solid axel. I have ridden the grizzly alot also. The grizz is nice, But i like the features of the kawai and the cost of the kawi better.

Just my .02

 

GREAT CHOICE; IMO you got the best buy on the market (Great Bang For The Buck)

 

My money would go on BF750 but would wait a bit until 2006 edition comes out.
I had a 2002 Grizz and was awesome machine until I rode my P700 and until Yamaha make unbelievable change to theirs Grizz, I will stay away...

 

The IRS machines generally have longer suspension travel; if you don't get more suspension squat with a longer travel suspension, the spring preload is is too high. The squat shows that the suspension is working; if it squats too much when hitting the throttle (to the point of almost bottoming out) you need more preload or heavier valving in the shocks.
The reason the Sportsman doesn't squat just by adding weight to a stationary machine is because the rear wheels move outward more than most machines as the suspension moves. Add 300lbs to the Sportsman as its rolling and you will see it squat.
300lbs directly on the rack of my P650 will put it within an inch of completely bottoming out.

 

Okay I'm coming from left field on this because it's not on your list but why not check out a Suzuki King Quad? IMO the BF is a nice quad as is the Grizz but the KQ will give you more power than the Grizz without the worry of flipping over with the power of the BF. IMO it would be a better quad for an older man. Can't go wrong with any of the three though. Good luck on his choice.

 

Well kfx40012tbirds, I’m older than your dad and I own both the Grizzly and the Brute Force and I enjoy them both, but for different reasons.

The Grizzly is more comfortable (softer seat, more suspension travel and softer ride), can be driven slowly over technical (especially rocky) terrain easier than the Brute, the CVT is more durable, the 4WD activation system is better than the Brute and the diff lock system is better for extended use but you have to stop in order to engage it.

The Brute Force has a stiffer suspension and feels more composed when landing jumps, the engine music is a lot nicer, has a significant power advantage over the Grizzly, can wheelie easily in low range, the CVT is more easily tunable (by changing springs / weights) for those that need to change it, the engine braking effect is better and the diff lock can be activated (when in 4WD mode) on the fly by pulling and holding in a handlebar mounted lever.

To further elaborate on some of these statements, the Grizzly is better on slow, rough terrain because of the softer ride and less power on tap that can result in an undesirable situation if the throttle were blipped unintentionally (which might happen when bouncing over boulders).

The Grizzly will switch into 4WD immediately at the push of a button (while stopped or moving, in forward high, low or in reverse) whereas the Brute seems to require some forward motion in order for the 4WD to engage after the switch is toggled and it only seems to engage while in forward high or low (if reverse is needed you can shift into reverse after 4WD has engaged in one of the forward gears).

To use the Grizzly diff lock (after the machine is already in 4WD) you uncover the activation button by sliding the cover sideways then push the activation button (while the machine is stopped). On the Brute Force once the machine is in 4WD all you have to do is pull in the diff lock lever (using a finger or two of the left hand) even while the machine is moving to activate 4WD diff lock mode. To disengage all you have to do is let go of the lever.

As for the CVT my Grizzly has over 2500 hard miles on it and no belt issues have surfaced so far. The Kawasaki system seems to require more frequent maintenance (belt tension adjustments) and care must be taken as to not burn out the belt (by using low range instead of high in rougher, slower situations whereas the only time I use low range on the Grizzly is when towing heavy loads or going down steep, technical hills).

So it all boils down to what your dad is looking for in a machine. As for me, I’m glad I have them both but most of my play time these days is spent on the Brute and all of the heavy work (such as dragging logs out of the woods for firewood processing) I save for the Grizzly...