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hogdriver · 11-08-2012, 05:56 AM

I stopped by the Spartan factory display at the Good Sam Daytona rally last week and was chatting with a factory rep who was with that nifty 25 ft long bare chassis. I mentioned I just purchased a 2013 Aspire and was asking some comparison questions to my old Monaco/Freightliner setup.

IFS vs Straight Axle - Of course the IFS is nicer ( more expensive) but they said the ride down the highway is not much different. The IFS difference is mostly in "handling". They said on a rutted road or maneuvering the IFS is better. On an Interstate highway they thought both would ride about the same.

Disc Brakes vs Drum Brakes - Very Interesting. The Rep said disk brakes stop shorter. Spartan chassis come with combinations of brakes depending on the manufacturer. The interesting part he said was it depends on how much you drive it. The problem with all disk brakes is the parts and disks tend to rust and unless they are exercised they can bind or rub. An RV in storage a lot is susceptible. He said drum brakes will last longer and can clean themselves when the shoes get above 1200 F when braking.

FYI....pop in someday on those guys, they seemed very friendly and informative

Route 66 · 11-08-2012, 07:26 AM

I'll respectfully disagree. IMHO, IFS is superior under all conditions.

Quote:

Originally Posted by hogdriver

IFS vs Straight Axle - Of course the IFS is nicer ( more expensive) but they said the ride down the highway is not much different. The IFS difference is mostly in "handling". They said on a rutted road or maneuvering the IFS is better. On an Interstate highway they thought both would ride about the same.

hogdriver · 11-08-2012, 08:04 AM

I don't disagree with you. I'd prefer IFS. I'm just pointing out what the reps said.

Cruzer · 11-08-2012, 08:04 AM

I've driven the Aspire with solid axle and the Anthem with IFS and on the smooth blacktop roads there was no difference. Both of these were Spartan. On my previous 2004 Allegro Bus I had a solid front axle under a Freightliner chassis while my current Allegro Bus has IFS under a tag axle Spartan chassis. Huge difference between the two, although I can't differentiate whether the improvement is tag axle IFS versus non-tax axle solid front axle or if it's a Freightliner versus Spartan thing. I suspect it's a bit of both but that's just my opinion.

IFS has advantages. Whenever you hit a bump or dip in the road, the suspension will try to keep the wheel in contact with the road. At the same time it will try to keep your chassis floating along in a smooth line. That's what the springs and shocks are for. What the shocks have to deal with is unsprung weight, which is everything beneath the springs. That's the part that needs to bounce up when you hit a bump without making the coach bounce the same amount. In an ideal world the spring allows this to happen without affecting the coach and the shock absorber controls the jounce and rebound so that it happens smoothly and once, not repeatedly porpoising back and forth. However, nothing is perfect so the ideal world thing doesn't happen in reality and you get some bounce and shock tansmitted to the coach.

The biggest factor is unsprung weight. A heavy solid axle that starts to bounce needs some good shock absorbers to control it. Make the shock absorber valving too loose and it porpoises. Make them too stiff and it rides like a lumber wagon. An IFS suspension has less unsprung weight so it's much easier to control that and you get a better ride.

If the bumps are little you won't really notice the difference between a well tuned solid axle versus an IFS front end. But, once you start getting into seriously rough roads or encountering potholes, the IFS is superior. Not only does it have less unsprung weight (which is one reason why aluminum rims are better than steel by the way) but a pothole only affects one wheel and leaves the other alone. With a solid axle the axle dips and transmits the effect to both wheels which makes it that much harder for the shock absorber to do it's thing.

A secondary benefit is when you encounter anything at an angle, such as a driveway approach or speed bump. With IFS you'll navigate that one wheel at a time. With a solid axle you'll tilt the axle and cause the coach to rock from side to side. The IFS coach will go over any angled obstruction with much lean lean or rocking.

Lastly, IFS is better should you ever experience a steer tire blowout. A solid axle requires some serious manhandling to keep it going straight but IFS requires far less effort.