its a lot better on the road i guess. all the solid axle trucks i own/owned drive like ass down the street
IFS will generally have the advantage in ride quality. Theres no denying that when both wheels can react to bumps independently, the ride can be quite smooth, however, thats not to say that a solid axle can't have a relatively smooth ride. With few exceptions, most trucks on the market, these days, have an independent suspension only at the front. Most trucks still use a solid rear axle.
Back in the days of the land yacht , those big Caddys, Lincoln's, Imperials, etc. all rode very smoothly, almost like they floated on a cushion of air, like a hover craft. All of them had IFS, but they also rode on solid rear axles. Some of todays trucks can offer a pretty smooth ride using the same basic set-up of IFS and solid rear. What makes a vehicle ride well isn't just the type of suspension used, but the springs that supports the vehicle. There were some trucks that had both front and rear solid also that did have a smoother ride, like some Land Rovers.
The solid axle has gotten a bad rap for ride for quite some time, but I don't always fault the type of axle being used. But the rest of the suspension supporting the axle may have been designed wrong. In stock form many of the older trucks that used solid axles also tended to have very little upward wheel travel, and the axle hit the bump stops frequently. The springs were sometimes too stiff for the expected load. Not only that, but if you went to a lift, some lift kit manufacturers used lift springs that were overly arched, or coils that were of a larger diameter. These things created a rough ride. OTOH, there's been a few IFS rigs that should have had a smooth ride but didn't.
Everything is relative, an IFS typically has the ride advantage, but solid axles are known to deliver relatively smooth rides too. IFS can also have a worse ride than it should too. I've driven IFS equipped trucks that rode like lumber wagons.
Thanks Ed, that's a pretty amazing response. ^O_O^ I think there should be a Reference Library of great posts on certain topics and that would be one of them.
Thank you
So in a nutshell, the solid axle is alot closer to 'self contained' - if i'm upping the strength, other than maybe changing the spring pads there's not much else that absolutely needs to be altered. Whereas the moment I start modifying the IFS beyond stock design (like longer arms that get more articulation) all the little parts and upstream stresses start needing further upgrades, weight of components change possibly needing other upgrades, etc.
I don't know if I can say that the solid axle is more 'self contained'. But I will say that, solid axles are generally very durable and have huge aftermarket support. The Dana family of axles in particular, is essentially the small block chevy of axles.
Every part of any Dana axle can be changed or altered, upgraded or simply replaced with a bigger model. Theres also huge support for other axle makes such as the popular Ford 9", the GM 14 Bolt, or Rockwells, so that you can build virtually anything using these axles as a base. Current IFS axles do not have no where near the support or adaptability of a solid axle. In the last few years some manufacturers have been coming up with better parts for these axles, but if you change a part somewhere, you can be pretty much on your own elsewhere in the system. And some parts simply don't exist yet, such as lock out hubs or a free spin system, to get rid of those cruddy wheel bearings. Nor are they economically adaptable.
Does unsprung weight notably change fuel economy? I know weight in general does around town, just wondering if an IFS 4x4 would get better mileage towing for instance or in extended highway travel.
In a nut shell unsprung weight can change fuel economy. The advantages are minimal but as you said reducing rotating mass will require less power to turn, thus saving fuel. In terms of suspension design, most manufacturers have gone to IFS because there is some weight savings that can be made. It's like front wheel drive cars. This design configuration has reduced weight because the axle and the tranny can be combined in a single, lighter package. Solid axles have to be heavy because the axle is designed not only to transmit power to the ground, but bear the weight of the truck, cargo and passengers. The IFS can be made lighter thus saving fuel because the axle only needs to transmit power to the ground, the vehicle, cargo and passengers are supported by the IFS suspension.
Ed
