Thinking out loud about suspension design

[briwayjones]

I like a lot of people find the IRS on 3rd gen X's disgusting. The fact that it's a glorified mini-van. The lower ground clearance, smaller articulation, less strength, more complex design, more expensive, inability to lift, ect. And basically all for just a better ride.

Anyway I was just thinking about design. What if the solid rear axle in the 1st, 2nd gens were hinged like in the picture? But the rest is the same. Leaf springs, everything the same but the hinges. I would think it would give better ride, but maintain the articulation, off road capabilities and strength as long as the hinge points are strong enough? What do you guys think? I'm not proposing I'm going to do this or anything I was just thinking because I'm all about design. You know like what if Ford engineers did this?

 

[IZwack]

Ah finally we see your idea

But I think if a straight axle was hinged right at the edge of the housing, it would get severely complex as a U-joint or a CV would need to be placed there in order to allow the axle-shaft to flex.

Also, another type of "suspension" would need to be placed near the center to allow the axle to return back to its normal "state" after flexing at the hinges.

 

[HappyGilmore]

i also think that the springs would have to be slightly at an angle becuase the tires are now goign to cycle in towares the middle of the car, like an i beam. or you could convert to coils....

 

[briwayjones]

Ah finally we see your idea

But I think if a straight axle was hinged right at the edge of the housing, it would get severely complex as a U-joint or a CV would need to be placed there in order to allow the axle-shaft to flex.

Also, another type of "suspension" would need to be placed near the center to allow the axle to return back to its normal "state" after flexing at the hinges.

Yeah there would have to be a U-joint or CV I was taking that as a given to make that design to work.

 

[briwayjones]

i also think that the springs would have to be slightly at an angle becuase the tires are now goign to cycle in towares the middle of the car, like an i beam. or you could convert to coils....

It seemed like to me when I've seen pictures of the solid axles in extreme articulation that they go in towards the center of the car anyway?

 

[Turdle]

Excuse me for thinking out loud.
It seems the only time a solid axle travels straight up and down is when BOTH rear tires are traveling in the same direction. If one is higher than the other, the travel path is now an arc---correct? With a hinge ( joint) there, the arc doesn't affect the opposite wheel. I am assuming a straight axle beyond this point--not a true ifs setup which has another cv joint at wheel end of axle.

This would allow much more flex I think, just visualizing in my head.

 

[IZwack]

Here you go, threw this together really quick:

Basically, your idea is turning out to be a floating-housed IFS design. Floating in that the differential housing is not fixed, and housed because the CV are housed instead of being exposed.

BTW, I forgot to make the axle tubes in my render bigger -- cauz the ID needs to be at least as large as the OD Of the CV/U-joint assembly.

 

[briwayjones]

Excuse me for thinking out loud.
It seems the only time a solid axle travels straight up and down is when BOTH rear tires are traveling in the same direction. If one is higher than the other, the travel path is now an arc---correct? With a hinge ( joint) there, the arc doesn't affect the opposite wheel. I am assuming a straight axle beyond this point--not a true ifs setup which has another cv joint at wheel end of axle.

This would allow much more flex I think, just visualizing in my head.

Exactly no CV at the wheel. The wheel would be mounted the same to the axle.

 

[Turdle]

Here you go, threw this together really quick:

Basically, your idea is turning out to be a floating-housed IFS design. Floating in that the differential housing is not fixed, and housed because the CV are housed instead of being exposed.

BTW, I forgot to make the axle tubes in my render bigger -- cauz the ID needs to be at least as large as the OD Of the CV/U-joint assembly.

wow
that is actually very sexy

 

[briwayjones]

Here you go, threw this together really quick:

Basically, your idea is turning out to be a floating-housed IFS design. Floating in that the differential housing is not fixed, and housed because the CV are housed instead of being exposed.

BTW, I forgot to make the axle tubes in my render bigger -- cauz the ID needs to be at least as large as the OD Of the CV/U-joint assembly.

That spring configuration looks like it would work too. Now that I think about it the diff. housing would have to be fixed like in a IRS for it to work right. How'd you throw that together so fast?

 

[IZwack]

That spring configuration looks like it would work too. Now that I think about it the diff. housing would have to be fixed like in a IRS for it to work right. How'd you throw that together so fast?

No it doesnt have to be fixed. You can still have leaf springs suspending the entire thing near the outer ends of the axle tubes. I just didnt include this into my render because I assumed that we all understood that leaf springs were still being used.

I threw it together really fast because I already had a model of a diffferential (given its a Dana 44 diff and not a Ford 8.8 diff ). So I just had to model the parts you described. The whole thing was done in Alias|Wavefront's Maya software.

 

[Rick]

I would think that would handle horribly with the massive camber change your going to get as the axle travels.

Might as well just swap to an IRS rear from an Explorer or Expedition.

 

[briwayjones]

I figured there were still leaf springs there. The thing is with the coil overs there also I think it would prevent the axle from flexing at the hinge points for the most part and turn it back into a solid axle more or less. Plus it would still allow the diff. house to flex down and in weird angles since there is a hinge on both sides and the housing is not fixed.

 

[IZwack]

I would think that would handle horribly with the massive camber change your going to get as the axle travels.

Assuming that the coil-overs are "tuned" so that the two axle tubes are perfectly inline with each other at ride height, the camber should be at zero.

But you're right, throw a few sandbags in the back and the camber will go out of whack.

However, I guess one could have a "lock out" to basically turn the axle into a solid-axle design when needed. This lockout could either be in the axle itself, or shocks can be built to have a "lockout" feature to stop them from compressing. But again, the complexity of the design increases.

 

[410Fortune]

what you are designing here is alot like a center mounted a arm suspension, diff in the very center, long upper and lower arms with cv axles, similar to trophey trucks..

works very well

People will argue the solid axle is better for traction, which it is (airborne tire forces planted tire into the ground = more traction) but thats why we have long travel sway bars....

 

[5.0 ANDY]

this idea is kinda sounding like an indipendant suspension, but also like a solid axle. guess u could call it a hybrid.

if only ford designers actualy came up with something good they might of thought of this.

 

[section525]

Dimple die that shiznit, Harold!

 

[Rick]

Assuming that the coil-overs are "tuned" so that the two axle tubes are perfectly inline with each other at ride height, the camber should be at zero.

But you're right, throw a few sandbags in the back and the camber will go out of whack.

Right, at ride height camber is zero, but for an offroad truck traveling at high speed, or even for rock crawling the wheel will be cycling throughout it's travel and the camber will be constantly changing forcing you to ride on the edges of the tire.

 

[CougarX]

There is one reason that this wouldn't work though, at least while retaining the leaves. When the center hinges pivot, it is going to cycle the ends of the axle tubes through an arc. Two lines of opposing arcs get closer together the further away from the centerline that you get. This would cause the leaf springs to be pulled towards each other, which would cause one of two things: either broken springs/spring mounts, or limited gain in suspension travel since the leaves would limit the amount the the differential hinges can rotate.

In addition to this, this design, along with any decent amount of torque (especially in low range) would give a whole new meaning to the term "axle wrap." since the center of the differential isn't hard mounted and can rotate around the two 'hinges'

 

[CougarX]

Right, at ride height camber is zero, but for an offroad truck traveling at high speed, or even for rock crawling the wheel will be cycling throughout it's travel and the camber will be constantly changing forcing you to ride on the edges of the tire.

If using hinges at the very edges of the carrier, the effect wouldn't be that much worse then the front end of a Ford TTB. The longer the pivot point is away from the wheel, the greater amount of travel you can get with less camber change.

1000th post! Woohoo!. Been here long enough, I just read a lot more then a write