rear suspension mods.

[IDIoit]

I disagree. Completely.
The reason you need the driveshaft to be telescopic is due to the up and down travel,
The flex you speak of from the front of the leaf spring to the axle is what creates wheel hop.
This is why the SD traction bars mount to the axle center point to the frame in front.
The rear shackles handle what you're thinking about.

 

[txbronco]

Ill Take some better pics sunday.

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[txbronco]

They hook up good. You can tell the difference
Like night and day.They pivot so i dont have a
problem when loaded.The spring hanger is
located just in front of the large hole on
the traction bar.It is fixed so all the flex happens
on the rear hanger.

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[IDIoit]

nice! thanks for the pics! i will be building something like these.

 

[franklin2]

Those long bars in the pictures above; I know most people try to mount the front of those long bars on the frame inline with the front u-joint. Let's say they did do that, and got them perfectly aligned with the front u-joint pivot point. Looking from a side view, you could not see the driveshaft because the bar was perfectly in sync with the driveshaft location.

If you did that, then would you still need the slip joint in the driveshaft? The rearend is still going up and down. If you tied the rearend directly to the frame with those bars, why does the driveshaft need a slip joint and those bars don't?

 

[IDIoit]

i attempted to make a diagram, if i had you here, i could sit you down at my drafting table and show you more throughly.

every rearend uses a means of location, either that being leafsprings, 4 link, 2 link( +panhard for side to side location)
this keeps the rearend in a specified location, you dont want the rear wheels to beable to walk, you want them at a set distance so that your car will travel straight down the road.
this is why you never see a leaf spring car/truck with shackles in the front of the leaf spring, only the rear of the leafs.
this is just 1 part of the equation.

the 2 nd is suspension movement, as you go over bumps, uneven terrain, and torque you want to create the least amount of load on the chassis and occupant.
this is where leafs are the most versatile. you can locate the rearend, and have a set type of ride all in one.
with this flex, according to where you have the rearend located at, creates an arc. your leaf springs, coil springs, and coil overs do there best to keep this arc to a minimum
none the less, there will still be an arc.
with any arc, the lateral dimension will change, granted ever so slightly, but it will change.
a U-jount and thin walled driveshaft will not beable to handle this stress.
so as the rearend goes up and down while your driving down the road, the driveshaft slips in and out to compensate.

hopefully i explained that well enough for ya to understand.
to me its alot easier to look at a diagram, but i could not find my damn chassis books.

i know you still have a question.

"what about the front leaf spring perch and the traction bar creating 2 different kind of arcs?"

yep. thats exactly what its doing. they are working aginst eachother to eliminate the stress on the leafspring, where the leafspring is trying to flex
thus eliminating "wheel hop"

 

[IDIoit]

heres a more expert way of describing it. im just a rookie, but i have read a few geometry books on suspensions

http://www.4x4wire.com/jeep/tech/susp/axlewrap/

and this is what your rear leaf springs look like under rapid acceleration

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[franklin2]

I agree with you on the axle wrap, what it is, and what causes it. What we still disagree on is the normal axle movement as you go over a bump in the road. You are saying the axle moves in a true arc. That is the point I disagree with. The axle moves in a modified arc. It moves in more of a slight arc, but to the rear also. The wheelbase of the truck actually lengthens slightly as you go over a bump, the leaf spring flattens out and this makes the spring longer, which moves the axle back when it goes over a bump. Here's a picture.

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A lot of people have these bars, and get away with it. I believe what happens when you have these bars is they bring the nose of the rearend up as you go over a bump. As the rearend tries to move a little bit rearward, the new bars mounted on the bottom of the axle resist this movement and actually twist the rearend. Probably all this will do is change the pinion angle, but if it's changed too much and you run around with a load of wood on it, you could get a vibration. It's just not geometrically correct if you think about it,, even though it seems to work for most people.

 

[IDIoit]

I see your point, what I should have said is that it it does move in a true arc with a 4 link or 3 link.
Leaf springs have been around since the beginning of the auto industry, but they are not the most geometrical
Sound equipment.
But for the average vehicle, they work.
Bottom like is that axle wrap and wheel hop SUCK
if this was not a family rig, I would be eliminating the leafs all together

 

[IDIoit]

I just wanna get rid of this damn wheel hop before I put my newborns in it and they spit up all over the place lol

 

[franklin2]

It will be fine if you quit doing wheelies and donuts with it.

 

[IDIoit]

It will be fine if you quit doing wheelies and donuts with it.

whats the fun in that??!!!??

 

[idiabuse]

I just wanna get rid of this damn wheel hop before I put my newborns in it and they spit up all over the place lol

http://www.sulastic.com/

to be more specific

http://www.sulastic.com/sa-06-sulas...RD&model=F-250&year=1987&motor=&viewmode=list

 

[dunk]

Holt stacked blocks txbronco, that's half your problem right there.

If your bushings or shocks are shot, or springs weak that can contribute. Stiffer springs won't wrap and hop around as easy but obviously limit traction and suspension flex and make for a harsher ride. Traction bars are pretty much the only solution. The type that bolt on to the axle probably would likely take some creativity like Franklin mentioned to make work on a truck due to the greater arch in springs. To the frame and you need to make sure everything is moving in the same arc or as close as possible to it but it will stop the axle wrap.

I'm more amazed you have this problem as bad as you imply and haven't mentioned going through a few ZF5s. I just sort of accepted on the 460 truck that there will be no hard launches. Your average Mustang/Corvette/whatever gets me off the line every time but I fly past them chirping on my shifts. I'm more worried about breaking the ZF5 just by looking at it or sneezing, let alone subjecting it to axle wrap so I avoid it. Once I had a new driveshaft made with 1350 joints I started popping transmissions more often than ujoints.

 

[BrandonMag]

http://www.sulastic.com/sa-06-sulas...RD&model=F-250&year=1987&motor=&viewmode=list

I haven't seen those before. They seem like a great way to improve your ride.