TED_fiestaHP
TED_fiestaHP Reader
April 10, 2017 9:34 a.m.

you can get threaded ends that weld into tubing, then thread in a rod end.

Pegasus sells the threaded ends, I tend to get all the steel from aircraft spruce. I am sure there are other sources for the threaded ends.

If you make one end right hand thread and the other left you will have some length adjustment without having to remove/disconnect  either end.

 Normal driving the leaf spring would be fine, but to prevent binding, you want a panhard rod.
JGRAHAM New Reader
April 21, 2017 8:47 a.m.

Getting back after it this weekend. I got the bed pulled this week so I can get better access to the rear suspension. I told myself I wasn't going to invest much time in the solid axle, but I just can't stand doing things 1/2 way.

When I pulled the extra leafs out of the springs packs the other week I could tell it really made the truck much more planted in turns. The truck didn't want to slide around nearly as much. By reducing the the spring rate though the rear end now has terrible wheel hop. I'm getting way more axle wrap than the OEM ford explorer traction bars can handle. The leaf spring bushings are also near shot. So the upcoming rear end "To Do" list will be:

1) adjustable traction bars 2) adjustable pan hard bar 3) urethane leaf spring/shackle bushings

What a dirty chassis

Bed off with 6 bolts and a tailight plug

Dusterbd13 UltimaDork
April 21, 2017 8:53 a.m.

Can you show me how the oem traction bars work/mount? May be a solution for the challenge car.

APEowner Reader
April 21, 2017 9:29 a.m.

Do you have lowering blocks on that? If so getting rid of them and de-arching the springs or moving the front spring eyes up will go a long way towards getting rid of the wheel hop. I wouldn't be surprised if moving the front spring eyes up matches the front roll center better. Really, there's no reason why you couldn't get that leaf spring setup to handle really well.

Spherical bearings in the front spring eyes so the spring is just a spring and not an anti-roll bar/spring combo.

Get rid of the lowering blocks to reduce the leverage that the axle has to wind up the spring.

Switch from shackles to sliders in the rear so the roll center doesn't change as the car rolls.

Move the right hand shock to the front of the axle to control wheel hop.

You may need to add an adjustable rear anti-roll bar to compensate for the front spring eye change.

I've used that combination on circle track cars on both dirt and asphalt as well as on the 640 HP road race Camaro in my avitar

JGRAHAM New Reader
April 21, 2017 10:03 a.m.

I'll take afew photos of the stock Explorer traction bars.

APEowner,

I don't have lowering blocks. It would't be hard to move the front spring eye mount. Do you think moving it up 1" would make a big difference?

APEowner Reader
April 21, 2017 11:34 a.m.
JGRAHAM wrote: I'll take afew photos of the stock Explorer traction bars. APEowner, I don't have lowering blocks. It would't be hard to move the front spring eye mount. Do you think moving it up 1" would make a big difference?

It'll make a big difference but whether or not it'll be an improvement will depend on where the roll center is on the front suspension. The closer you can get them to each other the more predictable the results of future adjustments will be. That's also the benefits of the other spring eye modifications.

Because shackles move in an arc the height of spring eye changes as the suspension moves and therefore the roll center also changes. With a conventional bushing in the front spring eye the spring twists as the body rolls adding an anti-roll component. So, you make a change like softening up the spring to improve rear grip that also makes the roll center move more and reduces the anti-roll even more than a softer spring normally would. Before moving the front spring eye you should either figure out where the roll centers are or I suppose you could make at adjustable and move it around until you're happy.

As I'm typing all of this it occurs to me that I should mention a downside to making the changes I'm suggesting. Once you've got everything moved around and adjustable you're going to have to adjust it. If you're happy with the balance and the grip that you've got now and you just want to get rid of the wheel hop you might be happier if you just invest in some adjustable shocks and move the right side one so that it's in front of the axle.

bluej UltraDork
April 21, 2017 11:53 a.m.

In reply to APEowner:

That's some great info, thank you!

JGRAHAM New Reader
April 21, 2017 12:08 p.m.

Thanks for the info! I'm going to take a good look at what I have tonight. I need to see what else would be affected if I raise that spring mount a little. A lot of things could potentially need to be adjusted; pinion angle, ride height, sway bar clearance, shock travel, etc, etc.

Nessumsar New Reader
April 21, 2017 5:41 p.m.

QFT.

APEowner wrote: Do you have lowering blocks on that? If so getting rid of them and de-arching the springs or moving the front spring eyes up will go a long way towards getting rid of the wheel hop. I wouldn't be surprised if moving the front spring eyes up matches the front roll center better. Really, there's no reason why you couldn't get that leaf spring setup to handle really well. Spherical bearings in the front spring eyes so the spring is just a spring and not an anti-roll bar/spring combo. Get rid of the lowering blocks to reduce the leverage that the axle has to wind up the spring. Switch from shackles to sliders in the rear so the roll center doesn't change as the car rolls. Move the right hand shock to the front of the axle to control wheel hop. You may need to add an adjustable rear anti-roll bar to compensate for the front spring eye change. I've used that combination on circle track cars on both dirt and asphalt as well as on the 640 HP road race Camaro in my avitar

What is the front eye diameter? I might have an off the shelf solution for the spherical bearing:

If you can get the leaf pack close to flat at ride height you could also put a stubby flat overload leaf on the bottom of the pack that would work like a traction bar, but not bind the suspension like a traction bar. We do that on our GM leaf springs and I run them on both of my Novas with zero wheel hop, you can kind of see it here:

JGRAHAM New Reader
April 24, 2017 6:23 a.m.

Here are a few photos of what I did with the stock Ford Explorer traction bars. I don't need them anymore so your more than welcome to get them for your project.

I don't think I'm going to raise the front spring eye location at this time. There's a fair amount of tweaking to get all the other things back right and I'm ready to race this thing.

I've got the urethane bushings on order but those spherical units look really nice. Nonetheless I'll let you know what size the spring eye is. If they're reasonable enough I'll swap them out.

Great idea on the overload springs. I originally had them in the spring pack, but took them out when I pulled the extra leafs. I didn't think at the time they would serve much purpose. I'll be adding them back this week.

Pan hard bar I got fabbed and installed this weekend.

new front traction bar mounts also got welded in. The actual bars will have to wait until I get the bushing ends and heim joints.

...and done with the fab work for the day.

I also got to try out the new foam cannon.....man this thing is nice!

Nessumsar New Reader
April 24, 2017 6:22 p.m.

Having never seen your truck drive, I doubt you want the panhard rod above the axle. That will put your rear roll center pretty high which on a leaf spring application you don't really want (typically). Panhard rods are typically run below the axle, somewhere around 8-10" high, to get the roll center lower and compensated with a larger RSB to help work the inside tire more.

We're you looking for more, or less rear end grip?

JGRAHAM New Reader
April 24, 2017 7:41 p.m.

You know your right about the pan hard bar height. I had googled what a few others had done to their 8.8 rear ends and ran with it. I didn't really think about how much it would affect RC. For simplicity sake it was the easiest route to get a pan hard bar on and I ran with it in my hast.

I got the traction bars mounted tonight and I'm still having way to much wheel hop.

When the spring bushings come in I'll take the leaf packs back off and reinstall the overload springs as well as an additional leaf. This two leaf spring pack might simply have too little of spring rate.

Dusterbd13 UltimaDork
April 24, 2017 9:52 p.m.

Take a look at a half leaf above the main leaf, and clamping the front of the pack. Works well in other applications.

appliance_racer
April 25, 2017 6:50 a.m.

You know if you finish up what you've got going on here maybe you won't even want to swap in the IRS? I agree you'll probably need to move the pan hard to the lower side of the axle. Once you get it sorted with spring rate, bars, etc this set up will probably work very well. I know the argument on the fox and SN mustangs between the IRS and SA really seem to come down to driver preference with the IRS maybe juuust a couple tenths quicker over a lap of a road course.

Of course if you want the IRS for cool and different factor I totally get it.

What is this foam cannon you speak of? It looks to be something I must have.

JGRAHAM New Reader
April 25, 2017 8:44 a.m.

Thanks all for the help and insight. Last night, with the help of a good friend I believe we maybe have hit on the issue. The pinion angle for whatever reason is at nearly 1 degree of positive angle (with respect to the driveshaft). It will be at even more with the bed back on. I had to verify my angles again this morning, but that definitely can't be helping matters. I'll be installing some 6 degree shims to test this thought.

What pinion angles are on your leaf spring setups? The internet seems to suggest 4-7 degrees of negative angle is ideal.

Appliance Racer,

I think your right and you know, I kind of like the thought of not having to re design the whole back end this winter either!

The foam cannon was bought off Amazon for like 25 bucks. Load it up with car wash soap, hook it on the end of your pressure washer and foam away.

Sky_Render SuperDork
April 25, 2017 10:09 a.m.

I think your panhard bar is a bit short, but I'm not sure how you could install a longer one.

Basically, if your panhard bar is long enough and you're using rod ends, you will get more lateral deflection from the tire carcass than you will from the axle.

I constantly have this argument with people who swear that your car cannot be fast without a Watts linkage, which just isn't true. The only advantage of a Watts link over a properly-setup panhard bar is adjustable roll center. And you can even adjust the roll center with a panhard bar if you get the right one.

APEowner Reader
April 25, 2017 11:20 a.m.

If you're going to run a panhard bar you really should mount it so that it matches the existing roll center. If you don't then it's going to stiffen the rear suspension as it rolls in a non-linear way and possibly even come to a full bind. I'm not really a fan of panhard bars on cars that turn both directions anyway because they tend to effect the suspension differently depending on which way you're turning. They're generally better then the lateral movement that you get from side loading the spring shackles and front bushings but a Watts link is better still. If you run spherical front eyes and spring sliders you may not need anything additional to locate the axle laterally.

Sky_Render SuperDork
April 25, 2017 11:55 a.m.
APEowner wrote: but a Watts link is better still.

Prove it. A properly-designed panhard bar has less lateral deflection than the tires under cornering.

FlightService MegaDork
April 25, 2017 12:05 p.m.
Sky_Render wrote:
APEowner wrote: but a Watts link is better still.
Prove it. A properly-designed panhard bar has less lateral deflection than the tires under cornering.

I will be the contrarian on this one.

YOU prove it. How long does a panhard bar have to be to provide less lateral deflection than the tires the user is using for the given suspension travel? Is there enough room in the application to have that much room?

It is widely known why and how a Watts Link is better than a panhard bar, so the burden is up to you to prove why your solution is better and/or functionally equivalent.

Just like in school, be sure to show your work.

Sky_Render SuperDork
April 25, 2017 12:12 p.m.

In reply to FlightService:

How about this video from Maximum Motorsports?

https://www.youtube.com/watch?v=I4ZjBnXQum8

In that video, they show that lateral deflection of a panhard rod is less than 0.079”, compared with the tire's deflection of 1.75".

FlightService MegaDork
April 25, 2017 12:18 p.m.

In reply to Sky_Render:

Nope.

You made the statement you get to show the math.

I know the math. You need to show the math for your argument with respect to THIS application.

Helpful Hint: Given the information in this thread, you should list your assumptions.

Sky_Render SuperDork
April 25, 2017 12:31 p.m.

Did you even watch the video?

If you make the panhard bar closer to the width of the chassis (see my length comment above), you will get approximately 0.050" of lateral deflection over 2" of suspension travel. (My figures are based on a Mustang, here, with a panhard bar length of 38".) Tire deflection is nearly 2". In other words, the lateral movement caused by a panhard bar's arc is irrelevant, because it is orders of magnitude less than that caused by the actual tires.

Sky_Render SuperDork
April 25, 2017 12:42 p.m.

Since you want calcs, here we go.

Assume: a 38" bar and 2" of suspension travel.

We'll have a deflection of about 3 degrees on that panhard bar with a compression of 2".

Taking the Sine of 3 degress gives us 0.052".

Like I said, far less than tire deflection.

So, if the OP can get his panhard rod closer to 40", he could forgo the use of a Watts link.

JGRAHAM New Reader
April 25, 2017 12:51 p.m.

I'll add some of my own setup dimensions.

The Ranger's panhard bar is 24" long I have 4.5" inches of travel

That means I have .1057" of side movement induced by the 24" panhard bar.

My work is shown below:

For curiosity sake I increased the bar too 36" (which I'd never be able to fit one that long)

The side movement decreased to .071"

In all honesty, driving the ranger blindfolded I highly doubt I'd be able to tell if it had a 24" or 36" long bar installed.

Sky_Render SuperDork
April 25, 2017 12:52 p.m.

Nice! Even the tenth of an inch of lateral displacement you get with that 24" bar is pretty small; even R-comps are going to deform more than that.

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