Hot Rods The Belly Button Bucket Build Thread

Hard to tell, my phone let's me see the pics you posted, but won't let me blow them up. There "might" be enough room for a setup like mine, the center pivot mounts to the top of the rear housing, your upper bar mount could stay the same, and this is where I can't tell, the lower bar would need to mount just below the upper shock mount on that side (probably using the same mount as the shock, just extended a little lower?). I also agree on the gloss black for the rear, assuming that's going to be the frame color as well? I don't remember what you plan to run at the rear of the body (shortened pickup bed, turtle deck, exposed tank?), but that choice will affect how ugh of the rear you can even see. With the 14" pickup bed, I can barely see my rear end.

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Longer is better with Panhard bars for the same reason, the shorter bar goes through a bigger radius at the loose end, causing more side to side push.


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My buddy has a buggy sprung 27 T RPU, it's been built and on the road for over 20 years now.
These pictures are of the original 20+ year old chassis ( Glasurit 22 line ) paint sprayed all those years ago Same with the body paint.

Anyway, I'm thinking that you may get 3" of suspension travel, that's typical.
He has a rear kick up in the frame and it's tight as in no room which is typical.

The rear end is an 8" Maverick.
He originally built with no rear panhard bar but quickly found that he had to add one to a finished car.
The car would shift sideways due to swing of the shackles as the car reacted to bumps and turns.
This is what he did, it's pretty simple and it works really well.
Maybe this will help?
Larry.

 

Gimpy is right. I came out here this morning and made a quick sketch after taking some measurements. It is much worse than I thought, so THANK YOU for bringing it to my attention. I have jotted down some additional measurements to do some PAD (PencilAidedDrafting), and I will hopefully end up with a replacement for rev Z. Lol.


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If your shackle angle is correct and they are short shackles you should not need a panhard bar.
You are doing a great job BTW!

 

So I have a question, on a transverse spring suspension, where is the theoretical roll center? Is it an imaginary line of where the shackles meet centerline? The center of the axle? The mounting point of the spring (crossmember)? I have read different things. I also have a suspension that roll center in this application is going to be out the window....or more like through the roof...


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The shackles look to be on an excessive angle though.
Looks like the spring is a a bit long for the mount width. She would have to rock a little.

Really nice little P/U!
Nice, stiff frame design. Must be a fun driver!

 

The spring is a relatively flat arched custom made one made in a local spring shop many years ago.
The car rides and handles really well and is a blast to drive and ride in.

It's the car that planted the T RRU bug in my system and is responsible for my build to a large degree.

 

Tim, How much spring stretch do you have when installing your rear spring ? If you have at least 4", you shouldn't need a centering device.

 

I have 3" stretch. From my brainstorming this afternoon, I think I have a solution of sorts. I will do some sketches tonight at work if I have time, but I won't be able to do anything until Wednesday at the earliest. I need to do some more reading that is similar to my application because the conceptual panhard bar sketches, while helpful, do not solve my problem. Thanks to each of you for posting criticism and ideas.


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There is no roll center, per se. It is more of a "roll blob".

Since the lateral links are flexible, it isn't a fixed-point.

It is roughly in the middle, under where the spring mounts.

 

Sketchy sketches of questionable material:



Note "Roll Blob" - I took the vertical distance between spring eyes on axle and center of spring pack on top and cut it in half.... so there's my benchmark.



Rev. aa - not the prettiest. Raises roll center. Have to notch floor. Have a giant bracket sticking up on axle, probably directly underneath my fuel tank waiting to puncture it. Note I said "horizontal displacement" here and "lateral displacement" in the next - I mean the same thing, and that both are a rough estimate using a compass following the arc length of panhard bar for +3" and -3".... also note I highly doubt I will have 3" vertical travel from ride height - I just don't have that kind of room and there will eventually be bump stops in place ~2" above the axle to save my spine...



Rev. bb - a little out there, but functionally superior to all other efforts on my part. Keeps roll center near the "blob", possibly lowers it. No notching floor. I will have to get some more 7/8" x 0.156" DOM tubing as I only have about 18" left. Will need to grab a couple more of those panhard bar mounts to repurpose. Will need to bug Paul to help me bend the tube. Will need to work some sorcery in the gusset department. Overall I like this idea.

Another option is doing what you see above, only below the axle. BUT... that chassis bracket on the right would have to hang WAYYYY down there, and I don't necessarily like that. At least up top it mimics the shape of the spring. Anyway, this is about all the ideas I have. I don't see a way to put a Watts link or Mumford link in there, but I have lots of ideas for the next car in this department! Ok, that's all for now.


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Tim, I really have to say I´m amazed by your skills and attention to detail... That´s a great build and yoiu are doing some outstanding work. I have drawn sketches before , but never in a quilty like yours. I´m more the " grap a piece of maybe long enough tubing from the scrap pile, tack it in and see where I end up " type of guy
That said, don´t you consider running the panhard bar( if necessary at all) under the diff housing, like in the last sketch, but mirrored " south " of the axle centerline?

 

Now we're at 21" panhard bar length, and the roll center has been lowered around 7", but like I said above, there is some massive bracketry hanging down there behind the rear axle to mount the panhard bar. In this concept I drew it as a "ladder bar" style..... not feeling it. I don't like the moment this creates on the rear crossmember, and I don't think a bent up bar hanging way down low will look good from behind...


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I may be onto something here.... if this works I am gonna throw myself a party. Instead of trying to keep the panhard bar mounts on the same plane as the shock mounts, what if I kept them on the same plane as the spring shackles? I would clear the pumpkin out back with no bends, and to do the chassis mount, I THINK I can support it in 3 places: two up top and one down low. I don't know if this one makes sense.... may need to attempt some 3D sketches to get the concept across.



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I like your last thought . Easy to tie togeather . Did something similar on 59 , although wats but could go to frame on other side . Blue

 

Or , have the spring eyes re-wrapped to get to the 4" spread Marty mentions & forget the panhard/locater.......
remember the K>I>S>S> principle

 

You can definitely make a panhard bar fit in there. I agree with the KISS principle as well. Sure you have a little less real estate in there but just think about what the panhard does. It keeps the axle/frame from shifting outside of mild suspension cycling. Having the mounting points for frame and axle level with each other is what you are after. Where you decide to make those points is up to you.


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One other thing you may have been able to do is triangulate that rear ladder bar set up whereby the front mounts are closer to each other. That would all but eliminate the need for the panhard bar.


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I made something like your last skiss.
But i wanted it in front of rearaxle.
To clear the pinion i made the axlemount on top of the tube
about where you have the ladderbar mounted.
And then in a little angle forward to the frame.
I checked the suspensiontrawel carefully by twising the
axle around without the spring and i got no binding.
And its low enuff to not hit my floor.
A few pics to show what i mean.

 

How do you figure that?
I've seen that posted before by others and I think its completely wrong.
For simplicity, lets assume a set of ladder bars that join together and use a single vertical attachment in front.
The whole axle assembly would basicly be able to spin a complete 360 degrees with no resistance.
Theres no limit to the side sway at all.
Use two attachments at front as per normal and eventually binding would limit side sway...but you would still see a foot or more before the binding even started.
Just like a parallel setup.
Besides...you can't use suspension bind up as a limiter.
That just results in parts breakage!

 

Could you weld a pivot on the top of your housing and use a horizontal pivoting panhard arrangement. One horizontal link in the front and 1 link horizontal behind the pivot. Roll center stays vertical no matter what suspension travel is. Most time the pivot is in the center rear of housing and the bars are 1 on top and the other bar underneath, somewhat messy. But on top it would be clean, tucked up away, and you should have room for pivot to clear between housing and frame loop.

If this does not make sense I can sketch something tomorrow.

 

That's assuming you have no other suspension components. In this case and in mine the transverse leaf spring positions the axle as well. Not by itself but in addition TO the triangulated linkage.

So, to say you would see a foot or more sway when the leaf spring does not allow for that makes no sense.







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Forgot to mention, with coilovers a panhard would be a must. That's what I run on my 28

So Cal and Pete n Jakes sell a triangulated ladder bar kit that doesn't call for a panhard and A LOT of people have run them for a long time.


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In an effort to not derail this thread I will step aside and let the OP continue on.

 

That is not a factor of the triangulation of the bars. That is a factor of the tension that the spring was installed under.

The triangulation facilitates far more articulation of the suspension that would be possible if the leading end of the links were farther apart.

No tension, no stability:

 

You said nothing about spring style.
You said triangulating the ladder bars would limit the side sway of the rear end.
A properly installed Model A transverse leaf system doesn't need any other additional bits to locate it side to side, Parallel ladder bar, P&J style.....4 bar...whatever.

 

Agree 100% there.






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I assumed you knew and had seen the pictures from the OP where he was clearly running a transverse leaf spring set up. I thought that was obvious. Anyway, back to the build.




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So I went out to the garage yesterday morning after work to take some measurements, and I think I can make this work. I know there are ways to eliminate the need for a panhard bar, but the way I see it is 1) I don't want to try to splice something in to a finished car, 2) if I can take the "roll blob" from the stratosphere down to somewhere reasonable-and less of a blob and more of a short line segment, why not, and 3) I feel like if I bag the panhard bar the car has beaten me. Lol. So, I tried to sketch this out in 3D on break at work, and it's not as easy as I had hoped! But, something along these lines:




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I'm looking at your sketch and I'm not seeing how this positions your axle in any way? Perhaps I'm missing something or a pic isn't showing up.


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