1931 Chevy Sedan now a TUB NEW INTRO

[berkelusa]

Hey gang, Not NEW just re-born since the forum changes.., Had to make a new account but glad I didnt lose my username...

I posted a few in the test forum to get the "hang of it" so let's try a POST..

and since it now makes me a NEWBIE I decided to do an INTRO POST

Rob in New Hampshire here...
1931 Chevy Sedan way to ROTTED to save as a whole..

So I saved the TIN and built around it "LOW-BUCK" as in NO JOB
Due to a car accident that left me in a wheel-chair for a YEAR!
( Shattered lower left leg, But "NO biggie" I am all better now... )

Let me show you a few pictures from the 190 pages of it's BUILD DIARY

Day ONE



Middle process (the designing years)


Three years later...


(_!_) end...


New sneakers...


Cross-steering Via 70's Nova manual box and Chevy Van I-beam...


Since we converted from leaf-springs to air-ride we needed some Bowtie-Bars!


29-30 Chevy Dash with MOON speedo and 1" thick Oak insert to hold it...


Now I dont want to overload this page with pictures.. So how about reading a little.. Say for the next 3 days?

190 PAGE BUILD DIARY IS HERE:
http://www.ammoman.com/chevy

Glad to be BACK on the RRT !

Rob

[berkelusa]

Rob is just a measly 36!



Boy do I look HAPPY in this picture or what?

hahaha

[Sean]

Looks like you're well on your way. Good to see another "youngster" on here. The old guys will quit picking on us once we outnumber them

[enjenjo]

Looks like you're well on your way. Good to see another "youngster" on here. The old guys will quit picking on us once we outnumber them

Ha, never. by that time you'll be an old guy too.

[berkelusa]

Wanted to mention if you get to a password page ignore it...
Click the tiny DOT in the bottom right corner of the same page (hidden link)

Had a few local MORONS trying to "take over" from the lounge chair...

Now they can watch the paint dry on the walls..

Rob

[berkelusa]

Wire-forming a rear apron from NOTHING...

First wire...


a few more...


a few more...


Wires DONE, Time to SKIN...


Other angle...


Sunken in license plate hole...


Skinning from the inside...


Looking good...


Lower lip skinned.. Time for the top...


One of the exhaust slot from the inside...


Hidden bolt-down points on each end...


SKINNED and 95% DONE ! (just needs detailing)





Backup lights... 12-volt 50-watts each in stainless tube


A thanks to everyone here and to my 100+ 30's Chevy guys on the Yahoo list for keeping me ROCKIN with the daily emails of encouragement that they send...



Regards
Rob

[berkelusa]

Here is the 35' Chevy Truck grill also wire-framed at the bottom as it was ROTTED TO DEATH...

Way before still mounted on the DONOR:


What remained that was save-able now on the 31' Tub


During: Wire forming the NOTHING...
40's badge at the bottom and 70s Nova LOGO across the top..




After: SKINNED with a lower pan added (drip slot across the back too)
now ready for fine-detailing and an insert (center wires are removable)
Total COST? $0.00






Sorry for all the pictures...

At least its not a stickered Honda!

Rob

[moondisc]

Just another 1-800 buy the parts and bolt it together kit car!  
Nice work Rob. Don't apologize for the pics, they tell the story.
If you know of any 4 door sedans in about the same shape as yours when you started up there in New Hapsha let me know.
All I need is the body shell, rear doors and frame.
I have a plan!  

[Phat]

Rob   Your gettin pretty * good with that welder...LOL  I bet your leg is liking this warmer new england weather. (bettter than this * winter) Nice work Have missed your site in the last month seems like your really rollin along.

[sedanman]

You are an artist, thanks for the pics.

[berkelusa]

Moondisc:

Yep, Just dial 1-800-Junk-Yards and GO!

"If you know of any 4 door sedans in about the same shape as yours when you started up there in New Hapsha let me know. All I need is the body shell, rear doors and frame. I have a plan!"

Rob: I'll hafta email the list of 30's Chevy Guys...
But I bet there is at least one close to you! (site link, one of 4 sites I run also) http://autos.groups.yahoo.com/group/ThisOldChevy/

Phat: Rob Your gettin pretty * good with that welder...LOL I bet your leg is liking this warmer new england weather. (bettter than this * winter) Nice work Have missed your site in the last month seems like your really rollin along.

Thanks Phat, Doing pretty good until yesterday when I tossed a small air-tank and my finger stayed in the threaded hole and peeled back some SKIN!, Not bad but hurts like HELL...

sedanman: You are an artist, thanks for the pics.

Thanks sedanman, Glad to see you liked the pictures.. If you wanna see about 5,000 more from day ONE go to this addy...
http://autos.groups.yahoo.com/group/ThisOldChevy/

or members site..
http://communities.msn.com/The1931ChevroletHotrodProject/

or my members page..
http://www.ammoman.com/CHEVY/default43.htm

Glad this site has a link adding feature in the html..

Rob

[PeterR]

I am going to sound like a spoilsport here after all your effort.    

The radius arms are exposed to the largest bending moment where they connect to the axle, but have been constructed with their lowest bending moment capacity at that point.    This is further aggravated by the method of attaching the plate to the bottom chord of the arm.     It is inevitable over time cracks will develop in the fillet weld due to flexing of the plate and the short load path. Although it would detract from the appearance, a significant structural improvement would be to fit an L shape bracket each side of the arm, with the bottom leg of the L going out to the edge of the plate, and a triangular shaped vertical leg flat against the side of the arm and welded along the top corner of the upper tube.

There is another wrinkle with the position of the airsprings.     Roll stiffness is a function of the square of the spacing of the springs.   Half the spacing means a quarter of the roll stiffness.    Further, leaf springs twist during roll and this adds about 50% to their nominal roll stiffness.   This means that if the air springs have been selected to provide a similar vertical stiffness to the leaf springs they replace, then the front-end roll stiffness will be about one sixth of the standard configuration.      There is quite a high likelihood a roll bar will be required to prevent excessive body roll and oversteer.

Also the highly non-linear load/deflection curve of the concertina shaped airsprings make them more suitable for IFS set ups where there is a motion ratio around 2:1.   The ride on a beam axle may not be a good as you hope.

[berkelusa]

You...
I am going to sound like a spoilsport here after all your effort.

Me...
Not at all.. After 4 years If you think this is a bad post you havent read ANYTHING ! hahaha

Let me break-down your post a little...

You...
"The radius arms are exposed to the largest bending moment where they connect to the axle, but have been constructed with their lowest bending moment capacity at that point."

Me...
So a suspended bridge at the ends is weak?, I have had 2 engineers look at the design and give me more ways to add to the strength.. But the best part they loved was the suspended bridge design..., One did say that "the square in the bowtie should remain to stop side-loads and any twist and they should have something reaching to the top of the triangle down to the perch-pads" (and it will soon)

You...
"This is further aggravated by the method of attaching the plate to the bottom chord of the arm. It is inevitable over time cracks will develop in the fillet weld due to flexing of the plate and the short load path."

Me...
Not done yet.. those were what I had at the time, The plan is for even more supports later on before it's on the road, You really gotta read the whole 290 pages to see how it's changed over 4 years..., Good point!, Just not finished yet...

You..
"Although it would detract from the appearance, a significant structural improvement would be to fit an L shape bracket each side of the arm, with the bottom leg of the L going out to the edge of the plate, and a triangular shaped vertical leg flat against the side of the arm and welded along the top corner of the upper tube."

Me...
That's part of the addition that will be made later on.. the plates will connect to the top of the bridge to stop any twist of the arms..., and a good thing you seen that was needed... So did the engineers

You...
There is another wrinkle with the position of the airsprings. Roll stiffness is a function of the square of the spacing of the springs.   Half the spacing means a quarter of the roll stiffness.

Further, leaf springs twist during roll and this adds about 50% to their nominal roll stiffness.   This means that if the air springs have been selected to provide a similar vertical stiffness to the leaf springs they replace, then the front-end roll stiffness will be about one sixth of the standard configuration.

You...
There is quite a high likelihood a roll bar will be required to prevent excessive body roll and oversteer.

Me...
I think you mean sway bars, They are almost DONE.. Still making them from using the OEM shock castings and another pair of the OEM sway bar perches... (actually that picture is old btw)

You...
Also the highly non-linear load/deflection curve of the concertina shaped airsprings make them more suitable for IFS set ups where there is a motion ratio around 2:1.   The ride on a beam axle may not be a good as you hope.

Me...
So your saying they are too close together and will affect the lean of the car in a corner and the LEAN of the body will be fairly easy with all the weight when you really dont want it to lean out... correct?

Directly OVER the beam they are fine, They were once mounted behind it on plates, But that twist UP of the nose of the beam would put more stress directly ON the raduis rods/bowtie bars, The need for a sway bar at the OEM mounting points cures quite a few of the problems, the ladders dont exactly GIVE like a raduis rod would...

Get the PDF from Firestone on the airbags I have, There was another on all the designs you can do with them as used in industry on a daily basis.. and dont go to rockcrawler.org and look at the green jeep because they used it on the END of a semi-ellyptical pair of leaf springs as LIFT for a rock-crawling vehicle..., I have studied hundreds of designs and it all comes down to a few things...

Is it strong?, Does it do what it's supposed to?

Will nothing JAMB or BIND?
Is the ARC correct?
Can it reach FULL arc?

Does it look like it will work? then it probably will...

Its all GOOD... and if something doesnt WORK.. it can be MODIFIED into something that does...

You spoilsport hahaha

Rob

[PeterR]

berkelusa,
I have responded at length, not with the intention of inferring you have not done proper planning, but to make the text more general in case others on the board choose to read it.

In regard to the radius arms.
Radius arms have to absorb the full braking torque reaction where they connect to the axle; accordingly the bending moment goes from zero at the pivot to maximum at the point of attachment on the axle.   This applies whether they are hairpins, pressed steel arms off an F Series truck or fabricated sections, and is the reason all the above mentioned components taper over their length from smallest depth at the pivot to maximum section modulus at the axle attachment.

A conventional steel bridge beam has no bending moment at the ends, only shear.   The maximum bending moment is mid span, so not surprisingly the section is deepest in the middle, tapering towards the ends.

Regarding the roll stiffness.
Yes, the narrower the spring base on a beam axle the lower the roll stiffness.   This is easiest demonstrated by studying extreme cases.     Imagine if the springs were mounted just inside of the kingpin.    The smallest amount of roll would start to compress one spring and unload the other so there would be a high resistance to rolling.    Now imagine the two springs side by side in the middle of the axle.     Rolling of the car would have hardly any effect on the spring length, and if the springs are not being changed in length then they are not developing roll stiffness.

This is of little consequence providing the roll bar is sized appropriately, as demonstrated by the Citroen DS series.

Airspring mounts.
My comment on motion ratio related to the difference between the effect of spring stiffness when installed on a beam axle compared to an IFS.    On an independent front end the springs are mounted about half way out the A arm, so the change in spring length corresponds to about half the wheel movement, while the springs above a beam axle have to deflect a distance equal to the full wheel movement.

If you study the Firestone data you will notice that the concertina type airsprings are soft mid range but stiffen up towards the min and max heights where the section area rapidly changes, and this is what makes them so good for vibration isolation.    

Now compare the diaphragm type airspring.    The flat section of the curve extends over a longer portion of the height range, and this means the sleeve type will give a better ride over a greater height range

Unfortunately the constant pressure lines plotted in their literature do not show this directly, and you have to do some extrapolation from their data.   These differences in load/deflection curves make the sleeve type more suited for direct mounting above beam axles and the concertina type for IFS.   You will notice this is now common practice.

The rock crawlers rarely deploy the sleeve type because they design for huge wheel movement which means when one wheel is at maximum droop and the other at maximum compression there is significant misalignment of the top and bottom plates which can cause the sleeve to rub against the piston quickly damaging the rubber component.     Careful design can accommodate this, but ride quality is not high on the rock crawlers list of priorities.

Mixed elliptic and airspring
The fitting an airspring instead of a shackle at the end of a semi elliptic spring has been used for years by truck operators as a cheap method of converting steel springs to air-ride.   As crude as this is, this simple addition makes a huge difference to the road shock transmitted to the goods being carried.    Conventional leaf springs develop friction between the leaves, and this means when the wheel hits a bump the spring will not respond immediately, but delays moving until the load increases enough to overcome the friction.     When travelling over corrugated roads a conventional leaf sprung truck will shake the sh#t out of the load.    An airspring at the end of the steel spring absorbs those high-frequency low-amplitude shocks.

The improvement of ride quality in air suspended trucks travelling over unsealed roads was demonstrated in an unexpected way when they first came on the scene.    Trucks operating on long haul routes over unsealed roads routinely replaced their batteries after every trip because the road shock damaged the plates making them unreliable.    After the first air-ride truck completed a run over one of the worse imaginable roads the batteries tested OK so were left in place.      Six trips later the same batteries were still testing OK but the operator felt it imprudent to leave them in longer and replaced them.    Air-ride trucks routinely travel over these roads today and battery damage is not even a consideration.

[PeterR]

Sorry, did the old double post trick.