Radius rods on the rear, open drive conversion ..Lets argue

Root, did you read "A-bone suspension question" in the Tech O Matic?
You will find some more info there...

 

Actually there are a couple of em in there....I forgot about em.

Thanks I'll read.

 

I was hoping this would come back up again

I never saw the pics of Tman's torq arm setup the first time around, so I thought I'd draw up an idea I had for replacing the structure lost when using an open drive rear end, 2 radius rods on the same pivot point as the radius rods, that way the radius rods are only locating the ends just as Henry did it.

I'm not an engineer, so if anybody sees something that won't work, tell me before I start buying stuff to do this.

 

When I got my 40 Tudor w/394 Olds and B&M Hydro 30 plus years ago it came with a 58 Chev rear with unsplit 36 Bones.
The Olds was a "full house" engine (12.5-1 Pistons, Wild Cam, Headers, Dual AFBs off the 425HP 409 motor), and the local older rodders suggested getting rid of the 36 Bones and getting a PSI rear end mounting kit that was a heavy duty copy (kind of) of the 36 bones.


So, I did some research in old rod magazines, mostly from the late 50s to very early 60's, and found a few mentions of crashes in drag races where the rear used 36 bones and the torque from the engine broke the weld where the tubular part connects to the rear cast iron part. Some guys died. Henry Ford's engineers did not design these bones or that weld to hold up to big torque. When R&C stopped publishing and they went to the square bound Quarterlies, they did a build up series on I think a 36 Roadster (with an AMC Motor maybe), and they used 36 bones, but they welded gussets to that weak area on the bones. I think Klazurfer once scanned and posted those photos.


I ended up getting one of those PSI kits after a year and a half mail order nightmare. Thay apparently did not sell a lot of them and they have not been available since the early 80's.


In the late 60's/early 70's I saw more than a few guys extend the forks on old Harley Springers by using sections of old ford wishbones, as they were pretty much the same size as the springer tubes. Most of the guys used 36 bones for some reason, although I was told that other years worked fine. Well, some of the bones that those guys cut up had been in a pile of bones at a junkyard for decades, and due to small drilled holes in the bones (probabaly for e-brake cables) sometime water had gotten in, and there was some significant rust inside some of them, and an inspection of the factory welds at the tube/casting mating point, sometimes showed not the greatest weld penetration.

 

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Mine have coarse threads 1-1/4" diam and are not locked where they thread into radius rod allowing that small additional amount of give as well as the forged 3/4" bore heims joint coupling the frame to the radius rod ends.

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I would be worried about the threads wearing out and eventually failing this way. We use alot of spherical rod ends at work, and everytime someone forgets to lock one down, it fails. The jam nut prevents the pieces from rocking against one another. Throw in a little sand and dirt from the road on top of loose parts rubbing against each other and you get something that isn't quite safe.

 

I just measured the scrap piece I cut off the '36 bones that I used on the Roach Rod.

The wall thickness is .130

You aren't going to break that.

The "weak" area in question must be the joint where the forged end is butt welded to the tube.

I've been doing a stress test for the past three years on my set... and so far, they've held up just fine. I would go as far as saying that I ABUSE them on a regular basis.

Anyway, if you were really concerned about them... you could weld a little fish plate over the area where they are welded together... effectively making them suitable for 7000rpm launches with slicks.

As far as the other bones go... I couldn't tell you how stout they are... I can only vouch for the '36 bones.

Also DON'T SPLIT THE REAR BONES!

Tie them together with either a Model A front wishbone yoke... or some metal.

Then fasten that to your tranny x member (A dropped tube member works best) via a 3/4" heim joint or original ball in socket set-up.

That way, the whole shootin' match will be triangulated... preventing it from moving side to side and allowing it to rotate about the axis of the ball and socket as each wheel moves up and down.

Sam.

 

My bones and the Torque Arm are almost eggzactly the same lenght. The travel is quite free, sorry, that pic just makes it look wierd.

 

Sam, what about driveshaft clearance? Is that an issue? I realize the torque tube used to be there but it was also stationary.

 

Try this one.

http://www.hotrodworks.com/radiusrodmount.htm

 

That looks like a pretty nice piece T. How did you mount your torque arm to the 9"?

 

4t64rd, think you just might have a solution if....
The wish bones are NOT SOLIDLY afixed to the axle.

SJ Fast once showed (might be in TECH still) an idea that he used. The outside wishbones are attached to a ring that can rotate on the axle. It would mean either removing and rewelding the bearing ends OR you could split the rings in half (like bearing shells) and weld them on the axle. (just the ring so it can rotate on the axle) To keep the ring/wishbone mount(s) in position, SJ then mounted narrow rings on the axle to keep the "slip/bones mount in location.

This would get rid of the "SWAY BAR" effect, and take the load off the bones mounting point. You could even mount a Zerk fitting on the ring to give it a shot of grease once and a while.

I have seen it done on some oval track racers, even with a banjo rear axle. The axle (straight tube or tapered) would need a bit of machining (very light) to give the captured slip/bone mount ring a smooth surface to ride on.

I think both the front and rear ends of the bars and the front end of the bones will need tierod ends or Heim ends to allow for twist.(in side to side motion)

Nice drawings BTW.

 

If you haven't been following THIS thread..
take a look! Has some pictures of interest!

http://www.jalopyjournal.com/ubbthreads/showflat.php?Cat=&Board=UBB1&Number=467568&page=1&view=collapsed&sb=5&o=7&fpart=all

 

Here's a quick sketch of what I'll be using on my lakesmod. The torque arm will handle all of the acceleration and/or braking forces. It will also provide a place for a loop to enclose the driveshaft (not shown). The oval tube wishbones, split to the side for a traditional appearance, will serve only to locate the axle fore and aft. Note that they are mounted at the same plane as the axle centerline. That way the forces are going directly down the oval tube centerline and having bushings or swivels at both ends, they encounter no torque forces whatsoever. All connections are in shear also.

There will be a panhard bar and a roll stabilizer too. This design will work with any springs the builder uses. I'll have torsion bars mounted parallel like the sprint cars from the 50's and 60's.

Most people don't see each component by itself. Think of it in those terms and this becomes a simple design.

Any questions ?

 

Thanks Dave. I actually missed that thread somehow. I started reading it the other day and got sidetracked before I got to the good pics.

 

Hacerbill, with only a Quad4 for power, there will only be about 160FT LBs of torque to deal with. That comes in way over 3000rpm. My real concern may be spring wrap, therefore wheel hop on hard braking.
DrJs arrangement looks ideal if one is going to use the old bones split to the outside of the frame. SamIam is right, dont split the bones and the geometries a whole lot better. I still think a torque arm is a good idea, though.
A well designed torque arm cam be below or at the axle centerline too. That can solve some problems for space critical situations.

 

Hey SJ, haven't "seen" you around for a while!

Did I explain the drawings you posted "long ago?" I might have explained the setup a bit different.

 

The more I read the more I feel this set up has some real issues. The rear axel is gonna twist. There is no question about that. So one end of the suspension needs to pivot. That is why it is recomended to use a rod end with a split bone in the front. SO it would make sence to use the same in the rear.

I'm talking about a OEM style tierod end here with a tapered shaft and nut. Or a hiem that would give with the twist of the suspension.

And I really see a proplem with them the farther you split them with out having some type of mounting that will give with the twist of the suspension.

Just my thoughts.

 

Ok so I checked out my banjo today,my bones unboltfrom the ends of the axels and are bolted together on the other end.So is this a 36 rear end?? Not the 40 I thought..
Has anyone tried a true 4 link with the stock spring and a panhard bar? Would the spring act like one??

 

I reply and it drops like a rock............

 

I think your OK with the 4-1/4 elliptics Cornfieldrodder!

The lower springs would be in tension and the uppers would be trying to chatter...but a couple of clamps should cure that.
Hmmm... The real issue might be the actual location of the upper and lower spring eyes in relation to the rear axle centerline. Trying to get the car really low would make it easy to put the upper eyes close to the axle centerline and that would aggrevate the chatter problem as the upper spring would have no leverage advantage over axle twist.
Of course you could always use a center torque arm as well!!!

My initial plan (IF I were building it! )would see them in vertical alignment with the center of the axle, as equally far apart vertically as possible front and rear and equal distances above and below the axle centerline.

Rollsteer might be an issue as well due to the short working length of the spring packs. I think it would be a good idea to set them up "flat" at ride height, as if they were a short 4 link...which they are really!

I wonder what the actual advantage was for the old racers to use this setup!?!?

Bill

 

The 37 on radius rods bolted on at the backing plates and bolted together thru a boss under the torque tube. It could be a 40 axle.

 

Root, no pics up close, but I have a heavy bracket that mounts a Pete AND Jake urethane rod end in double shear between to tabs. It bolts to two of the 3rd member bolts on the left side of the driveshaft. You can see how it works next month.

 

Root, I have TWO 1600# Airbags that are new if you want to use em for your truck? I have $100 in them but am willing to trade as well.

 

I built a four link using '36 bones as the lower links (mounted outside the rails) and triangulated uper links, stock '32 spring and no panhard bar. The spring alone should be enough to center the rear...thats how it works stock.

 

Digger_Dave....you explained it well. That connection to the rear axle is a bit more complicated than my rubber bushing concept but it does work. In fact, I've done that one.

How ya been ?

 

Here is that bracket Root.

 

Ahhhhh.....nice work. I may be interested in the bags. Bring em to the drags.