Diy - fail

[Damn True]

Hey, I'm all for guys making stuff themselves. Our own Lowbuck-X is a legend in this regard. But this......oh boy.

http://forums.corral.net/forums/showthread.php?p=9311510&posted=1#post9311510

Sometime in the near future this guy will need a sound clip of Jeremy Clarkson's Yorkshire accent uttering the words, "This has not gone well."

[Mr.VENGEANCE]

whooooooaaaa....

[Young Gun]

wow... thats not gonna be good

[moreHP]

no words.

[lipe33]

Threads like that make me cringe. It makes me wonder how many other would be engineers have decided to redesign their steering system, which is one of THE most critical safety features on their vehicle. Imagine what would happen if that failed at highway speeds.

I commute to work every day, and I such I spend a significant amount of time at 75 mph, or higher, with my fellow drivers. When I see a thread like that I spend the next week wondering which car is going to veer wildy into my lane as I FLY down the interstate.

[Rhino]

That's... well... interesting.

[6'9"Witha69]

I can't blame a guy for having the idea, or even experimenting, but his being clueless as to the danger he puts OTHERS in is scary.

[Vegas69]

He's just converted it to solid. I may be missing something here. Most of us are running solid shafts and two u joints with rack and pinion steering. If he doesn't have solid body bushings then there could be a definite issue.

[JohnUlaszek]

It sure looks like hell, but unless I am missing something, the aluminum sandwich is acting as a spacer with some shear loading and if you removed it altogether the bolts would still provide the load path.

Consider a rag joint provides isolation, and we probably have all driven a car with worn out rag joint -- the steering becomes imprecise, but not necessarily unsafe.

https://static1.pt-content.com/images/pt/2009/11/PIC_0208-1.jpg

[Damn True]

You are missing something.

Work + harden =

[JohnUlaszek]

You are missing something.

Work + harden =

What do you predict the failure mode will be?

[Damn True]

What do you predict the failure mode will be?

I'm not an engineer, nor did I stay at a holiday in express last night.

That said, a rag joint is used where there is a differential angle between a steering shaft and the input shaft to a steering gear or rack. The rag joint flexes each time the shaft turns at a relative point 90deg out from the vertical axis and is concentrated between the bolts. I would suppose, rightly I believe, that this assembly will flex at that same point, work harden and fail.

Either that or the bolt holes will eventually elongate until a failure develops between a bolt hole and the outside edge of the disk.

[marc_b]

whats wrong with having a rag joint. does going to a solid set up make that big a diffrence?

[JohnUlaszek]

The more I look at the photos in the original link, the more I think if he does get into trouble, it will be because he appears to have swapped out two of the shoulder bolts for fully threaded fasteners.

In theory you should still be able to drive without the disc so long as the shoulder bolts are used.

[mc84_zz4]

Without a u-joint, it could possibly bind enough it will not turn. If it does rotate, any side-loading will cause stress to the steering shaft knuckle and the steering box output shaft, one of those will fracture, losing all steering.
If he thought it thru a little longer, just drill out the rivets and replace them with bolts, tightening down the plates would eliminate most of the slop caused by a worn rag joint.

https://static1.pt-content.com/images/noimg.gif

[JohnUlaszek]

Without a u-joint, it could possibly bind enough it will not turn. If it does rotate, any side-loading will cause stress to the steering shaft knuckle and the steering box output shaft, one of those will fracture, losing all steering.


I agree with True that the rag joint does account for some misalignment, but there is, in fact, a u-joint based on the photos and I would assume a slip joint somewhere too.

https://static1.pt-content.com/images/pt/2009/11/PIC_0182-1.jpg

[6'9"Witha69]

Correct, there is now 1 ujoint where before there were 2. That means eother twice the work by one joint, or, as was mentioned on the linked site, the pilot bearing on the rack input shaft would more likely see the excess strain and possibly fail there. Also, a safty feature was the additional tabs coming off where the rivey had been. He removed it. They function to act as a very loose connection in the event of a rag joint failure. Now not only has he moved the misalignment from the rag joint location to possibly the rack, he has also eliminated a safety feature should the joint istelf fail. Not very well thought out.

[Jim Nilsen]

The problem of loose steering or bad road feel is not going to be solved by his fix, the problem he is having is somewhere else and he has failed to recognize it and is blaming the wrong part. Once he gets it in I would bet he will still have the same problem magnified by his fix.
We have all drove vehicles with rag joints that have precise steering. Corvettes in 1984 and 5 had a double u joint and an isolater that made it all very solid but would still dampen the vibration. I have one of these on my car right now and it is working well and the vibrations are not evident in my wheel. In 1986-7 the Corvettes went with an aluminum shaft and a rag joint, the reason for the change was to reduce cost and weight. The end result was just as good steering response and still good vibration isolation. Rag joints work, it's just that plain and simple. They have worked for years and are inexpensive to replace. The guy spent good money for bad and could have just bought a new $10 rag joint.

Aluminum will fail under the stresses that he is using it for, steel would have been a better choice. If he had ever seen aluminum couplers used like that and how they wear he would realize that he would be back to loose steering in about a week or is that weak moment. Steel couplers will even wear and get loose even in straight line scenarios. The jack shafts I have worked on over the years that were of the same configuration were always going in one direction and would wear soon enough but going both directions will really cause them to be loose in no time. The engineer was correct about the problems and could have gone further with with the reasons to not do it but he was trying to be nice.


I am glad he warned us about it so we can stay clear because it is going to be a dancing Ford soon enough.

[JohnUlaszek]

Jim,
I agree, rag joints work fine.

You mentioned seeing wear on jack shaft assemblies -- what was the application and input loads?

What do you think the loads are on a rag joint?

[LowBuckX]

Hey, I'm all for guys making stuff themselves. Our own Lowbuck-X is a legend in this regard. But this......oh boy.

http://forums.corral.net/forums/showthread.php?p=9311510&posted=1#post9311510

Sometime in the near future this guy will need a sound clip of Jeremy Clarkson's Yorkshire accent uttering the words, "This has not gone well."
My approach was a bit different.. Nice solid feel cost same as a new rag joint but took a whole hell of a lot more work...lol
https://static1.pt-content.com/images/noimg.gif (http://img193.imageshack.us/i/steeringcolumn1.jpg/)

[WS6]

He didn't use strong enough aluminum and used JBweld for laminate. He should have made it from solid aluminum. Aside from that, there's nothing at all wrong with how he was approaching the problem. Fourth gen fbodies have a similar steering shaft design and replacing the rag joint with a solid aluminum spacer is common and much cheaper than what the Mustang guys were paying. Here's where I bought mine http://unbalancedengineering.com/Camaro/

My rag join had slap wore out. So I replaced it with the solid unit. Worked fantastic. The rag joint is installed to isolate the steering shaft from vibrations and the flexing that is occurs in these cars. It's not needed to prevent ujoint failure as much as it's for comfort. I felt everything through my steering wheel after putting my solid spacer in.

[Jim Nilsen]

Jim,
I agree, rag joints work fine.

You mentioned seeing wear on jack shaft assemblies -- what was the application and input loads?

What do you think the loads are on a rag joint?

I have worked with them on packaging machines that had very low torque to turntables that rotated up to 600 lb to 900 lb of magnet wire all day long to load up drums. It doesn't seem to make a difference on the load sometimes because the pins or bolts will work the holes larger from the flex and the torque of the drive motor is what wears them not the resistance of the load, when more room is wanted for clearance of movement it just happens. Once you get them worn in you can go back and make timing adjustments on the machines if needed like inthe packaging machines and the turntables only went one direction and indexing was not really an issue. I see nothing but the same slop he is trying to fix coming back within hours of use.

The load on a rag joint is probably not a lot with power steering until you hit large bumps or impacts and that is why a rag joint is there to begin with and are easily and cheaply replaced by design. he spent more on JB weld and grade 8 fasteners than he more than likely would have spent on a new rag joint.

[Derek69SS]

I agree with True that the rag joint does account for some misalignment, but there is, in fact, a u-joint based on the photos and I would assume a slip joint somewhere too.Look at the driveshaft on your car, there's 2 U-joints on it for a reason. This guy effectively just made one end solid, which will bind if there's ANY misalignment of the shaft. Chassis flex = misalignment, and he says he "road races" it.

The reason for a rag-joint is to act as a U-joint, but with isolation from noise & vibration from the steering components. It makes the car quieter and more comfortable, but with the drawback of steering feeling more sloppy.

[JohnUlaszek]

The load on a rag joint is probably not a lot with power steering until you hit large bumps or impacts and that is why a rag joint is there to begin with and are easily and cheaply replaced by design.

I tend to agree, the largest input I can think of is that of the strongest person you can find, turning the steering wheel to full lock as hard as they can -- any misalignment could create additional stress in the entire assembly which may result in binding.

Given our friend has modified the bolted joint by eliminating two of the shoulder bolts, I am not quite sure how it would behave compared to stock in the event the isolating material fails. In stock configuration the joint is designed to continue working even if the isolating material (rubber) disintegrates, which it tends to do on 40 year old cars.

Regarding True's thoughts on work hardening, work hardening is a result of repeated plastic deformation as a result of loads being greater than the yield but less than ultimate tensile. I think the disc would begin to delaminate before any failure of the aluminum. If the bolted joint was maintained in OEM configuration, with the exception of the new disc, it could result in a loss of clamp load in the joint manifesting itself in sloppy steering; given the change in bolted joint design, the fasteners and the design of the joint should be scrutinized.

I certainly don't endorse this guy's efforts, but it is an interesting engineering problem.

[406 Q-ship]

The issue I have with this that isn't being addressed, he is checking the out of alignment at a static turning of the steering wheel. Well in a corner loading situation the chassis will be under deflextion and moving in directions that the orginal rag joint can compensate but that a solid or his goofy laminate can not do. What if in a high corner load he needs to adjust steering input and the steering shaft is in bind and will not move or requires a high amount of force, it could cause a major over turn in or over correction and loss of vehicle control. I have worked on the Fox and SN95 Mustangs and those chassis move all over the place, this is not safe in my opinion. Someplaces just are not worth looking to cheap out and this is one of them.

[arue333]

Where did you find the U joint replacement? I think that's the end all bee all of this matter. What did you have to do to make it work?

[mc84_zz4]

It is less than $6 at your local Autozone, O-Reillys
They have them in 2 sizes...
https://static1.pt-content.com/images/pt/2009/11/1353567_IMG-1.jpg