You know what’s fun about cars? I mean, there’s lots of fun things about cars, that’s why we’re here. But specifically, at this moment, I’m thinking about how cars are full of a vast array of wondrous and strange parts, and all those parts have names, and sometimes those names themselves are strange. So it might be fun to look into the entomology of these names, see what the insects’ opinions are, then dig into the etymology of the names, and find out why things are called what they’re called! Today I want to talk about a strange one: the rag joint.
That’s an evocative name, right? Rag joint. It sounds like a dive bar that caters to the textile industry, or something like that. It’s not that, though, it’s a bit less exciting. Or maybe more, depending on your own personal prejudices?
The rag joint tends to be used most often in steering columns, though they have shown up in drive shaft and other shaftly applications as well. Here’s a pretty typical habitat for a rag joint as seen in some Ford products:
See that bit highlighted in blue? Here’s an actual one:
photo: Borgeson
As you can see, a rag joint is a sort of shaft coupler, where we have two separate metal bits on either end that couple to the shafts, and in between is a disc or multiple discs of a flexible material, originally leather but more commonly rubber, usually reinforced rubber, much like the rubber material tires are made of. In fact, rag joints often use recycled tires for that middle bit.
A rag joint isn’t something that would replace a U-joint or a CV joint; it’s not about changing direction, it’s more about being forgiving. What I mean is that a rag joint’s flexible middle section absorbs vibrations and compensates for when things aren’t perfectly aligned. It’s a device made to soften the impact of slop in a system, like the system that makes up your car’s steering.
The rag joint absorbs and damps vibrations from the road to keep them from abusing your poor hands as they grip the wheel. Here’s a little video explaining them :
Now, why are they called rag joints? Well, for this odd term, I think it’s sort of obvious: the middle rubber bits are sort of like rags. I’ve heard explanations that say the ragged ends of the reinforcing cords inside the rubber contribute to the name, but I tend to think it’s more about the overall look and feel of the thing: it feels like a sloppy thing, and the middle does have a stack-of-rags like quality about it, doesn’t it?
I like rag joints because they acknowledge the imperfection of the world, and don’t just sit around complaining, they actually do something about it. It’s also a bit amazing that something as crucial as a steering shaft coupler relies on a disc of old tire rubber! But they’re tougher than you think! Cars – especially American ones – used them into the 1990s, and if your steering feels loose or wonky, it’s not a bad part to check out and replace.
Isn’t a rag joint essentially the same thing as a giubo?
https://en.m.wikipedia.org/wiki/Giubo
The only difference I can see is that a giubo is a single piece of material, whereas a rag joint is made of several layers bolted together.
If that type of coupling fails, there doesn’t seem to be any failsafe. With the rag joint, you at least have the bolts there to clunk around and keep the steering shaft or whatever functional
Mercedes-Benz used the recirculating ball steering system for the same reason.
This takes me back to when I delivered auto parts as a kid. The place I worked at had a few vehicles they’d picked up over time, probably as payment from garages that were closing and couldn’t settle their accounts – an ancient thunderbird, a couple of late 80s chrysler hatchbacks (one of which was “my” car most days there) and then this little early 80’s Ford pickup. That thing was absolutely terrifying when I got in it the first time. It was usually driven by one of the old timers there, and apparently he’d somehow gotten used to it and not complained.
Nobody warned me about this ahead of time. The “rag” part of the rag joint was entirely gone. There was about a quarter turn of slop before the steering wheel would do anything at all. Beyond that, whatever the equivalent part of the braking system was also shot. It required 2 pumps of the brake pedal to the floor before it would finally engage. More air than fluid, I’d guess?
I drove out of the parking lot and immediately went around the block and made them sideline it until it was safely driveable. As I recall, it took a while as the rag joint was hard to source for some reason.
The things we did for $5/hr…
A Rag Joint is a bar/saloon in which one would frequent to consume libations and listen to Ragtime music! 😉
Cue up some Scott Joplin.
（〜^∇^ )〜
Ah yes, had to replace the one on my fox body. Not my favorite engineering solution but it works. It fits with the agrarian nature of the vehicle. The more you work on one of those the more you realize it’s basically a souped-up tractor… a really endearing and stupid grin inducing souped-up tractor. A fox body is like a labrador of the automotive world. Did I mention I really like labradors?
As a note to anyone concerned about the ability to steer your car relying on a piece of reinforced rubber that can obviously fail catastrophically with age (like I was when I first came across these), the joints are designed so those big steal posts will prevent free rotation even if the rubber totally disintegrates. Your steering will be sloppy as heck (ask me how I know), but you will still have some.
I remember a car commercial many years ago where a guy was looking at his repair bill and says, “What the hell is a guibo disc?!”
I always figured they made that up (like johnson rods and muffer bearings), but it turns out that’s an actual part on BMWs! It’s like a rag joint for the driveshaft.
Mercedes uses the “Flex Disk” aka “guibo” on its drive lines.
Also Porsche.
Also Giubo. (Check your spelling)
Also my favorite name for a car part.
Ah yes, the rag joint. Not to be confused with the rug joint, which is either a rug store, or a roach marijuana cigarette rolled with a piece of 20 year old carpet
I was thinking something similar. “I’m all out of rolling papers, but here’s this old rag, I bet I can roll it tight enough.”
I feel bad for the guy who has to wu tang that lol
So out of curiosity, are these still used anywhere? Outside farm and garden equipment, I mean. It’s actually something I had kind of forgotten about until I saw the photo and thought, “Oh yeah, I remember those.”, but I can’t recall the last time I actually saw one in one of my own cars. I assume with modern electric rack & pinion these have gone the way of the dodo?
my 17 wrx has one, but the rubber bit is a very hard polyurethane. Also, used a Perrin stiffener that compressed the polyurethane, so now it’s almost metal filled.
Subaru calls it a steering dampener
In the drivelines of Porsche, BMW, Mercedes.
My 2004 Porsche anyway. And based on other posts here.
“A rag joint isn’t something that would replace a U-joint or a CV joint”
Well, unless you’re Colin Chapman. The Elan has those Rotoflex donut things.
I went for a drive in my now wife’s ’71 Corvette convertible. I noticed a bit of steering play whilst driving and stopped at a wrecking yard to ask about it. They had a same-generation Corvette atop a pole advertising the yard, so I figured they knew stuff. I was more familar with VWs. Sure enough the rag joint was broken about half way through. I tenderly drove it back to her place and let her know about it. This was about 40 years ago, and the yard still has the red white and blue Corvette still up on that pole as of a few weeks ago.
Astro Auto Wrecking in Federal Way. Just happened to drive by it a couple of months ago, for the first time in quite a while and was surprised to see that Vette up there all these years later. though like the sign Viper it apparently has come down off the pole for a refresh or two over the year because it was looking pretty good.
I know what they are but have never had to deal with one. The only steering column work I’ve done was on a VW Scirocco which used a U-joint
The schematic in the article has a u-joint as well, just above the rag joint. I wasn’t familiar with these, but I wonder if I’ve just never seen one because they are in a less conspicuous place.
In high school, I was coming home late at night from my job at Albertson’s. I was backing my ’60 Chevy El Camino into my carport that was off the alley behind my house.
I got about halfway in when all if a sudden, I had zero steering. It was late and I didn’t have a light. All I knew was my car was blocking the alley, and tomorrow was trash day.
I didn’t know it at the time, but my rag joint had failed entirely.
So I got my trusty floor jack, jacked up my car, and pushed it off. I repeated this until the ElCo was aligned with my spot. Then I backed it in and went to bed.
I fixed it on my next day off.
Some Lotuses (Loti?) used a similar rubber doughnut joint on half shafts.
I had a friend with a Triumph Spitfire with them no idea if they were aftermarket or original equipment on those, but were on the Lotus Elan and some formula cars I think.
That would be a Rotoflex joint which is more substantial and was factory installed on some late 60s Triumphs, mostly the 6 cylinder GT6 and Vitesse. Rotoflex joints fell out of favor when CV joints improved and there are aftermarket axles for the Lotus Elan etc. with CV joints.
Thanks for further jogging my aging memory and getting me in the right rabbit hole.
https://www.robush.com/wp-content/uploads/2018/08/Rotoflex-.pdf
The catalogue brings us back to a slightly more robust steering column joint. (-;
Land Rover used a Rotoflex-type joint on the rear driveshaft-to-differential coupling as well. Seems to have been popular in British automotive engineering. It seems to be useful as both a vibration damper and flexible joint where there’s not too much flex. Most vehicles put another U-joint on that end, though.
Interestingly, I racked up quite a bit of milage on a Disco I that came to me used-and-abused with high mileage. Never had to replace driveshaft U-joints. Ever. Replaced the flexible rubber coupler once, but never the U-joints and I know the thing had racked up enough miles just since I took it on that most cars would be needing the U-joints replaced. Seemed to have been a combination of extremely robust parts and maybe that flexible rubber coupler both absorbing driveline vibration and also keeping everything lined up due to it naturally resisting excessive movement. I wonder if using Rotoflex joints helps contribute to longevity other joints in the driveline?
I can see where using CV joints throughout a driveline would make sense from an engineering point of view — but the problem is that once one of the CV joints in the system wears enough to loosen up, the out-of-line movement and vibrations will increase stress on the others and accelerate wear in them as well. CV-joint drivelines last longer than traditional U-joint systems… Until they don’t. As long as they don’t have to make severe angles, traditional U-joint systems will last damn near forever as long as they have adequate lubrication and aren’t subjected to severe shock and vibration. Perhaps they were on to something by replacing one connection with a flexible and shock-absorbing coupling…
Eventually the industry would figure out how to use a needle-bearing u-joint and separate shaft damper, thus eliminating the semi-vulgar “rag” moniker and increasing the cost 5x as is proper.
“YES, Cheech, add this to the list with the CV and Ball joints you also can’t smoke. Put the lighter down, I’m trying to steer.”
I worked in the steering part industry for many years and I can’t count how many times I had to explain what a rag joint is to customers who were looking for the source of slop in their steering.
“I’ll take Jokes that write themselves for 200 Alex.”
If you put this in the driveline of a BMW, it becomes a Giubo, which I think of as the funniest name for a car part because owners almost universally call it a Guibo, which is a lot funnier on the east coast north of New Jersey.
Well done, most people spell it wrong.
Giunto Boschi.
I had to look it up. I had only ever seen it as a guibo in online forums and I’ve never owned a BMW myself.
Thank you for bring up BMW. Another BMW part that is cursed after 10 years.
When they fail, they fail spectacularly.
And Porsche.
Also Giubo.
Had a rag joint on my C10,was able to replace it with a universal from a Jeep XJ I believe. The part was nearly a direct swap. It didn’t seem to add any unwelcomed vibrations an did tighten up the steering. I’m sure a new rag joint would’ve as well but I was hoping to add a little more road feel
There used to be a strip club around here called “Ragtime.”
They didn’t think that one through.
IDK, for a certain clientele, that might be a big earner. I was once reluctantly brought to an especially sleazy strip club by people who are no longer my friends where a very pregnant dancer with cigarette burn scars on her arms was getting $20s after $20s laid out on the, uh, sneeze guard by a small group of individuals off to one side of the cruciform stage so that she certainly had no problem affording beer to drink between sets. Every time I think I reach a floor to my disgust for humanity, it drops out beneath me and I fall a little further down.
Crémieux Rouge?
I need to replace mine, along with the firewall seal.
Loose seal! Loose seal!
“You picked a fine time to leave me, loose seal…”
Little Richard or Kenny Rogers’ song?
B.B. King’s guitar
Popular with Walruses on shore leave.
A penguin takes his car to a local garage to get it fixed. The mechanic tells him it’ll be a couple of hours, so the penguin goes to burger joint next door for lunch. After a long lunch, the penguin walks back to the garage and the mechanic informs him that he blew a seal. Startled, the penguin says, “No, no! I just had an ice cream cone!”
He’s going to be All Right.
You son of a bitch. I hate this doctor
A rag joint is what Raggedy Andy always wants Raggedy Ann to play with.
Don’t rag and/or Bogart that joint!