CAUTION! Steering Coupler replacement - PeachParts Mercedes-Benz Forum

deportes · #1 08-01-2010, 05:36 PM

IF you are planning on replacing the steering coupler please read this story, it may save your life.
I replaced my 83 380 sl steering coupler and thought everything was OK, drove it for a month or so then we went to Lake Tahoe in the Sierras, hiway 50 with lots of turns and two way traffic areas.
On the way back I stopped at a burger place, while my wife was ordering the food I decided to let the car roll in neutral and drive it into the parking spot closer to the table, the top was down and the car interior was full of stuff.
As I start turning the steering wheel I hear a thonk and the steering wheel starts free wheeling, attached to nothing...I though that the new coupler gave out. Luckily I had a few tools and took the steering apart, I was able to fix it or so I thought and drove home. Next day I took the steering coupler and steering rod out and inspected them. I noticed that the coupler lip was shiny as well as the steering rod end. I realized that the two parts were only making a 64th or less of an inch contact when they came apart and that when I turned the wheel without power steering the rod slipped out of the coupler..

How the hell did I make that mistake! Was my first thought as well as I feeling really lucky!!!
I tried a few times to re install the coupler and came to the realization that the steering rod was not long enough to make a good fit, that the steering rod and gear box have grooves in order to make the correct fit and installing the bolts properly also keeps the rod and coupler from being able to slip out. I was looking at my steering rod and determined that the same design that will keep the steering wheel from impacting the driver in case of an accident was causing the lenght problem.
I was able to extend the length of the steering rod 3 inches and fit the coupler and rod to perfection. I can't figure it out how it became so much shorter that what was actually needed, it probably slipped into itself when I was installing the new coupler and being that you can't see a thing and most of the work was done by touch; what I thought was a proper replacement was actually a death trap. Please be carefull. Hope this info helps keep you safe.

abiby · #2 08-01-2010, 06:55 PM

Mine collapsed slightly when removing the coupler from the gearbox. Luckily I noticed before trying to reinstall.

That's definitely an important thing to bring up and an necessarky check to make on installation!

Thankfully yours came apart at an opportune time. It just as well could have come apart driving down the freeway.

Strife · #3 08-01-2010, 08:22 PM

You made me look again. I actually worried about this when I installed it and I definitely saw the dimples in the column line up when I put the bolts in.

It's supposed to take 800NM of force to collapse the column (like, in an accident). If yours collapsed that easily, that's not right - I'd consider replacing it.

I think it took courage to post this, because if you did it, someone else will, and might not be so lucky. God knows, I've made more than a few stupid, expensive, and life-threatening mistakes (having a hood fly up on me because I didn't latch it comes to mind, as does having a car slip off of a jack because I didn't check the emergency brake-and I really should have known better).

rowdie · #4 08-01-2010, 09:21 PM

Thank you! This will be the first thing I consider when replacing one
Gald you are safe.

Do you mind if I post this link on other forums?

abiby · #5 08-01-2010, 09:21 PM

Embarrassingly, the reason mine collapsed involved the use of a large hammer and drift. I was unaware of the grooves requiring removal of coupling bolts rather than simply loosening.

deportes · #6 08-01-2010, 09:43 PM

I was able to extend the steering rod by pressing the good old reliable vise grip pliers and hammering it to slowly extend the rod, it took some pretty good hammering to move it. I tested the lenght a few times until it fit prefectly, it was about 3 inches short. I do not know how it shortened because I did not remove it when I replaced the coupler, now the steering feels very tight.
After the last fit, the coupler went all the way into the steering box, where I was able to tighten the bolt on the coupler that attaches to it via the motor side, then I slipped the rod into the coupler all the way through the column. I was able to install and hand tighten the screw from the foot well. I turned the motor on, turn the wheel all the way to the right which allowed the screw top to be facing the bottom of the foot well and it was very easy then to tighten it from the inside.
Just making sure that someone doing the job will not have to rely on luck as we un-knowingly did. Sure glad I didn't loose the engine/steering pump coming down the hill at 65/80 and numerous curves. Now I consider my job done and can smile!

deportes · #7 08-01-2010, 09:47 PM

Quote:

Originally Posted by abiby

Embarrassingly, the reason mine collapsed involved the use of a large hammer and drift. I was unaware of the grooves requiring removal of coupling bolts rather than simply loosening.

Please recheck it, I removed the steering rod and that's when I realized that the bolt going through actually goes through a 3/4 inch groove that will not slide out unless you remove the bolt. Hope you extended it as much as it was needed to make good contact into both sides of the coupler.

deportes · #8 08-01-2010, 09:51 PM

Quote:

Originally Posted by rowdie

Thank you! This will be the first thing I consider when replacing one
Gald you are safe.

Do you mind if I post this link on other forums?

You can post it in any forum you want, we want to keep everyone safe!

deportes · #9 08-01-2010, 10:05 PM

Quote:

Originally Posted by Strife

You made me look again. I actually worried about this when I installed it and I definitely saw the dimples in the column line up when I put the bolts in.

It's supposed to take 800NM of force to collapse the column (like, in an accident). If yours collapsed that easily, that's not right - I'd consider replacing it.

I think it took courage to post this, because if you did it, someone else will, and might not be so lucky. God knows, I've made more than a few stupid, expensive, and life-threatening mistakes (having a hood fly up on me because I didn't latch it comes to mind, as does having a car slip off of a jack because I didn't check the emergency brake-and I really should have known better).

My wife asked me earlier today if I had posted my findings on this site. I could not have kept what I found to myself, knowing real well that If I missed it someone else will. I am not a great mechanic but can defend myself, rebuilt a few motors, breaks etc.
I do feel embarrased that I didn't notice the problem when I was installing the coupler but also more LUCKY than anything else. I have been tinkering with cars since I was a kid, I am pretty old now! I am not a pro by any means but usually I can make a safe repair, and follow a lot of safety precautions when working on cars. This issue just opened my eyes once again and from now on I will look at car repairs in a different light specially when it come to steering work.

Graham · #10 08-02-2010, 10:12 AM

[QUOTE=deportes;2516696]My wife asked me earlier today if I had posted my findings on this site. I could not have kept what I found to myself, knowing real well that If I missed it someone else will. I am not a great mechanic but can defend myself, rebuilt a few motors, breaks etc.
/QUOTE]

Thanks for posting this! I don't think my 38 year old SL has had any work done on steering box or coupler. But I will store this in the memory banks for future reference!

meltedpanda · #11 08-02-2010, 03:56 PM

Just did mine not too long ago, I will be under there tonight to check!

meltedpanda · #12 08-07-2010, 01:04 PM

I am a little confused by this as I looked at mine, if your steering rod was three inches short how did it get to the coupler at all?
The coupler fully seats on the steering box ( grooves/spline) the steering rod goes in the other end I'd say 3/4 to an inch . with the steering rod secured at the wheel i dont see how it could ever come out
I was thinking that the rod should go in further , but the design at lest the way I am looking at it does not allow it

deportes · #13 08-08-2010, 11:33 AM

That was the problem from the start, when I first replaced the coupler, I didn't have the coupler all the way into the steering box, only 1/4 of the way. Reason for it was that I was also trying to have some of the rod slide into the coupler. I thought I had more thna a 64th of an inch from the rod going into the coupler. I didn't think that the rod had slid into itself so I thought that it was correctly installed until it came out and I had to re-install the coupler. I realized that the rod had become shortand I wasn't getting the proper fit. The point I am trying to make is that the rod slid in without me knowing and what I thought was the correct installation was actually a death trap. Whw I was pushuing the rod into the coupler I was able to make ie slide into itself or it had slid before at a accident which I didn't know because it has had previous owners.

meltedpanda · #14 08-08-2010, 11:45 AM

OK then , I see. So - for all out there , coupler onto steering box - entire spline of steering box should be in the splined end of coupler, the steering shaft should be in the other end approximately 3/4 to an inch . With the ends in that way and thte steering rod secure at the wheel there is no way for it to separate,
glad you are OK, hope others check this thread when they do the repair

GGR · #15 09-15-2010, 07:46 AM

Glad you're OK. The absolute thing to check is that the coupler bolts go into the shafts' grooves both on the box and steering wheel sides. You absolutely have to take these bolts out of the coupling while intalling the latter otherwise it wont fit properly. Also, it's advisable to "open" a bit both sides of the coupling and test slide it on both shafts before assembly. Having it slide freely will ease assembly and avoid the column shaft to retract while trying to force-fit the coupling onto it. Then of course both coupler bolts should be properly tightened.