Steering coupler repair... drop the box or raise the column (w115)? - PeachParts Mercedes-Benz Forum

Shortsguy1 · #1 06-24-2015, 12:54 AM

I believe that the steering coupler between the steering column and the steering gear box has perished. This is for my 68 220d w115. I am getting that classic thunk when going over bumps or when rotating the steering wheel back and forth quickly. On these early couplers, you can replace the plastic internals, and I have my parts on order.

But am struggling with a major decision... in order to separate the column from the steering gear box, should I try to lower the gear box or raise the column. Based on my reading so far, it is clear to me that the answer is very specific to which chassis you are working on. But I could not find the definitive answer for a w115. Dropping the box is the official method, but it is very heavy and must be quite awkward. I bet getting everything lined up right will be hard during install. Also, MB says in bold to only install new bolts to anchor the steering box, but that is $60 worth of bolts if I follow their directions perfectly.

Raising the steering column seems a lot more pleasant in terms of the working environment. But if it was easy, I am puzzled why MB doesn't suggest it in the FSM. Does anyone know why MB doesn't recommend just raising the steering column for this job? Their directions for how to remove the steering column seem pretty straight forward, but may be I am missing something. Thanks for your time.

On a side note, there are some threads which mention that you can ruin the collapsible steering column if it collapses on you by accident. Does anyone for sure if this is absolutely true? If not, I guess a third option would be to try to temporarily collapse the steering column, and then lengthen it again to finish the job. MB provides lengths of the column, which I think is to help you know if it has collapsed by accident a little. One thread alluded to ruining the steering column by breaking some plastic insert hidden inside the column. I have been unable to verify if this is a real possibility, but obviously destroying my steering column is something I would rather avoid. Thanks again.

Stretch · #2 06-24-2015, 07:26 AM

I can't say with 100% certainty for the W115 (having never owned one and done that job) but on a W123 (OK different but not all that different) removal of the steering column involves more steps and more chances of busting something - it is a dashboard disaster waiting to happen - same goes for the W201 (just in case you're not wondering at all!)...

...I can't answer your concerns about buggering the collapsing mechanism on the steering column - my impression of the W123 one (which I think is the same as the last generation W114/5) was that it was pretty sturdy - yeah sure drop it on the floor at an awkward angle then you'd probably shaft it (!)...

...The steering box isn't all that heavy - sure if you're not ready for it it might catch you out but if you take it slow and support it with a jack / blocks of wood if you are working alone then there'd be no problem. I fit them with one hand under the box and the other arm reaching round the front wing to stuff the bolts in!

My vote goes for - "by the book" in this instance.

Stretch · #3 06-24-2015, 07:27 AM

Oh yeah bolts - they are fine threaded beauties that might be rusted - if they are in good condition I'd do the cleaning and degreasing and loctiting trick much like caliper bolts (which according to the FSM MUST be changed)...

barry12345 · #4 06-24-2015, 11:10 AM

Find the factory procedure. I suspect you have to insert a pin to prevent accidental collapse of the telescoping portion. Then just pull the steering box.

Not positive but suspect this might be so. Anyways there will be no loss one way or another by reading the proper information. No I have not done this myself on a 114 or 115 chassis.

Shortsguy1 · #5 07-13-2015, 01:59 PM

Despite the helpful advice above, I decided to raise the steering column for this job. I have a back-related injury, and struggling under the car did not sound like fun. While fiddly, doing it the steering column way is very reasonable, and relatively straight forward.

Key steps:
Soak those coupler allen bolts with AeroKroil over many days.

Have your front wheels straight ahead. You can lock the steering box if you want to ensure they are straight, but I didn't bother.

I was able to remove both allen bolts from the coupler without stripping them using two 3/8" extensions. For the lower one, I was able to get a straight shot at it from above beside the brake booster. For the upper (more rearward) one, I had to use a universal joint adapter to get the angles right. I I replaced them with MB's current version, which is a Torx.

Follow the FSM to release the steering column. Nothing really complicated about this. Only thing is that I kept forgetting to put in the ignition key when working on the car, so the steering would get locked. Without a steering wheel on, I could not release the steering lock. So a few times, I temporarily slid on the steering wheel to help release the steering lock mechanism.

I didn't lock the two parts of the collapsible steering column with the pin which is discussed in the FSM. Instead, I used a pair of vice grips very tightly fastened to the lower (internal) part of the column. These kept the internal part from being able to slid into the outer part as pushed on it all from the coupler location. Also, during replacement, I tapped my hammer on the vice grip to get the column back into the repaired coupler.

One thing I really liked about this method is that I could tap the fixed coupler onto the steering box via the steering column hole in the floorboard. This ensured that the coupler was fully seated onto the box. And then I watched very carefully while tapping the hammer on the vice grip mentioned above to ensure that the steering column was also going into the coupler an adequate depth. I read some thread about someone's thinking they had everything property seated, but in fact their column had collapsed slightly. So I liked that I could very clearly observe everything going together correctly.

I also used this as a chance to replace the rubber seal between the steering column and the car body. It was $20, but hopefully will keep noise and water from entering the car cabin.

Also, my column shift automatic shifter needed new vulkollan bushings (see M-100 Message Board - Horn "short" in column change cars.). I didn't want to wait for parts, but I found an acceptable "thick nylon washer" from my local hardware store.

All in all, it took me quite a few hours because I am very slow and not very good at this. But it is together and I am 100% sure it is safe. I never had to lift the car or climb underneath it, so that is a nice feature of this approach.

Oh, one last thing. I mistakenly assume that however I find something on the car is correct, but it is becoming clear to me that prior mechanics make plenty of mistakes too. So my advice to others like me who are somewhat new at all this is to read as much as you can ahead of time so that you can spot when some prior mechanic has made a mistake. In my case, they had the washers for the coupler in the wrong place, so I initially put it all together incorrectly. I could not get the two parts of the coupler to seat correctly, and then I realized there were supposed to be two washers between the coupler halves, to take up the space I was seeing.

If anyone has specific questions about this project in the future, send me an email via the forum, and I will fill in some of the details.

Stretch · #6 07-13-2015, 02:30 PM

Did you have any trouble aligning the steering wheel with the centre position of the steering box?

Shortsguy1 · #7 07-13-2015, 03:40 PM

Because access to the coupler bolts is so limited, there was only one position which still allowed me to have a straight shot to the lower one with my double extension. One tooth either way was clearly wrong, because I wouldn't have been able to get to it perfectly with my tools. I took photos before to have a visual reference for the angle of the bolts, but didn't end up using them.

I guess this is probably the main advantage of not removing the steering gear box. It is really easy to align everything when you only pull the steering column straight out (actually I levered it from below, but you know what I mean). Those teeth seem really small when you look at them, but when you see how many degrees of rotation is associated with one tooth, pointed straight up versus not pointed straight up is easy to differentiate.

Stretch · #8 07-14-2015, 05:21 AM

Well I that's enough encouragement for me to give it a go the other way round the next time I'm fiddling about with steering