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Steering coupler on 6.9

Started by daantjie, 12 August 2017, 07:11 PM

daantjie

Hi guys

Looking at accessing the steering coupler seems like a bitch on the 6.9 due to things being so tight in the engine bay.
Want to try and do this by using the "pull steering shaft up" method, but the start is of course getting the bolts cleanly out of the coupler and this can lead to a lot of shenanigans with a stripped hex bolt, which I would much rather avoid ;D so any 6.9 owners who have done this I would love to hear your thoughts/tips.

Cheers
Daniel
1977 450 SEL 6.9 - Astralsilber

TJ 450

Hi Daniel,

Yes you're not wrong about it being a bit of a challenge. When I did mine I turned the wheel so that the bolt heads were facing upwards, cracked them loose with a tight fitting socket and then went about the business of raising the steering column. Luckily I didn't run into and real issues, although I would remove and lubricate the bushing in the end of the steering column while you're in the area. With the column raised, you should just be able to pull it off the end of the outer tube.

Another option would be to access the bolts from underneath, but that's not something I've tried in the past.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

daantjie

#2
Thanks Tim I'm guessing on the RHD you have more room from the top? On the US LHD I can't even see it from the top with the brake booster and exhaust manifold in the way  ???  Unless on RHD you have a mirror image of the LHD setup not sure.  Just can't see how this can be done from top without at least pulling off the booster.
Daniel
1977 450 SEL 6.9 - Astralsilber

s class

I've always done it by working from underneath and just removing the steering gear.


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

daantjie

Thanks Ryan seems like this is the only way on a LHD 6.9.  I have no access to a lift so might have to farm this one out.
Cheers
Daniel
1977 450 SEL 6.9 - Astralsilber

s class

I've only worked on LHD 6.9's, always done it at home just with the car on trestle stands.  It's honestly max 30 mins to get the steering gear out.

Obviously the usually precautions for working under a full hydro car apply.


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

rumb

Quote from: s class on 13 August 2017, 02:46 PM
I've only worked on LHD 6.9's, always done it at home just with the car on trestle stands.  It's honestly max 30 mins to get the steering gear out.

Obviously the usually precautions for working under a full hydro car apply.

I use those drive up ramps all the time, would be plenty for you to get it out underneath using them. - just remember that box is heavy, when you pull the last bolt out!
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

daantjie

#7
Thanks guys might be time to invest in those ramps. Jacks, blocks and chocks don't inspire too much confidence that's for sure!
Daniel
1977 450 SEL 6.9 - Astralsilber

TJ 450

Interesting, yes it sounds like the LHD situation is different. I'd be getting the ramps as it would be a safer option and will be handy down the track for other repairs.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Jed

Daniel
There is a procedure out there that details step by step to replace the coupler. I can't Readily find it bu T I thought it was on this website.  I did the procedure a few years ago on my 79 6.9 as the coupler was worn out and made a  God awful rattle on bumps. From what I remember it was not difficult. I did it at my home garage with a floor jack.  The steering wheel Has to be removed, and the turn signal lever and / or cruise control lever (sorry can't remember) and the steering shaft has to be freed up. From below simply loosen the coupler, be sure to mark the position of the two ends so you line it up exactly the same way after. There was no reason to loosened or remove the steering gearbox! When the coupler is loosened and the steering shaft is freed up you push the shaft up into the cabin  just a short distance and then the coupler can be removed and replaced.

Again this is from what I remember! It was definitely very doable and not complicated or difficult. No special tools. Then again I may be smoking crack and have forgotten a few key steps.... I'll keep looking for the procedure. It is out there. It was one of the first procedures I ever did when I got my 6.9 so it's been a couple years.


1979 Mercedes 6.9 #5206 - restored
1979 Mercedes 6.9 #6424 - ongoing restoration
1976 Mercedes 6.9 #484 - restoration?

daantjie

Thanks Jed I think I'll tackle this one soon. I ordered some ramps to give me room to loosen those pesky hex bolts. I think after that it's downhill and ice cold beer to follow  ;)
Please let me know if you find the procedure. I searched a fair bit and could not find a play by play.
Daniel
1977 450 SEL 6.9 - Astralsilber

TJ 450

Hi Daniel,

The procedure will be outlined in the 450SEL service manual... it should be much the same.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

UTn_boy

Food for thought.....it takes much less time to take loose the steering gear box than it does the steering wheel shaft in the steering column.  Furthermore, when the steering gear box is removed, you don't have to remove the pitman arm, any of the steering linkages, or even any of the power steering lines.  You're only taking the gear box loose from the chassis just enough to get the coupler out. 
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

daantjie

#13
Okie dokie, only 18+ months have gone by ;D

I finally got round to doing this last night.  I followed the "pull steering column into cab" approach, and it worked quite well for me.  Dropping the box I think makes sense if you are doing other work on the linkages and such, but really for me I was not going to bugger around with that hunk of metal late on a Sunday night :o  I fully respect members' approach to want to do this job that way, but for me it's overkill seeing how easy the "in the cab" approach was.

Some tips from me:

1)  Yes, again, you ABSOLUTELY have to make sure you get a mega bite on those 6mm hex bolts on the coupler.  I spent probably 20 minutes cleaning the heads before I put the bit in, and even then I was super nervous.  Think about all the heat cycling those bolts go through being so close to the exhaust manifold.  Hilarity will not ensue if you round out these puppies...

2) I had some trouble at first to align the coupler on the shaft.  In looking at it more closely, at first I pushed the coupler slightly too far onto the spline of the box, and that caused the bolt catching on the "raised" portion of the splined shaft, and not "in the groove".  I could not figure out why the bolt would not run in easy, and then realized that it was catching on the splines.  So make sure you kind of jiggle the coupler so that you can easily run the bolt in by hand.  It still sits close to the box but it should not be close to flush of course.

Other than that it was a relative walk in the park.  I have yet to road test, but already the hella annoying "clang clang clang" is gone when I turn the wheel and it feels nice and tight, and how I love nice and tight ;)

The old coupler is crispy, but only the one bushing is completely gone and I could almost replicate the "clang" 100% just by hand.  Maybe the one sitting closer to the exhaust manifold?  The other one is crispy but still in there.  I think I am going to rebuild it with some heavy bolts and such when I am bored again...

Anyhoo...so yes this is very doable, but again, make sure you clean those hex bolts and get a good bite.  I even tapped the end of the breaker bar with a light hammer so that the bit really got in there good.  I do not even want to think about the shenanigans involved in trying to drill/dremel in that area.  On the 6.9 the space is super tight, will be a nightmare.

Cheers
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

Quote from: rumb on 13 August 2017, 03:22 PM
Quote from: s class on 13 August 2017, 02:46 PM
I've only worked on LHD 6.9's, always done it at home just with the car on trestle stands.  It's honestly max 30 mins to get the steering gear out.

Obviously the usually precautions for working under a full hydro car apply.

I use those drive up ramps all the time, would be plenty for you to get it out underneath using them. - just remember that box is heavy, when you pull the last bolt out!
I also did it from underneath with ramps.  At least I think it was ramps, maybe I had it up on blocks, can't recall.  Anyway, I was able to do it from underneath WITHOUT removing the steering gear.  It was tight but doable. I was actually a bit confused about the need to remove or loosen the steering box, it just didn't seem necessary at all.  Maybe some cars have more options or stuff down there than mine?
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0