w108 Steering Coupler Alignment

[tjohnson]

Spent the late afternoon removing the worn out steering coupler on my 72'. Bushings were completely nonexsistant. Looking forward to driving her after this repair. My question is this...good way to assure proper line up on the splines and end up with the steering wheel registered correctly. I gave it a good cleaning before the job in hopes to spot it with white spray paint for alignment but during removal it is gone away. Anyone who has changed one out knows how tight a space I am dealing with. Any tips/tricks will be appreciated.
I used this sequence for removal:
*removed 2 allen bolts from old coupler
*removed gearbox 3 bolts and lowered unit parting the coupler from the steering shaft
*worked coupler off gearbox splined shaft

[79Mercy]

I'll be doing this same job to my W115 on Saturday, it doesn't sound like its going to be a very fun job.

[tjohnson]

It is a knuckle scraper! Read several threads and seems like everyone ends up with the steering wheel not centered out. Easy to see how when off a couple of splines can be more than you'd think. We'll see when I reinstall in the morning..........

[Mike D]

I've always used a "centering bolt". You use a grinder to put a bit of cone on the end of a bolt. Remove the existing bolt on the gearbox (small bolt on the top with a copper/aluminum washer), move the gear box to align the pilot dimple, insert the bolt hand tight, install with the wheel in the straight ahead position and remove the bolt after you have the couple installed.

Someone on the board says you can remove the coupler by loosening the steering housing and pulling the assembly back. I've never tried it but if it works it's definitely easier and cleaner than pulling the gear box.

Be sure to replace and re-torque the gear box mounting bolts with NEW grade 10 bolts. Do not re-use the old bolts. TORQUE the bolts! Don't just whack them with an impact or "grunt" them in there with a breaker bar.

[tjohnson]

Worked on the reinstallation early this morning before the summer heat kicked in. Good wrestling match working the gearbox onto the coupler. Did a dry fit first to make sure penetration would go smoothly. My son worked from above with a rope, helping to pull it up and not letting it slip back down. My wife made sure the steering wheel stayed right and tires were straight as it lined up on the splines. Here's the fun part....gearbox would not come up far enough to line up on the bolt holes, missing about 1/2". Wrestled, giggled, and even tried to coax it with the floor jack.....no luck! Such a tight space just couldn't see what was holding it off. Possibly the upper stand off for the bolt thru hole. When removing the gearbox bolts it only took alittle pry and it jumped forward and down 2-3". Needless to say, i'll be unhooking everthing from the idler arm before another round. The gearbox is a component and that's the way i'll treat it...unhook the things that are binding it up. My son mentioned that the fact that the car is jacked up on stands may be working against the reinstall(weight of the front suspension hanging there)....possible but without being jacked up can't get under it! Still good thinking for a 15 year old.

[Mike D]

I usually have to spread the coupler by using a cold chisel. Give it a couple of medium raps. Don't go gorilla on it because it is a cast piece and will break.

Yeah, it's a pain. Wiggle, jiggle, swiggle it, hold your mouth just right and it slides on.

[tjohnson]

The dry fit and mating the coupler went pretty good. The gearbox needs another 1/2" of "up" to line up on the bolt holes, i can see it is in the coupler all the way(steering shaft & gearbox stem) Still thinking the suspension links are holding it down. I removed the castleated bolt on the idler arm hoping to part it from the suspension there and it slid off about halfway and stopped (not about to go beating on that gearbox!). Next went after the drag link and steering arm....both balljoints stucker than all get out. Balljoint seperater wouldn't break em loose. Go figure........it's all fun

[Mike D]

You left the steering links connected? Ummm, that's kinda of like doing a tune-up with the engine running (as I am sure you are discovering now!).

Drop the steering stabilizer if it's got one, split the drag link from the pitman arm and I think, the DS tie-rod inner end. Use a "pickle fork" since you dont have the box mounted.

You might have to use a pitman arm puller to yank the pitman arm from the box so you can really whale on the pickle fork to split the joints. MARK THE PITMAN ARM TO SHAFT ALIGNMENT or all the work you did in lining up the shaft will be undone.

[tjohnson]

Mike, you got that RIGHT! Like I said earlier, it is a component and should be treated as such.......get it unhooked, so it can be dealt with. Read several threads on this and if you follow the steps some suggest you'll work in circles! Thanks again for your interest and help!

[Zeppo2K2]

I just did these bushings on my 230SL, a car I purchased in boxes. The engine is out of the car. This was a really tough job even with me standing in the engine bay. I left the steering gear all connected. The first try was without the bolt in the steering box to hold dead center. My car did not have correct steering wheel alignment when I started, nor did it have it when I finished.

Try 2. I removed the steering wheel and steering box. I greased both ends of the coupler and tried its fit on each side. I found dead center with the turn signal cam, lined up the steering wheel, and the column lock worked dead center. I applied the bolt to the steering box locking it at center. I jacked up the front end so the front wheels easily moved. It was very difficult to get the steering box in place, but easier the second time. Now it all seems aligned, but I still have not driven the car.

That's not why I'm writing this. On the SL, I had a crunching noise when turning the wheel, that's why I found the bad bushings. But, my daily driver is a 220D, 1971. When I got the car 2 years ago, it was quiet in the bushings. When I worked on the master cylinder 2 years ago, the steering started crunching. Then it stopped. Just this week, I worked on the IP and sprayed that side with degreaser. The steering started crunching again.

So I sprayed WD-40 into the coupler and it quit crunching!

Bottom line: protect that coupler from chemicals that may destroy it, like brake fluid and engine degreaser. I've just purchased and will apply some silicon spay to the coupler to attempt to preserve the bushings. Maybe brake fluid spills and strong chemicals are a major detriment to the bushing's life. I'm going to try to make them last. My complements to those of you able to do this job with the engine in the car. What a pain that must have been.

Ron

[pch2021]

Use the factory steering lock bolt. It fits in the 13mm drain plug on the base of the box. You can use it to find the dead center. Install the steering wheel with the ignition in locked position.

[tjohnson]

Thanks for all the input guys. Going out to the shop this morning for another whirl. Yes, it is a tight space.....the 4.5 v8 really fills up the engine bay. I'll post results after todays adventure!

[GGR]

Check that your left exhaust manifold is not on the way. Clearance is tight, and if your engine and subframe mounts are abit tired the engine may sit lower than it should especially if you jacked the car up. Try to jack the car via the front subframe, not the body, and see if it makes a difference.

While the front subframe is sitting on jackstands, you can also lift the engine a bit on the left side with a bottle jack. This will give you more clearance to move the stering box around.

[tjohnson]

GGR nailed it. After breaking off everything from the pitman arm and the gearbox still wouldn't fit I changed direction. Put the floorjack on the left side of the engine just in front of the tranny and came up about an inch. That allowed the gearbox to clear the manifold. I could see the scar marks on the manifold where the box was hitting. I could have left all the steering hooked up as I did in my first attempts, could get it on the coupler but the manifold was holding it off. ALSO....study the geometry of the new coupling:notice the coupler bolt on the steering column side cannot be inserted until the coupler is slid on the shaft, so it can pass thru the machined out notch on the shaft. With the bolt put on too soon the coulpler will slide on the shaft, but not far enough....you'll wrestle the gearbox on for nothing!Live and learn.

[Mike D]

All right! Glad to hear you got it finished. You did use NEW mounting bolts, right?