idler arm repair, '64 230sl

[enochbell]

The squeak I have when turning, noticeable only when turning at very slow speeds, like turning out of garage, was diagnosed by an independent as idler arm in need of repair.  So I planned the repair, and while I am at it what the heck: new Bilsteins, steering shock, U and L outer control arm bushing repair, and a new brake line for the one I broke in the meantime.  Now I am down to the idler arm, and I can't figure out how to remove it and it may not even need repair: it was a nipple I missed for 5 years. It took what seemed like about 30 grams of greese.

OK, stop laughing, I am owning up to this freely.  

Is it possible that greasing this sucker will do the trick?  If not, how do I get the thing out?  The repair kit is the very early one, it cost $125 for a small handful of nuts and bolts.  If I can get away without opening this can of worms I would love to, but I will do it if I have to.

Your comments are appreciated.  Just no laughing.

Thanks,
g

'64 230sl, fully sorted out...ooops, spoke too soon

[Vince Canepa]

The idler arm pulls out from the bottom of the bracket.  The cap nut at the top, which is actually the upper bushing, has to come off.  The pivot pin is threaded, just like the control arm bushings.  The lower bushing is bronze.  After pressing it in, it needs to be reamed to size.  There is also an anti-knock bushing at the bottom.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[enochbell]

Thanks for the tips, do you know if the brass bushing is DIY pressable and are their specs for reaming or is it obvious from the fit?  The repair kit includes a brass bushing with a chamfered edge, is this the piece that gets reamed?

Appreciate the advice,

g

'64 230sl, fully sorted out...ooops, spoke too soon

[ja17]

Hello,
Often times the center drag link (center tie rod) will dry out. It will "creeeeek" like a giant oak tree! The vibration will travel through the front suspension and will sound like other things.
Since the noise did not go away with the greasing of the idler and it did take grease, I would be suspicious the problem may be somewhere else like the drag link. Try to pinpoint the problem.
I once added grease nipples to each end of the center drag link on my Mercedes 450SLC. It had began squeeking and groaning. After lubing it, The noise immediately went away and it did fine for another ten years!


Joe Alexander
Blacklick, Ohio

[Vince Canepa]

Joe brings up a good point - are you sure that is where the noise is comimg from?  I had a knocking noise from mine, not a groan, but then, the anti-knock bushing was dust.

The bronze bushing can be done DIY - I did mine.  However, I made some tools.  I made a pressing tool out of threaded rod and some various bits.  I made a guide to ream the bushing by boring a hole into a spare upper bush.  Then the upper end of my adjustable reamer was held in line with the bore of the bracket.

If you don't have the capability to make the tools, have someone do it.  I had trouble finding the clearance.  After some searching I found .0009 - .002" in my Intereurope Workshop Manual.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[enochbell]

Thanks VC and ja, I don't know if the squeak has gone away: the front end is in pieces and I won't know the effect of greasing the idler arm bushing until I put load back on the assembly.  But based on your advice I don't feel competent to do this job myself, getting the end float correct would just be a guess on my part.  "I have seen the abyss, and therefor I did not go in" ($1 for the correct quote and author) Dante?

Thanks much, I am beginning a new question on aligning the knukles on the king pin, hope I have better luck with that one.

Have a great weekend.

'64 230sl, fully sorted out...ooops, spoke too soon

[Benz Dr.]

Now here's one where I really do have the right answers.

 If you pound on the bushing from above you can actually peen it and it wil get so tight in the housing that it will never move. More on that later.

The threaded nut on the top does two things - it sets the height of the pin and it holds it in place. This is a very neat system as the pin has a coarse thread and the housing has a fine thread. I set it so that you can get full swing ( left to right ) without the pin binding up. If it's too tight you would need to turn it down about one full turn. The pin will actually move up and down a small amount because it threads itself into the nut. You want a 2 - 3 mm gap ( at the bottom ) at the centre position.

Removal of the bushing is pretty hard to do sometimes. After you remove the nut the pin should slide out from the bottom. Inspect the bottom of the pin where the bushing would have been in contact. If it's pitted or heavily scored get a new or better pin. Pitting is caused by water that got into the bushing area which is caused by lack of grease. Heavy wear would be from the same reason.
Normally the bushing which is brass will wear out first because the pin is very hard steel. You can't even mark it with a file - these things are machine finished on a cylindrical grinder.

Bushing removal can done with a hacksaw. Remove the blade and push it through the bushing and then put it back on your saw. By going slowly and carefully you can split the bushing and then it can be removed easily. I use a mandril which is a special MB tool to install any bushings like this. The trick is not to hit the bushing in any way. So, what I do is place the old bushing on the mandril first which is soft so it won't damage the new bushing and then I place the new bushing above it. Start the bushing so that the flat side is pointing to the bottom and knock it in level with the bottom of the tube or housing that it sits in.
 Try the pin which should fit. If not, use a small 1/2 round file and check for any burrs. The pin should slide in and turn freely back and forth when its in it's normall position. Greasing the pin before trying to install it should help out.
Once you know it will fit remove the pin and install the seal at the bottom of the housing.
 Placing the pin at about level with the top of the hole before you start the nut seems to work out pretty well. If the pin is too tight move it down a bit and try again. If it's down too far move it up. This is a trial and error sort of thing but not difficult.
Once you have it set up and the pin will swing back and forth knock the locking plate over on one flat of the nut. A small detent on the top of the housing locates this plate from turning.

Of course, you want to check the play at the idler arm in the first place before you do all this work. Push up and down on the arm which should NOT move at all. Having the left tire on the ground while moving the right tire in and out will make the idler arm pop up and down under load if it's really loose.
When the idler arm is worn the car will do one thing which is a bit scary. Driving into a tight turn at speed will cause the steering linkage to load and as you turn the wheel at bit to come out of the turn one wheel will go in a different direction. You will find yourself constantly making small corections as the car moves all over the place. On - ramps are a real thrill with all that bump steer. This is different than tie rod or drag link wear which gives a vauge or loose feeling. In this case the steering will feel normal but will be a handfull on certain corners or curves. Turning right seems to be worse than turning left.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org

[enochbell]

Dan,
Your instruction is clear and very much appreciated, spot on.  I am to the point of removing/pressing the bushing and was thinking dry ice and acetalene, but the hacksaw and mandril sounds a lot safer.  I will let you know how it ends up.

Do I gather that the bushing will seat properly and that the chamfer already cut in the top will suffice or will it need reaming?  That is really more of a rhetorical question, as I will find out when it is seated.

Thanks for your assistance,

greg

'64 230sl, fully sorted out...ooops, spoke too soon

[JimVillers]

Greg ... Yes ... teh bushing will need to be reamed.  I ended up useing a 14mm drill (if I rember correctly).  It does not do as nice a job as a ream, but when choices are few, a drill will work.

Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor

[Benz Dr.]

The chamfer is on the otside of the bushing to help to start it into the hole. You should NOT need to ream out the bushing if you follow my instructions.

 You really DON'T want to make the hole any bigger. The threaded end of the pin will usually be larger than at the bottom where you may have a small amount of wear. As long as you can get the pin to go into the hole and move upwards, you'll be OK. The pin will actually ream out the hole a little bit anyways and once you have it placed reaming it out the bushing before hand will now have it too loose. You just wasted a whole lot of time.
You want the pin to move freely once it's in place. Going into the hole you just want it to be free enough to keep from binding so it will continue to move upwards.
Later cars use a totally different idler arm so none of this applies to 280SL's.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org

[enochbell]

Many thanks, it worked.  Found a drift that fit perfectly, I think I just spent all my luck, hope I don't need any more.  The fit is very tight, but not binding, did not need to remoove any metal from the bushing.  Now I understand the cost of this repair it, the tolerances are serious and the pieces look to be all one-off machined.  Now that it is reassembled, one last (yeah, right) question: what is the permissable gap between the bottom of the bearing shell and the steering arm.  I have it gapped to about 3mm so that the surfaces clear through the steering arc, I assume it should avoing rubbing the arm at any point but don't have any source for the correct clearance, if there is one.

Thanks all, I really appreciate the help.

'64 230sl, fully sorted out...ooops, spoke too soon

[Vince Canepa]

Make sure you can grease it until grease comes out the vent hole at the top.  If the clearance is too tight, the grease will not flow.  I've only done two, but both had to be reamed.  The pin wouldn't even fit it - and I did NOT bang them in - I pressed them with the mandrel I made, which looks just like the factory tool.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[enochbell]

Vince, thanks, I was wondering what that hole was doing in the cap.  I just took a look and no, there is no grease pushed through the hole, I will go back and pump a couple of more squeezes of grease through the nipple and see if it can clear.  In the meantime, do you understand my question about clearance between the bottom of the bearing shell and the steering arm?  I am not sure I have the correct terms, let me know if I need to clarify, and thanks for the advise,

greg

'64 230sl, fully sorted out...ooops, spoke too soon

[Vince Canepa]

I think I understand what you are saying and I think you are OK.  As Dan points out, the arm actually rises as it arcs.  It should not touch the bearing shell.  You just have to find the right combination when simultaneously threading the upper bushing onto the pin and into the bearing shell.

My concern for the greasing comes from my experience.  While I understand what Dan is saying about going oversize, in my limited experience that was not the problem.  I had to ream the bushing to get the pin in at all. Perhaps that was because I used an aftermarket bushing?  Using an adjustable reamer, I reamed the bushing to .001" larger than the bearing surface of the pin, which is at the lower end of the tolerance (with the same concerns about oversizing that Dan has).  I mention this because grease flows with great difficulty at this clearance.

If grease won't flow, try moving the pin left and right when greasing.  The grease might flow better.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[enochbell]

Thar she blows: grease through the breather hole.  It took constant pressure on the gun while moving the steering arm back and forth.  Done, and thanks for all of the help.

Now if I can get this bottom CA bolt back in...

greg

'64 230sl, fully sorted out...ooops, spoke too soon

[Benz Dr.]

Not a problem. The bushing has grooves machined into it so grease can flow through and also stay around the pin to provide lubrication.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org