[glenlloyd]

Hey guys
I've replaced the idler arm bushing on my car but I still have a concern. When the wheels are straight ahead, parallel to the car, there is no play in the steering linkage at all. I can nudge the forward / rear edge of the wheel and it feels solid.

However, when the wheel is turned even partly (say 30 degrees or less) or full lock and I nudge the wheel there is a slack in the steering and you can feel it.

This leads me to believe that when the idler arm is in any position other than straight forward there is some malformation of the hole that the bolt goes through, perhaps the hole is oval side to side but not forward / back.

Has anyone else experienced this with suspension / steering replacement work and if so did you find a solution?

Also, lower bj's and upper control arms have been replaced.

Let me know what your thoughts are

Thanks
Steve A

 

[The andrew]

Just be sure that it is infact play in the steering, ie pitman arm, drag link joints. The LCA bushings are very very squishy and can be moved by hand especially when there's milage on them.

The front LCA bushing that is oil filled allows for a lot of play in the steering system but in return provides less feedback to the driver and chassis for the sake of precise handling assurance. Poly bushings may fix this, I'd like to try also the Meyle HD versions of this bushing that came on later cars, 98-99 I think.

The steering system itself is very tight, especially for a recirculating bearing setup. IMHO I think the missing link to a firm steering system that is more responsive is the absence of such large soft bushings.

I know Mercedes tried many many bushings before they were satisfied but they may have been leaning towards refinement, which is fine, but I still wonder what a more solid bushing in that location would provide.

 

[glenlloyd]

Just be sure that it is infact play in the steering, ie pitman arm, drag link joints. The LCA bushings are very very squishy and can be moved by hand especially when there's milage on them.

The front LCA bushing that is oil filled allows for a lot of play in the steering system but in return provides less feedback to the driver and chassis for the sake of precise handling assurance. Poly bushings may fix this, I'd like to try also the Meyle HD versions of this bushing that came on later cars, 98-99 I think.

The steering system itself is very tight, especially for a recirculating bearing setup. IMHO I think the missing link to a firm steering system that is more responsive is the absence of such large soft bushings.

I know Mercedes tried many many bushings before they were satisfied but they may have been leaning towards refinement, which is fine, but I still wonder what a more solid bushing in that location would provide.

Front LCA bushings not new but not bad enough to cause this. The problem is isolated to the steering components, you can physically see it shift when the wheel (or rather spindle) is turned off parallel.

While there's play in the bushings I cannot really move the LCA by hand, you have to use a pry bar, but I can see inside the rear bushing (front LCA) that there is some worn / torn rubber.

Correct me if I'm wrong but the front bushings don't appear to be oil filled (hydraulic). The rear LCA outer bushing is but I don't see any evidence / documentation that suggests the front LCA has oil filled bushings.

Thanks
Steve A

 

[The andrew]

Front LCA bushings not new but not bad enough to cause this. The problem is isolated to the steering components, you can physically see it shift when the wheel (or rather spindle) is turned off parallel.

While there's play in the bushings I cannot really move the LCA by hand, you have to use a pry bar, but I can see inside the rear bushing (front LCA) that there is some worn / torn rubber.

Correct me if I'm wrong but the front bushings don't appear to be oil filled (hydraulic). The rear LCA outer bushing is but I don't see any evidence / documentation that suggests the front LCA has oil filled bushings.

Thanks
Steve A

http://www.benzworld.org/forums/w14...control-arms-lcas-bushings-demystified-2.html

A good DIY thread there.

Hmm If I go for new bushings, might as well pop in some H&R springs lol, then it's off to the shop for alignment on the beatiful Hunter machine.

The later models with the lowered suspensions exibit much less wear because the lowered ride height allows for less movement overall of the suspension, with the older, higher suspensions the W140 rides about an 1.5 inches away from the bump stops in the dampers at all times so you could imagine how close it must be on face lifted cars and their lowerd stance.

Though I will say a customer of mine has 246k on his original suspension in a 96 S420, and the car does feel more driver friendly with the lower suspension geometry, steering feels a little more responsive and the car is flatter in corners even with the stock 16 in rims, and there is less side to side wobble on the highway, so Mercedes surely improved the ride and handling quality just by lowering the car about an inch. The only thing that's worn on that S420 is the swaybay endlinks up front, other than that the bushings look/feel like new.

Steve, can you take a video, the only other place there can be play is in the steering box itself, but if centered straight on and there is no play, I don't think you should have a problem at another steering angle.

How many miles on you car? Climate it's been in?

You have a number of balljoints, outer tie rod (2) inner (2) pitman arm (1) idler arm (1).

It's strange that straight on you're good but at full lock there's play.

If you notice in the video when they "scrub" the front wheel around you'll notice only the rear LCA bushing moves along with the subrame.

 

[G-AMG]

Nice Video!

I like the way they described the W140 as a "Road Fortress"

 

[glenlloyd]

Though I will say a customer of mine has 246k on his original suspension in a 96 S420, and the car does feel more driver friendly with the lower suspension geometry, steering feels a little more responsive and the car is flatter in corners even with the stock 16 in rims, and there is less side to side wobble on the highway, so Mercedes surely improved the ride and handling quality just by lowering the car about an inch. The only thing that's worn on that S420 is the swaybay endlinks up front, other than that the bushings look/feel like new.

My endlinks were shot, those and the front stabilizer bar bushings are set to be repaced when I pull to replace the LCA bushings.

Thanks for the pointer on the front LCA bushing replacement, the spring compression is what has held me up to this point, mostly because it's impossible to get in there with conventional compression tools I have. I have also looked at Haku's pdf of front LCA bushing replacement in the knowledge base

Steve, can you take a video, the only other place there can be play is in the steering box itself, but if centered straight on and there is no play, I don't think you should have a problem at another steering angle.

Yes, I can do a video but it won't show anything more than I've described, and there's a limit to where I can get in to video due to lighting.

How many miles on you car? Climate it's been in?

145k miles, serviced in Florida up to 80k, after that serviced in Georgia up to 110k, came to midwest after that and serviced locally either at the MB dealer or an import indy shop. Don't know the miles when it arrived but looks like last 35k at the most.

You have a number of balljoints, outer tie rod (2) inner (2) pitman arm (1) idler arm (1).

both lower ball joints (at LCA) are replaced. Both upper arms are replaced, new tie rods to install but there's no slack in the existing tie rods at all, and I will admit I was surprised by this. The center link doesn't appear to be deficient either.

It's strange that straight on you're good but at full lock there's play.

Strange yes, but not impossible, and that's why I suggest that when there's a particular stress on the idler arm an elongated hole, perpendicular to side of the car, would allow the arm to shift even when a new bushing is installed.

If you notice in the video when they "scrub" the front wheel around you'll notice only the rear LCA bushing moves along with the subrame.
http://www.youtube.com/watch?v=T6s8Me05chc

Yes, I did notice that, but there's a lot more stress on that front LCA rear bushing, far more than the forward bushing, which is almost parallel to the spindle mount. Triangulation of the degree they've designed into the front LCA makes that rear bushing susceptible to torsional stress, I'm surprised that they didn't make the rear bushing more substantial in the front LCA. Forward motion on this design puts all of the stress on the rear bushing.

Thanks
Steve A

 

[The andrew]

My endlinks were shot, those and the front stabilizer bar bushings are set to be repaced when I pull to replace the LCA bushings.

Thanks for the pointer on the front LCA bushing replacement, the spring compression is what has held me up to this point, mostly because it's impossible to get in there with conventional compression tools I have. I have also looked at Haku's pdf of front LCA bushing replacement in the knowledge base



Yes, I can do a video but it won't show anything more than I've described, and there's a limit to where I can get in to video due to lighting.



145k miles, serviced in Florida up to 80k, after that serviced in Georgia up to 110k, came to midwest after that and serviced locally either at the MB dealer or an import indy shop. Don't know the miles when it arrived but looks like last 35k at the most.



both lower ball joints (at LCA) are replaced. Both upper arms are replaced, new tie rods to install but there's no slack in the existing tie rods at all, and I will admit I was surprised by this. The center link doesn't appear to be deficient either.



Strange yes, but not impossible, and that's why I suggest that when there's a particular stress on the idler arm an elongated hole, perpendicular to side of the car, would allow the arm to shift even when a new bushing is installed.



Yes, I did notice that, but there's a lot more stress on that front LCA rear bushing, far more than the forward bushing, which is almost parallel to the spindle mount. Triangulation of the degree they've designed into the front LCA makes that rear bushing susceptible to torsional stress, I'm surprised that they didn't make the rear bushing more substantial in the front LCA. Forward motion on this design puts all of the stress on the rear bushing.

Thanks
Steve A

Yes, just think of the stress that's upon that rear LCA bushing under hard braking. The front bushing gives the car it's feel, my e46 BMW had a ball joint there, and then just a rear LCA bushing. Of course the steering was tight but as usual sacraficed comfort and noise. It was also a Strut and not a double pivot design. I suppose a rear poly LCA bushing would enhance the steering feel, braking feel, and wheel control whilist maintaining comfort due to the fact it's all, but the upper CA, that is isolated by the subframe mounts, even the spring which was a first and last on a Mercedes, previous (W126 spring integrated to frame rail) and post models (W220 and W221 with struts) all had the spring directly mounted to the body.

What I'd like to do is purchase a cheap web cam so I could mount it in and around the wheel well and take video of the suspension bits in action.

Me thinks the caster design allows for interesting wheel movements when hitting a bump and the soft rear LCA bushing allows for forward and aft motion of the wheel, which should have better control as to not let the wheel leave the pavement surface which would cause a jolt and discomfort through the chassis especially with a car this heavy. 2:37 in the video shows the rear bushing flexing a lot! I believe that kind of motion would upset other components, but only trying a poly bushing set will show for sure. I may pioneer this on this forum if someone hasn't already. Although I can only find the front bushing in poly, might have to make a custom rear...

I drew a pic to better explain, what I'm on about, I think it makes sense.
Tomorrow I'll check my steering and angles and get back to you.

 

[The andrew]

I know this is a BMW but the geometry is similar, a rear LCA bushing that is soft or worn can cause this: see as he jabbs the brakes the wheel moves about...forget aligning a car with that kind of play, it will always wander if the pavement is uneven.

Forward and aft movement from the arm rotating on flat plane. I wish to get angles like this when I set up the web cam in my car with a laptop

Then I can analyze the suspension visually, which will be perfect for diagnosis of my car and customers' cars. Good idea no? I could even inspect steering under load and use LEDs to light dim areas under the car.

 

[glenlloyd]

Your picture describes the issue precisely. The triangulation of the control arm places enormous stress on the rear bushing, which I would suggest makes this bushing wear quickly. I would think that a full rubber bushing for the rear would be better than the one there now, as it has webs inside that can move and eventually break down.

Granted, they wanted this car to ride smoothly and it does, but a bushing under such stress needs to be beefier I think.

I don't however, think this is related to my problem with the steering sector. It creates an alignment issue but it will not contribute to a slack in the steering linkage.

thanks
steve a

 

[chuckindetroit]

Your symptoms are typical of a recirculating ball (as opposed to rack & pinion) steering gear. Inside the gearbox the sector shaft is in greater contact with the piston/ball nut when the wheels are straight ahead. When the wheels are turned to one side there is more and more play between the internal components. This is natural for this system. A lot of this slop can be taken out by adjusting the steering box.

 

[The andrew]

Your symptoms are typical of a recirculating ball (as opposed to rack & pinion) steering gear. Inside the gearbox the sector shaft is in greater contact with the piston/ball nut when the wheels are straight ahead. When the wheels are turned to one side there is more and more play between the internal components. This is natural for this system. A lot of this slop can be taken out by adjusting the steering box.

How much can the boxes be adjusted for slop?

Google Image Result for http://www.mbzponton.org/images/mb_steering1.jpg

 

[chuckindetroit]

I have had good results on both of my older 126's and my 92 500SEL. The first thing to do is center the wheels and then remove the drag link form the pitman arm. Wiggle the arm. Chances are there is slop. Now with the ignition key turned to unlock the steering column turn the gearbox by using the pitman arm. As it goes toward one end of travel you will see more slop. By adjusting the gearbox a little at a time you will see the play decrease. I recomend reading the procedure in WIS or AlData to get the gist. It is possible to over adjust the steering. The sign of this is overly stiff movement when the wheels are near center.

 

[glenlloyd]

I have had good results on both of my older 126's and my 92 500SEL. The first thing to do is center the wheels and then remove the drag link form the pitman arm. Wiggle the arm. Chances are there is slop. Now with the ignition key turned to unlock the steering column turn the gearbox by using the pitman arm. As it goes toward one end of travel you will see more slop. By adjusting the gearbox a little at a time you will see the play decrease. I recomend reading the procedure in WIS or AlData to get the gist. It is possible to over adjust the steering. The sign of this is overly stiff movement when the wheels are near center.

Thanks for the suggestion. I'm going to try and video this tomorrow afternoon, showing any slop in the idler and pitman arm. I'm not guaranteeing much, the light in the shop is not the greatest and it will be dark outside by the time I get to it so the garage door windows won't help at all, but maybe I can better demonstrate the issue.

I do hope that you're right, that the slack I detect at any position off-center is attributable to the steering gear, because if it's isolated to the idler arm I'm not sure what can be done. The idler isn't faulty but my biggest fear is that the bolt hole for the idler is enlarged and that will either 1) require a larger bolt and boring of the idler bushing or 2) some type of inserted bushing in the idler arm mounting bracket.

Regards
Steve A

 

[glenlloyd]

I have an update. I surveyed the situation tonight and found that indeed the steering gearbox is the source of most of the slack when the wheels are not straight ahead. I hope that this can be adjusted out somewhat as per what was said before.

I did notice though that the idler arm still has some odd movements that I don't like. When the wheels are straight ahead there is very little slack but when the wheels are at lock the idler arm can shift up and down on the bolt just a little. I removed the idler and used the old bolt to constrict the bracket a little hoping to eliminate the slack, which it did a little, but I think I'll have to do it again, and even then I don't know whether it will remove all the slack. It did seem to be better when I drove it afterward.

I'm sorry that I wasn't able to do a video, it simply wasn't light enough in the shop to do it.

Steve A

 

[The andrew]

I have an update. I surveyed the situation tonight and found that indeed the steering gearbox is the source of most of the slack when the wheels are not straight ahead. I hope that this can be adjusted out somewhat as per what was said before.

I did notice though that the idler arm still has some odd movements that I don't like. When the wheels are straight ahead there is very little slack but when the wheels are at lock the idler arm can shift up and down on the bolt just a little. I removed the idler and used the old bolt to constrict the bracket a little hoping to eliminate the slack, which it did a little, but I think I'll have to do it again, and even then I don't know whether it will remove all the slack. It did seem to be better when I drove it afterward.

I'm sorry that I wasn't able to do a video, it simply wasn't light enough in the shop to do it.

Steve A

I'm just glad you are getting somewhere with this issue. Great!