Hi,
I recently rebuild the entire front suspension & steering system on my '85 W123, minus the guide rod mounts. I also rebuild the entire front braking system from the brake booster out (including wheel bearings). Before that, the car was pretty wayward due to horribly loose ball joints, etc, now it just consistently pulls to the right - at any speed.

I've had the alignment checked by two different shops, both agree it's fine. It does "seem" to get worse after a long drive, so I am assuming it's friction related. I've checked the wheels/brakes with an IR camera & thermometer, nothing seems abnormally hot, though that was done on the ground so I couldn't really the inner bearings well. (Front bearings & races are all new).

The shops keep telling me it's a tire pull, but I've swapped out the front right tire for the spare with no change. Could this be because I didn't change the guide rod mounts? The right side moved slightly more easily than the left side, but it didn't seem to have any real play. Could this be the culprit? Possibly there is a bit of slop there that's only showing when the car's moving?

Could it be something in the rear axle system causing this? Soon I'm going to get the whole car in the air and check for excess friction on any of the wheels. I'll also probably perform (or have someone perform) a full left/right front/back tire rotation to see if that helps.

The back brakes have not been changed since I owned the car (1.5 years, ~3000 miles) , but look pretty much brand new.

How did you adjust the wheel bearings?

I've noticed mine had a pull before adjusting wheel bearings according to the
FSM. Using a dial gauge made the difference.

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Sam

84 300SD 350K+ miles ( Blue Belle )

I used a dial indicator gauge to set them to the appropriate free play. I think I got that spec from the FSM somewhere

You can be just 1 revolution of a turn on the tie rods to have some affect at the steering wheel ,its safe to say their not wanting to play lift circus with your car and say to you its with in specs when your car tells you otherwise. Its close but no cigar. The real answer here is that you may have to play with the fine tunement yourself .Youll need a tie rod tool that forces the joint apart and not a fork and hammer. What youll be doing is a ONE ,JUST ONE revolution turn on the outer tierod to find that sweet spot for the tires to ride right .This could be in or out and youll have to make sure you dont loss track of what youve performed so WRITE DOWN your findings after each drive.Turn one side then check with a short drive then do the other side ,this may get you closer to achieving a solid middle ground.Again this is a service youve already paid for ,some shops dont have the experienced older techs that have dealt with a car like yours ,in the future you may want to go to and ask specifically about your model and make and not a salesman behind the counter that wants your benjamins.They are not mechanics some of the time and only perform clerical underwriting service to keep the work coming in to the shop and watch the coffee pot.To keep my tierods when replacing in an exact same location Ill pull the rod assembly and set it on a long board ,I then mark with some white out the exact center of the back of the tie rod .You then can mark the board on the corrospsonding length WITH A PEN .Do the same procedure once youve pulled the old ones off and new ones on the old rod(the position of the tierod end is important to note also. up down sideways ).You should end up with a duplicate of the old assembly with new tie rod joints with the exact same length as your old ones replaced.If they feel theyve performed you a good service ,keep them answering questions after youve gain more info ,if you feel answers are getting shorter and more abrupt ,take your business elsewhere ,they should be welcoming to service your car .If all new parts were put on at one time replacing old parts then it takes sometime to get the ride just right.The diesels carry alot of weight up front and will show odd tire behavior if not right on the money with alignment.

Swap the front wheels side to side. Have to be positive it is not a faulty tire. Once that is established have a look at the rear end.

When they did the alignment was it set up as a four wheel alignment? You are not describing back steer though but that does not mean that something is not bent at the back for example as well.

I really think the alignment shop should have looked around when you returned. Maybe they did and saw nothing and figured tires.

Once an abnormal tire issue is present there is no way to undo it usually. Finally did they give you a printout of the alignment? I also wonder if they might have missed a bad caliper so feel both front wheels for temperature after a short drive. Or when changing tires side to side check for the caliper being normal.

When it was sloppy before you replaced parts. Did it pull back then as well?

On the other hand between crooks and incompetence today it is sometimes hard to know what is going on.

I have a hard time believing it could be something in the rear suspension could cause that much pull but never say never. The issues with rear suspension (trailing arm bushings) are usually rear tire wear and a weight shift in turns.

I'm suspecting the alignment shop doesn't know how to do a full alignment on a MB. So many shops anymore, only know how to set toe-in because that is the only thing you can adjust on many new cars. Usually a shop with a Laser Alignment Machine has the capability because the computer basically tells them what to adjust. Many, here on the forum, have had to go to the dealer to get it done (~$150).

If tire rotation doesn't change things, you may have to look around for another alignment shop.

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Sam

84 300SD 350K+ miles ( Blue Belle )

I'm pretty sure I've swapped both tires before, I think - though I'll likely try that again. It was a 4 wheel alignment, and I do have a printout (not on hand right now)

It did pull before, I think, but it was hard to tell since it wandered so badly.
I've checked the wheels with an IR camera, they were fairly even - though I'll probably borrow that again soon and try it again.
I don't think there's anything defective in the front steering/suspension, I checked everything over pretty well and replaced pretty much everything but the LCA, springs and spindles.

I'll check the brakes and wheel bearings one more time. I did have a hard time getting good hardware to mount the brake pads. I have the Bendix calipers (rebuilt), which came with horribly mismatched springs/pins that simply don't work. I think I ended up re-using the originals, so I might have a brake drag. I'll double check that and see if I can find a source for some original hardware. (Fun tip, use a large C clamp to install those stupid pins. Trying to tap them in is an exercise in frustration)

Their are shocks to consider here also in ride control ,go for a new set and see what happens.I bought a car and drove it home with some really strange road ride feedback ,it turns out to be shock related later issue later on.

Years ago, I chased a pull to the right. The shop swore it wasn't the tires because we swapped them. Once the tires were replaced, the pull went away. Granted, that is not common.

I've had a difficult time finding a shop that can do a proper alignment on my SDs. One tire shop was starting out and offered to put the car on the machine. Their machine disagreed with the Firestone that had done an alignment 2 days before. I got to talking diesels with the tech & he showed me how any tech can make the print out of the machine be anything he wants by bumping the heads instead of doing the final adjustment.

With all of that said, I would want to know what the spec number are. These cars are very adjustable and can be set to compensate for wear. Unfortunately, techs tend to think that owners are idiots. Caster changes cause camber changes and the tech has to anticipate the relative changes which are estimated in the FSM otherwise, he will be chasing his tail trying to get it right. The incompetent techs don't want to put out the effort and declare "adjusted to specs" when anyone knowledgeable will know by the specs that it will pull.

Also, you replaced everything except for guide rods. Unless caster is changing, the car should handle like new. Can you post the specs? Do you have another car with wheels that will fit? I have 2 SDs and could swap wheels & tires to test.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Front shocks are brand new when I did the suspension/steering. Basically every wear item in the front of the car is brand new. I'll get the alignment specs tonight. I have a full size spare with matching tire I can swap, but not an more than that. Also, I've had the alignment checked repeatedly by the people who did the alignment first, they keep saying it's fine. I also took it to the shop where I got the tires, and they checked the alignment and said the tires looked fine (Though, why they didn't do a full rotate is beyond me..."Oh, our tech just left" when I got the car back. Thanks guys...)
I haven't touched the back side of the drivetrain since I got the car, except for changing the diff fluid and fixing a leak (amazingly, fill & drain ports work better when they're actually tight, go figure eh?) It could use new rear shocks soon, I'm just really not up for going down that road right now - just want to be able to drive the car)

The rear can definitely cause it to pull. The alignment shop should have caught it though it it were a bent trailing arm....unless it is weak and only pulls sometimes.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I would expect a MB to pull to the right.
I would expect a Volvo to pull to the left.

Not universally, just on average.

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Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO

This is enough of a pull to make it want to leave the lane within a hundred feet or so. I would definitely not call it a normal pull based on the crown of the road (my GLA barely needs any input to keep it in the lane. 30 years newer car, of course). The 300d pulls right even on roads that are cambered to the left

Drive car to a level parking lot then remove the hubcap/center wheel cap of both wheels on rear.

Now get a tape measure and check exact distance from rear wheel center to front wheel lip on each side
Make several measurements.

If they are not EXACT left and right, the car will pull to the short measurement side.

Also measure center tread of tire front tires. Forward of tire and rear.

Car should be slightly wider in front than rear.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!