84 300d 315k miles eating up tires negative camber

[petecooke]

I have a 84 300d with 315k miles. The front end has probably never been rebuilt. What is the first thing I should do to fix the negative camber?

Thanks for any info.

pete

[qwerty]

Originally Posted by petecooke

What is the first thing I should do to fix the negative camber?

Upper control arm bushings are at the top of the list of suspects. Assuming that it's not just an alignment issue. (In basic terms, it is an alignment issue.)

With that mileage, it's a safe bet that every moving part in the steering and suspension system is history.

[Hit Man X]

Bad ball joints and LCA bushings attribute to this condition also.

If you are at 315,000 miles on an original front end... you are well over due. Just do it all at once since many jobs overlap each other.

[petecooke]

I bought the car about 6 years ago and I didn't get any records on what had been done to the vehicle.

Is there an easy way to check if the upper control arm bushings are bad?

If I jack up each wheel and try to shake each wheel, will there be play or any noise if the bushings are bad?

Thx

pete

[Diesel911]

In general inner Tire Wear Lower Control Arm Bushings; outer Tire wear Upper Control Arm bushings.
I don't know what other issues like Ball Joits and Tie Rods can cause.

The Upper and Lower Control Arms pivot on the elasticity of the Rubber. Unless there was some accident it could be all of the Rubber Bushings are on the way out.
That makes a tough decision; replace one or all.

[qwerty]

Originally Posted by Diesel911

In general inner Tire Wear Lower Control Arm Bushings; outer Tire wear Upper Control Arm bushings.

Sagging upper control arm bushings on a W123 will cause negative camber. I have seen it countless times.

[Diesel911]

Originally Posted by qwerty

Sagging upper control arm bushings on a W123 will cause negative camber. I have seen it countless times.

Changing the Chamber also Changes the Caster.

[97 SL320]

From the pic it looks like a combination of tire wear issues.

Measure tread depth across the tire. From the picture it looks like the air pressure was a bit low ( wear on both outer edges )

Run your hand left to right across the tread ( be careful of the steel belts sticking out ) do the tread edges feel sharper in one direction? If so, the direction of the sharp edge points is the direction of excessive toe. ( Pointing in at the front too much toe in, pointing out, too much toe out ) Excessive toe is the number one cause of tire wear and will make a slight camber issue appear worse.

What to change? How much longer do you think the car will last? If a while, change all bushings and ball joints rather than chasing 1/2 worn parts.

[qwerty]

Originally Posted by 97 SL320

Measure tread depth across the tire.

When the cord is showing on the worn side, does it matter how deep the good tread is?

Originally Posted by 97 SL320

Excessive toe is the number one cause of tire wear...

This tire was done in by the number two cause.

[97 SL320]

Tread depth across all of the tire matters. Measure depth in all grooves, if the center grooves are deeper than both outer grooves, some of the wear is due to low tire pressure. Low tire pressure will make a slight camber issue appear even worse.

To clarify, excessive toe will cause more wear in a shorter period of time than camber alone. It will also increase camber wear as well. When camber is slightly out, the contact pressure across the tire is higher on one side than the other causing long term wear. When toe is excessive, the tire is scrubbing across the road surface causing it to wear rapidly.

Excessive castor will cause camber wear as well _IF_ the car is predominantly driven in a city / burb environment with lots of sharp turns and sandy road surfaces as the tire is now being held at odd angles and is sliding around much more than being held straight rolling down the highway.

[qwerty]

Originally Posted by 97 SL320

Tread depth across all of the tire matters.

Unfortunately, the thick tread one one side won't make up for the tread on the other side being worn down to the cord. That tire is history; no measurement required. Measuring tread depth now is sort of like taking he pulse on a corpse.

Originally Posted by 97 SL320

To clarify, excessive toe will cause more wear in a shorter period of time than camber alone.

Could you clarify how excessive toe causes wear on one side only?

Originally Posted by 97 SL320

Excessive castor will cause...

Caster.

[whunter]

Here is all the educational material you need.

Suspension basics/ Alignment - YouTube

http://www.peachparts.com/shopforum/mercedes-parts-reference-library/216147-w123-front-steering-suspension-rebuild-list.html

http://www.peachparts.com/shopforum/diesel-discussion/134630-wheel-alignment-diy.html#post988903


.

[97 SL320]

Originally Posted by qwerty

Unfortunately, the thick tread one one side won't make up for the tread on the other side being worn down to the cord. That tire is history; no measurement required. Measuring tread depth now is sort of like taking he pulse on a corpse.

Who said anything about trying to call the tire good?

The original poster is trying to find out what parts to change to correct the tire wear problem. In order to do so, tire wear must be analyzed and the interactions understood.

If the old tire was run on the low side of air pressure and the new tire is run at the same pressure, he will continue to wear out _BOTH_ outer tire edges at a higher rate than the center. The current tire appears to have worn both edges more than the center due to low air pressure with one edge worn more than the other due to excessive camber.

If the camber issue was not there it would have likely worn both edges at the same rate while leaving tread in the center. If the air pressure issue was not there, only one side of the tread would be worn. Mix in some excessive toe to either / both of these issues and the wear rate goes up dramatically.

Originally Posted by qwerty

Could you clarify how excessive toe causes wear on one side only?

To replay my previous posts, camber wear is long term due to uneven pressure distribution. Toe wear is short term due to the tire being scrubbed across the road surface. Combine slight excessive camber with excessive toe you now have a tire being unevenly loaded and scrubbed across the road surface.

Try this. Take a single tire on an axle and place it on a sanding belt so it will roll. As the belt moves, tilt the tire to simulate camber. The tire will roll along pretty well but will eventually wear on one side due to uneven loading.

Stop the belt, now scrub the tire left to right ( axialy ) to simulate excessive toe. You will now be sanding tread off of the tire.

Couple _slight_ excessive camber and _excessive_ toe and you will have what appears to be _excessive_ camber.

Originally Posted by qwerty

Caster.

Cast_o_r is the measurement of where the point of pressure is relative to the axle location.

Cast_e_r is a wheel system that has self steering to bring it to center.

For general use, either is considered interchangeable, trying to " win " an argument by trotting out nearly irrelevant minutia only signifies " I've run out of logical counters to your argument and therefor have to rely on spelling in an attempt to discredit the other person."



97 SL320

ASE Master auto tech cert 1981 ( NIASE back then )
ASE Master HD truck cert 1982 ( NIASE back then )
Auto shop owner / operator 88 to 97
Equipment tech at a major electronics manufacturer 97 - 06 ( robotic controls, PLC , automated systems and more )
Now electromechanical equipment engineer at a factory.

Still feel like going a few more rounds?

[qwerty]

Originally Posted by 97 SL320

Try this. Take a single tire on an axle and place it on a sanding belt so it will roll. As the belt moves, tilt the tire to simulate camber. The tire will roll along pretty well but will eventually wear on one side due to uneven loading.

I posed the question poorly. I meant "one side of the car," not "one side of the tire." Seems to me a that toe error is a shared phenomenon, except as it applies to the steering wheel.

Originally Posted by 97 SL320

... trying to " win " an argument by trotting out nearly irrelevant minutia only signifies " I've run out of logical counters to your argument and therefor have to rely on spelling in an attempt to discredit the other person."

Generally, I would agree with you, but there is nothing like someone presenting themselves as an "expert," then demonstating a less-than-complete command of the associated terminology.

I suppose that the camber measurement is properly known as "cambor."

[nelbur]

I don't believe the OP said whether BOTH tires on the axle had the same wear pattern. A toe problem will cause the mirror image wear on the other side of the car. Toe out will wear the inside edges of both tires, while toe in will wear the outside edges. since the OP thought he has a negative camber problem, I assume the wear is on the inside of the tire. If it is on the inside of both tires on the axle, a toe problem is a real possibility.

Camber is easy to check with a 2' level. When on level ground, see if the wheel is standing near plumb. You will probably need a couple of small identical blocks on the rim edge so the level can clear the tire bulge.

Worn lower ball joints can cause both negative camber and toe problems on front wheels. If your steering rack is behind the axle the toe problem would be a toe out problem which would wear the insides of both front tires. Ball joints are checked by jacking the wheel up using the front jack point, behind the wheel to be checked. Grab the wheel at 12 and 6 o clock and push in and out to see if there is any play in the ball joint, or either ball joint, if you also have upper ball joints.