Gents,

Those good with measuring dimensions, please advice if I can improve my method.
I attached the 4 PDF of WIS on chassis measurement and the tools MB uses.

Surely I won't invest in such special tools...

Why I am measuring my chassis is for when I replaced the 4 bushings of rear subframe, I can then re-measure and have some comparison data.
It is also a physical exercise to produce sweat .

I use this magnet as centering tool and also as line holder for the DIY plumb-bob.



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NOTE : While my floor is flat, there is a decoration line on it which is raised a bit, rough texture. Thus even with wooden plank as a surface for my ruler, see that the wooden plank is a few millimeters jacked up at the right end above,
that is LEFT REAR.

This is the decoration line, in green.





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Measurement.




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The China steel ruler above is 1 millimeter OFF once more then 500mm / 50cm , it read 800 mm as 801mm. I measured it with my Mitutoyo caliper.


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The H5 is a bit tricky to measure as I do not have a fixed steel ruler longer than 1 meter.

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My own question to myself :

01. Is QuickJack lifting up equally front and rear of my car ?
I will measure lifted height vs normal ride height at 4 corners, rear and front.
I shall update this information.

02. How is the design of rear subframe bushing ?, the one responsible for H4 measurement.
H4 = 797 mm (791 +- 2mm ). Too wide by approx 4 to 6 mm
Can it be that the bushing has deformed and caused 4 to 6mm widening of the 2 bolt center position on these two bushings ?


Right Rear bushings position is outward. Dang !!!



This H4 region bushing is on purpose made by MB to be "accommodating". East West orientation or Left to Right.

Up is NORTH,measured for its West to East.

15.80mm less 11.8mm bolt shaft of M12 = 4mm allowance or 2mm East and 2mm west..... play or adjustability.


Measured its North to South, this bushing uses M12, thus the hole is 12.99 mm or 1mm bigger for North South orientation.



Bolt for the bushings.




East or West adjustability





Will continue..............

 

The RIGHT rear H4 and H5 bushings are located as shown below

ABOVE subframe, its H5 bushing is different compared to mine. But it is useful as reference.


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My H4 bushing RIGHT side is not having proper NORTH orientation.



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There is an arrow on H4 bushings for NORTH/FRONT




The H5 bushings are simply round over sized bore hole. No orientation. These 4 bushings all uses the same bolt, M12 or 12mm shaft OD.

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H5


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H5, below.





I can't see H5 bolt center-ness in respect to its bore hole, unless I remove this plate, item 110



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Is my RIGHT REAR camber being higher in its negtive value compared to LEFT REAR due to this H4 bushing not centered ?
I don't know....maybe.


I shall update more measurement values tomorrow..........

 

I taped my 100cm and 30cm ruler together. Taped at 90cm of long ruler till its end at approx 103cm or so. Thus short ruler value is to be reduced by 10cm, for the overlap.
Easier to work this way. Acccuracy 0.5mm.




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Righr Rear bushing is the one which is not centered





So , H3 measurement which should be 1,070mm +-2mm by spec

RIGHT REAR big bushing to LEFT FRONT small bushing = 1,074mm
LEFT REAR big bushing to RIGHT FRONT small bushing = 1,072mm


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Next I will try to figure out how best to measure H1 and H2.

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Maybe I missed it but I did read them all - so many - LOL.

ANy ways question?
How do you know car is level when lifted?
front to back
side to side
corner to corner?

Most lifts have rubber pads which deflect and arms that deflect etc.
All which could add up to your plumb bobs being off a few degrees in random directions.

 

Yes, you missed it





MB WIS shows car is on alignment rack kind of lift, so car is at ride height. Not using 4 points lift and thus chassis does not flex.




I am sure W212 will sag a bit when supported at the 4 jack-pad points.
My front right plastic fender always have loud cracking sound when I lifted up the car, that meant there is deflection on the monocoque chassis, at least for my front right.


I will re-do the measurement again using my wheel stand to be at RIDE HEIGHT , but all 4 wheel stands, the raised height is not similar accurate to 1mm I think


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Something is weird for H1 and H2 measurement.


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Maybe facelift model has its own ,newer data ?

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Something is NOT RIGHT with my RIGHT REAR !! . .

I did a second measurement of H1 Right Side.


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Even if my floor decoration section is raised a tiny bit ( rough surface) and for RIGHT REAR, and twice the measuring tape has to be disturbed by
the decoration tile , 21mm too short is not right. Something is wrong. Even if my measurement error is at another 4mm = 17mm, its twin sister mirror location is only -9mm and that is 8mm difference.

If anything, that decoration tile will make measurement reading longer and not shorter.





I will measure below : X1, not in MB WIS, but I can compare Left and Right side






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I think the WIS is wrong about H1 dan H2 value, at least for my facelift model.

If all below in red and pink is within -9mm to -12mm values I would say it is purely measurement error and not dimensional eror.
I mean data wise it is probably MB WIS is +9mm too long for H1 and H2



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I have measured the lifted height of the car using Quick Jack, its within 1mm, so it wont effect anything.

LEFT-REAR = 576mm
RIGHT - REAR = 575mm

LEFT FRONT = 484mm
RIGHT FRONT = 483mm

These are the reference zero point of the above measurement


REAR



REAR




FRONT I choose similar curve of the bumper as zero point.


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FInal numbers, while on Quick Jack




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Next measurement is on Wheel Stand at Ride Height for H1 and H2, both sides.
Will continue tomorrow.......... me tired crawling so many times under the car. Enough Under-Carriage Gymnasium for today.

 

H1 and H2 are the only measurements that matter for rear suspension assembly alignment with respect to the front suspension.

H3, 4, 5 are given by the steel rear subframe, not the rubber bushings. These are specified by MB to clarify good vs bad rear subframe and good vs bad body (chassis) structure in case of collision/accident.

The car needs to be perfectly level in 2 axes: front-rear and side-side. The floor or measuring plane needs to be perfectly parallel with the car.

 

Dang....the K centerline is tool assisted and created, that K and not the bolt I been using.
I search deeper in WIS and got this document, attached.



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I will need to measure my bolt if it is actually exactly in the middle or not ? I assumed it is in the middle
If it is exactly in the middle, it is good enough to compare H1 and H2 of Left and Right side.


MB special tool will replaced both bolt A , to place their own "fitting" or adapter called 07N.



Thanks Chassis....

 

Can you check with a different measuring tape as well? I have found they vary by a few MM, also sometimes the higher end tape measures are more accurately painted, I found this out when one tape is used for cutting and 3 other guys tapes are used for measuring.

 

Indeed, I just checked too, 3 grade of accuracy. Class 1 is best, no marking nothing means Class 3.
https://www.thetapestore.co.uk/knowl...e_Measure.html

I have ordered Class 1 JIS. Tajima brand, Japanese.
I also ordered Class 1 , a 100cm ruler from a Japanese Shinwa brand.

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The so called I-thought-a-center-bolt on tranny is not in a true center.



Dugghhhhh !!!!!

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My DIY plumb bob rigging is bad, I just tested. I can screw up to 5mm difference.
The problem is with the small magnet, with 2 fishing string it can not produce a true center on the bolt.
The poor dimensional accuracy of the cone shaped fishing lead weight of the plumb bob is also an issue.

I have to re-engineer a method to be really center when placing the string on those bolts.


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I was experimenting with self centering effect using two smagnets. not good. Fishing line has friction albeit it is slippery, repeated true center won't happen.
Easy 3mm drift can occur.

The cheapo inclinometer is showing 0.3 degress of flatness. That tranny support is not purely flat surface for magnet sticking.


This is 5.28mm drift. This is how bad it can be, simply from all combined factors.

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Ready to buy dimensionally OK plump bob smallest is 200 grams, too heavy for me to use it.. Thus I DIY my own plumb bob and I can place a sewing needle as pointer.


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Quick Jack Lift Up vs ride height


My measurement accuracy at best 3mm.

 

Lots of info here and I haven't gone through it all in detall, three comments...

(i) having just changed my transmission oil and messed around trying to get the car level I decided that if I do it again I'll place the car on level ground, take a spirit level and tape shims to the roof such so I have level references in the front to back and side to side axes planes.
(ii) if you need to center on those large torx bolts, and if they can be readily removed, I'd take them to a machine shop and get a small thread machined in the center of the head such that I could thread in an eyelet.
(iii) there are some interesting home use laser leveling tools out there, might form part of a solution.

Good luck,

Peter

 

may I suggest some sort of laser alignment tools?

Maybe rifle bore laser site and then Make some sort of new NUTS to replace stock so this can mount?

or dot laser where you make little stands so they or something to let them be shine up and down - up you center onbolt and down is for your tape,
Johnson Level GreenBrite® 5 Dot Laser | Johnson Level & Tool Mfg Company

Self leveling version:
Johnson Level 40-6680 Self-Leveling 5 Beam Laser Dot | Johnson Level & Tool Mfg Company

Laser distance measure then just make something that attaches to bolt threads and use this to measure between between them,
1/16" per 330ft is pretty accurate.
LDM330 JLX® 330' Laser Distance Meter w/Angle Sensor and Bluetooth® | Johnson Level & Tool Mfg Company

Time to get the AMAZON hunt on and find a new tool.

OR if bored...
YOu could drill and screw in tiny self-tapping eye screws at end of each stud/bolt. then hang plumb bob from it.

 

Sounds good thank you Peter.

 

Thank you for the suggestion.

I was thinking of what you said about "angles" and how the plumb bob could land at wrong spot on the floor.

I was testing to see, to my best effort, are the rear big bushings bolt truly zero down 6 o'c'clock without angle ?


Its like 7 to 6 degrees tilted.


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The car is almost zero degree flat, or say 1 degree.

Below is 0.50 degree and not 5 degrees.




The Left side is not as angled as ride sight. Right side has that UN-Centered bolt.





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I took a closer look at the big rear bushing.
I wonder if this is already sunken/tired or it is already settled + sunken/tired?





Today and vs new one un-installed aka not compressed.


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The direction of bushing compression. The red zone is what moves or became shorter over time. Green zone stay, that is like round bushing outside bore.


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The new bushing is "taller" by approx 6 to 7 mm.



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I think this bushing is already at its end of compressed life, no visible tearing but its spent already. 43,000 KM and close to 11 years in the tropics.


This is sign of tearing actually. Afterall that area is the one working hard.





Looks like dropping the rear subframe this year then................ and replace all 4 subframe bushings + 3 of DIFF bushings (2 at rear ) and 1 in front.

 

The tool Mercedes uses is called a TRAM GAUGE

Of course when only +-2mm accuracy allowance is involved, the unit must be well machined, smooth but rigid.
Any telescoping measurement device if not well made will have play.
The pointed ends also need to match the car to measure.
No need laser leveler, a liquid level gauge is good enough as one can measure with shortest pointed ends, floating in the air, and do not need the floor as zero , actually.



US made one, but does not seems robust.
https://www.killertools.com/Tram-Gauges_c_18.html


China made one :


But is limited to supposedly 2,250mm only and its borderline enough for H2 measurement of 2,248mm.
Its one end fat magnet mount is also not suitable to be used on bushing bolt.


Or I can DIY myself one, but me zero skill and equipment for welding

This version for accuracy to 2mm is questionable.

 

I am going to DIY a Tramp Gauge.....Without welding. Only machining a bit, which I can outsource.


The main bar will be a 4040 T slot alu profile. 4040 means 40mm x 40mm.
Been reading the difference between V and T slot.
This is way stiffer than hollow square tube, I am sure. So it probably will be true straight and not sagging at 240cm long.


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BELOW UGLY DRAWING OF MINE :
Label B, Left Side : One end will be fixed distance,but height adjustable for the pointy spike.
Label A. Right side : One end will be variable distance, but fix height for the pointy spike.

I only need 20cm long pointy spike as the fixed one ( label A ) , and the other one will be height adjustable pointy spike at label B.
20cm is the longest height to clear exhaust and rear suspension arm.


Above In grey is the 4040 square bar.
Label B, Left Side = One end will be fixed distance,but height adjustable for the pointy spike.

Something like below, but I will make Tee and not an L shape 4040 assy. Uslng 2 of L bracket ( Label D ).. The L bracket is called Gusset.



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Label C is hose clamps (2 pcs ) to secure a 16mm OD solid ALU rod, which is the poiinty spike.
I can buy solid rod 16mm OD ALU rod and machine one end to become pointy spike or machined M8 female thread and buy speaker stand pointy spike with M8 male thread.

The 16mm OD alu rod at the left side Tee will be secured using 2 hose clamps ( label C )
16mm OD alu rod will sit pretty as the opening is 8.2mm to 8.3mm there will trap it.


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One end will be variable distance, but fix height for the pointy spike.
For the label A - right side pointy spike to be able to slide to make distance adjustment., it will be using the sliding nut of 4040 accesories.




I only need to buy M8 stud bolt of 1 meter and cut it say 40mm. 16-20mm stud length goes to the sliding nut and the rest for machined female thread at the pointy spike bottom.



The 16mm OD ALU rod


Will machined M8 female thread at the base/bottom of this OD 16mm rod. Will slim down the round alu at some part to be 14mm flat, so that I can use M14 wrench and no need plier.

I can use speaker stand spike instead of making pointy spike on the ALU rod, only need to machine female M8 thread.
Would be easier to tap/machine M8 female thread than to make point spikeI think.



I will only use the Dracula spike


I will place 3 of these bubble level on the 240cm long 4040 alu profile. One on each end and 1 in the middle.




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20 cm long pointy spike will clear everything on the car which may block a straight line measurement.



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That is a JIS Class 1 accuracy, Tajima brand measuring tape. Double print on both sides, big letters, super awesome.


.The H1 and H2 longest measuring point.


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Rear spring arm is the lowest hanging obstruction of all. If its plastic cover removed, I will gain easy +2cm more clearance.




That red line on the bolt, is the true center of the tranny support plate.



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For rigidty sake of the 4040 profile. I probably buy 240cm continuous length, not cut , thus no interconnection.
I will also need to get another one at 140cm long, to do all other coordinates and more importantly the front ones, called V2 at 131.5cm , thus single piece 4040 for all measurement.




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Perhaps in 2 weeks I would be able to fabricate all above.

 

another suggestion.

IN lieu of spike to center on bolt.

Why not make the ends square and utilize appropriate SOCKET that fits bolt heads.
Maybe deep sockets but if you make it TIGHT fitting head of bolts and your tram beam you would be easier to afi and center on bolt/nut and get your measurement.

So you get a friend to hold one end up and you do the other adjusting on tram and once it fits to the bolt /nut on each end you can drop it and then measure on ground.

 

I have thought about that too, I already bought 2 spares T14 Torx tool, for that test purpose and its coming soon.
I am worried about the angled projection of the T14 bolt head of rear right big bushing will force the 4040 profile to twist .


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20CM is long enough distance for the vertical rod to get 7 degrees twisted/angled.

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so you are saying the bolts could be angled?

OR the socket slop allows it to angle?

If slop you can put Plumbers putty or some thick CLAY inside socket grooves to take up slop. It works.

What do you do if the bolt/nut are not at the same elevation?
Then you are measuring point to point and not Center to Center.

and lastly for those with Very DEEP pockets
Get a 3d measuring arm. pricey but very cool.
Gage FaroArm® 3D Measuring Arm | FARO

 

this one might be more pocketfriendly

Leica iCON iCS

3d counter top measuring systems. they have some for 3D
Just set up the sensor and use special pen you click at desired points and computer puts points in 3d space so you can measure between any way you want.
XYZ axis or straight like in3d modeling software

 

The bolt T14 is angled more on the Right Rear than Left Rear big bushings. To why I can only speculate .....it is not centered, that is why pointy spikey vertical rod makes more sense,
say 2mm diameter contact patch only at middle of bolt or that "K" at tranny support plate.

MB OE tools also uses what I believe as T14 adapter and a few short extensions to make the vertical length suitable a single Tramper Gauge for the various job.
If both spikey rod is truly 90 degrees / perpendicular from main bar/tube, different elevation of the bolts center point does not matter, as long as main bar is properly level by bubble gauge.


This seems to be the brand of Tramper Gauge MB uses. German brand.
https://www.wielanderschill.com/en/T...2610-mm/871001
WS Wieländer+Schill GmbH & Co. KG is one of the world's leading manufacturers of professional bodywork specialty tools and has established itself as an internationally successful company over the past 50 years.


The orange triangle like bulge on the right side, that is the rolling tape measure inside.

Item a below is T14 for sure. A torx tool. The item 05 seems to be a standar 3/8" or 1/2" drive and if so, drive like that has lots of play, at least 6-7 degrees. I tested that already.
Should use the putty you advised to remove the play.

 

Proof of concept :


The 4040 ALU T-slot profile I got is so well made, I am very happy.
Below is the 140 cm soon-to-be Tramp Gauge.


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I am experimenting the Tee installation, between type A and type B locking device.


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Rigidity wise both are good, but I guess A style would be better if maximum strenght is what I am after, but I am not after strengh. I am after ridigity and a nice 90 degree Tee.


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The pointy end, which will be machined into the 16mm OD ALU rod.




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The 230cm soon to be Tramp Gauge




Worth the price. The seller price is 300% or more than others, but I can buy minimum llength of 10 cm and no need full 4 meters.
The qulity is superb. It is heavy, damn, it is thick.



Will update next week when I am done machining the OD 16mm alu rods for M8 female bore.

 

IDIOT !!! IDIOT me........

The K being the center need another special tool, as per WIS.


I can't again use that mini bolt I marked with red line , which represent CENTER, or my version of K.
It is correct for being CENTER, but it is not correct for being not FORWARD enought by nearly 10mm.





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So a 2nd small Tramp Gauge for center reading or finding "K" is needed.





Anyway, my Tramp Gauge works well.

The 140cm version


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The height adjustable , but not distance adjustable side, with the Tee frame.


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THE OTHER END
The fix height but distance adjustable side. Final height is 235mm


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All H3, H4 and H5 values are within the 2mm tolerance. I am happy. Happy thart finally I can measure them properly





H2 both are within 1mm of each other, based on my own K center. That red line on mini bolt.
Short of 10mm compared to WIS, using the true K.

H1 I will measure tomorrow, today only managed 1 side and not both.


The 230cm version tramp gauge.


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JIS Class 1 accuracy measuring tape 5.5 meters by Tajima and 1 meter ruler.by Shinwa


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I need two person to measure accurately anything longer than 65cm if using measuring tape.
My hand stretch and my eye position get parallax error reading millimeters mark if not true in front of me, center or me eyes and I dont have a 65cm left hand stretch LOL.


Must learn how to remove measuring tape "sag", when doing long measuring the middle part will sag and touch the floor for sure and that eats up a few millimeters.

So two men job and hard pull on the tape.



Will continue tomorrow.........