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gine39530d

wheel alignment camber toe with weights?

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What's the correct way to align wheels? 

with 68kg * 2 front and 68 kg rear plus full tank and 21kg luggage? 

or this is outdated now? 

 

BMW specialist told me that they have special bmw software for alignment and 225kg  not required 

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I'd like to offer a couple of comments on this topic

 

According to TIS, the point of weighting the car is to bring it to what BMW terms "normal position". TIS goes on to say that once weights are in place one should then measure ride height. If not within spec make any repairs necessary. Only then perform the alignment.

 

The crucial issue is that every suspension angle changes as the car is loaded. The alignment angles BMW provides are based on the car's suspension being in a particular position, i.e. normal position. I recall reading a post by a reliable person on B-fest and B-forums in North America that he found rear camber changed by ~1 degree from weighted to unweighted. Another post, purportedly by an ex-BMW R&D tech, recommended weighting the car on the shock towers and trunk until car was a spec ride height. The idea being that getting angles right is more important than the actual weight needed to achieve a particular ride height. The chassis designers had ensured the car would handle well at all loadings, i.e. through the range of ride heights expected in normal use. Assuming it was aligned at specified angles and ride height. And note that in most cases one would be driving the car with less than the weight specified in TIS for "normal."

 

So, if a shop says it "compensates" for not weighting the car, is that done after measuring ride height and therefore applying just the correct amount of correction?

 

Regards

RDL

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I’m not sure if a Specialist would have access to buy it, but the Beissbarth KDS machine that BMW Dealers use does indeed compensate for and change the target data once the ride heights are entered so weighting the car is no longer necessary.

Also, when weighting the car and measuring the heights, if they’re within +/-10mm of the spec, you are then meant to adjust (add or remove) weights until the the heights is within +/-2mm of spec before carrying out the alignment.

Very few people ever do this........

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35 minutes ago, gine39530d said:

so i guess then it is  just another case of "specialist" bs'ing me again

 

Perhaps not intentionally. There is a lot of BS floating around that the unwary or naive pick up and adopt as an article of faith. But certainly possible - there is a fair amount of sharp practice in the auto repair business. At least here in North America.

 

My recommendation is to figure out the loading needed to bring the car to "normal position" yourself. I use 20kg bag of water softener salt (which I then use up over the coming months.) Other folks have used gas (petrol to you?) cans filled with water, but anything heavy will do. Best to do this on a flat surface such as a garage floor to avoid the effect equivalent to one tire/wheel "jacked up" as though resting on a curb. It needn't be level, only flat is necessary. FWIW, given the sagging in my 15 year old springs I needed only 60 or 80 kg vs the ~220 odd kg described in TIS.

 

Then take the car to the alignment shop with those weights in place and ask them to align it "as is" ... without any correction or adjustment for weighting, or lack of, in the alignment rack. :D The "after" results should be within published BMW specs.

 

 

Regards

RDL

 

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