About weighting the seat for alignment

K

Kamuela

Member
... which apparently BMW in their boundless wisdom thinks is necessary, although I suspect most drivers weigh considerably more than 50 lbs. Anyway, yesterday, while getting a second alignment after replacing the lower control arm bushings, I noticed the technician got in and out a couple of times to fiddle with the steering wheel. The Hunter laser thing gives you real-time display of the alignment parameters, and I noticed that when he got in the car, what changed was, NOTHING. Not a thing. Perhaps the "sport" suspension is sufficiently stiff that the driver weight doesn't make that much difference, or perhaps the geometry is good enough that a bit of weight change has no effect, but I saw no change due to the weight of a driver while it was on the rack.

Perhaps another myth busted? or maybe others have had a different experience.
 
I'm not sure what the TIS recommendation is for the passenger weighting but the tank should be full as well, which always seems odd to me, how long is a tank full for? surely half tank would average the weight out? :?

But as you say it probably makes very little difference anyway, a fat driver or moose in the passenger seat would have far more effect :driving:
 
When my alignment gets done they measure the arch height and weight the car accordingly. The front doesnt need weighted on mine.(probably original springs sagging slightly) but he put two big water containers in the boot. Rear has had springs fitted at some point.
 
So I had a discussion about this when I got my alignment done on a 3.0si sport. The chap didn't weight it though they had weights. He said that as the springs are so stiff the recommended weight makes no difference and sure enough he demonstrated this.

Maybe there's more to it but I'm no expert....
 
When I used to work at a Porsche dealer, we were told by Porsche specs to have the same weight as 1/2 tank of fuel in the front (911's and Boxster/Cayman)

Obviously if someone came in with more than that... oh well, but if it was under, we used to put a few weights in the front as a "guesstimate" considering you don't get a readout of exactly how much fuel is in the tank.

Never really made any difference, the only thing I can see it effecting is the camber levels..
 
Not sure where the 50lbs comes from. The TIS instructions for alignment says you need the fuel tank full, 68kg in each seat (drivers and passengers) and 14kg in the boot. Assuming a tank of fuel is 50kg, that's 200kg put in an 'empty' car.
 
fearless said:
Not sure where the 50lbs comes from. The TIS instructions for alignment says you need the fuel tank full, 68kg in each seat (drivers and passengers) and 14kg in the boot. Assuming a tank of fuel is 50kg, that's 200kg put in an 'empty' car.
Click to expand...

That's what happens when mine gets done, they use sandbags on seat covers.

Mike
 
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