sub frame question?

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Olivier

MB Enthusiast
Joined
Oct 30, 2008
Messages
1,666
Location
Edinburgh
Car
E300 TD
Does other cars have a sub-frame like the MB?
It seems a little over engineered to me, it might help a bit the vibrations but I am not certain its worth the bugger it create. Might be standard in the car industry? Just wonder what a frame welded to the car would be as different?
Anyone on that?
Cheers.
Olivier
 
i think its somthing to do with flexibility so the car can flex properly through the bends, and is dampened correctly via the mounts.
 
Subframes primarily allow the designers to isolate the cabin more effectively from road noise, vibration etc as you can mount suspension components, steering etc to the subframe and then isolate the subframe with bushes etc from the bodyshell.
 
Cheers,
still seems over engeneered to me as every single attachement has bushes already, the wheels, the diff etc...
 
Best thing to do is to weld it up solidly, and then report back.:)
 
I would, but I did my sub frame bushes last year. Over to you.
 
Damned! mine are OK too, I did them about 2 years ago only. Shame... Who could/ would try now? :dk:
 
There are many reasons why rear suspension assemblies use a subframe. The major one is isolation of road and suspension noise and vibration from the passenger cabin as has been said. The hysteresis and vibration suppression of rubber or fluid filled mounts can address problem vibration and shock frequencies outwith the range of conventional steel sprung suspension components which are designed to cope with relatively large amplitude low frequency movements . Did you realise that the springs in the seat base are also " tuned" to complement the suspension damping?
There are structural reasons also since the high point loadings fed into subframe by the suspension elements are easily coped with by making it of thicker gauge steel than the main bodywork which derives its strength by consisting of large box sections of fairly thin steel.
Finally it also facilitates the assembly of the car from discrete units on the assembly line e.g engine +transmission / body shell/ rear suspension and differential etc.
Mercedes may have been among the first to adopt the subframe [ front /back or both] method of construction because they were one of the first to adopt the monocoque method of body shell construction rather than the older separate body + chassis design.
You might be surprised how many manufacturers use rear subframes [ some of them masquerade as " rear axle assemblies" in front wheel drive cars] in the search for greater refinement. Last one I recall was the Honda Accord which adopted a new rear subframe in its latest incarnation.
 
Hi Grober,
what was it about the spring seat tuned?
I changed the dampers ( the 4 of them) a wee while back and wonder ( not worry)about this.
Cheers,
Olivier
 

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