Mazda CX-7 (2007 - ) - General Question - subframe damage

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Wed 24 Dec 2008 09:26
General Question - subframe damage - doobus
Hi - newbie here needing some advice/reassurance!

Had rear impact on my '08 model 4x4 - my vehicle struck on rear drivers side wheel by another driver (low speed impact). No panel damage. COuldn't see any damage then realised wheel at an angle and steering wheel offset to the right.

Car now been examined by engineer prior to insurance repair. I've been told it's rear subframe damage and that it's a "big piece of metal" that just slots in and no big deal. Also been told there's no chassis damage but this will only be confirmed 100% when the new part is fitted as it won't slot in if chassis bent.

Firstly, is this serious as i was expecting a snapped control arm or something similar given the low speed impact? Or is rear subframe a term used to cover any rear suspension damage, even if minor?

secondly, why can they not say for certain now that there's no chassis damage?

thirdly, can someone explain the repair process in laymans terms? Is it easier to replace a subframe on modern cars than to mess about with individual suspension components?

Just a bit paranoid that the damage isn't being under/over played.

Any advice/views much appreciated

Edited by doobus on 24/12/2008 at 09:30

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Wed 24 Dec 2008 17:04
General Question - subframe damage - Number_Cruncher
If the subframe and chassis have deformed together in the impact, it can be quite subtle, and difficult to see, and it is only when a new, undeformed subframe is offered up that any chassis deflection may be seen.

The suspension is connected to the subframe, which in turn is connected to the car body - this gives 2 opportunities for vibration isolation, and also allows the suspension to be assembled as one large sub assembly, and bolted up to the car as one unit. The subframe is a substantial piece of metal, and any undamaged suspension components will be swapped from your old subframe to the new one, and any damaged parts should be renewed.

It sounds to me like the assessor is taking a sensible aproach, warning you of possible complications way ahead of time.
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Wed 24 Dec 2008 17:42
General Question - subframe damage - yorkiebar
NC is right, but......

they should be able to measure accurately to the specs given, assuming the bodyshop is "good enough".

hth
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Wed 24 Dec 2008 17:46
General Question - subframe damage - Number_Cruncher
>>they should be able to measure accurately to the specs given

With the subframe still in place?
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Wed 24 Dec 2008 17:54
General Question - subframe damage - yorkiebar
I dont know the car in sufficient detail to answer definitely but I would have thought so.

But to clarify, I would expect measurements to be taken before they even begin to offer up the new subframe, ie check for distortion rather than look for distortion by trying to fit new subframe assembly
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Wed 24 Dec 2008 18:19
General Question - subframe damage - Number_Cruncher
I would expect measurements to be taken before they even begin to offer up the new subframe


Yes, fair enough - although from a practical point of view, if the holes line up to the new subframe, it's very unlikely that there's a problem.
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Wed 24 Dec 2008 18:59
General Question - subframe damage - doobus
Thanks for the replies. Still a bit confused as to what kind of impact it takes to damage subframe as opposed to smaller components. I was surprised that a low speed impact could cause this damage, especially as panels were undamaged.

Also, is it a fairly simple repair to get the car in to it's original condition? - just a bit worried that it won't feel the same
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Wed 24 Dec 2008 19:09
General Question - subframe damage - pmh2
>If the subframe and chassis have deformed together in the impact, it can be quite subtle, and difficult to see, and it is only when a new, undeformed subframe is offered up that any chassis deflection may be seen.<

Surely if they have 'deformed together' then fitting the new subframe to the 'chassis' will not show up any problem. Any twist in the shell will cause the problems.

Sorry to be pedantic!

I suppose that fitting a new subframe then allows measurements to be taken to determine if there is a problem (and takes away the problem of any subframe damage affecting the measurements).


p
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Wed 24 Dec 2008 20:35
General Question - subframe damage - Altea Ego
"Surely if they have 'deformed together' then fitting the new subframe to the 'chassis' will not show up any problem."

yes it will because the new subframe wont be deformed, and hence will not fit the deformed shell like the old deformed subframe did - the new subframe makes an instant standardised jig to check the shell.


To the OP wondering why a subframe (or any suspension part) can bend so easily. Its because it took a knock and stress in a way it was not designed to take. For example it was never designed to take a sideways blow
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Thu 25 Dec 2008 12:01
General Question - subframe damage - Number_Cruncher
>>the new subframe makes an instant standardised jig to check the shell.


Yes, that's exactly the point I was struggling to make.
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Thu 25 Dec 2008 12:53
General Question - subframe damage - pmh2
The point I was trying to make (unsucessfully!) was that the fitting of the new subframe only confirms that the mounting points are are aligned wrt to each other, ie it will not show up anytwist or similar in the shell. I suppose it all depends on how rigidly the subframe is fixed to the body, and the angle of the impact .




p
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