Does a lightweight K-member cause more shake in the verts?
10-14-2004, 07:32 PM
#1
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Does a lightweight K-member cause more shake in the verts? I have the engine out now and was thinking about a K-member to save the weight. I read in here somewhere that a lightweight K-member was not as strong as stock and amplified the body shake over bumps that the verts get. Is there one that is stronger than the others to eliminate this? Opinions or experiences are appreciated.
10-15-2004, 09:08 AM
#3
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I have a 94 conv. with a k-member and roll cage. I cant really say if just the k-member will cause any other problems or not cause i have the cage. But I can say that the car rides very well. and there is no shake at all. I also have Qa1's all the way around , so im not sure if that would make a major difference or not either. Basically what i mean is that i love the ride of mine and it has a k-member.
10-15-2004, 02:36 PM
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I have a lot more shake now, than I did with the stock
K-member. It's bothersome when turning on rough
pavement and even going straight, a good bump will
make the whole front shake. Before the swap the car
was pretty solid. I do not have SFCs, but plan on
making my own bracing along those lines (already have
the box and flat stock, just have to get some lift time
one weekend).
I think the BMR K is probably the most solid, but it still
is no match for the stocker (50 lb lighter and only one
tube side-side, so no way for it to buck any but straight
in-line stresses). I think with 10lb of steel in the right
places I can triangulate it enough to settle it down, and
still be weight ahead.
K-member. It's bothersome when turning on rough
pavement and even going straight, a good bump will
make the whole front shake. Before the swap the car
was pretty solid. I do not have SFCs, but plan on
making my own bracing along those lines (already have
the box and flat stock, just have to get some lift time
one weekend).
I think the BMR K is probably the most solid, but it still
is no match for the stocker (50 lb lighter and only one
tube side-side, so no way for it to buck any but straight
in-line stresses). I think with 10lb of steel in the right
places I can triangulate it enough to settle it down, and
still be weight ahead.
10-17-2004, 12:05 PM
#7
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I have the STB too, it tightened up the stock feel on
corners, but the shake now is worse than original was,
without it.
I think for the track the K-members are great but they
are just not designed to snuff out all the body flex you
will get on non-uniform surfaces (I also have stiffer
than stock springs - Hotchkiss / SLP Bilstein front
suspension).
corners, but the shake now is worse than original was,
without it.
I think for the track the K-members are great but they
are just not designed to snuff out all the body flex you
will get on non-uniform surfaces (I also have stiffer
than stock springs - Hotchkiss / SLP Bilstein front
suspension).
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10-21-2004, 08:04 PM
#8
I have a PA K-frame, cage, and STB in my vert....and I dont really like how it feels with that K. In fact, I am going to take it out and put it in my coupe and return the stock K into the car.
Not really worth the trade off a little weight for less rigidity/more shake in a vert from my experience
Jason
Not really worth the trade off a little weight for less rigidity/more shake in a vert from my experience
Jason
10-23-2004, 08:41 PM
#9
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I wonder how much weight you could take out of the
stock K-member, with a hole saw or plasma cutter,
before you started to lose real stiffness. Seems like
you could drop some poundage by swiss-cheesing it
and still be near stock effectiveness. And fab up a
pair of lighter motor mounts than those 10-lb-a-side
iron pedestals....
stock K-member, with a hole saw or plasma cutter,
before you started to lose real stiffness. Seems like
you could drop some poundage by swiss-cheesing it
and still be near stock effectiveness. And fab up a
pair of lighter motor mounts than those 10-lb-a-side
iron pedestals....
11-08-2004, 12:40 PM
#10
I have a PA k-member , BMR tubular upper and lower control arms , Strut tower , BMR subframes , and a 6 point wolfe roll bar . My car is worlds more ridgid , but it still does have cowl shake .
So what Im getting in here is that I would probably be happier with a BMR k-member ? Going back to stock is not an option for me .
So what Im getting in here is that I would probably be happier with a BMR k-member ? Going back to stock is not an option for me .
11-11-2004, 07:16 PM
#11
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I know BMR appears more beefy, but I just don't
think one tube is going to snub all of the front end
flex (and the cage really stiffens from the firewall
back, not forward unless you're like a 8+ point,
serious dragster cage that goes through the firewall
and picks up the shock towers). Just try and find
a date who wants to climb over that, twice. Chick
who'd do that and smile (especially in a short skirt)
would have to be a "keeper"
Anyway, I think it isn't that PA and BMR are worlds
different in what they can do; it's the lightweights
lacking the rigidity relative to the stock stamping.
I think the PA or the BMR want some gusseting,
triangulation, something to stiffen them against
torsion and "angle skew". I'm paranoid about the
butt-weld between the transverse tube and the
two side channels too, as the only things holding
the two sides together and the motor, up. But
they seem to last, at least usually.
think one tube is going to snub all of the front end
flex (and the cage really stiffens from the firewall
back, not forward unless you're like a 8+ point,
serious dragster cage that goes through the firewall
and picks up the shock towers). Just try and find
a date who wants to climb over that, twice. Chick
who'd do that and smile (especially in a short skirt)
would have to be a "keeper"
Anyway, I think it isn't that PA and BMR are worlds
different in what they can do; it's the lightweights
lacking the rigidity relative to the stock stamping.
I think the PA or the BMR want some gusseting,
triangulation, something to stiffen them against
torsion and "angle skew". I'm paranoid about the
butt-weld between the transverse tube and the
two side channels too, as the only things holding
the two sides together and the motor, up. But
they seem to last, at least usually.
