firebird6786

I cant find to much about aftermarket k-members. what company should i go with?

RAREws6

I too need an answer to this question, the only K-members i am aware of is UMI and BMR, i wish Spohn would come out with one alredy have a-arms ( aftermarket a-arms are requiered w/ aftermarket or tubular K-members.

i am going to save for a K-member / A-arms / LT all in one pop (i figure that is smartest, since the K-member is down to install LTs or what ever headed you want)

firebird6786

anyone?

OldeSkool

If you at all care about handling or street manners/durability... you will keep your stock k-member... The stock K-member is stronger than all aftermarket tubular k-members.. Only look for a tubular k-member if you are a dedicated drag racer looking to shed lots of weight.

Also... most LT's are installed with k member in place

LTSpeed

Ditto!

RAREws6

you say this from personal experience, rummor, cold hard facts... what???... i'm NOT calling , i never herd anyone say good or bad things about the effects of an aftermarket tubular k-member on the handling of an f-body.

i figured the significant drop in weight would help the ''plowing'' issue most f-bodies have. i could be wrong, help me with this one, i don't wanna drop 6 stacks one a suspension/chassis conponet which will decrease my cars handling ability.

BJM

iTrader: (1)

There are many K -member threads out there. Typically they are characterized by people saying their car shudders, vibrates, or the K member cracked. I believe you are taking your life in your hands with an aftermarket K member. The aftermarket guys have no standards to meet and they will not tell you its acceptable to use them on the street. They know you will but they cannot say you can.

Read this thread on a broken torque arm and my post for what I am getting at. I am not trying to be a wet blanket but I really wish those products were pulled off the market.

jimmyblue

iTrader: (11)

My car shakes more with an aftermarket K. None
of them will be as sturdy as the stocker. If I was
to do it over again I think I'd go and swiss-cheese
the stocker and replace the pig-iron pedestals.
Hole saw plus a $50 used K-member, I forget who
sells the lightweight motor mount pedestals.

John_D.

iTrader: (2)

72 holes was good for 8 lbs on mine this past weekend.

Madman motor mounts were good for another 12 lbs vs the cast stands and poly mount combo.

I'm within 10 lbs of the weight savings I had with a BMR.

jimmyblue

iTrader: (11)

Pics!

firebird6786

first off i find it hard to believe that box steel is stronger than tub steel but **** happens. if your k-member is shaking check your A-arms or your install. i know that its not recommended to have stock arms on a aftermarket k-member. 2nd its okay to go to the track and run your car over 100mph in the shortest time possible, but u cant drive on the street some please help this forum with provin FACTS.

LETHL_SS

iTrader: (21)

I have the BMR K member with A arms and cant complain about it. My car is a street /strip that I drive everyday. FWIW, I always keep an eye on the K member just in case it does crack (normally give a real good look over every other week).

jimmyblue

iTrader: (11)

Tube strength is not the problem, the problem is
critical welds holding the front of the car together
(small ones, at that). Compare to a pair of continuous
sheets of hydroformed steel of the same thickness.

My shake is only transient, on road irregularities.
After the K the front is more "floppy" in torsion.
There's nothing wrong with using stock arms and
the car drives fine and straight, just more front
shake when a wheel gets kicked up by a bump.
For the "floppiness", consider the K I have as a thin-
wall, 40mm hollow sway bar (its only tie being the
one tube, 1-1/4" or so) and the stocker as, oh,
maybe 500mm?

It's not street driving on clean pavement that
breaks welds, it's the accumulated impact over-
stress events that start and propagate fractures
in / about the weld. Those welds had better be
metallurgically perfect to be anything like the
stock piece for impact toughness. Are they?
How can anyone know on a mail order piece?
Even the manufacturers disclaim street duty,
now (not when I bought mine, I picked it because
the web site said it was the only one up to street
duty, subsequently "backed off"); only wishful
thinking recommends it or believes the pieces are
anything alike, in their failure limits.

OldeSkool

The FACT is...
*Driving down a (usually) smooth drag strip at any speed is NOT real hard on your front suspension... so a flimsly lightweight k-member is great.

*I've seen and heard of a handful of broken aftermarket k-members and have never seen or heard of a broken stocker.. and considering there are WAY more stockers out there, the odds are not in the tubular k-members favor.

BJM

iTrader: (1)

There seems to be a huge amount of faith in steel when its shaped like a tube, that somehow its different than other shapes. A tube is fine, its the welding that is the real problem. Nothing in an aftermarket K member is analyzed, Fatigue is your enemy here and process consistency will vary tremendously. No licensed engineers signed off on those aftermarket items. Unlike a brace where the car is strong without it, a K member is too critical an item to trust to anyone who does not and more importantly, will not certify their designs.

BADFNZ

iTrader: (19)

I'd like to see pics too. Making holes in the k-member doesn't sacrifice too much of its strength?

sikws6

The torque arm thread you quted broke from the bolt coming loose plain and simple. The best designed part is worthless if not properly installed and maintained

sikws6

Don't buy much aftermarket do you?

BJM

iTrader: (1)

True, but the failure of the arm was a fatigue failure, regardless of what instigated it. There are several threads with K members cracking at the welds, cracking occuring with the part properly installed. The welds are fatigueing due to inadequate design.

BJM

iTrader: (1)

Is the after every post supposed to tell me something? Are you disagreeing with me, I can't tell. I buy aftermarket very carefully for the reasons I stated.