Phoenix 5.7

iTrader: (7)

i have read that some don't recommend running a tubular K member on a DD for fear of it cracking/failing. who has actually had this happen? how long did you have it b4 it broke? what brand?

ROCNDAV

iTrader: (100)

I'd like to know this too, as I'm starting to assemble mine.

CaliboyTA

iTrader: (2)

some guy that posts on norcal-ls1 broke his bmr tubular k-member. His car is a daily driver.

ROCNDAV

iTrader: (100)

Damn, that scares me a bit. I live in San Gabriel Valley and work in San Fernando Valley. The roads around my office are so bad, they should rename the city to Potholeville.

I wonder if they tend to brake at a weld, and if it is easy to repair? Or better yet, how many people with tubular K members with high mileage that have not broke their K members.

jimmyblue

iTrader: (11)

There was a spate of postings about this like
last month? Some people who broke were in
there.

SIK02SS

iTrader: (11)

i'm pretty sure that guy on norcal broke 2 tubulars and a couple stocks as well?

nothing serious in power if i remember right

EPP

iTrader: (22)

I've had my BMR K Member on my Z28 for several years, many miles on broken Indiana pavement, no problems at all. Bob

WS6WRX

iTrader: (1)

BMR, broke w/ in a few months, maybe 12 drag runs and 1 AutoX event.

Foxxtron

iTrader: (1)

Broke mine after 36K of mostly street use and only 4K worth of RR. Didn't run up on curbs, parking berms, or flew over speed bumps.

ROCNDAV

iTrader: (100)

Foxxton was that a BMR too? Has anyone broke a Profab?

Phoenix 5.7

iTrader: (7)

have they all been BMR? what about PA?

Foxxtron

iTrader: (1)

Hate to slighty tarnish my reputation, but it actually wasn't just one brand, but another as well. I've had two, and was disappointed with both, and while only one of them broke, both decreased front-end rigidity. I'd really like to avoid the ethical taboo of stating brand names outright. Just stating my experience as other are also.

WS6WRX

iTrader: (1)

Also agree w/ Foxxton, while they may decrease front end weight, they ruin the handling of the car. So I guess it's fine for drag junkies, but if you care at all about how the car corners then an aftermarket K memeber is not for you.

Foxxtron

iTrader: (1)

Oh yes, and for those who want to reinforce their aftermarket tubular k-members, just bear in mind that by the time you successfully reinforce the k-member, your nearly back to the OEM stamped steel k-member's weight and still not near the OEM's rigidity.

Also, the k-member has a very important duty of not only holding the engine, but also holding the engine at it's right height so it properly mates with the transmission and it's parts that go all the way to the rear wheels and the power steering rack, and the lower a-arms which in turn support the other front-end suspension parts. A good f-body chassis with an OEM k-member is pretty rigid, but if you care to run a road course with a wobbly front end, then you now know what gamble you're in for.

ROCNDAV

iTrader: (100)

so, I take it that you went back to stock? Where did the K member break? was it the same place on both of them?

Strokinit383

iTrader: (22)

How many percent of them will actually crack though? Is this a common problem or what?

Foxxtron

iTrader: (1)

Yep, returned to stock, and both aftermarket K-frames broke around the weld areas closest to the engine mounts. For my purpose, I'm waiting on something that will not only be lighter, but also more robust than the factory k-member, which has fared quite well.

Foxxtron

iTrader: (1)

Don't know percentages, but what I'd be concerened about would be it's overall design. I think that they're okay for dedicated drag racing, but for street, AX, and RR, they're definitely out of the question until there is something that is much more robust. If two or three are known to fail in the same fashion and also cause the same undesirable charactersitics when being operated on a road course, then that's enough for me to avoid any design that resemble the ones that did fail on me. My 2 cents.

jimmyblue

iTrader: (11)

I can't say mine has "ruined" handling although it did
return a little front end shake that was not there with
the stock K.

In my opinion it would take a couple of pounds of steel,
tops, to toughen up the BMR K to street duty. I have
never gotten up close to any of the others.

But if you're not in a testing mood, just leave the pig
iron do its job I reckon.

Foxxtron

iTrader: (1)

Or if you're in a testing mood, you could attempt to create a chromoly boxed style K-member similar to the LG proposed design at one point (just don't know if it would be patent infringement in case the design is patented).