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BMR K member concerns

I am in the process of turning my 2013 Boss into a serious track day car and I was considering the BMR K member as a way to lose some weight. Are there any concerns regarding the safety of this part as opposed to the stock K member? I am going to use some modified (better bushings and ball joints) stock lower control arms in conjunction with the K member.
 

TymeSlayer

Tramps like us, Baby we were born to run...
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I've had my BMR K-member on for about six track days at this point and have had no issues. You will lose the ability to bolt on the Boss transmission cooling scoop. This took about 20 pounds off the front end of my car.
 
You might want to look at the Maximum Motorsports K member and read the Tech, Tech 2 & Tech 3 down were the description is. There is some really important information that I feel you should at least consider before doing the swap.
 
5,765
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You might want to look at the Maximum Motorsports K member and read the Tech, Tech 2 & Tech 3 down were the description is. There is some really important information that I feel you should at least consider before doing the swap.
The Maximum Motorsports is a nice piece, but there's no weight savings to be had.
Its stiffer and has better geometry, but it's 2 pounds heavier than the stock K member.
 
Are you going to run slicks? If so, id reconsider.

Is there any actual info on the BMR not being able to stand up to the abuse? Honestly asking as I myself have a BMR K-member installed (bought it before I decided to turn mine to a track car). I will say I have already thought about getting the MM K-member to replace it, but was curious if anyone has actually seen problems with one. I know we had a BMR Tech at one time on the site. Is that person still active?
 
5,765
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Exp. Type
W2W Racing
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Pleasanton: 1/2 way between Sonoma and Laguna Seca
Is there any actual info on the BMR not being able to stand up to the abuse? Honestly asking as I myself have a BMR K-member installed (bought it before I decided to turn mine to a track car). I will say I have already thought about getting the MM K-member to replace it, but was curious if anyone has actually seen problems with one. I know we had a BMR Tech at one time on the site. Is that person still active?
I've had my BMR setup for years and run 335/18 Hoosiers up front.
Only problem I ever had was with the first gen radiator support.
They did tend to rip the sway bar brackets off but that has been resolved in the second gen units.
I have heard of some breaking the tubular A Arms but so far mine have held up fine.
BMR told me that replacing the bushings with Delrin helps stop the flex that breaks the arms or to switch to their A Arm with the rod ends for the same reason. I used their whole setup with the optional A Arm Brace and front brace that ties the K Member to the Radiator support so that adds considerably to the rigidity.
Running the K Member alone would not be nearly as strong and I would worry about that.
Though I have so far never broken one, I can't help but wonder if there is some flex in there, not enough to fracture but enough to alter the geometry under load but not enough to cause failure.
It is for this reason that I recently ordered the Cortex setup and will now retire the BMR.
I'll do a weight comparison here in the near future.
 

Duane Black

Curbs go brrrppp
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Is there any actual info on the BMR not being able to stand up to the abuse? Honestly asking as I myself have a BMR K-member installed (bought it before I decided to turn mine to a track car). I will say I have already thought about getting the MM K-member to replace it, but was curious if anyone has actually seen problems with one. I know we had a BMR Tech at one time on the site. Is that person still active?

I've heard rumors of failures, but they're a bit like lochness monster... google searches and forum searches cant seem to yield any results.

Why is the maximum motorsports so heavy in comparison? Somethings fishy.

Someone on this forum did bust a factory k member at vir if i recall right tho
 
5,765
6,905
Exp. Type
W2W Racing
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Pleasanton: 1/2 way between Sonoma and Laguna Seca
I've heard rumors of failures, but they're a bit like lochness monster... google searches and forum searches cant seem to yield any results.

Why is the maximum motorsports so heavy in comparison? Somethings fishy.

Someone on this forum did bust a factory k member at vir if i recall right tho
The MM part is very heavy duty, strength vs weight is always a trade off.
They prioritize strength. BMR prioritizes weight.

Arizona Boss broke a stock K member but he is doing something very different with it so its not a typical case.
 

TymeSlayer

Tramps like us, Baby we were born to run...
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Brighton, Colorado
I have about the same BMR front set up as Fabman and have has no issues to date. A-arms, radiator support, K-member, sway bar, motor mounts and end links. All work in unison. I know our friend from Chile broke an A-arm (In an Endurance race?) but all my components have been working out well.
 
5,765
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W2W Racing
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Its that brace between the Rad support and the K member that holds this all together.
Plus of course, the a arm brace. I think without those pieces this thing may not have survived as long as it did.
1173808_10151782806633535_889586727_n.jpg
 

Duane Black

Curbs go brrrppp
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Durham, NC
So you guys are running the a arms no problems too? Hows the ball joint hold up? I generally find greasable parts dont last as long, oddly

What is the advantage or potential advantage to adjustable a arms?
 
Last edited:
5,765
6,905
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
So you guys are running the a arms no problems too? Hows the ball joint hold up? I generally find greasable parts dont last as long, oddly

What is the advantage or potential advantage to adjustable a arms?
Yes no problem thus far with anything.
The adjustable a arms have a rod end instead of a bushing so it doesn't flex under braking.
Apparently that's what causes the failures. When the bushing deflects it stresses the opposite end of the control arm.
The rod end addresses this.
 

Duane Black

Curbs go brrrppp
509
353
Exp. Type
Time Attack
Exp. Level
5-10 Years
Durham, NC
Yes no problem thus far with anything.
The adjustable a arms have a rod end instead of a bushing so it doesn't flex under braking.
Apparently that's what causes the failures. When the bushing deflects it stresses the opposite end of the control arm.
The rod end fixes this.


So, do you want the adjustable to prevent deflection or do you want the non adjustable to allow the give and prevent stress? The wording here is a little ambiguous to me, sorry
 
5,765
6,905
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
So, do you want the adjustable to prevent deflection or do you want the non adjustable to allow the give and prevent stress? The wording here is a little ambiguous to me, sorry
The bushing flexes=Bad.
 

TymeSlayer

Tramps like us, Baby we were born to run...
3,777
2,704
Exp. Type
HPDE
Exp. Level
3-5 Years
Brighton, Colorado
A-Arms are holding out quite well. I do, however find myself checking on them after every track day. One can never do too much maintenance.
 
5,765
6,905
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
Is the bmr k member compatible with the steeda lightweight radiator mount?
The rad support is compatible but the optional BMR front K Member brace if used would not fit.
 

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