dennisbernal91z

iTrader: (2)

Looking for what everyone thinks the best K-member is for an LS3 swap. I will be running the black heart headers and full exhaust.

I have read that the stock K-member is OK, but I don't have one at the moment. I have found someone that is willing to sell me one for $20.

My PA racing unit is OK, but it is an older design and with all the money I plan to put into this build I want something new.

BMR, UMI (autocross), Spohn, etc...

//<86TA>\\

iTrader: (14)

Best for anything the street or you can throw at it would be the stock one.

If you must go with an aftermarket one, UMI makes a nice piece.

articwhiteZ

iTrader: (56)

2nd the UMI unit..

QwkTrip

iTrader: (22)

Agree, stock is best for street use but does require cutting and welding.

BMR is most versatile to fit with anything. UMI is stronger but needs a high-mount AC bracket.

skinny z

Are any of the aftermarket parts strong enough? At one point I recall one of manufacturers pulling their "race" part due to durability concerns.
Personally, I'd rather notch the OEM piece for pan clearance (if that's even necessary with right pan) than gamble on the tubular parts. Then again maybe others will chime in with their success stories.
Does anyone have a reference for weight savings?

QwkTrip

iTrader: (22)

My BMR piece is pretty flimsy if you ask me.

You know these things are fabricated and not engineered. Huge difference between those two concepts.

dennisbernal91z

iTrader: (2)

I won't be running AC. Here is MA it doesn't ever get hot enough to need it, at least not in my eyes so the low mount AC issue doesn't matter for me.

I believe I will be buying my crate motor from Pace Performance and they will swap to the correct pan, check the motor and even dyno it and break it in. All things I plan to have them do. So I don't think notching will be an issue.

I guess I am on the fence about stock K-member and UMI with aftermarket A-arms (DSE, Sohn, UMI, etc... whatever fits stock K-member)

I know the stainless LS headers that Hooker sells are made to fit the stock k-member, so I guess there is no issue there.

In terms of cost, it looks like getting a stock unit, maybe powder coat it and call it done is the way to go. About $600
To make the build look a bit more "race ready" the UMI K-member would be the way to go. About $1,200.

Since I plan to mostly just drive the damn thing and not autocross or anything like that, I think the stocker is the way to go. Throw some nice A-arms on there and call it a day.

Tibo

iTrader: (15)

The added clearance overall as well as how easy it is to change motor mounts now is what really sold me. Look and marvel at the clearance

//<86TA>\\

iTrader: (14)

I took a stock k member, added welded in weight jack, clearanced the cross member and control arm mounts to better clear exhaust and oil pan. Probably best bang for the buck and gains you whatever clearance you need.

Ed1LE

iTrader: (39)

pics?

alan91z28

i have used the UMI road race k-member on 4 of my 3rd gens so far, both on SBC and LSx upgrades / swaps... i like it much better than the BMR, both in terms of robustness and motor positioning... you can see pics in my swap threads if you are interested

skinny z

Absolutely understood. This is something I deal with on a professional level and the cost of engineering often precludes any given item from getting into the marketplace. Unfortunately, said engineering often comes from introducing something to the retail space and the R and D comes from customer feedback. I'll refer back to the introduction of the 700R4 by GM and the ensuing callbacks that resulted from the transmission actually being used and failing. There's nothing like having a test bed of a million units to determine where the shortcomings are.

dennisbernal91z

iTrader: (2)

Right on. Happy to know the UMI RR unit is working out well.

But since I plan to use the Blackheart Holley headers and exhaust, I think clearance won't be an issue for me.

I also plan to use the Holley oil pan as well.

This leads me to the conclusion of stock K-member and some aftermarket A-arms.

UMI Sales

We just installed our RR unit in Dragonlady GTA with an LS3. Pichette's auto-x all over the country with it.

ramey

Beater79TA

The one thing no one pointed to in this thread is clearance to reach other items. As Ramey stated, we run the UMI RR unit on our car. We've found the low mount alternator to be problematic when the car is driven hard in all weather on the street and driven hard on the track. The extra clearance from the tubular unit to reach all the way around the alternator for rapid removal and replacement is another factor.

Having run the stock unit, the BMR tubular, and the UMI tubular I would rate the BMR as the worst for fitment and quality, stock second, and the UMI unit first. The BMR unit positions the engine back and up and makes fitment of other items an issue. Stock has lots of options for mounts and oil pans and work well. The UMI unit shaves a little weight and makes access to some items much easier for trackside repairs while allowing quite a bit of adjustment in terms of engine position.

Just remember the weak point isn't the center of the unit, the weak point is where the arms attach and all of them use about the same thickness of steel there.

If this is primarily a street driven car, I would go with the stock K member and stock arms. Put Del a Lum bushings in the arms and call it good. For track use where weight and pit access to everything becomes a bigger factor, I'd recommend the UMI pieces.

yevgenievich

iTrader: (4)

After some research, unless it is going in to a drag car trying to loose some weight or open up space for headers/turbo, I did not find any benefits on the tubular other than easier access to things. I am running notched stock cross member with weight jacks welded in

QwkTrip

iTrader: (22)

Another option is the Heidts piece.

//<86TA>\\

iTrader: (14)

Heidts prototype cross member was beefy as hell, but it seems the production one is different.

dennisbernal91z

iTrader: (2)

I have not seen any one on here have their unit and the website images are junk.

Would take a lot of convincing for me to drop cash on a unit like that, almost sight unseen.

My car will be just about all street, but I do like the idea of dropping some weight. From an engineering perspective less mass and just about equal strength is the holly grail. So now I may consider the UMI setup... Time will tell. This is a bit down the road. Plus I need to sell my PA racing setup first.

dennisbernal91z

iTrader: (2)

After a lot of thought, I think I will go with the UMI RR unit.

I only plan to have this be a street car now, but in the future I can see myself wanting to autoX the car. Less weight is always good too.

Beater79TA

Good choice on the UMI part. If you want to keep low mount AC, Kwik Performance sells a low mount kit that fits very well with this k member.

dennisbernal91z

iTrader: (2)

No AC for me, but thanks for the heads up. Always good to know my options.

Dreambird

Would you happen to have any pictures of that low mount AC install on your car?