Sub Frame Connectors

[JonnyG2132]

What do you guys think of sub frame connectors? I am not worried about cornering at all. I just drag race. Worth it?

Jon

[Eidolon]

I could've sworn I felt a tangible improvement in the solidity of the body, such as over bumps, when I put my BMR Subframe Connectors in. Plus I take my car to road courses. So I figure they're worth it.

That said, I don't know of a thing they'd do to actually improve your times down the strip. If this were a classic car forum and you were running something from the late 80's or older, frame stiffeners would be a necessity for serious power to keep your car from twisting itself nearly in half. But for us? The body's good enough at keeping itself straight, already. And to my knowledge, the subframe connectors won't do anything for wheel hop or traction or the like. You'd be better served with bushings or trailing arms, etc.

[Panzer Leader]

I had the sub frame and tunnel brace from BMR. But I also had the Pedders Street II, rear LCAs and a lot of other stuff. That car never wallowed, never swayed, never rolled.... It was stiff, and I loved it. Some thought a tad too rough, but not me. .......Never got blown around on a highway by cross winds or 18 wheelers. :thumbsup:

[rocket69GTP]

I could've sworn I felt a tangible improvement in the solidity of the body, such as over bumps, when I put my BMR Subframe Connectors in. Plus I take my car to road courses. So I figure they're worth it.

That said, I don't know of a thing they'd do to actually improve your times down the strip. If this were a classic car forum and you were running something from the late 80's or older, frame stiffeners would be a necessity for serious power to keep your car from twisting itself nearly in half. But for us? The body's good enough at keeping itself straight, already. And to my knowledge, the subframe connectors won't do anything for wheel hop or traction or the like. You'd be better served with bushings or trailing arms, etc.

This. When I backed out of my driveway each morning and felt the body twist, you could hear the sunroof creak a bit and after installing these, it completely disappeared.

[JimmyJazz]

This>
This. When I backed out of my driveway each morning and felt the body twist, you could hear the sunroof creak a bit and after installing these, it completely disappeared.

[Executor999]

They definitely make a difference on my G8. No more body twist and mysterious hits during cornering.

[Fatdaddy]

Similar experience as others. I don't think they made much difference with front to rear flex motions The car is pretty good that way as built. They made quite a difference with side side twisting and rotational movement. Overall a plus addition in my opinion.



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[BMR Sales]

What do you guys think of sub frame connectors? I am not worried about cornering at all. I just drag race. Worth it?

Jon

The subframe connectors will definitely help out with more consistent and predictable launches but it is hard to say that you will actually see a difference in your 60ft or ET other than consistency. They will help stiffen the chassis which will in turn get rid of some of the creaks and other unwanted noises that the G8 are kind of known for. The way I look at subframe connectors is that there is nothing negative that can come from them and all of our customers really like them so you can't really go wrong with them.

[Chewy]

They're on my lists of items to put on...

[unitofstuff]

They're on my lists of items to put on...

Same here. They can't hurt, and for the price it seems worthwhile. Plus you can get them in red, which everyone knows makes your car faster.

[gr8lover]

I am going to be selling mine real soon due to not needing it and the extra weight is not helping me at all. Since I have a roll cage, my car is much stiffer than it was before and no longer need the sub frame connectors.... mine are black though so it may slow you down :)....

[rocket69GTP]

Chuck is of course talking big money now. LOL

[Lucifer]

I am going to be selling mine real soon due to not needing it and the extra weight is not helping me at all. Since I have a roll cage, my car is much stiffer than it was before and no longer need the sub frame connectors.... mine are black though so it may slow you down :)....

Interested, pm a price?

[Dcg8554]

I would be interested as well. Please PM as well.

[Rob@WretchedMS]

Just a clarification, there is no Subframe Connector made for the G8, there are only Unibody Braces and Unibody braces will not positively effect the car for drag racing at all.

How much do these weight? I'm sure it's not a ton, but adding weight will not speed you up.

If you want to stiffen the unibody, that's another story, but it will not help with drag racing and ET's.

[rocket69GTP]

Just a clarification, there is no Subframe Connector made for the G8, there are only Unibody Braces and Unibody braces will not positively effect the car for drag racing at all.

How much do these weight? I'm sure it's not a ton, but adding weight will not speed you up.

If you want to stiffen the unibody, that's another story, but it will not help with drag racing and ET's.

http://marylandspeed.com/bmr-sub-frame-connectors-pair-2008-pontiac-g8-sfc013-p-2093.html

Maybe I missed something....:huh:

[Rob@WretchedMS]

They are named subframe connectors, but they do not connect to the subframe.
Something that was just named wrong back in the day and never has been corrected.

[Eidolon]

They are named subframe connectors, but they do not connect to the subframe.
Something that was just named wrong back in the day and never has been corrected.

Rob's correct on this one. When the braces came out, BMR stated that the ideal design for something like this is welded-in supports more like what they make for the Mustang, which actually physically connect to the front and rear subframes on the Mustang. But the maintenance needs - you have to drop the rear subframe to remove the fuel tank - and non-rigid mounting of the G8 rear subframe rule out such an installation. So the "subframe connectors" that BMR sells really are just unibody braces.

And as Rob stated, and as I stated in the second post of this thread, they won't really do much for strip times. There are other parts in the suspension parts bin that will do more for you than the subframe connectors. Subframe bushings, trailing arms, and differential bushings, to name a few.

[iisme13]

Rob's correct on this one. When the braces came out, BMR stated that the ideal design for something like this is welded-in supports more like what they make for the Mustang, which actually physically connect to the front and rear subframes on the Mustang. But the maintenance needs - you have to drop the rear subframe to remove the fuel tank - and non-rigid mounting of the G8 rear subframe rule out such an installation. So the "subframe connectors" that BMR sells really are just unibody braces.

And as Rob stated, and as I stated in the second post of this thread, they won't really do much for strip times. There are other parts in the suspension parts bin that will do more for you than the subframe connectors. Subframe bushings, trailing arms, and differential bushings, to name a few.

Then why advertise them as. "Subframe connectors" when they really arent. Isnt that false advertisement?

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[SpeedRacerX]

I have been exploring this issue for two years. The BMR sfc's do not come all the way back and grab and hold the rear subframe.

D3 accomplishes this for the CTS-V, Hotchkis has a killer one for the Camaro, etc, etc.

Watch the D3 before and after video to see how the subframe movement practically disappeared.

I have several design ideas of my own. My belief is that if you can stop the rear subframe from moving left, right, fw, back, you can retain the softer factory subframe bushes as 90% of the rear subframe issue is lateral movement and not up and down.

I will probably play with my idea in a few months.

At minimum, take bmr's and add another arm or triangle that holds the rear subframe. I've shared my ideas with BMR but there was no interest.

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[Rob@WretchedMS]

if you want to minimize the movement of the subframe, then the subframe bushings is where you should be looking, anything else is a rube goldberg attempt at preventing movement.
Attack the problem at the source, not the symptom.

[SpeedRacerX]

if you want to minimize the movement of the subframe, then the subframe bushings is where you should be looking, anything else is a rube goldberg attempt at preventing movement.
Attack the problem at the source, not the symptom.

Tell that to D3 Cadillac Rob. Factory bushings get retained for a reason when they stop the movement. Less nvh than poly.

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[Rob@WretchedMS]

not the reason,
D3 does that because it's easier to build and install a brace than it is to manufacture and install a bushing or insert.

We have solid Poly bushings for the Camaro, as well as inserts similar to the ones we have for the G8, and there is very small change in NVH.
Others have used solid aluminum bushings and have not noticed a big change in NVH.
Corvettes from what i understand are hard mounted rear cradles.

with that said, how do you feel a brace that is hard mounted between the unibody and the cradle will be magic and not make any NVH increase, but a bushing that does the same job, but absorbs NVH will be worse?

[SpeedRacerX]

not the reason,
D3 does that because it's easier to build and install a brace than it is to manufacture and install a bushing or insert.

We have solid Poly bushings for the Camaro, as well as inserts similar to the ones we have for the G8, and there is very small change in NVH.
Others have used solid aluminum bushings and have not noticed a big change in NVH.
Corvettes from what i understand are hard mounted rear cradles.

with that said, how do you feel a brace that is hard mounted between the unibody and the cradle will be magic and not make any NVH increase, but a bushing that does the same job, but absorbs NVH will be worse?

Good point Rob. All I know is the more poly I put on my car, the gain is met with more nvh. But then again, I see, feel and notice the slightest changes in my car.

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[SpeedRacerX]

The other reason I leaned toward a brace was so that driveway, bolt-on installers like myself could have a fix without dropping the whole rear subframe. Yes, this approach addresses a symptom and not the cause, I know.

Something tells me keeping the rubber bushings in the subframe, if you can find another way to stop it from stepping out, is a good idea. Sort of like when 50% of members who added poly or solid bushings to their rear differential, wish they didn't or wouldn't do it again. Maybe that's not quite apples to apples - what do I know.

[Rob@WretchedMS]

The Subframe Bushing Inserts that we use stop the majority of subframe movement, and don't increase the NVH much at all,

The Diff Bushings can increase it a bit, more so with the HD version of them, but they are two different things.