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2004-2007 Cadillac CTS-V Performance Mods Discussion, Front sub-frame bushings in Cadillac CTS-V Series Forum - 2004 - 2007; I think it's all personal preference really. Sub frame connectors do stiffen the chassis but they do it at the ...
  1. #16
    RyRidesMotoX is offline Cadillac Owners Enthusiast
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    I think it's all personal preference really. Sub frame connectors do stiffen the chassis but they do it at the cost of rude quality, that I will admit. And like i said i bet 90% of Vs in the world don't see the track. They aren't for everyone, fuzzy is right about that. But, for an application like what I want too do (trailer the car to the track and drive it a little more rarely on the street) it would be preferable to have add little flex as possible. When money allows, I'm going to build a sweet track car. It may take me a while but it's going to happen eventually.

  2. #17
    nikdsctsv is offline Cadillac Owners Fanatic
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    Re: Front sub-frame bushings

    Quote Originally Posted by RyRidesMotoX View Post
    I think it's all personal preference really. Sub frame connectors do stiffen the chassis but they do it at the cost of rude quality, that I will admit. And like i said i bet 90% of Vs in the world don't see the track. They aren't for everyone, fuzzy is right about that. But, for an application like what I want too do (trailer the car to the track and drive it a little more rarely on the street) it would be preferable to have add little flex as possible. When money allows, I'm going to build a sweet track car. It may take me a while but it's going to happen eventually.
    Which again, would dictate a cage. You get the chassis support you're looking for and safety to boot. To add the weight of a chassis brace for racing instead of a cage makes no sense to me.

  3. #18
    RyRidesMotoX is offline Cadillac Owners Enthusiast
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    Quote Originally Posted by nikdsctsv View Post

    Which again, would dictate a cage. You get the chassis support you're looking for and safety to boot. To add the weight of a chassis brace for racing instead of a cage makes no sense to me.
    Yea I'll admit the V chassis is much stronger than any of the old limp noodles the 80s cars were. I intend to start with a cage and then do connectors after that and compare lap times. The added 50-60lbs of steel should offset any flukiness of track days. I'll just compare lap times. If they don't significantly improve over the average I'll probably just grind em off. That is for a while though... As fist my money will be spent on drive train.

  4. #19
    Dan_Gurney is offline Cadillac Owners Fanatic
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    Re: Front sub-frame bushings

    Quote Originally Posted by RyRidesMotoX View Post
    I said I could feel the body flex. If you put your hand where the top of the door meets the frame, you can feel it. Just do a hard highway pull or do it when you are getting on a banked on ramp for a highway. You can feel it. It doesn't take a mic or any gauges to feel it. And its not super dangerous or anything its just an observation.
    You are also assuming that this is not just the door moving in the opening vs the body moving around the door...

  5. #20
    RyRidesMotoX is offline Cadillac Owners Enthusiast
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    Quote Originally Posted by Dan_Gurney View Post

    You are also assuming that this is not just the door moving in the opening vs the body moving around the door...
    Either way shows some amount of chassis flex which is necessary in a street car for comfort. Since a door is connected at the hinges and at a latch. it's fairly secure and with a stuff enough chassis I would venture to guess there is little to no movement.

  6. #21
    PISNUOFF Guest

    Re: Front sub-frame bushings

    Quote Originally Posted by ctsv247 View Post
    In the absence of the instrumentation and the controlled environment needed to make such an analysis, I guess the easiest way to figure this out would be to build a full set, front to rear, side to side and start cutting pieces out of it until you start noticing a substantial difference in the behavior of the car.

    Have we ever seen a car that is too stiff?

    54, as the only person currently pursuing this, is this something you care to take on??
    The rear subframe connectors on the V are NOT anything new. They were attempted 5-6 years ago and the idea scrapped because of the obscene amount of road noise, diff noise and vibration transmitted into the cabin. It was an attempt to use only part of the KARS solution. It was all over this forum prior to the concept of different modulus of elasticity axles being adopted as the best solution to cure wheelhop.

  7. #22
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Front sub-frame bushings

    The subframe connector concept needed revisiting. If I remember correctly, the KARS kit tied directly into the diff which transmitted all the noise whereas a set like 54 is building should not. The question to answer in regards to the 54 setup, is should the design be expanded a little to pickup more chassis points or not?

    Will a set of subframe connectors make sense on a street driven V? Maybe, maybe not but based on how well they've worked on previous platforms, it's worth a shot. And while I think we would all appreciate a complete scientifically chassis strength analysis, it's easier to just make them, put them on the car and try them out.

    54, if you are reading this and want to discuss the design, build and purchase of a set of these, please PM me. Thanks

  8. #23
    RyRidesMotoX is offline Cadillac Owners Enthusiast
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    I doubt many folks that street drive a V would take the tradeoff of the added performance, noise and vibration over the comfort. Depending on the bushings people use in the rear cradle, one would experience some of that noise and vibration anyways.

    I doubt that simply extending them a little further down the frame will do much to further strengthen anything. To really be of use, one must tie both subframes together. You're basically trying to make a half of a tube chassis. As we covered before, Fox bodies are terribly notorious for catastrophic chassis flex. The V is larger and therefore more solid. The unibody needs to support over 1000lbs more in a V so naturally the chassis should be a bit better... Not taking into account technology and design improvements over 10 years separating the two.

    I think that when you look into it, you will find we both have the same conclusion... Subframe connectors are a rather extreme solution to a problem that is somewhat necessary. There needs to be chassis flex for comfort. But for me, comfort is one of the last things I care about. When I start trying to get the V track ready, its all about going fast.

  9. #24
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Front sub-frame bushings

    Quote Originally Posted by RyRidesMotoX View Post
    I doubt many folks that street drive a V would take the tradeoff of the added performance, noise and vibration over the comfort. Depending on the bushings people use in the rear cradle, one would experience some of that noise and vibration anyways.
    My F-bodies typically rode better and the squeaks and rattles were substantially reduced by tying it all together. Because the V is light years ahead of any F-body I've ever owned as far as chassis refinement goes, it doesn't squeak and rattle (yet) so this may be my weak ass attempt at keeping it from becoming the squeaky rattly mess most of my other GM products eventually turned into. Besides, I have a feeling that by the time I go with poly bushings, the noise and vibration damage will pretty much already be done.

    Quote Originally Posted by RyRidesMotoX View Post
    To really be of use, one must tie both subframes together.
    Ding, Ding, Ding! I'm with you...check out my second post.

    Quote Originally Posted by RyRidesMotoX View Post
    There needs to be chassis flex for comfort. But for me, comfort is one of the last things I care about. When I start trying to get the V track ready, its all about going fast.
    I doubt Mercedes is intentionally building chassis flex into their platforms to insure they ride well. You need suspension performance for ride comfort and we aren't sure the V's suspension is up to compensating for any extra chassis rigidity.....guess we'll see.

  10. #25
    RyRidesMotoX is offline Cadillac Owners Enthusiast
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    Quote Originally Posted by ctsv247 View Post

    My F-bodies typically rode better and the squeaks and rattles were substantially reduced by tying it all together. Because the V is light years ahead of any F-body I've ever owned as far as chassis refinement goes, it doesn't squeak and rattle (yet) so this may be my weak ass attempt at keeping it from becoming the squeaky rattly mess most of my other GM products eventually turned into. Besides, I have a feeling that by the time I go with poly bushings, the noise and vibration damage will pretty much already be done.

    Ding, Ding, Ding! I'm with you...check out my second post.

    I doubt Mercedes is intentionally building chassis flex into their platforms to insure they ride well. You need suspension performance for ride comfort and we aren't sure the V's suspension is up to compensating for any extra chassis rigidity.....guess we'll see.
    I only rode in fox bodies with connectors. This was back when I was on the dark side of motoring (Ford). Mine is starting to squeak and rattle a little when I really get after it. 92k miles on the odo so I'm guessing its been run hard for some time before I got it.

    Whether or not Mercedes designs flex in, it will be there in any chassis. That's what happens when you have spans of metal held together by bolts with rubber bushings. Things flex. Its all part of how the suspension reacts, as a whole from the tires to your spine. Its all in a constant state of compression, rebound, or if you drive in California... Pothole. Lol

  11. #26
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Front sub-frame bushings

    Quote Originally Posted by RyRidesMotoX View Post
    I only rode in fox bodies with connectors. This was back when I was on the dark side of motoring (Ford). Mine is starting to squeak and rattle a little when I really get after it. 92k miles on the odo so I'm guessing its been run hard for some time before I got it.

    Whether or not Mercedes designs flex in, it will be there in any chassis. That's what happens when you have spans of metal held together by bolts with rubber bushings. Things flex. Its all part of how the suspension reacts, as a whole from the tires to your spine. Its all in a constant state of compression, rebound, or if you drive in California... Pothole. Lol
    Everything flexes...agreed. To what degree varies greatly.

    The suspension design in an older fox body mustang wasn't very sophisticated so indeed chassis flex could be interpreted as suspension compliance. In a perfect world, you could put a 100% affective suspension system on 2x4 and make it ride like its on air.

    To what degree our chassis flexes and how well our suspension actually works is still open for debate and about the only way to really know if there's any realistic improvements to be made, short of a full blown engineering study, is to weld some connectors up and try it out.

    With that said, there are a couple of things that concern me about 54's current design but this could change.

    1. The need for 2 attachment points on the rear subframe to achieve bolt-in rigidity. Looking at the rear subframe mounting points, it looks like the connectors might, maybe, could possibly interfere with the "wide tire" lower control arms I just purchased from Creative Steel. Plus, having to find 2 attachment points per end complicates the design and construction of these significantly.

    2. Good points have been raised about simply transmitting the movement of the rear subframe straight into the body of the car....spreading it out to both frame members and leaving the body alone makes more sense to me in the long run.

    At this point, I think I'll eventually work towards a set that are isolated from the body (to help eliminate noise transmission) and span from the front subframe to the rear. In lieu of finding 2 attachment points per end and making them bolt-in, weld-ins would be easier to design because you don't need as much contact area to achieve rigidity. Of course, they will need to be flanged on either end to allow for subframe removal.

    But, I haven't had a chance to spend time under my V (had it for 4 months) so I haven't eyeballed this at all. After taking a closer look at it, I may have to change my position entirely but time will tell.

    Either way, I'll have to shelve this for a while but I appreciate the conversation!

  12. #27
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    DavidBoren is offline Cadillac Owners Enthusiast
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    Re: Front sub-frame bushings

    Sorry for resurrecting an old thread, but did anything ever come of this? I was looking for chassis braces back when I had my V6 CTS, but I could only find them for the second generation cars. My CTS was totalled last year, so I plan to replace it with a V once my baby is born.

    Even the braces I found for the second gen V's were not really what I want. What I really want is four 1" heavy wall tubes connecting the rear subframe to the front subframe, with two on the driver side and two on the passenger side. One tube on each side as close to the outside of the car as possible, and one tube on each side as close to the centerline as possible (without interfering with the exhaust). And then add cross braces between the two tube on each side to make a series of equalateral triangles.

    Excuse the crappy phone picture and the worse sketch, but something like this:
    IMG_20140717_110014_544.jpg

    It would require both front and rear subframes to be dropped as one, essentially making it a body on frame vehicle. The bracing between the two subframes would not attach to the body in any way. The front subframe would still be mounted metal on metal, and rear would still attach with bushings (preferably RS reds).

  13. #28
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Front sub-frame bushings

    In a word...no

    54 has designed and built a set that look great but I think he's too busy doing everything else to produce them on mass.

    Plus, thus car has plenty of other issues to address that yield probably more substantial results than connectors will. Great idea but not needed as much as let's say cradle bushings an ls7 clutch motor mounts 8.8 etc etc....

    If you move forward keep us posted!

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