RevShift - Blue Differential Bushing, Starting to "clunk"
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2004-2007 Cadillac CTS-V Performance Mods Discussion, RevShift - Blue Differential Bushing, Starting to "clunk" in Cadillac CTS-V Series Forum - 2004 - 2007; The more I drive my car lately the more I am noticing the revival of "the clunk". I've double checked ...
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    SevillianSTS is offline Cadillac Owners Enthusiast
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    RevShift - Blue Differential Bushing, Starting to "clunk"

    The more I drive my car lately the more I am noticing the revival of "the clunk". I've double checked all three diff bolts and all are still torqued. I did not have this at all when I put in the RevShift BLUE diff bushing with the Creative Steel "block". I figured by putting both in there it'd be bulletproof...

    I've got about 4000 miles on these bushings.

    I will say my new Michelin PSS can really grip; so that puts added stress on the diff bushing when getting on it. But if you watch this video, it torques up now just at idle.



    I"m just looking for some feedback on possible replacement / upgrades: the Creative Steel differential Bushing, and the RevShift RED bushing ? Noise / Vibrations, anyone have a video while driving with the Red one in ?

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    JFensty's Avatar
    JFensty is offline Cadillac Owners Enthusiast
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    I had the same issue when I changed to the blue diff and red subframe bushings. The increase in whine was immediate and the clunk came soon after.

    Then this happened

    ForumRunner_20131105_185632.png

    Upgrade to a used 3rd gen and used same blue diff bushing and clunk is not there. It actually is a lot tighter than with the old diff. Let me get some mileage on it and I will report back. If it gets clunky again I will be replacing with a CS bushing.

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    FuzzyLogic is offline Cadillac Owners Connoisseur
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    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    It's not the bushing. The same thing happened to me with the Creative Steel bushing (87A) and block. It's your differential developing excessive lash. I believe that installing a stiffer bushing accelerates the rate of decay of the differential. It's an unfortunate tradeoff...either deal with the extreme deflection and hope that you don't break the ears off the differential, or shore up the mounts and hope that the bearings and crush sleeves hang in there now that they're being forced to deal with the full power output of the car.

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    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    Quote Originally Posted by JFensty View Post
    Holy Schnikies!

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    Quote Originally Posted by FuzzyLogic View Post
    It's not the bushing. The same thing happened to me with the Creative Steel bushing (87A) and block. It's your differential developing excessive lash. I believe that installing a stiffer bushing accelerates the rate of decay of the differential. It's an unfortunate tradeoff...either deal with the extreme deflection and hope that you don't break the ears off the differential, or shore up the mounts and hope that the bearings and crush sleeves hang in there now that they're being forced to deal with the full power output of the car.
    So are you simply stating that either we deal with the soft rubber sloppiness, or upgrade the bushings and degrade the diff more quickly?

    I have to say, this is somewhat hard to swallow. Granted my gen 1 diff had 155,000 miles on it with multiple 1/4 mi track days and spirited driving almost daily, most would say it held up pretty good.

    ----------

    Quote Originally Posted by SevillianSTS View Post
    The more I drive my car lately the more I am noticing the revival of "the clunk". I've double checked all three diff bolts and all are still torqued. I did not have this at all when I put in the RevShift BLUE diff bushing with the Creative Steel "block". I figured by putting both in there it'd be bulletproof...

    I've got about 4000 miles on these bushings.

    I will say my new Michelin PSS can really grip; so that puts added stress on the diff bushing when getting on it. But if you watch this video, it torques up now just at idle.

    YouTube Link: http://www.youtube.com/watch?v=qt83ifmMpFI

    I"m just looking for some feedback on possible replacement / upgrades: the Creative Steel differential Bushing, and the RevShift RED bushing ? Noise / Vibrations, anyone have a video while driving with the Red one in ?
    I actually just watched the video, I didn't get a chance to earlier, and the diff actually doesn't look like it moves that much. The entire car is jumping a bit but the diff just seems to move with it. Or should I say, it doesn't move as much as I figured it would.

    Maybe pisnuoff will chime in here. He has broken every other part in the rear end..... I don't recall him actually breaking a diff though.

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    FuzzyLogic is offline Cadillac Owners Connoisseur
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    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    I think so. It seems that the differential has to cope with either major misalignment, or normal V levels of thrust loading. Neither of which it was designed for.

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    Revshift is offline Cadillac Owners Fanatic
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    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    Quote Originally Posted by FuzzyLogic View Post
    It's not the bushing. The same thing happened to me with the Creative Steel bushing (87A) and block. It's your differential developing excessive lash. I believe that installing a stiffer bushing accelerates the rate of decay of the differential. It's an unfortunate tradeoff...either deal with the extreme deflection and hope that you don't break the ears off the differential, or shore up the mounts and hope that the bearings and crush sleeves hang in there now that they're being forced to deal with the full power output of the car.
    This. You beat me to it, Fuzzy.

    The clunk is gear lash related. I posted in another thread a couple days ago talking about this. I have the same issue with my M3 which has very similar bushings to the CTS-V. My M3 has 95a red polyurethane everywhere. Nothing is loose and the bushings are still in perfect condition. The clunk and slop is inside the differential. I know this because we cracked the diff open a few months ago and confirmed it. The car only has 70,000 miles and the diff fluid was changed out for high quality racing stuff. It is getting rebuild this winter. It is not an uncommon occurrence and it has very little to do with bushings.

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    SevillianSTS is offline Cadillac Owners Enthusiast
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    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    I somewhat disagree. I understand how a bunch of that "snap" is releasing all the tension in the diff; but, it is moving too.
    The car does not move until the diff snaps back. I can see the diff pulling up as I had it in 1st a few times and then I see it pushing down when I had it in Reverse. Focus on the bottom edge of the bumper and notice the car does not move until the diff snaps back. You can also hear a clicking sound as the diff is torquing down (in reverse) @ :21 seconds. That clicking as I backup in the driveway, is what made me put a camera under it to see what was going on. It has only been doing that for maybe the past month.

    It's still a lot better than it was with the stock rubber mount; I'm just trying to figure out if I want to upgrade to the firmer mount. Obviously since this mount should slide out vs. being cut out, shouldn't be too bad of a job.

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    Sevillian, did you run the blue diff bushing with the diff block? If so, did you notice any interior noise increase with the block?

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    PISNUOFF Guest

    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    I really don't want to get into this debate on Revshift blue bushings. I have had the UUC 95A front diff bushing since they were released many years ago. I have not broken my gen4 diff casing and mine doesn't clunk, but either my ring gear or pinion is missing some/all of one tooth.


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    I completely understand this conversation can get sideways rather quickly, but I am more concerned with Fuzzy's comment about the diff degrading faster with a stiffer bushing.

    When did you find this wonderful present? Edit: I just saw you other post. Over a year ago with the daily beatings you give it???

  13. #12
    PISNUOFF Guest

    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    Yes, over a year ago with over 500 rwHp daily launches and beatings. It howls but it's still chugging along. I believe it's been three stock CV's and two DSS stub shafts since I found this.

    I'm not sure what engineering principles would support the claim that a joint with less articulation would accelerate the wear of gear teeth. Especially when the articulation is outside the case. Generally the case breaks from overangulation of the CV and it locking up. All that points to the case above having been damaged and weakened prior to stiffening up the bushings.

    Stiffening up all the bushings would put the initial spike load through the case, but that is less than if it were to 'wind up' and move an 1" then hit at the bushing joint which is the case when the stock bushing wears out. The blue bushing would help this scenario by providing a softer cushion for the initial hit.

    Edit: My car was down for 5 months while building the 427 LSX so it's really only been about 7 months of abuse.

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    SevillianSTS is offline Cadillac Owners Enthusiast
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    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    Quote Originally Posted by JFensty View Post
    Sevillian, did you run the blue diff bushing with the diff block? If so, did you notice any interior noise increase with the block?
    I have both installed, I don't think the block transmits the noise as much as the bushing itself would; I can tell a difference, but it's not much, but my diff is a gen 4 with maybe 10k on it. Pretty quiet diff.

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    Quote Originally Posted by PISNUOFF View Post
    Yes, over a year ago with over 500 rwHp daily launches and beatings. It howls but it's still chugging along. I believe it's been three stock CV's and two DSS stub shafts since I found this.

    I'm not sure what engineering principles would support the claim that a joint with less articulation would accelerate the wear of gear teeth. Especially when the articulation is outside the case. Generally the case breaks from overangulation of the CV and it locking up. All that points to the case above having been damaged and weakened prior to stiffening up the bushings.

    Stiffening up all the bushings would put the initial spike load through the case, but that is less than if it were to 'wind up' and move an 1" then hit at the bushing joint which is the case when the stock bushing wears out. The blue bushing would help this scenario by providing a softer cushion for the initial hit.

    Edit: My car was down for 5 months while building the 427 LSX so it's really only been about 7 months of abuse.
    Yes but that is similar to dog years vs calendar years

    ----------

    Quote Originally Posted by SevillianSTS View Post

    I have both installed, I don't think the block transmits the noise as much as the bushing itself would; I can tell a difference, but it's not much, but my diff is a gen 4 with maybe 10k on it. Pretty quiet diff.
    Thanks. I just have some noise on decel / slower speeds and had just installed the block with this diff. Same blue bushing installed on both and is still in like new condition.

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    Re: RevShift - Blue Differential Bushing, Starting to "clunk"

    [QUOTE=FuzzyLogic;11264266]It's not the bushing. The same thing happened to me with the Creative Steel bushing (87A).[/QUOTE

    I should state that our black bushing is not an 87A. It's is more for guys that want performance over oem but not the harsh ride of a stiffer bushing. We do have a 95A bushing out now for race guys.
    Jordan @ Creative Steel Inc.

    503-316-1811
    Open M-F 8:00-5:00 PST
    Jordan@creative-steel.com

    Check us out at: http://www.creative-steel.com
    We're on Facebook! https://www.facebook.com/pages/Creat...39612609499435

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