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2004-2007 Cadillac CTS-V Performance Mods Discussion, Help needed with LS7 clutch install - rock hard pedal in Cadillac CTS-V Series Forum - 2004 - 2007; jmargo - what makes you think that?...
  1. #31
    Derek5.7 is offline Cadillac Owners Member
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    Re: Help needed with LS7 clutch install - rock hard pedal

    jmargo - what makes you think that?

  2. #32
    jmargo is offline Cadillac Owners Fanatic
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    Re: Help needed with LS7 clutch install - rock hard pedal

    You went from a rock hard pedal to one that now feels good but won't properly articulate the clutch. Sounds like you are getting close but may need a little more bleeding. But not being there and getting everything second and third hand is just speculation.

  3. #33
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Help needed with LS7 clutch install - rock hard pedal

    Quote Originally Posted by FuzzyLogic View Post
    [Deleted following personal attack by moderation team that is inconsistent with published Cadillac Forum terms of use.]
    No they probably took your post down because you had pictures of products you are offering for sale on your forum that had nothing to do with this post - door lock pulls, trunk knobs....hello.

    As far as your clutch goes....

    I read fuzzy's post before it was deleted and what he forgot to mention about the shimming was that what seemed to have caused the need for shimming in the first place - inconsistencies in aftermarket flywheel dimensions. Some of the lightweight aftermarket flywheels must be just slightly different dimensionally than the factory ls7 flywheel which affected the slaves ability to disengage the clutch. There has been much controversy surrounding this but at this point you need to consider exactly what kind (and brand) of flywheel you have. To my knowledge, and I'll get flamed for this although I'm not saying it isn't possible, I have not heard of any reports of anyone needing to shim an ls7 clutch and flywheel assembly that came straight out of a GM box. If you went with some sort of lightweight flywheel, there is a good chance (based on the symptoms you're having) you will need to shim the slave cylinder and as far as I know (again, just saying as far as I know, not saying it can't happen) a new master cylinder assembly won't compensate for a slave that needs to be shimmed because the flywheel isn't built to a factory design dimension. I believe Fuzzy hinted at that but can't read it now.

    Bleeding is definitely your next option. Do a search on "motive bleeder" for the tool you need to really get this done although pump it up hold it down will eventually work.

  4. #34
    Derek5.7 is offline Cadillac Owners Member
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    Re: Help needed with LS7 clutch install - rock hard pedal

    ctsv-247 - you think I should still pursue bleeding the clutch (again) BEFORE purchasing a new MC and having my mechanic install it? I'll push for more bleeding if you really think I should before persuing the next option (he's done it manually and high pressure many times). I purchased a GM out of the box LS7 clutch, slave, and flywheel from Luke at Lindsay Cadillac. As of today, I've decided NOT to pursue the shimming option and I've decided NOT to have my mechanic drop the tranny and bellhousing to inspect the hardware for manufacturing defects and/or incorrect installation. So bleed more or do the MC (a factory MC was installed in 2011 @120,000 miles - car now has 150k) so I guess it could be shot. I think I hear you saying/suggesting that despite all the previous bleeds it still can't have been done right. And just to be clear on the symptom I'm having: start the engine with clutch pushed to the floor in first, let off brake and the car creeps forward. Start to let out clutch pedal and car stalls. Start the car in neutral, push clutch pedal to the floor and try to put it into any gear you can and it absolutely won't allow it! So again, this pretty severe clutch drag could just be a result of an improper bleed?

  5. #35
    garrettg is offline Cadillac Owners Fanatic
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    Re: Help needed with LS7 clutch install - rock hard pedal

    Try revving the engine some with the clutch pedal pushed in and trans in first. I did a ls7 install and clutch engagement was really odd until I tried this. The ls7 clutch engagement when new is unique until this self adjustment is done. Revving in gear seems to speed this up in my case. Why did I try this is because I was figuring out if mine was fully disengaging or not to determine if philistines master was something I could use. I could shift when my ls7 was new but it was right off the floor until I revved with clutch pedal in.

  6. #36
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Help needed with LS7 clutch install - rock hard pedal

    I think purchasing Philistine's MC upgrade kit would be a good investment if you can afford it and plan on keeping and modifying this car but i don't think it would overcome a slave shimming issue but thankfully, you went with a factory clutch kit so the chances you'd need to do that are pretty low based on reports around here.

    With that said, bleeding the clutch is your next cheapest option. At this point, I have a feeling a Motive Bleeder would be as good an investment for you as a Philistine's MC upgrade kit. These things are a pain to bleed and need fluid changes semi-often to keep performance in check and with this product you can bleed the system by yourself in 10 minutes. I turned wrenches for many years and this has to be one of the best tools I ever purchased.....

    http://www.amazon.com/Motive-Product...s+and+trucks+-

    http://www.amazon.com/Motive-1109-Po...leeder+Adapter

    You will need both parts but it is money well spent. You can have them in a couple of days and you may get lucky! If you ever sell the car you could sell this thing in a hurry so keep the box!!

    If that doesn't work, do the clutch master thing, but in my mind it ain't overcoming pp bolts that were torqued too tight....could be wrong but me thinkin not....

    ----------

    Quote Originally Posted by garrettg View Post
    Try revving the engine some with the clutch pedal pushed in and trans in first. I did a ls7 install and clutch engagement was really odd until I tried this. The ls7 clutch engagement when new is unique until this self adjustment is done. Revving in gear seems to speed this up in my case. Why did I try this is because I was figuring out if mine was fully disengaging or not to determine if philistines master was something I could use. I could shift when my ls7 was new but it was right off the floor until I revved with clutch pedal in.
    Never know, worth a shot!

  7. #37
    Derek5.7 is offline Cadillac Owners Member
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    Re: Help needed with LS7 clutch install - rock hard pedal

    garrettg - I am willing to try anything. Thanks for this interesting tip. I will definitely try it. What type of RPM should I apply with the clutch pedal down and in first? And for how long should I rev the engine to kick-start this self-adjustment?

    ----------

    You guys are really helping me weigh the pros & cons on this tricky decision of what to do next - thank-you. I think I might just pay my mechanic for the LS7 clutch install, call AAA and have them tow my car back to my house and then, on my own time and at my own pace, try the motive bleed mentioned above and move to other options like a new MC depending on what I learn/happens. On the plus side, I have an awesome new clutch - I just can't enjoy it yet. And of course, I would love it if the fix came down to what garrettg just suggested!

  8. #38
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Help needed with LS7 clutch install - rock hard pedal

    That sounds like a pretty good idea really. The Motive Bleeder can be sold for about what you paid for it if money is tight! Overall, its the cheapest next move besides what garrettg suggested.

    Keep us posted!

  9. #39
    FuzzyLogic is offline Banned
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    Re: Help needed with LS7 clutch install - rock hard pedal

    Quote Originally Posted by ctsv247 View Post
    No they probably took your post down because you had pictures of products you are offering for sale on your forum that had nothing to do with this post - door lock pulls, trunk knobs....hello.

    As far as your clutch goes....

    I read fuzzy's post before it was deleted and what he forgot to mention about the shimming was that what seemed to have caused the need for shimming in the first place - inconsistencies in aftermarket flywheel dimensions. Some of the lightweight aftermarket flywheels must be just slightly different dimensionally than the factory ls7 flywheel which affected the slaves ability to disengage the clutch. There has been much controversy surrounding this but at this point you need to consider exactly what kind (and brand) of flywheel you have. To my knowledge, and I'll get flamed for this although I'm not saying it isn't possible, I have not heard of any reports of anyone needing to shim an ls7 clutch and flywheel assembly that came straight out of a GM box. If you went with some sort of lightweight flywheel, there is a good chance (based on the symptoms you're having) you will need to shim the slave cylinder and as far as I know (again, just saying as far as I know, not saying it can't happen) a new master cylinder assembly won't compensate for a slave that needs to be shimmed because the flywheel isn't built to a factory design dimension. I believe Fuzzy hinted at that but can't read it now.

    Bleeding is definitely your next option. Do a search on "motive bleeder" for the tool you need to really get this done although pump it up hold it down will eventually work.
    Incorrect. I took my posts down, which I've done in the past as well. And I'm not selling trunk knobs, door pulls, or anything else on this forum.

    Everything has dimensional tolerances, but you're barking up the wrong tree here. Based on a sample size of five different LS7 clutch and flywheel combinations in three different CTS-Vs, GM's spec tolerance for the complete clutch assembly (the A to B measurement) is great: approximately 0.010". One of these days, when you make an attempt to learn how clutches and transmissions function, you'll realize that no amount of bleeding or shimming will correct a design shortcoming of this magnitude.

    Based on my pioneering measurements back in 2011 (the summer where I pulled the transmission out of the car seven times to figure out what nobody else could), we know that the LS7 clutch kit is incorrectly sized for this car. By installing it with the GM recommended 52 ft-lbs of torque for the CTS-V1, you're preloading the clutch by 0.080" ± 0.010" (in other words, the LS7 slave piston is about 0.200" too long). If you reduce pressure plate bolt torque to 48 ft-lbs per my recommendation, the preload increases to 0.100" ± 0.010". However, this barely allows the clutch to function under perfect conditions: low RPM, cold fluid, and an OEM clutch master cylinder with seals in perfect condition. It really doesn't begin to function reliably until you increase preload to 0.150".

    Before we lose sight of what's important here: the very fact that we have to have about 0.150" of preload on an LS7 clutch to reach the design disengagement point of 0.550" means that the clutch master cylinder needs more bore or more stroke. The Tilton 76-876 that Jaysen (Philistine) is packaging with his adapter kit has a 1.100" stroke and 0.875" bore (2.646 cubic inch displacement), providing 36% more fluid per press of the pedal than the OEM MC, which has a 1.100" stroke and 0.750" bore (1.944 cubic inch displacement). That's the only way that you're going to correctly gap the clutch and still be able to shift the car.

  10. #40
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Help needed with LS7 clutch install - rock hard pedal

    "Based on a sample size of five different LS7 clutch and flywheel combinations in three different CTS-Vs, GM's spec tolerance for the complete clutch assembly (the A to B measurement) is great: approximately 0.010""

    Interesting insight.

    Please describe a little further how these measurements were taken? Were all clutches newly installed, never used? Were the clutch parts by chance measured before being installed to set baselines on the parts themselves or are these installed tolerances?" Were all the pressure plates torqued to the same specs with the same wrench? Could these tolerances be in the bellhousing, the face of the transmission or the crankshaft hub?

    Thanks!

  11. #41
    FuzzyLogic is offline Banned
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    Re: Help needed with LS7 clutch install - rock hard pedal

    Quote Originally Posted by ctsv247 View Post
    Please describe a little further how these measurements were taken? Were all clutches newly installed, never used? Were the clutch parts by chance measured before being installed to set baselines on the parts themselves or are these installed tolerances?" Were all the pressure plates torqued to the same specs with the same wrench? Could these tolerances be in the bellhousing, the face of the transmission or the crankshaft hub?
    All new LS7 clutches and flywheels from Luk, F1 Racing, and Fidanza--copies built to the GM OEM spec--never used. All used the PowerTorque CS2529 slave cylinder sold by O'Reilly. The parts were never measured by themselves because the installed dimensions were the dimensions that we focused on. All of the pressure plates were either torqued to 52 ft-lbs, 48 ft-lbs, or both in the same day. The tolerance is likely a combination of the clutch and the bell housing, and T-56 adapter plate. The tolerances described were within the accuracy of the measurements: steel ruler held across the face of the bell housing or adapter plate and caliper held perpendicular. Subsequent measurements within several thousand miles of the initial measurements did not reveal significant changes in these dimensions, however, none of the cars in question saw harsh use. Track use, strip use, or misuse would likely wear the flywheel and friction disc much faster.

  12. #42
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Help needed with LS7 clutch install - rock hard pedal

    Quote Originally Posted by FuzzyLogic View Post
    All new LS7 clutches and flywheels from Luk, F1 Racing, and Fidanza--copies built to the GM OEM spec--never used. All used the PowerTorque CS2529 slave cylinder sold by O'Reilly. The parts were never measured by themselves because the installed dimensions were the dimensions that we focused on. All of the pressure plates were either torqued to 52 ft-lbs, 48 ft-lbs, or both in the same day. The tolerance is likely a combination of the clutch and the bell housing, and T-56 adapter plate. The tolerances described were within the accuracy of the measurements: steel ruler held across the face of the bell housing or adapter plate and caliper held perpendicular. Subsequent measurements within several thousand miles of the initial measurements did not reveal significant changes in these dimensions, however, none of the cars in question saw harsh use. Track use, strip use, or misuse would likely wear the flywheel and friction disc much faster.
    so you installed the flywheel, clutch and pressure plate and were taking measurements off the adapter/transmission face to the highest point on the pressure plate finger? and you're getting the preloaded measurement variance by taking the adapter off and retorquing the pressure plate from 52 to 48lbs?

    to be all wrong for the car, mine works very well.

  13. #43
    ctsv247 is offline Cadillac Owners Enthusiast
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    Re: Help needed with LS7 clutch install - rock hard pedal

    Quote Originally Posted by FuzzyLogic View Post
    All new LS7 clutches and flywheels from Luk, F1 Racing, and Fidanza--copies built to the GM OEM spec--never used. All used the PowerTorque CS2529 slave cylinder sold by O'Reilly. The parts were never measured by themselves because the installed dimensions were the dimensions that we focused on. All of the pressure plates were either torqued to 52 ft-lbs, 48 ft-lbs, or both in the same day. The tolerance is likely a combination of the clutch and the bell housing, and T-56 adapter plate. The tolerances described were within the accuracy of the measurements: steel ruler held across the face of the bell housing or adapter plate and caliper held perpendicular. Subsequent measurements within several thousand miles of the initial measurements did not reveal significant changes in these dimensions, however, none of the cars in question saw harsh use. Track use, strip use, or misuse would likely wear the flywheel and friction disc much faster.
    You can't claim that this variety of aftermarket parts are built to factory specs. To substantiate this, you would need to take a GM assembly out of the GM box and measure it for baselines and then measure each and every other brand to confirm.....no baselines were taken so any conclusions you reached with this assortment of parts is questionable at best. Not saying there aren't variations here, but it could just as easily be different manufacturing tolerances by multiple manufacturers.

    You also stated that all of 5 different pressure plate assemblies were torqued in the same day in 3 different cars...you must be superman.

    Beyond that, curious as to what brand of torque wrench you're using and whether it's ever been calibrated or dropped for that matter. Do you unload it when storing it? A change of 4 lbs isn't much...margin of error on the wrench and the fastener could easily approach 5% of value which would be half of your change from 52 to 48. Things get a little murky here but many have torqued their ls7 pp to 52lbs without issue.

    just sayin....

  14. #44
    Derek5.7 is offline Cadillac Owners Member
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    Re: Help needed with LS7 clutch install - rock hard pedal

    Well, I tried garrettg's suggestion of revving the engine with the clutch pedal pressed to the floor in first but unfortunately it only "freed" things up a bit - from not being able to pull away in first or put the car in ANY gear with the engine running I was able to drive it around the block a couple of times and even shift it from second to third but not without a lot of rough-handling and rev-matching. As soon as the clutch started getting hot (and smoking) I had to shut things down. I think my problem is that the clutch drag is "severe" enough that this trick won't work. I bet if I had fooled around a bit more driving it around and jamming it into gear it would have freed up more, but I didn't want to take that risk.

    So, I've asked my mechanic to bleed the clutch one last time in the hope that I freed up something by driving the car around and then I will be calling a tow truck to take my car home tomorrow. I will post here on what I do next (for those who may run into my problem w/an LS7 clutch swap), hopefully to report a happy ending to this saga.

    This has NOT been a good experience so far (several sleepless nights) and I'm not even sure I'd recommend doing it to those who are contemplating this swap - too many unanswered questions. The only reason I went for this mod is because I had read so many positive reviews of this LS7 clutch swap. In my case, it has not been a simple, straighforward swap.

  15. #45
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    Re: Help needed with LS7 clutch install - rock hard pedal

    It's mod hell. Hopefully when you get this straighten out you can coast for a while.

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