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    Results 1 to 8 of 8
    1. #1
      Join Date
      Jun 2008
      Location
      Lafayette, Indiana
      Posts
      4

      Drive Line Angles on Lowered 1968 LeMans (A-Body)

      Hi All,

      I thought I would drop in from being a long time lurker to see if you all might be able to help me chase down a driveline angle issue on my lowered 1968 Lemans. The car was lowered all the way around with a Hotchkis lowering setup. If I recall correctly it was a two inch drop from stock. The rear end is an upgraded BOP ten bolt that was original to the car. I went ahead and put in adjustable upper control arms over the Winter and now am ready to try and sort out the vibration that the car is experiencing at 65 MPH +. It is indeed a drive line vibration as I tested that last year by nuetral dropping the trans at speed and the vibration remains until the car drops below 65ish.

      So here's where we stand.

      I've got an inch of clearance before the transmission is resting against the floor. So it could be shimmed up if needed. Using the Tremec app this morning I measured

      Engine / trans: 2.3 Degrees down
      Shaft was up 1.4
      Yolk was down 1.7

      I corrected to
      Trans still down 2.3
      Driveshaft settled to .7 up
      Yolk corrected to 2.3 up

      Car felt better at lower speed, but wants to shake itself apart at 70. The app showed an updated working angle of 1.7

      So what do I start moving to start correcting this? Do I start trying to shove the trans up which seems to be suggested by @AndrewB70 or can we make adjustments both places? I've done a lot of reading but just really confused about what adjustments to start making and where.

      Thanks all,
      Derek

    2. #2
      Join Date
      Nov 2006
      Location
      Mountain Springs, Texas
      Posts
      4,488
      Country Flag: United States
      Raise the transmission. Listen to Andrew....

      Don
      1969 Camaro - LSA 6L90E AME sub/IRS
      1957 Buick Estate Wagon
      1959 El Camino - Ironworks frame
      1956 Cameo - full C5 suspension/drivetrain
      1959 Apache Fleetside

    3. #3
      Join Date
      May 2010
      Location
      kitchener,Ontario,Canada
      Posts
      2,336
      Country Flag: Canada
      X2 Andrew knows his stuff
      Spinnin'my tires in life's fast lane

      Ryan Austin
      On twitter @raustinss
      On Instagram austinss70

    4. #4
      Join Date
      Jun 2008
      Location
      Lafayette, Indiana
      Posts
      4
      I agree Andrew knows his stuff. I've read many of his posts here and on Team Chevelle and other places relating to this issue. I just got in from the shop and have identified that in order to raise the transmission to get it to zero that I'm going to have to cut the floor to give the front yolk some room. Not ideal but doable. The flip side of that is that I've seen a number of people mention a CV Driveshaft from The Driveshaft being the ultimate solution. Again, the $1100 is not ideal but also doable and if it can be done without cutting the floor it would be nice. So now the question is what is the best option, I'd appreciate hearing from the first hand experience of this group.

    5. #5
      Join Date
      May 2010
      Location
      kitchener,Ontario,Canada
      Posts
      2,336
      Country Flag: Canada
      ok so let me ask you this , how do you feel about doing both ? you by the driveshaft and it doesnt solve it then guess you have to raise the tunnel . You raise the tunnel you can always add the shaft later ..yes ?
      Spinnin'my tires in life's fast lane

      Ryan Austin
      On twitter @raustinss
      On Instagram austinss70

    6. #6
      Join Date
      Jun 2008
      Location
      Lafayette, Indiana
      Posts
      4
      Quote Originally Posted by raustinss View Post
      ok so let me ask you this , how do you feel about doing both ? you by the driveshaft and it doesn't solve it then guess you have to raise the tunnel . You raise the tunnel you can always add the shaft later ..yes ?
      Haha, honestly would prefer to do neither! I know that's not an option to get this really squared away. I was much younger when I made the decision to install the Hotchkis springs. I didn't realize the can of worms I was opening. Over the years the issue has been a minor annoyance. Since having the rear end rebuilt last year and really wanting to get the car dialed in so I / we can really enjoy it, this has become more of a priority. I may see if we can find a happy medium setup for the summer just so we can cruise around town and then tackle this over the Winter when I'm ok with the car being down for a few months.

      What comes to mind is just how much of the tunnel am I going to have to clearance in order to get the transmission to 0, or does the transmission even need to be level. Would getting it to 1 degree down be enough?

      Hopefully Andrew sees this and chimes in.

    7. #7
      Join Date
      Nov 2006
      Location
      Mountain Springs, Texas
      Posts
      4,488
      Country Flag: United States
      I think whether or not raising the transmission works depends on your ride height. In a nutshell you don’t want a vee shaped driveline.

      CV driveshaft should fix it regardless of ride height.

      Don
      1969 Camaro - LSA 6L90E AME sub/IRS
      1957 Buick Estate Wagon
      1959 El Camino - Ironworks frame
      1956 Cameo - full C5 suspension/drivetrain
      1959 Apache Fleetside

    8. #8
      Join Date
      Apr 2001
      Location
      The City of Fountains
      Posts
      15,971
      Country Flag: United States
      Quote Originally Posted by The Jury View Post
      Haha, honestly would prefer to do neither! I know that's not an option to get this really squared away. I was much younger when I made the decision to install the Hotchkis springs. I didn't realize the can of worms I was opening. Over the years the issue has been a minor annoyance. Since having the rear end rebuilt last year and really wanting to get the car dialed in so I / we can really enjoy it, this has become more of a priority. I may see if we can find a happy medium setup for the summer just so we can cruise around town and then tackle this over the Winter when I'm ok with the car being down for a few months.



      What comes to mind is just how much of the tunnel am I going to have to clearance in order to get the transmission to 0, or does the transmission even need to be level. Would getting it to 1 degree down be enough?

      Hopefully Andrew sees this and chimes in.
      I think my thoughts on the matter are pretty clear from the various posts where I have addressed the question. The solutions are, either raise the back of the trans or get a CV driveshaft. Raising the back of the trans can cause other issues, like accessories crashing into other components in the engine compartment.

      If there are more specific questions, I'd be happy to address them. Incidentally, I have the CV shaft out of my GTO and I can't use it now because I am moving the engine and also swapping my transmission. It MAY work for you, depending on engine and trans...

      Andrew
      1970 GTO Version 3.0
      1967 Cougar build
      GM High-Tech Performance feature
      My YouTube Channel Please Subscribe!
      Instagram @projectgattago
      Dr. EFI
      I deliver what EFI promises.
      Remote Holley EFI tuning.
      Please get in touch if I can be of service.

      "You were the gun, your voice was the trigger, your bravery was the barrel, your eyes were the bullets." ~ Her






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