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    1. #1
      Join Date
      Mar 2013
      Location
      Sunny Calif
      Posts
      307
      Country Flag: United States

      inverted driveline angles?

      1968 Camaro Convertible
      Hotchkis UCA - Detroit Speed LCA - Hotchkis 600 LB rate springs front - 178-180 lb leaf spring rear
      Hotchkis tuned fox shocks front and back
      18" wheel, 275 35 18, 25.6" diameter - 3.5 drop in front - 3" drop in rear, 8.5 GM 10 bolt,LS2, 4l65E, zero vibration.
      Front ride height measured from fender lip is 25.25 front and 25.75 rear
      No odd harmonics accelerating or decelerating and none present at cruising or freeway speeds.

      Driveline angles are backwards due to lowering of vehicle?
      Engine,trans is 2.6 down - driveline is 2.9 up - pinion is 1.2 down with the pinion angle above the trans/driveline ride height.
      Should i try and correct to eliminate the 5.5 and the 4.1 working angles?
      if so how best to proceed?
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    2. #2
      Join Date
      Dec 2008
      Location
      Detroit
      Posts
      2,584
      Country Flag: United States
      Probably want to state what vehicle you have to give and idea of how the suspension is setup.
      Big dreams, small pockets....

      Chris--
      '72 Cutlass S LSA/T56 Magnum
      Bowler Performance, Rushforth Wheels, ATS, Holley EFI, KORE3, Ridetech

      Project Motor City Madness

    3. #3
      Join Date
      Oct 2011
      Posts
      696
      What is driveline angle? Is that the angle of your driveshaft? If it's a positive number that means your rear end u joint is higher than the transmission, many on here have lowered their cars 3" in the rear, I don't think their rear end is higher than the transmission output shaft. Also you are measuring at ride height? With your cars full weight on the ground? I don't think it makes sense that your driveshaft is pointing up coming out of the transmission.

    4. #4
      Join Date
      Mar 2013
      Location
      Sunny Calif
      Posts
      307
      Country Flag: United States
      Driveline angle is positive 2.8 deg and yes pinion is higher than transmission.
      yes ride height on level ground with full tank of fuel minus driver.
      no, eng and trans is 2.6 down when connected to driveline which points up forming a downward V with a working angle of 5.5 deg.
      driveline is 2.9 up in relation to pinion forming an inverted /\ at a 1.2 deg with a working angle of 4.1 with the pinion angle above the trans/driveline ride height.

    5. #5
      Join Date
      Oct 2011
      Posts
      696
      Can you adjust the transmission up to match the 1.2 degrees up on the rear?

    6. #6
      Join Date
      Mar 2013
      Location
      Sunny Calif
      Posts
      307
      Country Flag: United States
      There is some room, i can shim up trans, not sure how much though, will need to raise at least 1.4 deg but not sure how much that is in inches.
      Will give it a shot this weekend.

    7. #7
      Join Date
      Dec 2010
      Location
      Fredericksburg, VA.
      Posts
      3,155
      Country Flag: United States
      Are you currently experiencing any drive line vibration?
      Steve Hayes
      "Dust Off"
      68 Camaro

      Given sufficient initial acceleration, even pigs can fly!

    8. #8
      Join Date
      Feb 2016
      Location
      Texas
      Posts
      93
      Country Flag: United States
      Your schematic shows the pinion pointing up 1.2 deg, but you say it's down. Are you referring to the working angle between the pinion and the DS being down? If your trans is pointing down and your pinion is pointing down it's definitely wrong. If the pinion centerline is actually pointing up, at least you're getting close to having the centerlines of the trans output shaft and the pinion being parallel. Shim up your pinion to make it parallel to the trans centerline and see where you are at that point.

    9. #9
      Join Date
      Mar 2013
      Location
      Sunny Calif
      Posts
      307
      Country Flag: United States
      Okay finally got driveline angles close enough, i think any thoughts on new dims?
      eng trans 2 deg up, driveline 3 deg up, pinion is above trans centerline pointing up 2.4 degrees.
      trans to driveline working angle 1 - driveline to rear pinion working angle 3.0 degrees - final driveline operating angle is 2.9 deg with zero harmonics at all velocities.

    10. #10
      Join Date
      Oct 2011
      Posts
      696
      I think you need to lower that pinion angle to something down. If your tranny is pointing up because your rear is higher than your tranny centerline then your pinion angle should be down not up. It’s great you don’t have any vibrations but I think everything will wear out very quickly. Your tranny angle basically has to be opposite your pinion angle so that they cancel each other out. Idk that’s my .2 cents

    11. #11
      Join Date
      Mar 2013
      Location
      Sunny Calif
      Posts
      307
      Country Flag: United States
      alright, raised trans and lowered pinion.
      engine/trans is 1.5 down - driveline is 1.9 up and driveline is 0 with pinion above trans center line.
      this calcs to front working angle of 3.5 and rear working angle of 2.0 and a final driveline operating angle of 1.5
      this look acceptable to anyone else, keep in mind car is lowered and pinion center line is ABOVE transmission center line.

    12. #12
      Join Date
      Apr 2018
      Location
      Oakland
      Posts
      68
      Hey, I’m having the same problem. My trans is -3.6, drive shaft is +1.8, and my pinion, I set it to -3.4.

      my angle 1 & 2 is out of spec but my working pinion angle is good according to tremec app.
      mid I could somehow get my driveshaft into the negative, I’ll have all free light on the angles.

      what did you do?

    13. #13
      Join Date
      Sep 2016
      Location
      Bakersfield, CA
      Posts
      603
      Country Flag: United States
      The Magnum T56 in my 69 Firebird points down and my local driveline shop re-welded my leaf perches so the pinion is up, that way they are both opposite the same amount and cancel each other out. I think my trans is like 2.8 degrees down and my rear is 2.8 degrees up.

      I've been chasing what seems like a shifter rattle in the higher RPMs but I've also read recently that the pinion should ALWAYS be down, meaning just having them opposite is not good enough. I bought my kit from SST being told I didn't need to modify my trans tunnel and they said nothing about the rear pinion needing to be down. I'm going to be a little pissed if that turns out to be the case and I have to modify my trans tunnel.

      Any thoughts?
      http://www.TheFOAT.com/92GTA
      1969 Pontiac Firebird
      w/535ci IAII aluminum block, Dailey dry sump, Holley EFI (full road race build). Primer black w/black interior.
      1992 Pontiac Trans Am GTA w/SLP Performance Package. Dark Jade Grey Metallic, grey leather, T-Tops.

    14. #14
      Join Date
      Oct 2015
      Posts
      362
      Country Flag: United States
      I’m running into the same uphill driveshaft angle on my 67 Chevelle. When I get the new rear end setup in I think I’m going with a CV driveshaft from the driveshaft shop. I have no room to raise the trans.
      My half a$$ed build thread.https://www.pro-touring.com/threads/...elle-6-0-4L60E

      Tighten it till it strips & back it off a quarter turn.

    15. #15
      Join Date
      Apr 2001
      Location
      The City of Fountains
      Posts
      15,971
      Country Flag: United States
      Quote Originally Posted by anguilla1980 View Post
      The Magnum T56 in my 69 Firebird points down and my local driveline shop re-welded my leaf perches so the pinion is up, that way they are both opposite the same amount and cancel each other out. I think my trans is like 2.8 degrees down and my rear is 2.8 degrees up.

      I've been chasing what seems like a shifter rattle in the higher RPMs but I've also read recently that the pinion should ALWAYS be down, meaning just having them opposite is not good enough. I bought my kit from SST being told I didn't need to modify my trans tunnel and they said nothing about the rear pinion needing to be down. I'm going to be a little pissed if that turns out to be the case and I have to modify my trans tunnel.

      Any thoughts?
      If your situation is anything like this:

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      Then you have to either raise the back of the transmission or use a CV joint driveshaft from The DriveShaft Shop.

      Andrew
      1970 GTO Version 3.0
      1967 Cougar build
      GM High-Tech Performance feature
      My YouTube Channel Please Subscribe!
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      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

    16. #16
      Join Date
      Sep 2016
      Location
      Bakersfield, CA
      Posts
      603
      Country Flag: United States
      It is like that. I already have my new DynoTech DS installed, it would suck to get another.

      So it's an absolute must that the tail shaft be UP and the pinion be DOWN no matter what?
      http://www.TheFOAT.com/92GTA
      1969 Pontiac Firebird
      w/535ci IAII aluminum block, Dailey dry sump, Holley EFI (full road race build). Primer black w/black interior.
      1992 Pontiac Trans Am GTA w/SLP Performance Package. Dark Jade Grey Metallic, grey leather, T-Tops.

    17. #17
      Join Date
      Oct 2015
      Posts
      362
      Country Flag: United States
      I know your driveshaft is the opposite direction but the trans and pinion are to be at the same angle parallel. Depending on your rear suspension the pinion should be down up to 4 degrees or so.

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      My half a$$ed build thread.https://www.pro-touring.com/threads/...elle-6-0-4L60E

      Tighten it till it strips & back it off a quarter turn.

    18. #18
      Join Date
      Mar 2020
      Posts
      199
      All of this conversation appears more complicated than it needs to be.
      Here are a couple basic items to take into consideration...

      1. Generally the engine/trans is angled downward towards the rear (typically 3-5 degrees with respect to the frame) because they are usually mounted higher than the differential.

      2. On a leaf spring vehicle, you typically want the pinion lowered an additional 1-2 deg to compensate for torque reaction. Some go as high a 5 on a drag race only application. 3 & 4 link or torque arm style suspensions do not typically have as much rotational issues, but care must be taken to see what happens through the full range of suspension travel.

      3. Once you lower the car to where the driveshaft becomes close to straight (under a 2 deg angle), it Is best to start to level the engine & rear to keep some angle in the u-joints. It is preferable to always keep at least 1 degree minimum in each joint. The Ideal situation is to have equal angles on each U-joint, but this contradicts item #2.... so some compromise must be made.

      On a very low vehicle (where engine/trans is lower than the rear), I typically start with trying to make the trans & rear parallel, then check the u-joint angle to make sure there is about 2 degrees minimum on each. If not, raise/lower the trans accordingly to get it dialed in. I then tweak the pinion down slightly to compensate for torque reaction.

      Generally on lowered vehicles, there is limited suspension travel & stiff springs, all of which help to keep the drive line in alignment & require less pinion offset.

    19. #19
      Join Date
      Sep 2016
      Location
      Bakersfield, CA
      Posts
      603
      Country Flag: United States
      Quote Originally Posted by Alwhite00 View Post
      I know your driveshaft is the opposite direction but the trans and pinion are to be at the same angle parallel. Depending on your rear suspension the pinion should be down up to 4 degrees or so.



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      Thank you. That diagram showing how they need to be parrallel helps a lot.
      http://www.TheFOAT.com/92GTA
      1969 Pontiac Firebird
      w/535ci IAII aluminum block, Dailey dry sump, Holley EFI (full road race build). Primer black w/black interior.
      1992 Pontiac Trans Am GTA w/SLP Performance Package. Dark Jade Grey Metallic, grey leather, T-Tops.


    20. #20
      Join Date
      Apr 2014
      Location
      JAPAN
      Posts
      147
      Country Flag: Japan
      Quote Originally Posted by MAGONSTERZ68 View Post
      Driveline angle is positive 2.8 deg and yes pinion is higher than transmission.
      yes ride height on level ground with full tank of fuel minus driver.
      no, eng and trans is 2.6 down when connected to driveline which points up forming a downward V with a working angle of 5.5 deg.
      driveline is 2.9 up in relation to pinion forming an inverted /\ at a 1.2 deg with a working angle of 4.1 with the pinion angle above the trans/driveline ride height.
      My Camaro has the same problem.

      How did you fix it?

      Speed tech torque arm suspensions

      1970 Camaro Help me. A difficult problem in Japan.

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