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Driveline Angles

Discussion in '40- & 55-Series Tech' started by fussy_cruiser, Jul 28, 2005.

  1. fussy_cruiser

    fussy_cruiser

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    Need some help on my driveline angles. Have some vibration driving 50+ MPH, here is my driveline angles below. I have lifted shackles. I have read that you want to keep the two angles as close to each other as possible.
    under.jpg under1.jpg under2.jpg
     
  2. fussy_cruiser

    fussy_cruiser

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    But the SOR site says to install the shims with the fat end forward. That would increase my angle diff.
    287-82_front.gif 287-82_rear.gif
     
  3. fussy_cruiser

    fussy_cruiser

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    With the fat end towards the rear this would increase my angle and decrease the difference. Does this sound right?
     
  4. HawkDriver

    HawkDriver

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    You know I think I was puzzled by that on the SOR site a long time ago as well. Funny, Ya I'd say that you are right. Do what you need to in order to decrease the angle. But from my understanding, the most you want is about 2-4 degrees off center of the shaft and that they should basically be the same at both ends. If you can't accomplish that you need to have zero at the pinion and a CV joint at the other end. May want to research that some more, but that's the basic idea. Check 4xshaft.com it's very descriptive of shaft angles.
     
  5. Pin_Head

    Pin_Head

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    In your case, you want the fat end of the shim toward the rear or shackle end of the spring.

    What's up with the U bolts?
     
  6. HawkDriver

    HawkDriver

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    I concur.
     
  7. fussy_cruiser

    fussy_cruiser

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    Got those from CCOT when I added the leveler block. Super freaken' long, think I should cut 'em. How do you do that?
     
  8. HawkDriver

    HawkDriver

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    With a 4 1/2 inch grinder. One of the best cheap tools you need to own.
     
  9. andrewfarmer

    andrewfarmer

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    Change the pinion angle.
    Has your driveshaft been modified (looks like a weld where the diameter changes)?
    Did you have it balanced?
    Also, looks too short - not a lot of spline engaged - and is there wear in the spline?
     
  10. dgangle

    dgangle total rice SILVER Star

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    I'd buy/instal some 6* shims with the fat part towards the front. This will rotate the rear axle CCW as looking form the driver's side to get the angles very close. 90-81=9, 90-74=16, 16-9=7*. I don't ever remember seeing a 7* shim. Most come in 2* increments. i found some very durable and well-made brass/ alloy shims at my local truck spring shop. Beats the heck out of those cheesy aluminum shims. The best way to do this would be to cut off your stock spring perches and weld on new, heavier duty ones like Proffitt's or Quadratec sells at the right position to give you the same angle on the pinion and p-brake drum. I have done all this and it worked for me.

    The way I reason it is if you put the fat end towards the rear then it will rotate the axle CW and increase the pinion anglwe from 74* to something higher. The objective is to make the angles match, thus cancelling out the pulsation induced by the rotational travel of the ujoint.


    Tell me about that gas tank. I've never seen one located there. What year is your 40 and what is that tank out of? How does it mount?
     
    Last edited: Jul 29, 2005
  11. Trollhole

    Trollhole THC Supporting Vendor Moderator

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    Your diveshaft is way to short. And your yoke is probably worn.

    I had the exact same problem with vibration and had a new yoke and lengthened driveshaft made. can you grab the driveshaft in the middle and move it back and forth any?

    Look familiar

    [​IMG]
     
  12. dgangle

    dgangle total rice SILVER Star

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  13. fussy_cruiser

    fussy_cruiser

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  14. Trollhole

    Trollhole THC Supporting Vendor Moderator

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    well the fact that you anly have an inch or so in the yoke it doesn't matter how new it is it will still wobble causeing your vibration.

    When they balance the drive shaft I guarantee they don't do it with the yoke out that far. Half way or all the way in only.
     
  15. Trollhole

    Trollhole THC Supporting Vendor Moderator

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    Well there you are. WHen add new springs he didn't lengthen the driveshaft. or he didn't move the perches forward on the spring pack. It probably took 6 months of driving with the driveshaft like that to wear the yoke.
     
  16. cruiseroutfit

    cruiseroutfit Supporting Vendor Moderator

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    OME tank out of a late model FJ40 :D
     
  17. CruiserMax

    CruiserMax

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    I bet this is it. On the positive side you have a PO that replaced a lot of stuff tracking this down. Do you think the shaft is the same length and the perches are in the same location? If you are considering a SOA then I would time the new drive shafts purchases to go with that. When I did mine I had long beef shafts made by Arizona Driveshafts and moved my purches at the same time. Get the math correct but in the meantime don't install fancy drive shafts until you have that figured out.

    Max
     
  18. John Smith

    John Smith In the garage

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    I believe you intended to type OEM. That sure looks like a stock tank to me, my 79 used to have the same one in the same position.

    Meanwhile, I put a 4in. skyjacker lift on my 79 and did not have to lengthen the rear driveshaft. I doubt that is the original DS. You are correct that you want to shim the rear so you drop the pinion down so put the fat part of the shim in the rear.
     
  19. cruiseroutfit

    cruiseroutfit Supporting Vendor Moderator

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    Yup, I meant Original Equipment Manufacture, not Old Man Emu :D

    (I say them both everyday, usually wrong ;):D)
     
  20. dgangle

    dgangle total rice SILVER Star

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    oh, 79 and on. I never had one that new so my tanks have always been under the pass seat. I feel silly for asking. :doh: