Blue printing axle end play

Discussion in 'Transmission & Driveline Topics' started by newschool72, Oct 4, 2013.

  1. newschool72

    newschool72 Veteran Member

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    I am running fixed calipers on the back of the ol 72 and have a lot of play in the axles. I don't want to run into the dreaded caliper piston bump back while doing some spirited driving and need some input on the best way to handle the issue. I heard that Toms differentials has c-clips in different thicknesses ,but on his wed site ,he says they are undersized to allow aftermarket axles to be installed without grinding the ends. It is also my understanding that .005 to.008 is about the right end play. I have .045 and .055 clearance between the center pin and the axle tips with the c- clips installed. Can I get over sized c-clips to fix the issue or am I going to have to weld the ends of the axles and grind them down to get the right clearance or can I use shim washers between the c- clips and the recess they sit in. The axles are nearly new Summit brand untappered axles and the rear is the standard 8.5 10 bolt.
    Big gear head, if you are out there ,give me a hand on figuring this out, Or anyone else that has the inside scoop on what Im trying to do. Thanks in advance!
     
  2. big gear head

    big gear head Veteran Member

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    First of all you should never weld on an axle. They are induction hardended and welding will ruin them.

    I need to know which differential you have before I can give you much advice. The axle end play is coming from the differential, not the axles.
     
  3. newschool72

    newschool72 Veteran Member

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    Its a factory style limited slip with the s- spring and spider center pin. There just seems to be excessive play and with the fixed calipers I don't want to run into pad bump back. The center pin shows some wear, but I don't know that it will make more than a couple thousandths up with a new one.
     
  4. big gear head

    big gear head Veteran Member

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    You need to shim the clutches, or replace them and then shim them. Clutch wear is what causes excess axle end play with those differentials. As the clutches wear the axle end play will increase.
     
  5. newschool72

    newschool72 Veteran Member

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    I cant get my head wrapped around that. The center pin is fixed in the diff and the recess for the c-clip is outside the clutch area, right? I don't understand how either point can move with clutch wear. I was assuming the Summit axles "end button "was too short. Help me understand that because my mechanical brain cant wrap around the clutches affecting the end play. I will go back out and try to see what you are saying.

    EDIT!!!!!!! I see what you are talking about now!!! On a budget, what is going to be the best way to shim the clutch packs out. Does someone sell just the shims and is this a job someone with fair mechanical ability ( I built the car from front to back myself) can pull off? Thanks Big gear head.
     
    Last edited: Oct 5, 2013
  6. newschool72

    newschool72 Veteran Member

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    Im not having an issue with both tires hooking that I can tell, so could anyone see a problem with drilling and tapping a 1/4x20 hole in the end of each axle, installing a grade 8 bolt and carefully grinding the head down till I get .005 to .008 endplay ? That would push the axle out to reduce the "play", where the new clutch pack/shims would pull the axle in more to do the same thing. Any negatives to move the axle about .040 out, other than moving the wheel out that much, like less spline contact or, with fixed calipers, pushing the caliper centerline too far out ?
    Im just not cleared by the boss ( wife ! ) to spend another shiny dime on this build and if doing the " bolt " trick isn't going to compromise anything and can be done with stuff I have on hand, I need to go that route.:shy:
     
  7. big gear head

    big gear head Veteran Member

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    Last edited: Oct 5, 2013
  8. newschool72

    newschool72 Veteran Member

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    I drilled and tapped the axles, installed the grade 8 bolts with JB weld as a little insurance. Tomorrow ,after the JB sets good, I will start the grind and fit deal. That's going to be labor intensive , for a man with a blown out disc in his back, anyway, LOL. Big gear head, what would you shoot for on end play? I read an article that said .005 to .008 is ideal. Does that sound about right? Thanks for the input.
     
  9. big gear head

    big gear head Veteran Member

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    Yes, .005 to .008 should be just right. Just remember that the bolts are going to wear against the cross shaft when you turn corners. The more side load you put on the car in a corner the more pressure is applied to those bolts. You should probably check the end play from time to time to be sure that they are not wearing.
     
    Last edited: Oct 5, 2013
  10. jakeshoe

    jakeshoe Veteran Member Lifetime Gold Member

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    Also, one of those bolts should be left hand threaded (drivers side).
    I think the bolt setup is a bad plan for long term use. You need to case harden the bolt to prevent wear. A Grade 8 bolt doesn't have a very hard surface finish.
    A button (that can spin in the axle) made of 8620 steel and carburized would be the best setup.
     

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