Wrecked diff. in '70 skylark custom, going posi!

Discussion in 'Got gears?' started by stordahl, May 25, 2016.

  1. stordahl

    stordahl Active Member

    Nice! Original pinion shim was .035. I did hold my hand on the ring gear to create drag.

    So this actually means I can start final assembly?

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  2. monzaz

    monzaz Jim

    Still would widen the backlash to see if you can get a better swipe.
     
  3. BrianTrick

    BrianTrick Brian Trick

    The Richmond gears are a very hard material,and less forgiving to any error. They can be a little finicky to setup,but totally necessary.
     
  4. monzaz

    monzaz Jim

    just remember Richmond is not what it use to be.... it is now Motive Gear and may have taken a back seat. I do know that Fab Craft usually is adimit of getting the better quality material.... I do not know about Richmond gear name these days...BUT that seems the deal with anything and everything produced these days. :( Jim

    Usually it is the Pitch of the Richmond gear that gives it less forgiving set-up feature will handle more power... Lots of copiers out there of the Richmond straighter cut gears made for a lot of noisy gears... Less helical of the gear will give more surface touch on the drive side increasing the strength at launch. But if you are off by a few thousands and you will get your whine.
     
  5. stordahl

    stordahl Active Member

    Allright. I will give it another shot to see if I can get it even closer to .010! It's hard to find the correct shim combos while maintaining carrier preload, should have had thinner shims for the last tweaks.

    But do we agree on the .032" pinion shim is the right one?

    Thanks!
     
  6. BrianTrick

    BrianTrick Brian Trick

    For right now,leave the .032 shim in it.
     
  7. stordahl

    stordahl Active Member

    Should I try to get a pattern with a .030 or .028 shim at the same time to speed things up a bit? Or do you think the .032 is the right one?
     
  8. BrianTrick

    BrianTrick Brian Trick

    Another good question:
    Is your current checker bearing the same brand as your first bearing that you damaged pulling off? Is your final assembly bearing the same brand as your checker bearing?
    Specs can sometimes vary between manufacturers,so you could keep the same shim,swap bearings,and possibly get a different setting/pattern.
     
  9. stordahl

    stordahl Active Member

    yes, I bought two brand new, identical bearings to avoid this issue. The two new bearings are actually the same brand as the first bearing I damaged as well (National M804049, etched KOYO on the bearing itself).
     
  10. stordahl

    stordahl Active Member

    Puuh, this shimming job is no joke! Finally, after some more tweaking I got as close as I can. .032" pinion shim and .0095" backlash.

    This is how the pattern looks. I think this is quite close to the fabcraft instructions. What do you think?

    [​IMG]

    [​IMG]

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  11. stordahl

    stordahl Active Member

    Hey, the following two images are with .029" pinion shim and .0102" backlash.

    Which one is the better pattern?

    Sorry, my usual image host with thumbnail feature failed today.
    [​IMG]

    [​IMG]


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  12. stordahl

    stordahl Active Member

    I feel I'm really close to getting the axle back in the car now, so awaiting a comment on these patterns with gratitude.

    Sorry to nag, I'm just too eager to wait.:Brow:

    Painted the axle in the meantime:

    [​IMG]


    [​IMG]

    Thank you!
     
  13. BrianTrick

    BrianTrick Brian Trick

    The one with the .032 shim was better. With the .029 shim,you are starting to get too high on the tooth,a result from the pinion being too far away.
     
  14. stordahl

    stordahl Active Member

    Allright, thanks for the feedback Brian! So does this mean I can start final assembly with .032 pinion shim and .0095" backlash?

    With the shims I got, I am not able to make anything between .032 and .029 for the pinion, so guess .032 it is.
     
  15. BrianTrick

    BrianTrick Brian Trick

    Definitely the .032,unless you have a .033.
    I like to use thread sealer on the pinion splines,to help prevent any oil from wicking through. Use red locktite on the pinion nut.
     
  16. stordahl

    stordahl Active Member

    I'll see if I can make 0.33, but i doubt it. The shims only let me create certain intervals. I'll remember to add locktite to the pinion threads!

    Wish me good luck on that crush sleeve... :)
     
  17. stordahl

    stordahl Active Member

    Did not have any shim combinations between .035 and .032, so I installed the .032 shim and assembled the axle. I managed to get the pinion bearing preload within spec on the first try. I was really careful when tightening and did many measurments. Ended up with 25 in lbs preload.

    The axle is now back in the car, and all that remains is to tighten the axle cover, fill it with oil and bleed the brakes.

    I was planning to carefully drive for a short while without the limited slip additive, then change oil. Is it ok to run it without the additive?

    I will go for a test drive later today.

    [​IMG]
     
  18. BrianTrick

    BrianTrick Brian Trick

    Put the additive in with the oil and you're done.
     
  19. monzaz

    monzaz Jim

    Second that. You must use the limited slip additive for the break in as the cones will also be breaking in on each turn you make.

    make the first run short 5 mins or 2- 3 miles ONLY.... listen go through ranges up to about 50 mph... No super hard accels or decels if stick shift... bring it back and check for leaks, let cool for 40-50 mins till cool as ambient temp of outside air.

    Next run a bit longer 5-7 miles no more than 10 mins on the road. No hills burn outs etc. The more of the heat up and cool down cycles you can get on the gears the more deep the hardening will be in the faces... If after the first short run you have whining heavy. You need to get back in and adjust your set up...Another reason for the short run. The longer you keep it with a heavy whine the gear will sooner or later eat it self.

    A slight decel or accel whine can be tolerated and a coast to drive transition pitch change also can be tolerated in a RPM range... Hope it all goes well for you the first time. :)
     
  20. stordahl

    stordahl Active Member

    I added the lsd additive to the oil and went for a short test run, about 3,5 miles. No noise at all from the rear. No whining or humming. Let the car cool for about 30 mins (it was 40*F outside) and drove the same route back. No leaks, no sounds. Looks like your guidance has brough very good results!

    There is a big amcar meet this weekend, so I will do a lot of short drives with cooldowns in between. The rest of the season I will go easy on the rear.

    Thanks a LOT to everyone that has contributed, this would NOT have been possible for me as a novice to complete without your guidance. It feels really good to have the car back on the road, with a self built rear. I know a lot more about rear axles now than two months ago.

    Thanks!!


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