Diff Gear change 3.08 to ??

Discussion in 'Got gears?' started by 68 Skylark cust, Jun 23, 2021.

  1. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    While anything is possible with a 53 year old car, from what I can tell, this is a Canadian built Skylark that came with the Chevy 12 bolt.
     
    Dwayne B and 68 Skylark cust like this.
  2. BrianTrick

    BrianTrick Brian Trick

    A quick picture of what is actually under the car will confirm which one it is.
     
    68 Skylark cust likes this.
  3. 68 Skylark cust

    68 Skylark cust French Canadian Member

    Gonna try to show a picture this week !
     
  4. bobc455

    bobc455 Well-Known Member

    Based on your stated goals, I would also consider going to a TH350. I drove with the ST-300 for a bunch of years and liked it, but when I switched to a 3-speed there was a noticeable difference from stop signs. (At the time I had a 2.93 gear so might have been even more noticeable for me)

    The Th350 has a 1st gear ratio of (I think) 2.52:1, and I think the ST300 has 1.77 or thereabouts - so you'll notice a difference for sure.

    -Bob C.
     
  5. 68 Skylark cust

    68 Skylark cust French Canadian Member

     

    Attached Files:

  6. BrianTrick

    BrianTrick Brian Trick

    Yup. 12-bolt Chevy
     
  7. monzaz

    monzaz Jim

    And it looks to be original to BOP from the yoke. You have the BOP yoke on the 12 bolt chevy 1 1/8" cup.
     
  8. 68 Skylark cust

    68 Skylark cust French Canadian Member

    Received my stock last week ! gear2.jpg gear_331.jpg Gear cover.jpg
     
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  9. PGSS

    PGSS Gold Level Contributor

    I see you have dual exhaust which is nice..
    Your signature mentions its a 2 barrel 350. If your still running a 2 barrel I would swap it out for even a factory cast iron 4 barrel manifold.. They are still easy to find I hear.
    With your new gears it would really wake it up even more.

    What ratio are the gears that you just bought? I'm guessing the 3:31
     
    Last edited: Jul 29, 2021
  10. 68 Skylark cust

    68 Skylark cust French Canadian Member

    3.31 indeed

    I'm gonna write something as soon as I will have in running
     
    PGSS likes this.
  11. monzaz

    monzaz Jim

    Watch that red seal that is a TRUCK seal and will be right on top of the outer pinion bearing ...You might get a leak. I have the proper depth seal CAR of you need. Jim
     
  12. 68 Skylark cust

    68 Skylark cust French Canadian Member

    Jim , I Send you a message
     
  13. 68 Skylark cust

    68 Skylark cust French Canadian Member

    I received my seal from Jim !

    Just like if you can remind me how (or why) the blue one will work better than the red ? Thank you Seal.jpg
     
  14. BrianTrick

    BrianTrick Brian Trick

    033CC00F-EF59-4F53-85C9-1820E05FD963.jpeg Here is a perfect illustration.
    Look at this pinion yoke and notice how the wear mark is on the very edge of the seal journal. This rear had a history of a pinion leak,and this was why. They had the wider/deeper seal buried flush into the housing,which is what anyone would think to do. However,the journal on the yoke can barely reach the lip on the seal. The remedy is to either leave the seal out of the housing some,or get the thinner seal,like the one on the right in your picture.
     
  15. monzaz

    monzaz Jim

    If you can not see alone from the picture... Well. ?? I do not Know. Look at the seal and the metal difference.
    YOU gave a PERFECT picture to see the difference.
     
  16. 68 Skylark cust

    68 Skylark cust French Canadian Member

    Thank you Brian, with your picture in addition that will help better to illustrate those (like me) who are not specifically mecanic. And thanks to Jim to notice it in first place.

    A la gang on sais tout ! Suffit juste qu'on s'parle! :cool:
     
  17. 68 Skylark cust

    68 Skylark cust French Canadian Member

    Any recommandation for diff oil ? Which grade ? Any additive ? Aprox 2.5 litre I was told ?

    I am supposed to have it installed in the next month or so

    Thank you
     
  18. BrianTrick

    BrianTrick Brian Trick

    I like the 85/140,but 70/90 is fine. If you have a clutch style or cone style posi unit,you will need to use conventional oil. Do NOT use synthetic. ONE bottle of posi additive.
    If you are using a Tru Trac,Detroit Locker,or spool,NO additive is needed.
     
  19. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  20. monzaz

    monzaz Jim

    I do not recommend Vavoline ANYTHING to anyone. We have had nothing but issues with that oil. BUT that is our trials on the oil
    We have used LUCAS, Coastal, super tech (walmart) conventional (non Synthetic) oils with out failures. You do not ever want to use oil that says it has additive in the oil already.... Why? How much % did they put in? YOU DO NOT REALLY know. So do it separately and you will know.
    Remember it is your choice and this is a discussion forum. Use what you feel will do the job.
    Jim
    JD RAce
     

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