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Question on gearing with a SM465

Discussion in 'The Garage' started by 84CUCV, Jan 17, 2007.

  1. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    I can get cheap axles with 4.56 gears in them. I was going to put this in a 86 K5 with 5.0 sm465 and 208. I am going to run 35s. No plans to go bigger. Dont know much about gearing so i was thinking with 35s and 4.56 i would be OK or am i just way off. as always thanks for the help
     
  2. sandawgk5

    sandawgk5 3/4 ton status

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    PM Readymix that is the setup he runs and he just recently went from 36s to 39.5. He should be able to tell you how it worked with the smaller tires.

    Ira
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Highway driving won't be much fun, but it will work. I've got 4.10's, 35's and no overdrive in my K5. The engine is really spinning at 70+ mph. 4.56's would mean even more revs... Right now I have 4.10's, 35's and a 700R4 in one of my Suburbans. Overdrive makes it much more tolerable on the highway than my non-OD rig. :cool1:
     
  4. NEK5

    NEK5 3/4 ton status Premium Member

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    theres a few here running around on 35s and 4.10s with the sm465...Chevy305 is one of them, and he thinks its the ideal setup...
     
  5. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    OK how can i find out what RPM i will be at with that set up?
     
  6. 84 K5 4x4

    84 K5 4x4 1/2 ton status

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    I just swaped a 465/205 in my 84 k5 and i have 4.56 with 35s and i think its awsome on the trail but is to low for the highway. I am swapping back to 3.73s this weekend. But it all depends on how you drive your truck. I do a lot of highway time but the best gear calculator i have found is at
    WWW.FLORDIA4X4.COM
     
  7. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    OK link didnt work. thanks
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    2850 rpm at 65 mph with 4.56's and 35's.

    Gearing (4.56) X speed (65 mph) X 336 / tire diameter (35")

    Rene
     
  9. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    so is 2850 alot of rpms or not? seams kinda high from what i know.
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Too high for my liking, but only if you drive on the freeway much. 2850 is at a conservative (slow) 65 mph too. 75 mph would be almost 3300 rpm...

    Rene
     
  11. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    I usually like to target my small blocks to about 2200 rpm, thats their sweet spot :)
     
  12. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Ya thats true, I run the 5.0L/SM465 with 4.10s and 35"s. I think its a great all around combo. I think about 2950 is 75mph.

    4.56 would be fine, but only if you plan on not going on the highway much or take long trips in it.
     
  13. 6.2Blazer

    6.2Blazer 1/2 ton status

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    That's a little higher rpm than what would be considered ideal for highway cruising, but it's not horrible or anything. There were tons of trucks that came from the factory in the 70's, 80's, and even 90's that would spin that type of rpm at 65 mph, and might even have a higher rpm at that speed.
     
  14. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    starting to think i should get some 4.10s
     
  15. big dan

    big dan 1/2 ton status Premium Member

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    x2. Ive always been told that you get the best mileage on the highway with the motor turning between 2000 and 2500. anything over that and it will start to drop. on the other hand if most of your driving is around town rather then long highway trips then the lower gears will help it get better mileage cause it will pull itself around better in the stop and go stuff. personally I think 4.10s would be a better choice if its gonna be a dd.
     
  16. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    Only was going to go with 4.56 axles because i can get them for 100 bucks. So i was thinking what the heck. 4.10s are sounding like the way to go now thanks guys
     
  17. 84 K5 4x4

    84 K5 4x4 1/2 ton status

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  18. 84 K5 4x4

    84 K5 4x4 1/2 ton status

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    I give up
     
  19. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    thanks for trying
     
  20. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    OK a new turn a friend of mine said he found 4.10 60 and 14b that i could get for a ok price. now my question is with 4.10s could i pull off a 38-40" tire and be ok with it? thanks
     

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