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Regear? 4.88 or 5.13 w/37" tires/350/700r4/241/D60/14B

Discussion in 'The Garage' started by az88k5, Jun 2, 2006.

  1. az88k5

    az88k5 1/2 ton status

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    I am rebuilding a D60 and a 14bolt to put in my 1988 K5. The current D60 has 4.56 gears in it. I have a new crate 350 with a new 700r4 tranny with a 241 transfer case. I will be running 37" tires and will not go much bigger. This is my recreational truck and it will see the Highway too and from trips. It is not my daily driver. Sense it will see the highway I would like to be able to cruise at 75 without winding the guts out of it and heating up my tranny ext. I would think 2500 rpms would be a good cruising rpm on the highway. I am not sure because I do not have a tachometer. I did talk to a guy that builds rear ends and He said he would go 4.88 with my set up and 37" tires because of the pinion size on the 5.13 and the fact that 5.13's would generating a lot of heat at highway speeds. I have had problems with trannies and don't need anymore. I am currently running 10bolts with 3.73's and 35" not the best setup. I will be adding a tranny cooler this weekend. Please let me know what you guys have experienced and think. :D Thanks
     
  2. sandawgk5

    sandawgk5 3/4 ton status

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    I run 37s right now and at 75 MPH I turn about 1800 RPM with 4.10s. I personally will be going 5.13s because I plan on 42s. You say you will not be going much bigger how much is not much? I have not heard any adverse things on 5.13 pinion size or heat generation. There was a calculator in a thread on here where you could plug in tranny gear size and tire size and it would tell you engine RPM. It is also quite accurate.


    All that to say 5.13s have my vote:D .

    Ira
     
  3. az88k5

    az88k5 1/2 ton status

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    I would not go any bigger than 39" tires. I know I have over drive and many CK5's say hands down 5.13 but after I talked to this guy Steve that builds rear ends and has plenty of experience off road. I started to think if I really need that low of gears. He didn't say 5.13 would generate to much heat just more then 4.88 would and the size of the pinion is much smaller. I really just want to hear some more options from you guys on here with personal experience. I just want the best setup for off-road and highway use If I am going to spend the money to re-gear both axles. Thanks for your input. ;)
     
  4. jarheadk5

    jarheadk5 1/2 ton status

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    THIS is by-far the best gearing calculator I've ever seen.

    Since you've got the 700R4, I'd go 5.13. Pinion size isn't as big an issue with a 14BFF as other axles because of the extra pinion bearing. Run a diff cover with some extra capacity and a high-quality synthetic gear oil, and put a couple magnets in the cover & housing. Follow proper ring & pinion break-in procedures and don't swewat it.
     
  5. sandawgk5

    sandawgk5 3/4 ton status

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    That is the one I was looking for:D

    Ira
     
  6. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    With the transmission you have , the first gear and torque converter are pretty low , and the transfercase is pretty low for stock .

    Considering you look like you are going to drive more highway than trail miles , I'd stick with 4.56 . Then you only have to find a 4.56 14 bolt , or regear one axle .

    Mikey with the bronze stepside that wheels with Marv all the time ran 37's with a 350/350/205 combo and 3.73 gears forever . He just went with a doubler setup for trail use , but still DD's with the 3.73's :thumb:
     
  7. 6.2Blazer

    6.2Blazer 1/2 ton status

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    There is really not much difference between 4.88 and 5.13 gears when it comes to physical size........or engine rpm.......or really anything. Do the math and the gearing difference is only about 5%, and I've never heard of anybody saying that 5.13's were a weak spot in the 14-bolt.

    With that said I would go ahead and do the 5.13's. When the 700r4 shifts into overdrive it would be equivalent to having 3.59 gears in the diff and a non-overdrive trans and should allow you to cruise on the highway with no problems.

    However I might even be tempted to stick with the 4.56 gears for now and see how it does.
     
  8. az88k5

    az88k5 1/2 ton status

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    Do you really think it is worth it to keep the D60 w/4.56 and regear the 14 bolt to 4.56? Or go for the full gear swap front and rear with 5.13's. It seems no one on here thinks 4.88's are worth it sense they seem to be about the same as the 5.13's.
     

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