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Gears and Traction...!

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by jimmup, Dec 19, 2001.

  1. jimmup

    jimmup Registered Member

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    Finally,

    I just purchased a set of 4.10 gears for my 72 GMC Jimmy. The rig came with stock tires and 3.73s. I installed a 4-inch lift and 33s and lost a ton of low-end. After rebuilding my motor I decided it was time to lower the gears so I was not getting robbed of HP and low-end from the increase in tire size. My loss of power was further compounded by the fact that I often pull a trailor and quads and found that my right foot was doing a lot of work on hills. I hope the gear reduction helps makes a noticeable difference!

    Additonally, I also purchased and will be installing a Detroit Tru-trac for the rear (GM-12blt) and a Trak-Loc for the 44 in front. Not true lockers, I know, but definitely better than open diffs! Also, this is my daily driver.

    What is best about this is that none of it would have been possible if I had not won a jack-pot at a local casino. I could not believe it.

    PS-I had to spend the money quick before the wife caught wind of things :-)!

    Anyway, I wish everyone a safe and great holiday season!

    Cheers!
     
  2. 82GMC

    82GMC 1/2 ton status

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    Hey! Some Congrats are in order I'd say[​IMG].

    I am the hunter Who live's in the darkness, And grows through your fears...... And you are the hunted.
     
  3. ImpalaSS

    ImpalaSS 1/2 ton status

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    sweet! be sure to to give a review on the parts when installed.... especily the tru trac and track lock

    68 SWB 4x4 1 of 1,449 made 327, 465 4 speed, rockwell tcase, dana44, 14 FF, <a target="_blank" href=http://communities.msn.com/68K10>http://communities.msn.com/68K10</a>
     
  4. Burt4x4

    Burt4x4 3/4 ton status

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    I went from 373 to 410 with 33s and I did notice a diff. I have a 4spd SM465. I now have 35s and it is still more grunt than 373 w/33s so I think you will like 410.
    Oh and congrats on the cashola!!!![​IMG]

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
    <a target="_blank" href=http://coloradok5.com/gallery/Burt4x4>http://coloradok5.com/gallery/Burt4x4</a>
     
  5. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    I had a buddy that put a tru-trac in his 12 bolt and he had it for all of two days. The thing broke while he was mudding.

    If you build it, the mud will fly!
    72 K5 blazer with a 427 tall deck and TH350/NP205 and 9"of lift with 40"tires.
     
  6. jimmup

    jimmup Registered Member

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    Well,

    After doing some serious checking around I decided to drop the Detroit Tre0trac in favor of an Auburn-GearPro Series posi for my truck. After talking with several credible folks it is very apparent, NOW, that a True-Trac is likely to fail in moderate to extreme wheeling situations when combined with over-sized tires and a high horsepower motor (i.e. 300+hp). Also, I learned that a person would automatically void the manufacutuerers warranty if the True-Trac is installed on a vehicle with tires in excess of 31-inches. Give me a break...!

    Anyway, I went ahead and spent a little more for the Auburn-Gear unit as I know for a fact that it will hold up..

    Just wanted to pass what I learned along...!
     
  7. frito

    frito Registered Member

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    yeah i went from 31's to 35's with 3.73's, big differience ... i lost 500-600 rpm on the highway (witch is nice now i only rev 2400 RPM but around town the miliage went down a little it's still got some bottom end and it pulls but it takes longer before it reaches my motors powerband
     
  8. Steve_Chin

    Steve_Chin 1/2 ton status

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    If your 3.73:1 gear sets are in good condition I might know someone who wants them for a reasonable price. Let me know and I'll get your phone number to him.
     
  9. Burt4x4

    Burt4x4 3/4 ton status

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    Steve~
    You can have my used 3.73 R&amp;P D44 &amp; D60Rear R&amp;P. They were both in working order when removed. The Rear is only hmmmmm mabie 25- 30K miles, the D44 ?? I think it's the original R&amp;P. Both are Dana R&amp;P brand.
    Oh and for a D44 I would install a Dana Power-Lok. Rebuildable and THE closest thing to being locked but still allows slipage. Which I think is the key to saving Ujoints. Just my thoughts. The Auburn will last a long time but it is not rebuildable, last time I checked anyway......

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
    <a target="_blank" href=http://coloradok5.com/gallery/Burt4x4>http://coloradok5.com/gallery/Burt4x4</a>
     
  10. jimmup

    jimmup Registered Member

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    A buddy and I will be tearing into the gear swap project this weekend. I will let you know what kind of condition the R&amp;P sets are in. I do know that I change the diff fluid, regardless, every year and there is NO sign of bearing debree or unusual wear. Also, I would likely be willing to part with this including the Eaton/Gov-loc unit for a very reasonable price. I like Bud-Light...!

    Lastly, I don't want to bag on the Detroit Tru-Trac unit too much. In my previous message I stated that the unit would likely fail under certain tire, HP and wheeling conditions. That was not entirely accurate based on what i was hearing from buddies, etc...! I should have stated that this has been the case, in there experience, when the device is being used in the REAR differential. Regardless though, if Detroit only warranties the unit on 31-inch and smaller tires it has NO place on the majority of wheelers rigs anyways.

    PS-The Auburn units, at least the Pro-Series model I purchased, can be rebuilt. I made sure of this before I bought the unit...!

    Check out www.auburngear.com for product detials...!

    Take care...!
     
  11. huggerk5

    huggerk5 Registered Member

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    If you don't mind. What is all this costing or what could I expect to pay for these type of gear changes and lockers? I don't do gears failed at it years ago and have never tried again. My 35"s took alot of my power. Also are you putting lockers front and rear? TIA, I will have to do something in the near future, one of my spider gears has a tooth missing.
     
  12. Steve_Chin

    Steve_Chin 1/2 ton status

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    Thanks Steve, but my buddy has a 12-bolt rear. Email me at bigiron@pacbell.net and maybe we can at least work something out for the D44 R&amp;P...
     

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