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why dont most trucks have 4.11?

Discussion in 'The Garage' started by 79 blazer, Jun 13, 2005.

  1. 79 blazer

    79 blazer 1/2 ton status

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    so i was looking at the chevy blazer catolaouge website and it said that the standard gear ratio was 4.11 in 1979 at leaste. but my experience is that most trucks dont have 4.11's stock so why did so many trucks get ordered with worse gear ratios?
     
  2. 3rdshiftdesign

    3rdshiftdesign 1/2 ton status

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    well, my guess is that around 79, or whenever, is when people were concerned with gas mileage, and not everyone plans on running 35" tires so 4.11 gears may be overkill for your average person. someone else probably has a better explanation.
     
  3. Pookster

    Pookster 1/2 ton status

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    might have been around the time that they had the inline 6 too. I recall reading that they had a high rear end number and a really low first gear number.
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I think the most common ratio through the 70's was 3.07/3.08 from what I've seen. like Pookster said the 4.11's were prolly the standard ratio for the inline 6 (V-8 was optional)

    Rene
     
  5. 6.2Blazer

    6.2Blazer 1/2 ton status

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    I've heard there were 4.10/4.11 ratios available in the half ton axles back then, but they are pretty rare. I've personally never seen a 10 or 12-bolt with factory gears lower than 3.73.
     
  6. diesel4me

    diesel4me 1 ton status Premium Member

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    Rare,but they are out there...

    I have seen only one 2wd K5 with 4.11 gears in the rear--never looked to see if it was a 10 or 12 bolt,but I'm leaning towards it being a 12 bolt...my friend bought the Blazer a few miles from me,and after we changed all 4 of the brand new but now junk dry rotted flat tires on it(guys wife we bought it from never got her license,let the truck sit 5+years in the yard with brand new tires on it! :screwy: ),I looked the truck over good,since he had a long ride home..

    -I noticed the glove box "build sticker" actually listed the axle ratio next to the "code"--first time I saw that listed,and it said 4.11 ratio!...the K5 was 2wd,and had a 350 4 bbl motor,an with those gears,it went like a raped ape!...my friend drove it 70+ miles home,and he said he was loving the acceleration and takeoffs!..had no trouble cruising at 70 mph on the highway too....

    I havent seen many other trucks (1/2 tons) with gears lower than 3.73's either,no matter how many" bolts" they had,10 or 12....3.08's were THE most common ratio they had,95% of all the trucks I've owned or seen in junkyards had the 3.08's in them (most of the rest had 2.73's,even worse!)--even in GM vans and cars it was rare to see any other ratio's than those 2...I searched for a long time to find a 3.42 ratio axle for my G10 van,but I got a 2.73 ratio for free,so I put that one in--

    I wish I had waited,for 2 weeks later a 3.42 ratio one arrived at the junkyard in a crashed conversion van--- :surepal: --the van was slow enough when it had 3.08's!--its even worse now with 2.73's....the 3.42's would have been a much better choice,and even lower than that would have been even better!...but you just dont see them around--I guess its a "special order" to get any other ratio than 3.08 or 2.73.... :thinking: ..and not many were ordered evidently... :dunno:

    ...guess GM thought the "high" gears would give better fuel mileage,but in many cases they actually REDUCED mileage,because the motor was lugging most of the time and not running in its peak power band..then they added overdive trannys on top of that,and things really went downhill...dont know how they expected a tranny to live for long when its always under strain.. :confused: :crazy:
     
  7. ntx78k5

    ntx78k5 1/2 ton status

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    I've got a 78 Full time 4x4 with 342's and came stock with a 350 and a tow package???
     
  8. Shaggy

    Shaggy 3/4 ton status

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    I believe that it was standard with the I-6 engine. My truck is a '78 K10, the stock axles were a D44 and a 12 bolt and they had 4.11s (4.09 in the rear actually, IIRC) in them from the factory. It topped out at about 55-60 mph on the freeway in 4th gear. I still have the factory ID tags from the diff covers that say 4.09 and 4.11 on them.
     
  9. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    wow really?
    my truck with 33's factory 4.56's still did 95mph!!!!! :cool1:
     
  10. Shaggy

    Shaggy 3/4 ton status

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    Sure it did, at about 4500 RPM. The engine that was in my truck at the time was tired and I wasn't about to go all Johnny-speed-racer on it, It was pushing 3000 RPM at 60 mph.
     
  11. 79 blazer

    79 blazer 1/2 ton status

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    so then it seems chances are that if someone would like to regear there axles it would be more cost effective to find some axles from a inlinesix rig?
     
  12. ZooMad75

    ZooMad75 1/2 ton status Premium Member GMOTM Winner

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    Finding an inline 6 rig should prove to be just as tough. Not nearly as many 6's made as the v-8 trucks.

    My 75 came factory with 3.73's, but it also came with the 465 trans and 205 case too. I think most of the trucks/k5's sold with the 203 full time case came with the dismal 3.08 axle ratios. One would need to look at the options available then to see what the most common would be. Most of the time, there was only a choice between 2 or 3 different ratios depending on what engine and trans choice was made. One axle ratio was standard and one or maybe two optional.

    I think it might be easier and cheaper in the long run to just swap to 3/4 ton or 1 ton axles as most of the time 3.73 was as high as you could get and 4.10s and 4.56 were also available. Much easier to find them as you would a 1/2 ton 4x4 with a 6 in it.
     
  13. gravdigr

    gravdigr 1/2 ton status

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    The proud PO of my 79 K5 still had the factory order sheet from it when he ordered it new in 79. He pointed out the gear ratio, 2.73 "I ordered those special for towing" he says :rotfl:

    I now have a set of 4.10 3/4 ton axles to swap in.
     
  14. 79 blazer

    79 blazer 1/2 ton status

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    it just seems crazy that the standard ratio was 4.11 or so it says in there sales material, and yet its a rare thing to find one
     
  15. R72K5

    R72K5 Banned

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    std ratio was 4.11 just for 6 cyl models

    look in the original gm options specs sheets, in power teams section and you will see this reflected

    this was only for 73-up years but before 81

    by 81 the std ratio was changed to 2.73(more gas mileage)

    72 and older std ratio was 3.73 for 6 cyl and some v-8 models, but 3.07 in other cases such as 350 + 4 speed (certain trannies affected changed the ratio installed), and 4.11 with 3 speed + overdrive unit

    3.07 didnt happen til later on in the 67-72 years


    the std ratio is the ratio that is std for a given engine/trans combo in a certain year make model vehicle- and not optional for it

    it is wierd but it is how it worked

    good luck
     
  16. resurrected_jimmy

    resurrected_jimmy 1/2 ton status

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    I'll jump in with my two cents worth. Two years ago I came across a screaming deal on a new Z71 tahoe. When I inquired as to why the price was so low I was told it had 4.10 gears and no one wanted one "geared low" for "heavy towing." After looking at the window sticker and and confirming the option code in the glove box I walked away smiling and wishing it was a suburban for it would have found a happy home.
     

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