Can we talk about the Detroit Bull Gear?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Hanadarko, Mar 27, 2012.

  1. 66truck

    66truck Light Load Member

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    And how do you know which one you have without opening the motor up?


     
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  3. catmechanic07

    catmechanic07 Bobtail Member

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    I know all the older 12.7's and 11L's have the roller bearings. The new 14L's may have a new style gear train but Ive yet to be in the front of one. I thought this thread was on 12.7's. The 14L is a whole different "pig" than the 12.7, 12L was one of the best engines Detroit ever made. 14L's are ook but have many issues as far as EGR and due to that overhauls are occurring sooner mileage wise than the 12's.
     
  4. catmechanic07

    catmechanic07 Bobtail Member

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    NUMBER:
    11–60–02 S.M. REF.: 1.23 ENGINE: 60 DATE: December 2002
    SUBJECT: COMPACT GEAR TRAIN ASSEMBLY
    INTRODUCTION
    Detroit Diesel has released a new Compact Gear Train Assembly for the Series 60 2002 engine. This
    new assembly offers weight savings, noise reduction and height reduction. The bullgear is a straight cut
    gear that now rides on bushings.
    DETAILS AND REASON
    Series 60 2002 Engines are equipped with a new Compact Gear Train Assembly. Camshaft, Camshaft
    Drive Gear and Camshaft Gear Cover will be installed and removed as a assembly.
    For engines equipped with a Compact Gear Train Assembly remove camshaft assembly as follows.
    1. Rotate the engine by hand to get the No. 1 piston at TDC. Do this by installing the crankshaft
    timing pin J 45947 into its bracket and the barring engine over by hand until the timing pin
    drops into the locating hole in the crankshaft, the engine is now at TDC on cylinder No.1.


    Very well!!!! I found this does not sit on a "spindle"! This was released in 2002 for the 14L production. Like I said, I haven't replaced a bull gear in one of these but at the same time.......haven't been given a reason by managers to replace or even check into one. This was found on Detroit's website.
     
  5. catmechanic07

    catmechanic07 Bobtail Member

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    You will know by knowing if you have a 12.7 or 14L. 14L has compact!
     
  6. GrapeApe

    GrapeApe Road Train Member

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    The only truth to this is that the 14L has compact. But we know that it's a 12.7, which could have either. The 12.7 was still available until 2007, starting in 2002, they used the compact gear train. But they started building them in 2001, so some late 2001 engines do have compact. The 14L engine came out at the same time, but it did not totally replace the the 12.7L engine until 2007. The bull gear in the compact gear train does ride on a spindle, it's just a smooth spindle for the bushings in the gear.

    The original post did not say what year, so accurate advice cannot be given until the type of gear train is known. 2000 and older has roller bearings, 2002 and newer has bushings. 2001 needs to be verified, the best way is to call Detroit with the serial # and ask (if you cannot tell the difference in the 2 housings).

    Many fleet trucks stuck with the 12.7, there are a lot of them out there.
     
    Deezl Smoke Thanks this.
  7. 66truck

    66truck Light Load Member

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    Thanks guys, this is something I have never heard before, I have an 2003 12.7 , so is the compact the only version to have straight cut teeth ? Nothing wrong with mine at this point, but its something I have considered changing out before long as mine is at 1000,000 mile mark.
     
  8. catmechanic07

    catmechanic07 Bobtail Member

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    If you read the post I got from Detroit, you will notice that the engines with the compact gear train have the top cover of the cam gear, cam gear and camshaft all in one assy. You can tell if the top where the cam gear is located has 4 bolts holding it down to the rest of the front cover. Old style gear train doesn't have this.
     
  9. catmechanic07

    catmechanic07 Bobtail Member

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    I don't know where you get your info but all the Detroit site says in 2002 there was a compact gear train released but it is IDENTICAL to the old style. All the adjustments and torques are the same. When the 14L was released, the whole engine set-up changed. I can copy the link if needed. BUT, you are right about taking ESN to dealer for 100% accuracy. There were so many changes year to year with different components of 12.7s it isn't funny.
     
    robbiehorn Thanks this.
  10. GrapeApe

    GrapeApe Road Train Member

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    It is not identical. It may or may not have the 4 bolts to remove the came drive gear, that came with EGR. EGR started in 2002, but many 2002 and 2003 engines do not have have it due to pre-ordered engines. My info comes from http://www.ddcsn.com The reason that I do not give exact info is because we do not know the exact engine. All we know is 2003, which was an overlap year for a few major changes. With an engines serial #, I could look up correct info for you if you do not have a log in.

    I understand the differences in the 14L, I'm just confused about why it was even mentioned to begin with when we were all clear that it was a 12.7L. I was simply correcting the post that claimed that that way to tell if you had the compact gear train was if it was a 14L or not. 12.7L engines could have had either depending on order date.

    I posted because I seen a lot of info posted assuming that it was the old style bull gear. Not wrong info IF it is the old style bull gear, but we don't know that it is, so lets be sure before we spend a lot of his money. If it is the old style with roller bearings, 800,000 since an over haul on the original gear means well over a million I suspect. I'd get it changed ASAP. If it's the newer style with bushings, I'd check lash, if it's in spec, I'd keep running it. The best hole to check the condition of the gear teeth is the accessory drive. The reason for it is that on the compact gear train, the accessory drive is what drives the water pump. So if you can turn the water pump with it removed, it's the compact gear train. If the water pump is driven off the bull gear, it is not the compact gear train.
     
    areelius Thanks this.
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