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Freightliner Differentials

Discussion in 'Freightliner Forum' started by zaheerkarim, Jul 8, 2013.

Page 1 of 2
  1. Jul 8, 2013 #1
    zaheerkarim

    zaheerkarim Light Load Member

    73
    3
    Jun 21, 2011
    Malawi
    0
    Hi Guys,

    I need your assistance and advice once again.

    I have a 2001 Freightliner FLD with a Cummins ISX motor, and the issues I am having is with the front differential. It originally has a Rockwell 2.64 ratio Differentials (14/37) and a 10 speed Meritor Gearbox.

    A few months ago the crown wheel teeth broke and I discovered that it was caused by a faulty bearing in the diff. I got it repaired and it was running well, but now it seems it has the same problem again. I was advised to replace both 2 differentials with the 3.73 ratio diffs (11/41) as there are common here in Africa. My problem is will it not have any affect on the engine and gearbox? Since it was running on a 2.64 ratio and now it will have a 3.73 ratio.


    I will appreciate any advice.
     
    zaheerkarim, Jul 8, 2013
    zaheerkarim, Jul 8, 2013
    #1
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  3. Jul 8, 2013 #2
    KANSAS TRANSIT

    KANSAS TRANSIT Road Train Member

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    Jul 28, 2011
    Glasco,Ks.
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    If your gearbox is a direct drive (10th) gear, which I am sure it is with a 2.64 rear gear, you will be running a LOT more rpm with the 3.73 ratio's, You didn't say what you are doing with the truck, so with unknown parameters it is hard to give you an opinion, BUT, if you liked the job the truck was doing with the 2.64, I would think that you will NOT be happy with the 3.73, too much gear.

    IF you are dead set on the 3.73 and still want the speed and power you had at a set rpm, you will also HAVE to change your tranny over to an overdrive unit, (10th being a .75 over)
     
    KANSAS TRANSIT, Jul 8, 2013
    KANSAS TRANSIT, Jul 8, 2013
    #2
    25(2)+2 Thanks this.
  4. Jul 8, 2013 #3
    zaheerkarim

    zaheerkarim Light Load Member

    73
    3
    Jun 21, 2011
    Malawi
    0
    The reason I want to change the diffs is because the front 2.64 diff is damaged (both the crown wheel and pinion) and I can't get the diffs here in Africa. Its the second time that this is happening the 1st time I had to get the teeth on the crown wheel re-built and it hasn't lasted long. I can't get the 2.64 diff parts or even a complete diff here. The only ones I can easily get and I already have are the 3.73 diffs. So my only option is to change both the 2 diffs to 3.73.

    I am not going to do any other modifications or changes apart from switching the differentials.
     
    zaheerkarim, Jul 8, 2013
    zaheerkarim, Jul 8, 2013
    #3
  5. Jul 8, 2013 #4
    25(2)+2

    25(2)+2 Trucker Forum STAFF Staff Member

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    the road less travelled
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    You will be running approximately 30% higher rpm at any given speed in any given gear switching from 2.64 to 3.73 rears. Say from 1400 rpm to 1800 rpm.
     
    25(2)+2, Jul 8, 2013
    25(2)+2, Jul 8, 2013
    #4
    KANSAS TRANSIT Thanks this.
  7. Jul 8, 2013 #5
    KANSAS TRANSIT

    KANSAS TRANSIT Road Train Member

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    Glasco,Ks.
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    Well if you are going to put in 3.73, and NOT change the tranny to an overdrive, you will essentially be running close to your 9th gear speed and rpm but only you will be in 10 gear.

    With your direct 2.64 set up right now you have of course a 2.64 FINAL drive in high gear, IF you do what you are wanting to, you will have a 3.73 FINAL drive in high gear.

    IF you put in the 3.73 and then put in an overdrive tranny, the .75 over, times your 3.73 will give you a 2.79 FINAL drive in high gear, VERY close to your 2.64 that you have now.

    Let me put it another way, these are only ROUGH numbers, because I don't know what tire size your running, BUT, if right now you are running let's say 1400 rpm in high gear at 70 mph.

    IF you change JUST the rear diffs to 3.73, with that tranny you will now be running about 1900 rpm at 70 mph so you are going to PICKUP about 400 plus rpm OVER what yo have now throughout your entire gear range.

    That is a lot.
     
    KANSAS TRANSIT, Jul 8, 2013
    KANSAS TRANSIT, Jul 8, 2013
    #5
    25(2)+2 Thanks this.
  8. Jul 8, 2013 #6
    fortycalglock

    fortycalglock Road Train Member

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    Jun 25, 2011
    Tourist Town, FL
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    What are your top speeds in Africa? I am ignorant to the highway systems or speed limits there, so putting in those rears could actually be fine if you rarely do 55mph or over.
     
    fortycalglock, Jul 8, 2013
    fortycalglock, Jul 8, 2013
    #6
    25(2)+2 Thanks this.
  9. Jul 8, 2013 #7
    zaheerkarim

    zaheerkarim Light Load Member

    73
    3
    Jun 21, 2011
    Malawi
    0
    We do 55 to 60 MPH normally its very rare that we go above that. And I am using 22.5" tyres.

    What do you mean by direct drive (10th) gear? Are you suggesting I change the gearbox?
     
    zaheerkarim, Jul 8, 2013
    zaheerkarim, Jul 8, 2013
    #7
  10. Jul 8, 2013 #8
    KANSAS TRANSIT

    KANSAS TRANSIT Road Train Member

    4,080
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    Glasco,Ks.
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    ONLY, if you are wanting to get close to you original overall gear ratio. At 55 mph you can just change your rears and go, should work ok.
     
    KANSAS TRANSIT, Jul 8, 2013
    KANSAS TRANSIT, Jul 8, 2013
    #8
    zaheerkarim Thanks this.
  11. Jul 8, 2013 #9
    zaheerkarim

    zaheerkarim Light Load Member

    73
    3
    Jun 21, 2011
    Malawi
    0
    Can you please explain to me what it means when they say 10 direct or OD. How do I check to find out what transmission I have on the truck?
     
    zaheerkarim, Jul 8, 2013
    zaheerkarim, Jul 8, 2013
    #9
  12. Jul 8, 2013 #10
    25(2)+2

    25(2)+2 Trucker Forum STAFF Staff Member

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    the road less travelled
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    You would have to have a direct with a 2.64, from the year, I'm guessing a Rockwell-Meritor, but it could be an Eaton-Fuller.

    I drove many FLDs from the mid 90s to the early 2000s that had 9 and 10 speed Rockwell transmissions.
     
    25(2)+2, Jul 8, 2013
    25(2)+2, Jul 8, 2013
    #10
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