Outboard planetaries on a 14 bolt...?

Discussion in 'The Garage' started by mikey_d05, Nov 7, 2005.

  1. mikey_d05

    mikey_d05 1 ton status GMOTM Winner

    Nov 23, 2004
    Likes Received:
    A guy brought up an interesting idea over on Pirate to use a planetary somewhere on a 14 bolt to get ratios lower than 5.13 or 5.38 if it's actually available.

    Now, don't get me wrong, this wouldn't be a production piece due to cost and labor, but I gave it some thought and don't think it'd have to be all that wild.

    The parameters would be:

    #1. Uses the factory spindle and takes the place of the OE hub.

    #2. Allows the use of factory drums or normal disc conversions.

    #3. Bolts directly to the wheel with an 8 on 6.5" pattern.

    #4. Uses a ratio that would match up commonly available 14 bolt gears to commonly available D60 gears.

    #5. Fits inside a 15" rim.

    Using an outboard planetary would take a lot of stress off the internals (not like a 14 bolt really needs it), add some width for those of you who don't like your truck being narrower in the back, and give you access to deeper gearsets than the third 14 bolt pinion support would traditionally allow.

    A 1.43 or 1.44 gearset would turn 3.73's into 5.38's and 4.10's into 5.86's. A 1.49 or 1.5 gearset would turn 3.73's into 5.57's and 4.10's into 6.17's.

    The same gearsets for D60's are cut for industrial use (noisy but strong) so the only real problem would be in the 60 shafts if a combo like this were set up. (I'm thinking of the additional torque multiplication from the gears)

    Honestly, I'm off on a tangent here, and this is impractical considering you could just go D70, but I think I might take this into consideration for a CAD design project in the future. Although planetaries have been around forever, they're limited to huge applications and nobody has really ever made one for light duty stuff.
  2. diesel4me

    diesel4me 1 ton status Premium Member

    Jul 24, 2003
    Likes Received:
    look at an old VW bus..

    The older VW "bus" used a reduction gearbox on the outboard end of the transaxle,to lower the gear ratio,and increase ground clearence!.(otherwise,it was the identical transaxle and brakes as the "Beetle" used!.

    I had a 1963 "Transporter"--I remember changing one rear wheel bearing,after one of the balls fell out,and lodged between the gears in the reduction box!..suprisingly,all it did was lock the wheel,no damage occurred to the gears..they were straight cut gears,not planetaries..

    I think a similar setup for a 14 bolt FF would be cool..it would lift the truck and the diff higher off the ground,without using any kind of a lift kit,it would give you at least 7-1 reduction instead of being limited to 5.13's,and if they made the gearbox similar to "quick change" rear end like some race cars use,you could just swap cogs around,higher ratio for the ride to the rocks,and a low ratio for crawling.. :thinking: :laugh:
  3. 78Suburban

    78Suburban 1/2 ton status

    Jul 4, 2005
    Likes Received:
    Don't monster trucks use planetary reduction (in much bigger axles of course)? I think you may be on to something here..... If the 14ff could be made to use deeper gears than 5.13, everybody could run bigger tires... I say, if you can engineer it, get a patent on it, start your own company.... there would be plenty of people that would buy it..

Share This Page