Putting reduction drive starter(tiny one) in direct drive starter equipped Suburban

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by phoebeisis, Dec 25, 2011.

  1. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    A while back I posted asking if you can just put one of those tiny reduction drive starters in a 1998 Suburban 5.7 1500 2wd
    if it originally came with a direct drive starter.
    Through dumbness lack of knowledge cheapness brokeness trying to save a $$ ness
    I ended up with TWO YES TWO "WRONG" starters.I had a direct drive ended up with two tiny reduction drive starters.
    I found this out when I pulled mine and immediately noticed it was HUGE next to the new(and used) starters
    Even worse the DD had a 9 tooth gear the RD had a 11 tooth gear.
    I just put the old starter back in and hunted here-and other places for the answer.
    Well the answer is GM used BOTH STARTERS in the same models same years!!??
    Yeah it seemed odd to me, but that is it!
    Not sure why- pretty sure it was for more than one year(1998)-so not as if they had to use up the old starters but maybe I am wrong about that.

    Well back to can you switch them.
    Yes-direct bolt in.
    But there was 2 curve balls.
    1)My starter cable was TOO SHORT-ABOUT 1/2 inch too short.There was no way to just pull it very hard put eyelet over stud- and screw nut on-just couldn't do it-AND IT WOULD HAVE BEEN PRESSING ON A BRAKE LINE- bad idea all around. The fat old direct drive starter put the connectors closer-higher- to the battery-that is it.

    I finally took off one of the hold down "cable directors" off-the 1st one you come to from the battery-holds cables to top of fame rail I think- Downside of this- biggish downside-it now is just 1/2-3/4 inch from the exhaust manifold.I won't leave it like this-hunting for a longer cable-maybe I will make one??What gauge is that wire-it is REALLY HEAVY-maybe 1.8" to 3/16" of multistrand copper wire- really really heavy! It is also heat insulated with aluminum "foil" and some sort of now
    crunchy brittle insulation.

    2) The old heat shield doesn't fit-too loose-so I left it off.This is also a big downside-the starter will fail early if it is getting cooked. I'll modify adapt the old shield soon- before the summer-Most of my trips are very short-6 miles-so no big deal until then-and I only drive maybe 60 miles/week.

    So they do interchange-starts just fine-not chewing up the flywheel-
    I did carefully look at the 9 and 11 tooth gears- tooth spacing exactly the same-about 8.5mm between points of teeth.
    Did look at how far the gears would be from where they were mounted on both starters- exactly the same in both dimensions-the mounting depth and length is exactly the same.
    Now the newer mini starters do seem to have slightly stouter mounting "holes" and the length of the mounting holes is slightly-about 1 thread- longer-so might be a good idea to use the very very slightly longer mounting bolts-1 thread longer.

    Well that is it.
    Probably better to just stick with whatever GM stuffed in there to begin with- but if you end up with a "ministarter" for some reason it will fit and work.
    Direct Drive weighed 13 3/4 lbs
    Reduction drive weighed 7 7/8 lbs
    6 lbs heavier-almost twice as heavy.
    The new starter does sound slightly different-just different-doesn't seem to spin the motor any faster or slower-
  2. wildmans92

    wildmans92 Member

    the reason the tooth count is not the same is becuse the gear reduction spins faster needing a different gear ratio so it doesnt spin the engine too fast.

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