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Tach's and gears

Discussion in '1982-Present GM Diesel' started by fbronson, Mar 2, 2004.

  1. fbronson

    fbronson 1/2 ton status

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    Tach\'s and gears

    So I've been looking around for a while and am not finding any tachs in the local parts stores for a diesel. It seems that all anybody has are the tachs that attach to the distributor. /forums/images/graemlins/mad.gif Obviously not going to work on a diesel. Where can I find a tach for my 6.2L? Second question: 4.10's or ??? Current equipment is 6.2L, 700r4, 241, 10b front and rear, and 33 inch tires (Next set will be 35's) I can't seem to find the info on the axles that are under the truck now. I do know that the axles are bone stock. (It's an 83 K5, and came with 31's originally). Are the original gears 3.53's? After putting the 33's on, I can barely keep it in over-drive, and it wants to drop into 3rd on anything but the slightest hill. I plan on doing some mild wheeling (eg Moab, but nothing serious) and possibly a little towing. Some gearing guidance would be a huge help! /forums/images/graemlins/1zhelp.gif
     
  2. 75-K5

    75-K5 3/4 ton status

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    Re: Tach\'s and gears

    From what I understand, diesel tachs are much more complicated. They involve a magnetic sensor attached to the crank to determine how fast it is rotating. That's all I can really tell you. I'm certain more people will pipe up with better responses, but I thought I'd give you a quick one to (hopefully) ease your mind. /forums/images/graemlins/waytogo.gif
     
  3. imiceman44

    imiceman44 1 ton status

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    Re: Tach\'s and gears

    [ QUOTE ]
    So I've been looking around for a while and am not finding any tachs in the local parts stores for a diesel. It seems that all anybody has are the tachs that attach to the distributor. /forums/images/graemlins/mad.gif Obviously not going to work on a diesel. Where can I find a tach for my 6.2L? Second question: 4.10's or ??? Current equipment is 6.2L, 700r4, 241, 10b front and rear, and 33 inch tires (Next set will be 35's) I can't seem to find the info on the axles that are under the truck now. I do know that the axles are bone stock. (It's an 83 K5, and came with 31's originally). Are the original gears 3.53's? After putting the 33's on, I can barely keep it in over-drive, and it wants to drop into 3rd on anything but the slightest hill. I plan on doing some mild wheeling (eg Moab, but nothing serious) and possibly a little towing. Some gearing guidance would be a huge help! /forums/images/graemlins/1zhelp.gif

    [/ QUOTE ]

    If you do a search you will find a couple of posts that dealt with the tach story.
    I myself got the tinytach
    It's $65 plus $25 shipping.
    It's easy to install and works off the fuel line pulses.
    /forums/images/graemlins/waytogo.gif

    As to gearing: your stock ratio is likely 3.42 if it was gas, 3.08 if it was diesel.
    You would kill your tranny if you keep using it like this with the 33's.
    What you want is 4.10's, with the OD tranny you should be fine, but for now putit in drive all the time untill you hit a nice flat stretch to reduce the gear hunting which raises the temp and fries your tranny.
    /forums/images/graemlins/thumb.gif
     
  4. Diesel Dan

    Diesel Dan 1/2 ton status

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    Re: Tach\'s and gears

    Do a search for diesel tachs.
    I gave the part #s for a 3 3/8" dia tach from carquest. It gets its signal from the teeth on the flywheel. I installed one on my brothers 6.2 and it works great.
     
  5. fbronson

    fbronson 1/2 ton status

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    Re: Tach\'s and gears

    Thanks for the info on the tach. /forums/images/graemlins/thumb.gif I did a search on the carquest website, using the part numbers you supplied last Auqust, and unfortunately came up with nothing. However, from the Stewart-Warner website I was able to get the locations of a few distributors here in Denver.
    Also, thanks to Imiceman44 for the info on the gears. /forums/images/graemlins/bow.gif It looks like I can find the gears for pretty cheap. Now, forgive me for being a novice, but will I be able to just buy the new gears and put them in? Will I need new carriers, special tools, etc...? Thanks for all your input! /forums/images/graemlins/grin.gif
     
  6. u2slow

    u2slow 1/2 ton status

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    Re: Tach\'s and gears

    The 10-bolts are quite forgiving when it comes to ratios... 4.10 will fit on the same carrier as the 3.08. The split is 2.56-down & 2.73-up.

    Also factor in the cost of the gears and shop install vs. the cost of 3/4-ton axles (that already have 4.10 ratio) that you can install yourself.

    On my Burb, I upgraded to a heavier axle (14bFF), got the ratio swap I wanted (from 4.10 to 3.21), and got functional brakes (mine were dead) for about $200 ($150 for used axle, ~$50 in misc parts). /forums/images/graemlins/waytogo.gif
     

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