Who makes a good Torque wrench for doing the crank hub bolt 400 ft lbs?

Discussion in 'PSI Superchargers Tech Questions' started by Soldierboy0098, Mar 28, 2015.

  1. Soldierboy0098

    Soldierboy0098 Active Member

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    #1
  2. jay70cuda

    jay70cuda Well-Known Member

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    So am I missing something, I use my snap on 18 volt 1/2 impact and blue lock tite. hammer it down tight with that and never once had a problem. No micro welding or nothing. 400lbs seems wild to me.
     
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  3. secondwindracing

    secondwindracing top alcohol

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    SNAP ON also you can use a multiplier
    and yes 400 foot pounds is what you do it at..did you get your crank bolt from bob auto? (automan)...Dave
     
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  4. blown1969camaro

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    what i do

    mike baxter had a multiplier u could use trevor
     
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  5. Soldierboy0098

    Soldierboy0098 Active Member

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    Torque wrench

    Hi,

    400 ft lbs is the official spec, I know it sounds crazy but I have triple checked that.

    The bolt I think is a nice RCD unit with the lightened head.

    Thanks Chris, that would work for the initial build but I still need to buy one since I will be servicing the motor once we start running. I used to just put a breaker bar on it and stand on it, which is what Tim did previously but I am a little worried not to mention if the breaker bar slips off I am getting hurt. Dad wants to make the crank hub holding bar tool so I think we have that settled.

    I used anti seize on my crank hub bolt, is that a bad idea?

    Thanks,
    Trev
     
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    Last edited: Mar 29, 2015
  6. tad1011

    tad1011 Member

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    Torque wrench

    Keep an eye on ebay Ipurchased my snap on torque wrench for around $250 and it had been calibrated
     
    #6
  7. Soldierboy0098

    Soldierboy0098 Active Member

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    Ebay

    Checked on Ebay,

    Thanks for the heads up.

    Trev

     
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  8. AFC357

    AFC357 New Member

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    200# Crew Guy on the end of a 24" Breaker Bar is what I do:cool:
     
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  9. Soldierboy0098

    Soldierboy0098 Active Member

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    Hi Tim,

    Yeah I am just worried it will slip and I will hurt myself. I am 195 so the weight isn't a problem. Is the anti seize going to screw up anything or do I should I be using loctite?

    Thanks Tim,
    Trev
     
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  10. boostedgt500

    boostedgt500 Member

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    One can get torque multipliers for a reasonable cost off of ebay.
     
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  11. Mike Kern

    Mike Kern Member

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    Anti-seize is ok. Loctite is unnecessary. If it comes loose, you did something wrong. We use "peanut butter" and go to 350# on our TF car. The peanut butter is a friction reducer/modifier, hence the lower torque value. All bolt compounds have different friction coefficients and require different torque values. Do what the bolt mfr. recommends and you should be ok.
     
    #11
  12. Soldierboy0098

    Soldierboy0098 Active Member

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    Torque multiplier

    I have seen these and was confused on how they work, the one I saw looks like it had its own bar for tightening but then said it had an 1/2 input and 3/4 output but if it has its own bar what do you put on the input? So how do these things work?

    Thanks,
    Trev

     
    #12
  13. Dan Parker

    Dan Parker TAFC

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    Torque multiplier

    Don't know what the big deal is about torqueing the crank bolt.
    Socket on crank braker bar on frame.
    Use the blower as the multiplier at 1.92 over or what U have,
    and torque to 209 lbs = 400.

    If you need a good snap-on torque I have a few left.

    Dan Parker
    480-220-8954
     
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  14. oldskooldigger

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    Trevor,

    Think of that type of multiplier as a planetary type drive. The 1/2" input is for your torque wrench, the 3/4" output is for your socket to fit the bolt, and the bar attached to the body of the unit needs to contact something fixed (like the frame) to keep the body from rotating. The torque value to set on the wrench is derived from the ratio of the multiplier.

    Steve K.
     
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  15. blown1969camaro

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    this

    I do this but I never told anyone because I was un sure it worked lol
     
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  16. Mike Kern

    Mike Kern Member

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    The basic theory here is correct but... there are so many variables that you cannot account for that I would never use this method. Just the amount of torque needed to take the of the slack out of the belt would probably make the final torque not even within 30% of what was desired.
     
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  17. blown1969camaro

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    slack on belt

    please explain how slack effects the torque
     
    #17
  18. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    bolt

    If you have an RCD bolt it is not designed for that amount of torque. I think most of the people going to 400 lbs are using a grade 9 bolt with some sort of conical flange bracket that the crank bolt goes through the flange that bolts to the pulley. RCD's design just bolts the hub to the crank, it does not pass through a load spread flange. I have snapped an RCD bolt off before trying to get that kind of torque on it, but it was an older bolt. I haven't tried that on any of their newer stuff. I would call RCD to check their recommended torque.

    I think with that kind of torque it is going to have to be a grade 9 bolt - anything less might be stretched past yield.

    The bolt tightness is mainly to try to keep the hub from galling. The splined deal kind of eliminates that. With my splined stuff I just run it down with an impact.
     
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  19. Mike Kern

    Mike Kern Member

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    Slack was maybe not the best term to use. There is a certain (loss of) stiffness in the belt that needs to be overcome before the torque is transferred through to the opposite pulley. What that exact number is, I do not know. It can best be illustrated on a dyno by using 2 different type, style, stiffness belts on a supercharged (typically) engine and measuring the output torque at the flywheel. There is known to be a VERY distinct and measurable difference between types (brands) of belts. If you were to drive the supercharger with a gear that loss seen would be much lower. The same is true for FWD transmissions that use a chain instead of direct gearing. There is a bigger loss of torque across the chain than there is gear which is much stiffer and can transfer the full load to the driven object. The best way to transfer torque is through an infinitely stiff connection. This is not possible in real world. So therefore, in the theory for tightening the crank bolt. You could theoretically tighten the bolt using that method, but you would need to know the loss associated with the belt (and any other connections, i.e. ratchet extensions, etc.) and then add that to your torque setting to get the proper torque transferred to the bolt. There are just too many unknowns to trust that type of method.
     
    #19
  20. Mike Kern

    Mike Kern Member

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    Will, maybe for TA stuff you can get away with that, but on TF stuff you want/need the max achievable load. Do you guys use counter-bored crank snouts with a long bolt or do you still use a short bolt?
     
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