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Lets discuss the solid motor/tranny mount issue again

Discussion in 'Center Of Gravity' started by Mudzer, Jun 22, 2004.

  1. Mudzer

    Mudzer 1/2 ton status Author

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    Im in the process of swapping over the motor/trans/t-cases over to my new frame and have these Moroso solid motor mounts setting here.

    Im inclined to install them, then solid mount the t-case as well.

    Would you guys box the frame between these two mounts to help stiffen it up? Give me your input.

    I dont want to destroy an expensive 700R4!!! /forums/images/graemlins/thumb.gif
     
  2. miniwally

    miniwally 1/2 ton status Premium Member

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    I firmly belive in the run similar stiffness mounts theory.
    Run the stiff motor mounts and then run a stiff transfercase mount. Not solid unless the motor is mounted solid.
     
  3. Pookster

    Pookster 1/2 ton status

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    if your gonna do something hard, make it all hard. /forums/images/graemlins/rotfl.gif

    Engine, tranny, transfercase.
     
  4. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    FWIW, I have run the Moroso solid motor mounts and polyurethane t-case mounts for years with no problems. Looking back I may have simply been lucky since I mostly run in the mud. I'm building a K5 now and (being older and wiser) my plans are to run the ORD motor mounts along with polyurethane t-case mounts.

    BTW - over the years, I have had 3 sets of the Moroso mounts and they all developed cracks.
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Having just broken my trans, I'm no longer confident in my views on mounting.

    However, if your going to stiff/rigid mount the trans and engine, I think you are on the right track and MUST make the frame rigid between them or risk a high probability of breakage. Problem is, if you make that section of the frame rigid without doing something about the rest, you will risk a high probability of breaking the frame. That rigid section is like clamping a piece of wire in a vice and then wiggling the piece sticking out. It's going to work against the rigid (boxed) area and fatigue. As I've said before, IMO, if you are going to start trying to make any of the frame rigid, you must do it all. It's an all or nothing proposition. Anything in between is going to cause problems.

    To me, the main point of focus would be the suspension mounting points. If you can lock them in with respect to each other, the rest takes care of itself. For instance, if you had a space frame cage/body that had mounts to the frame at all 8 suspension mounting points (assuming leafs) then the 3D rigidity of the cage has pretty much stabilized the frame from articulation induced flex. At this point, boxing the frame is probably just adding weight for little or no benefit, and the stiff/rigid mounts would likely be just fine.
     
  6. TorkDSR

    TorkDSR 1/2 ton status

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    Am i wrong in being concerned that the flex will be distributed to the aluminum case?

    cast aluminum doesnt bend very well...
    and eliminating frame flex would seem futile.
    are there benefits to this i dont see?

    edit: this was posted before i saw
    that response /forums/images/graemlins/tongue.gif
     
  7. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    BTW, partially boxing the frame would still let the 2 sides move into different planes (basically, articulate with respect to each other) due to frame flex in the overall ladder frame. Assuming the 4 corner points of the square start out coplanar (basically, assuming the frame is not already warped), then just plating that portion of the frame rails between the cross members/mounts is of little benefit. It is not necessary for the sides to flex in order for the 4 mounting points to move off the common plane. In order for this to do any good *at all*, you would need to make the box formed by the motor mounts and trans cross-member(s) almost completely rigid in 3 dimensions, and I don't think that is possible without a space frame like I suggested. And *with* a space frame, the boxing is unnecessary (at least for this purpose).

    This is basically why I thought a 3 point system would be best since there is no way for three points to NOT be coplanar, so there is no chance of mechanically twisting the assembly due to frame flex. Unfortunately, torque loads due to bouncing are much higher than I realized and that (I think) is what broke my transmission.
     
  8. jac6695

    jac6695 1/2 ton status

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    I am still not sold on the idea of solid mounts. I have had my 454, TH400, and Gen 1 Doubler now for about 5 years and haven't broken anything in the drivetrain. I have rubber motor mounts, poly transfer case mount (1, under the 205) and the old school side mount to the frame with new rubber in that. I have beat on this combo A LOT and even have a repaired 205 adapter that has a small crack and hasn't spread. Maybe I am lucky, and a TBI 454 isn't much, but with all that I have done with a 5600-6200 lb. Blazer, it has held up. Besides rockcrawling, it has been a tow vehicle (Timmay would NOT approve /forums/images/graemlins/wink.gif), truck pulling and drag racing.

    With all of that said, it seems that most people break TH350's and 700R4's, which does concern me going to a 4L60E. I think I will replace all worn rubber and stick with the same setup and add another crossmember under the 203 for more support. I don't think making an aluminum transmission case rigid with the frame is a good idea, and I think a lot of weight needs to be added to a stock GM frame to stiffen it enough to reduce the stress on a solid mounted transmission, and weight is not our friend. /forums/images/graemlins/hack.gif
     
  9. BlazerGuy

    BlazerGuy 3/4 ton status

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    [ QUOTE ]
    Besides rockcrawling, it has been a tow vehicle (Timmay would NOT approve ), truck pulling and drag racing.

    [/ QUOTE ]

    Not to mention random power braking.... /forums/images/graemlins/whistling.gif
     
  10. miniwally

    miniwally 1/2 ton status Premium Member

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    [ QUOTE ]
    it has been a tow vehicle (Timmay would NOT approve )


    [/ QUOTE ]

    Your' lucky to be alive. Never ever,evver,evver,evver tow with something like that. You will die in the future if you tow with a setup like that. Remind me to stay off the road any time you are towing. /forums/images/graemlins/whistling.gif

    TIMMAY /forums/images/graemlins/bow.gif
     
  11. BlazerGuy

    BlazerGuy 3/4 ton status

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    Your one to talk, I saw your tow rig! What the hell are you thinking endangering everyone's life towing with that pickup? I'd recommend you step up to a Peterbilt, Kenworth, International etc...just something that can handle all that weight!!! /forums/images/graemlins/histerical.gif
     
  12. BlazerGuy

    BlazerGuy 3/4 ton status

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    Oh, and to keep us on track....I ordered some motor mounts from your brother this morning, so I'll post up with some pics of 'em.... /forums/images/graemlins/waytogo.gif
     
  13. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    I know this isn't new but you have 2 things to do with the mounts:
    1: keep the motor from twisting off the back of the trans in high range when it's trying to torque against whatever you use for a t-case and mounts.
    2: keep the t-case from twisting off the trans from it's multiplied torque when you're in low range.

    Solving problem 1 brings us to stiff motor mounts, either tough poly or solid.
    Solving problem 2 brings us to stiff t-case mounts, either poly or solid.

    You really want the drivetrain to rotate as a single module so I recommend using the same stiffness front and rear.

    Cramer, you probably get away with it because of the side mount on the 205, that makes the t-case mounting system pretty stiff, which probably matches up to your motor mounts pretty well.

    Neil, if you're going to mount one solid, mount both solid, but you better not get any frame flex.....
     
  14. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    Neil, if you're going to mount one solid, mount both solid, but you better not get any frame flex.....

    [/ QUOTE ]

    Exactly. And because I think it is impossible to control frame flex sufficiently to cause this to never be an issue, I would never run all solid.

    Maybe solid mounts at one end and poly at the other to take up the slack, but solid everywhere? No way. I think that is a very bad idea.

    There is no way that the cast iron engine, mild steel frame, aluminum transmission/adapter and cast iron transfer case will always flex the same amount and the same direction.

    That is why I think that it is absolutely essential to have at least one mount that is soft enough to flex.

    I may catch flak to this but I think I am definitely on to something. As to the ideal mounting, I will not comment at this time.....but I will say that I don't think solid is the answer.

    If it was a perfect solution I'd certainly do it though.

    Baddog,

    I would be willing to bet money that you breaking your transmission was based on another factor besides mounting. Once again, I may catch flak for this, but there are a number of forces that play into what may have broken your tranny, and I would put mounting way down on the list.
     
  15. Mudzer

    Mudzer 1/2 ton status Author

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    [ QUOTE ]
    Neil, if you're going to mount one solid, mount both solid, but you better not get any frame flex.....

    [/ QUOTE ]

    Anybody want to buy some Moroso motor mounts? /forums/images/graemlins/doah.gif
     
  16. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    [ QUOTE ]
    Neil, if you're going to mount one solid, mount both solid, but you better not get any frame flex.....

    [/ QUOTE ]

    Anybody want to buy some Moroso motor mounts? /forums/images/graemlins/doah.gif

    [/ QUOTE ]

    My point exactly. And no. /forums/images/graemlins/thumb.gif
     
  17. miniwally

    miniwally 1/2 ton status Premium Member

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    Tim I have eliminated frame flex.
    Stephen has eliminated frame flex..
    Beck has eliminated frame flex.
    There are more here that have eliminated frame flex.
    Please explain how we didn't eliminate frame flex with a well designed cage.

    I think you need to understand cages and triangulation better.
     
  18. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    It's not clear from the way it's worded, but I think he is talking about your typical truck/K5 with cages you would find in something like that. Once you go to buggy/truggy it's certainly possible to almost completely eliminate flex with a well designed cage. But in general, for most on this site, even for many of the truggies, it would not be a viable solution.
     
  19. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Exactly.

    I think it's do-able on a buggy but not in a full bodied machine and not in hardly anything with a stock frame in my opinion.

    The stock frame is engineered to flex and unless you completely re-engineer the frame (incorporating your cage into that) it will flex and break something eventually.

    On a buggy I think it's certainly possible but I personally still wouldn't try it.
     
  20. jimmy88

    jimmy88 1/2 ton status

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    [ QUOTE ]
    I know this isn't new but you have 2 things to do with the mounts:
    1: keep the motor from twisting off the back of the trans in high range when it's trying to torque against whatever you use for a t-case and mounts.

    [/ QUOTE ] Not trying to be a dick, but I still don't follow this. The torque in high range is two to four times less than in low range and well within the stock adaptor and cases' design parameters. Are the cases somehow only capable of handling the torque in one direction of rotation? Seems unlikely. On the other hand, the thought of running trails with all that engine weight being violently bounced around and having the side to side motion of all that mass restrained by the tcase mounts is another story. So when your talking about using the four point mount setup, is it the torque or is it the inertia of the engine mass thats most important for the motor mounts to control?
     

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