Register now to get rid of these ads!

Technical Hanging trans off rear of engine? Rear mount/Mid-plate question

Discussion in 'The Hokey Ass Message Board' started by 57JoeFoMoPar, Feb 20, 2020.

  1. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,126

    gimpyshotrods
    ALLIANCE MEMBER

    I forgot about this one: IMG_20180210_104816.jpg IMG_20180210_104742.jpg
    IMG_20180210_104844.jpg
     
  2. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,524

    57JoeFoMoPar
    Member

  3. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,126

    gimpyshotrods
    ALLIANCE MEMBER

    Well, you can go with speculation, or you can go with evidence.
     
  4. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,214

    56sedandelivery
    ALLIANCE MEMBER

    ^^^And what was the outcome with the shipper?^^^ I am Butch/56sedandelivery.
     
  5. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,344

    2OLD2FAST
    Member
    from illinois

    Most anything can be subjected to stresses that they were never meant to endure , then when they fail , be held up as proof that they lack strength . a common 2x4 ,on end , can support a lot of weight , lay it flat between 2 supports , and it can easily be broken .AFA I know , transmissions aren't designed to survive being dropped .
     
    Last edited: May 24, 2020
  6. jimmy six
    Joined: Mar 21, 2006
    Posts: 6,336

    jimmy six
    Member

    That’s what our 1/2 mile dirt Super Stock looks like.. if you hit the wall hard enough the upper left ear will break.... it’s the only one.
     
    Boneyard51 likes this.
  7. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,009

    Boneyard51
    Member

    We got to race that car Friday night, fir the first time! We didn’t do so good. Broke a right front shock, in two, got plowed into while stopping to avoid a wreck! But even we we were racing, before the shock break, we weren’t pulling as good as the fastest cars. So it back to the shop, this week for some changes.Our car is legal, some of our friends car’s aren’t, and THEY were getting out run. Racing!






    Bones
     
  8. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,524

    57JoeFoMoPar
    Member

    Totally understood. I'm going to try to engineer a rear crossmember for the trans. I will certainly have to lose part of my current exhaust and go to a 2" pipe instead of the 2.5" pipes that are there. I'll probably have to figure something where the pipes to through the crossmember and a portion is removable to allow removal.

    the main reason I have this issue is because on these late 50s cars, they recess the floor pans to make up the seating space and leg room, so you've got a real small window of room to fit a crossmember and exhaust. Just going to take some head scratching time.

    Thanks for the replies everybody.
     
  9. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,126

    gimpyshotrods
    ALLIANCE MEMBER

    They claimed improper packing, which was exactly correct.

    That TH400 was loose in the box, and the box was loose on the pallet.

    Thankfully, my customer was understanding, and the vendor replaced it.
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,126

    gimpyshotrods
    ALLIANCE MEMBER

    That is not a GM automatic.

    If you break the transmission case on your race car, the tow truck comes out, takes it back to the paddock, and you trailer it back to your shop.

    What does the OP do, if he's at a car event, 100-miles from home, and he breaks the transmission case?

    Failing to plan for the worst is how disasters start.
     
    Last edited: May 24, 2020
    57JoeFoMoPar likes this.
  11. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,524

    57JoeFoMoPar
    Member

    You're 100% right. I drove this car to Canada last year, 400+ miles one way. I had a lifter collapse about 4 hours in and was too far to tun around. Made for an ass-puckering drive waiting for something terminal to occur, which thankfully never did. The whole point of this engine swap is to address the innumerable issues at once so that when it hits the road again, it's done for good. Setting it up in a fashion that risks terminal failure defeats the purpose.
     
    gimpyshotrods likes this.
  12. Fitnessguy
    Joined: Sep 28, 2015
    Posts: 1,362

    Fitnessguy
    Member

    Agree with Gimpy a hundred percent. I have front engine mounts on the 409 in my coupe. I fabbed them myself off of the general Hurst mount design. Then I have a rear tranny crossmember mount part of my Deuce aftermarket frame. I bought those mid mount brackets someone posted a pic of on here and I fabbed mid mount tabs that I welded into the frame that those mid mount brackets bolt to. So my engine/tranny is fully supported front, middle and rear. Each mount uses a poly bushing. Tranny is a B&M 700r4. With the weight of an old vintage mill I would not want to take a chance and don’t understand why even take the chance? Not a hard project to do.


    Sent from my iPhone using H.A.M.B.
     
    gimpyshotrods likes this.
  13. jimmy six
    Joined: Mar 21, 2006
    Posts: 6,336

    jimmy six
    Member

    Our track is still shut down Bones. We are all looking to get back...
     
    Boneyard51 likes this.
  14. DDDenny
    Joined: Feb 6, 2015
    Posts: 13,429

    DDDenny
    Member
    from oregon

    My 67 Nova sits real low, I built this tubular crossmember with exhaust pass through to address the exhaust routing/clearance issues.
    20181223_105933.jpg
     
  15. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,009

    Boneyard51
    Member

    I hope Bonneville is going to happen this years. We have big plans to attend, for the first time!





    Bones
     
  16. 73RR
    Joined: Jan 29, 2007
    Posts: 6,325

    73RR
    Member

    In general engineering terms, having three (3) sets of mounts can result in something getting bound up while the frame is twisting under load. This would include changing from a curb lane into a sloped driveway.
    Two mounts will simply follow the frame twist, three will not likely be happy.
    For those who had/have/use three mounts...congrats on your success.

    .
     
    Bearcat_V8 and egads like this.
  17. Fitnessguy
    Joined: Sep 28, 2015
    Posts: 1,362

    Fitnessguy
    Member

    Understand what you’re saying. With my three mounts, the poly bushings have enough size to them that they would easily allow/compensate for any frame flex.


    Sent from my iPhone using H.A.M.B.
     
  18. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,524

    57JoeFoMoPar
    Member

    So what about the stresses of running front mounts and a rear crossmember? It would seem like similar stresses on the bell just in the opposite direction.
     
  19. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,126

    gimpyshotrods
    ALLIANCE MEMBER

    An engine front mount, versus engine side mounts, puts that mount about 6-7" forward.

    Skipping the tail mount on a transmission, versus side bell mounts puts the mount about TWO FEET forward.

    All OEM applications that have a cantalever transmission have a transmission with an Iron case, and the race ones are steel bells, and most often Iron cases.
     
  20. I have run a mid plate/mount on race cars without a tail shaft mount. It used to be called "floating the tail shaft." more than doable in a 1320ft bandit. I know that some larger cars with pretty heavy transmissions (slant pan hydro for example) came that way. So I guess it is doable.
     
  21. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,524

    57JoeFoMoPar
    Member

    A good point. Even for the Olds Hydro that I took out of this thing, and even the 55-57 Chevy, the mounts came off the sides of the bell rearward of the mating surface with the engine, or in the case of the Olds, the bell housing is cast in as part of the block. Both reduce the amount of length of transmission cantilevering beyond the mounting point. Whereas the Howe/Mid-mount, mounts at the front of the bell rather than the rear, and maximizes the force on the bell mounting surface. Plus the Rotohydramatic had beefy mounting surface with 8 bolts going all the way around the mounting face, as opposed to the Chevy that would just have the 6 standard bolts. The area with the inspection cover is unsupported.

    I'll just have to put my thinking cap on and design something that is very low profile, and allows the exhaust to pass through, but also be very sturdy to hold up the rear of the drivetrain. Thankfully I'm going with what is a reasonably light drivetrain (a SBC and aluminum 700R4), and is easily 200 lbs lighter than the 394/Rotohydramatic that it's replacing.
     
  22. Most Chevys that are factory mid mount (front motor mounts and side mounts at the bell) have them cast into the bell housing and they use a cast iron bell housing that is pretty beefy. That is standard transmission cars and trucks anyway.

    I think where a lot of guys get themselves into trouble trying to float the tail shaft on their hot rod is that they are using a more modern aluminum automatic. So you got a 150 LB transmission being supported by an an aluminum bell (light casting) opposed to a 40 lb transmission being supported by a heavy cast iron bellhousing.

    *****This does not take into account the cast iron power slip that Chevy used prior to '58. I don't recall if it had a tail shaft mount or not.
     
  23. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,344

    2OLD2FAST
    Member
    from illinois

    No tail shaft mount , 55-57 Chevy trans , manual or auto .
     
  24. 73RR
    Joined: Jan 29, 2007
    Posts: 6,325

    73RR
    Member

    Given the weight of a 700r4 I would expect that it would survive w/o a rear mount, however, 'something' is always better than nothing...how about an over head cross member and support/hang the trans with something like a torque-limiting strap?

    .
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.