The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by 57JoeFoMoPar, Feb 20, 2020.
I forgot about this one:
Well, you can go with speculation, or you can go with evidence.
^^^And what was the outcome with the shipper?^^^ I am Butch/56sedandelivery.
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 .
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.
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!
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.
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.
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.
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.
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.
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Our track is still shut down Bones. We are all looking to get back...
My 67 Nova sits real low, I built this tubular crossmember with exhaust pass through to address the exhaust routing/clearance issues.
I hope Bonneville is going to happen this years. We have big plans to attend, for the first time!
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.
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.
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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.
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.
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.
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.
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.
No tail shaft mount , 55-57 Chevy trans , manual or auto .
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?
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