RWD and Powerglide? ? ?
;)
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RWD and Powerglide? ? ?
;)
I'm a firm believer that when one decides to "stir the pot" it is better to use a boat oar than a coffee straw.
Thanks for that explanation. I think see what you're saying there. How much force is put into the attempt at twisting the diff perpendicular to the axis of the axles? I would think that the snout of the diff would be a pretty good distance to counteract that with no problem? I could be way off as I'm like a child walking into the middle of a movie...
I really don't know why people would add all the weight of the scatter shield and not add a little extra to make it structural for the whole end of the case that seems to keep failing. I have wondered about how I kinda cheat and remove at least 1 block bracket to bell housing on some of my 3.0's (front usually) and on a high output setup, thats probably a bad idea.
BTW, how is all the shockload that transfers into the stock location rear mount playing out? I would tie scatter shield into that hardpoint instead of using the case to carry all the load.
I would love to know the forces of push out. Even straight cut gears have radial forces pushing the gears apart
The added scatter shield weight is appreciated by my nuts having run only prototype clutches in the car for 15 years and more than half of that without one.
Rear mount (and all mounts) are solid so nothing moves, but I too have wondered about the forces. Need to sketch of a free-body diagram... is DJ board at work this week? :eyebrows:
Pulled the trans out of the Z today. Looks like some cracks in the same general area but more by the case and not in the diff area. The cracks are flush so I might try to weld them shut then gusset the crap out of it...
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Is the engine/tranny mounted solid? Are you still using the bobble strut bracket? Is that mount solid with no bushings?
I'm a firm believer in rubber mounts. my engine moves a good inch or so and I truly believe that it's part of the reason I never broke an axle beside being an auto. my left axle is a stock L body from NAPA that's been in the car for 17 years. another added bonus, my car dose not shake like hell at idle. on a RWD you have a few places that take up the shock. FWD is a hole new ballgame.
You can get away with this as long as the suspension works in such a way that the angle on the joints and shaft aren't all whacky. Most people don't get that right (and it's not easy with things being that dynamic), so they find that limiting movement is the better choice for them.
There's nothing wrong with that, but as you said things start vibrating more. This brings fatigue. I'm wondering if what we are seeing is partially a fatigue stress failure as well as a strength through design failure? We are talking about aluminum.
Yes, solid using stock mounting points that were originally designed for rubber. Have been thinking about a motor plate like Warren Stramer uses
I'm sure the rubber damps it some. I'm guessing the automatic pre-loading everything is the biggest help. You are right about needing some place to take up shock and right now its really only the clutch and axles. Twin disk clutch not so forgiving LOL
I didn't get that far, need to draw free body diagram to figure out vectors / direction of forces.
In other news, upon disassembly, this case is cracked almost all the way thru so gonna use a different Trans.
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Damn! Sorry about all the trans trouble you're having. I hope to see you at the Nats again this year.
Looking at your pics earlier I was wondering if the stress riser is at the base of the threaded hole for the selector bolt. The ones you just posted suggest this even more. Do you have an old broken case you could cut up to see how thin it gets there?
As for the bobble strut it would be a good idea to move. It only adds stress into the case that doesn't need to be there. I would try to build something off the bolts that hold the tranny/engine reinforcement plate at the back of the engine. I have hard time believing it will solve your failure issue as I don't think it has anything to do with it but it will remove some stress.
Interesting, I think the latest crack is taking the shortest distance thru that section. I have some old cases, just need some sawzall action...
Played origami tonight... think cardboard covered with JB Weld is strong enough? ;)
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I wonder if it is adding to it DJ. When the engine rotates backward, the bobble strut bracket is transferring the force in a counter clockwise rotational direction. That part of the case would see those forces, plus the typical gears pushing apart, the ring & pinion trying to side step each other and finally the "way over stock" HP & torque he sends through it. Add that this area is less reinforced than the 555 and my feeble understanding of force vectors, it looks like all added up are causing the issue. If one or more can be lessened and reinforcement added, maybe it will live longer.
Then again.......LOL.
The backwards rotation should put that area into compression. Compression doesn't generally produce fatigue cracking but as you said it does still remove stress that doesn't need to be there. Without doing some FEA on the part it's hard to say anything for sure.