I have... Thanks for the responses guys. The physics involved in these machines just boggles my mind. I really enjoy looking into what goes on behind the scenes in our cars and learn what I can along the way...:Handshake
The friction between the converter and the flexplate carries some of the load as well. Plus, the bolts are on a pretty big circle, so that also decreases their load. That's why you need 6 5/8 bolts to hold the flex plate to the crank, but only 4 3/8 bolts to hold the converter to the flex plate. How's that for mind boggeling?
Scooper, Imagine two electric fans facing each other...or better yet a fan facing a pinwheel ( like I had as a kid)(am I dating myself?? ...........How the convertor works is you turn the fan on( the engine spinning the torque convertor) the "air" (tranny fluid) that is being blown at the pinwheel will cause the pinwheel to spin( the other "half" of the torque convertor that spins the shaft in the tranny) there is'nt a "direct bolting-up" of the engine to the trans through the convertor. That's why you hear of stall speeds, which is basicly the speed (RPM) that the first fan starts to spin the "pinwheel"
Not to worry, the u-joint is transferring the force, the bolts just keep it from slipping out of place. They are mostly under clamping force. I'm not an expert either, but I did stay at a Holiday Inn Express last night*.
just think about all that stuff when you hold the trans brake.... hammer the pedal, its bouncing off 6 grand and then you let go of the button
You misunderstand. I was not accusing anyone of anything, but this is not exactly my first rodeo and I've seen discussions like this go from zero to stupid very quickly. My post was what you call preventative maintenance...
I'd advise one to absolutely NOT think of all that with the transbrake on and the foot to the wood! hehe
it's not JUST the bolts that keep everything put. The bolts are tightened up, which pulls the converter tight against the flexplate. The bolts are usually about 24 pitch threads, and at 40 lb-ft, the tremendous force that pulls the flexplate and converter together creates friction between the converter & flexplate. Kind of like holding both of your hands together tightly--the harder you push them toward each other, the harder it is to move them across each other. Besides, if you think about it, if you have 400 lb-ft of torque and 4- 3/8" bolts, it really isn't that much force. if it's a 3/8-24 bolt grade 8, it has around a 75,000 psi shear strength. And there's 4 of them so that's 300,000 psi of shear strength. I'd be more worried about the flexplate being ripped to shreds before I'd worry about the bolts. As if that wasn't enough--keep in mind that GM used 3 bolts forever (and they still do) and rarely do they have failures. Mine has 3 bolts too....all of them are 7/16" though.
The Shear strength of a grade 5 bolt is 34100 psi or 3766 pounds for the bolt in single shear conditions. (like a flex plate and converter.) More than enough to take the loads of an engine with 500 ft lb of torque at 6 inches from the center - which would be 1000 ft lb of force. This assumes no clamping force but no play or impacts. If you add in the clamping force of 4941 pounds with a properly torqued bolt the force required to initiate shearing force is considerably higher. The 3/8" grade 8 bolts or studs have a very high level of safety margin built in.
