Truck suddenly stopped pulling

[telsrt]

So I'm going down the road @ 45 mph and suddenly my transmission quit pulling and my accelerator goes all the way to floor and sticks @ 5k for a few seconds until I turn the truck off. When I try to restart my truck only the starter ( the starter is only 1 1/2 month old) will spin and the engine won't move at all and I have no idea what happened. I'm baffled by this as in all my years ( I'm 61 years old) of driving and working on cars I've seen or heard of this happening. Anyone else ever had this to happen and if so what was the cause? Truck is a 1996 Ford Ranger 4.0 with 4 speed automatic and the transmission has always changed as it should with no slipping. BTW it did develop a bad vibration just before this happened. It only has 139k miles on it.

 

[Snoranger]

First guess... broken flex plate.

 

[RonD]

Second guess, broken flexplate

Also 3rd and 4th guess, so.......................................thats what it is

Flexplate connects crank shaft to torque converter, which is why you stopped moving forward when it broke
Flexplate also has the Ring Gear on it that the starter motor spins to turn the crank, but its no longer connected to the crank

Picture of what it will look like when transmission comes off: https://www.explorerforum.com/forums/data/attachments/8/8050-e31f5d3d2c0dc870c7fe07545d07307d.jpg

Ford changed the 4.0l Crank in 1997 from 6 bolts to 8 bolts to try and prevent this, while it wasn't "common" it was a known issue
You will, of course, have to put in another 6 hole flex plate unless you want to change the crank

Make sure the alignment dowels in the block are in good condition, these center the crank and trans input shaft so less "flexing" on the flexplate

 

[telsrt]

Well I was thinking the same thing while talking to my buddy at least now I know for sure where to start, not going to pull the transmission anytime soon though as we are having rain in the forecast and my health isn't what it once was when I was younger. Thank you sir very much for the assessment, i've worked on car since I was a kid and never saw this before today.

 

[adsm08]

While replacing the flex plate also make sure to replace the spacer. It is a cheap part that can get damaged during the initial failure and cause repeat failures in the future.

 

[telsrt]

Can't find any information about a spacer on ebay or amazon, I've already ordered my flexplate for it though.

 

[adsm08]

Can't find any information about a spacer on ebay or amazon, I've already ordered my flexplate for it though.

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Second hit on my Google search.

 

[telsrt]

Thank you very much for the link, I got it ordered.