I recently swapped from a 200I6 to a 250I6. I kept my original rear, drive shaft and c-4, just swapped out bell housings. I reinstalled my drive shaft and it looks like too much sticks out of the transmission. I'm pretty sure it was like that before but not positive. I did a search and found that 70 -72 6 cylinder cars had a drive shaft about 1" longer than 73 and up. Does anyone know why? I think the longer shaft would fit my car better and I believe I have 2 of them in the yard. Was thinking about changing it out.
That's the amount that should be sticking out of the tailhousing. The shiny part exposed is the amount that slides in as the suspension geometry changes. Without that freeplay, you'd have massive problems as the yoke bottomed out on the tailshaft.
The only difference in length is 2 or 4 door and if its a 6 cyc or V8. So, what you did wouldn't change the length for the drive shaft.
First off. Is that the exposure with ALL the weight off the rear tires? IOW.. at full droop? If not?.. then I'll just speak my mind here and leave it at that. IMO.. that sure looks like a bit too much exposure for my taste. Not major.. and it is just a 6 in a light car(no offense, Don).. but that's surely farther out than all the other Fords I've ever owned. And.. farther out than necessary can cause the rear seal to wear out prematurely from slight wobble(which may not even be noticed from a vibration standpoint) and also wear out the internal bushings/bearings at accelerated pace. Another way to look at it is that these things don't fit extremely tight to begin with and less seating depth means more lateral movement between the two machined/splined surfaces. Don't believe me?.. stick a jack under the front yoke and watch for changes in movement at various depths. To go even further with that test.. disconnect the rear universal and measure the slop at various depths. It DOES change and less is always better up to the point where we need sufficient clearance to avoid bottoming out the shaft or butting against the housing under heavy loads/acceleration. Before deciding if it's an issue worth fiddling with.. I'd figure out how much out of the 5" or so of available tail shaft real estate that the driveshaft has covered over the tail-shaft as the best indicator. Be sure to figure the 1/2" or so of tail shaft that sticks out past the housing and add it to the amount that the driveshaft engages past the seal to come up with the number. And FYI.. a driveshaft doesn't float in and out over 2" under heavy throttle to warrant that much exposure either. 3/4" - 1" is about all the shiny surface I ever see on any cars I've ever owned. 4x4's?.. well, that's another story. Regardless of what anyone here says or thinks.. the proper way to measure stick out is to remove the rear and slide the slip yoke as deep as it will go(be sure to clean it first so the seal isn't contaminated/damaged).. mark it.. and reinstall the rear again. Measure the difference from the mark.. be sure to add that 1/2" of tailshaft exposure past the housing end.. and you have your measured stick out. In fact.. I just went and looked at my Comets driveshaft and it's shiny almost all the way to the yoke itself. Now, while that's a bit too much towards the other extreme for my taste.. it clearly shows the 3/4" or so of typical travel("wear area") caused by the seal riding along the shaft.
The pic was with full weight on the wheels. That question caused a light bulb to go off in my head. The car was jacked up when I installed the drive shaft which I suppose would make it look even worse. After I took the pic, I actually thought to myself "that looks like normal".
If that was with full weight.. then it will only get worse on full droop. I wouldn't run it like that for very long and would swap to another slightly longer shaft. Especially if I had spare parts laying around. Which brings up another idea. Why don't you just compare this one to the others to see what the difference is?
what is the yoke length compared to the others? some yokes are longer than others... do all of your shafts have the balancers on them?
