Looking to get after a pair of seals – the pinion seal has a good leak, and the trans tail-shaft has a decent drip. However, I can’t get the driveshaft to move forward and into the trans enough to get it out. I get about 1/4” of separation in the rear u-joint – but looking at the front, there doesn’t seem to be much room before the yoke hits the rear housing. See pics. It’s a ’73, so 8.5 10-Bolt with a 700R4 and I have the rear at the lowest point, with jack stands under the frame. So, besides the how the heck they got the driveshaft in question, have any of you run into something like this before? Wouldn’t I notice some banging as the shaft bottomed in the trans? Could explain both seals going bad with relatively low miles on the trans and redone shaft. I don’t want to have to dig out my Sawzall if I don’t have to, so I welcome any thoughts!
Take the caps of the U joints. That will probably buy you enough space to get the shaft out. You'll need to have that shortened about an inch or so.
Try turning the shaft so the pinyon yoke is vertical and see if moving the joint so top cap is angled back and bottom cap is forward if it will drop out. But pulling caps should work.
You have the rear end hanging which is causing it to be at its closest point to the transmission. Jack the rear up to level with trans and then remove driveshaft
When your lower control arms are parallel with the ground your rear is at its furthest from the transmission
When you get it out you should check to make sure the driveshaft is the proper length. Go to Denny's Drive Shaft Service. Com and they have a page on measuring the drive shaft and the length it should be. Lots of good informative info on the site.
You can also remove the rear shocks that will give you more play and a jack under the pinion snout of the casting center, jack it up or down where every you need to go. Worse case remove a couple of control arm bolts ... You have to do what you have to do... Should be NO NEED for a sawzall lol Jim
Thanks all. I've jacked and lowered the rear suspension... didn't really help but I didn't measure the difference at the front yoke. The Southside Machine Bars might be hindering a bit. I have a pair of Dr. appointments tomorrow, but will get back at it in the afternoon. Vertical pinion yoke first, Caps first, then rear end bolts... Oh, I came across the Denny's Drive Shaft Service website last night when I was researching - have the Diagram B page already printed! I'll update!
The rear axle should be up,with the suspension under load,to remove the shaft. This makes the distance from the trans to rearend the furthest apart. Having the rear hang makes them closer together. This is also a sign that your driveshaft might be slightly too long and also why you are having seal leaks. I’ve seen this more than once.
So... it's out. Didn't get back to it until about 9pm tonight. Jacked the rear back up but it was still a touch too tight so I pulled off the caps, and wallah. The front u-joint is loose, the rear tight but has scoring marks under the caps... so it's definitely time for some attention along with the new seals. Side note, does the shaft with the taper look like an original? Something had to change, as from what I see, the 700R4 is something like 3" longer the the T-400. I didn't get a chance to measure much, but the shaft is 52.5" long without the 3.625" barrel length front yoke. Thanks again for all the suggestions!
The tapered shaft is an original. It might have been shortened or sourced from another car,but everything you mentioned points to it being too long. This can result in the leaks and other issues. With the rear up,suspension under load,and the yoke all the way into the transmission,you should be able to pull it back about 1.25” to seat the rear u-joint into the rear yoke.
While the rear diff may be slightly further away "under load", I can confidently say I've removed hundreds upon hundreds of driveshafts for normal service work on cars/trucks/suvs using a lift with the rear diff hanging and never had to bring the rear to ride height to remove the shaft. You need to get that shaft shortened by at least an inch.
So it looks like the current shaft is 52.5" long, and the distance from the trans housing to the yoke flange face is 53" - explains a lot. It appears to have about the shortest trans yoke out there at only 5.5" - with a barrel length of just 3.63" Yes, leaks abound. I have the pinion seal, need to order the one for the trans tomorrow. It's been in the car like this for a long time. And while I haven't removed anywhere that many, I've R&Red a few in my time - even have one ready to go back into my Mustang. Never had this issue. Going to finish up with all of the measurements needed from the Denny's worksheet, and then figure out a plan.
Just noticed this post...THIS is the reason your drive shaft is in way too far to the trans etc. The south side bars are shorter and will pull the pinion UP and moving the whole rear closer to the transmission. If you have time measure the bolt eyelets distance compared to the south side machine bars you will see the shorter distance in length from the stock. Jim
Hmmmm. The bars were on before the trans went in, but the shop used for the trans and install left a bunch of clues that their reputation wasn’t what it was cracked up to be. Very possible they wedged the original drive shaft in, or perhaps tried to get away with a shorter front yoke. Again, thanks for all the insights!
Jim, Not necessarily. I had a car with Southsides and it did not alter pinion angle or axle position. Some of the more recent knockoffs might,not sure. My guess is the driveshaft was not addressed when the 700R4 was installed.
What is the point of a south sidebar? All those aftermarket lift bars pulled the pinion up. That was the reason for them. Other than that they are just aftermarket boxed control arms. ?? I do not know...I always used the No Hop bars...Never like anyone knowing what was going on from a quick glance. More stealthy . Check them out anyway.
