Driveshaft rebuild

[wetminkey]

I believe that my '79 Spider's newly acquired horsepower (due to the recent 28/32 ADHA/dual plane intake to 32/36 DFEV/single plane intake manifold) has allowed me to fracture my 'pillow block' (AKA center support)! The center of the support and bearing have fractured away from the outer part of the center support.
Interesting that I rebuilt the driveshaft completely eighteen years ago with repro parts from Bayless, Inc., Marietta, Georgia. A great old vendor, long since gone,...
I believe that an ATF leak may have damaged the pillow block before I sealed the transmission a while back.
Front wheels on ramps/stands, wheels blocked. I used a center punch and my sledge to mark the rear axle flange and driveshaft flange with adjacent alignment marks before disassembly. I also marked the transmission output yoke opposite the driveshaft zirk. These marks will allow me to reinstall the factory balanced driveshaft in exactly the same position.
A pair of big 19mm combination wrenches did a nice job of busting loose the 51 ftlb torque on the guibo nuts/bolts (bolts and nuts are in great shape so I'll reuse them), and a pair of 13mm combinations made 'easy' work out of loosening the bolts/nuts to the rear axle (I'll replace all of the nuts, as they are kinda beat up,...bolt heads are nice).
13mm removes the 'safety' crossmember (just behind the transmission), and the 'pillow block' bolts. I then removed the center support crossmember with the 13mm and the whole driveshaft will then pass over the emergency brake cables,...and out the back. Guibo comes out separately,...so mark it if it's going back in.
I'm replacing guibo, center support with bearing, both universal joints, the center support crossmember grommets and bolt sleeves, and the rear axle flange nuts.
I slipped the tranny into neutral, raised one rear wheel, and rotated it to turn the driveshaft for bolt access,...don't forget the wheel blocks! And I put it in P and wheel down before I get back underneath,...
There's other threads covering portions of this on the forum, and a video, too. But this kind of sums it all up in one post.
I'll have more after I receive parts from AutoRicambi and make some arrangements with Northern Colorado Driveline Service in Greeley.
Todd.

[wetminkey]

Well, all would be good if the center support bearing had not seized on the shaft and gouged it terribly. The short end of the driveshaft must be repaired or replaced. About $400. New driveshaft is that much before shipping.
Anyone have a good short (front) portion of a driveshaft that they'll sell? I'm unsure if there is any difference in this part between the automatic and manual transmission applications,...
Thanks, Todd.

[AndyVAS]

The short front section is automatic only. Not a lot of those floating around.

[dinghyguy]

Todd,

Clearly this is the time to upgrade to the manual tranny......so much better control of all that new Hp!

cheers
dinghyguy

[wetminkey]

For cripe's sake, dinghyguy! I'm NOT selling the bug to be able to swap trannies, and I'll stick with the TH180,...it shifts faster.
But I just got done picking up my old driveshaft, and the diameter of the shaft that the center support bearing should be pressed onto is FAR too small! The U-joint splines are of a larger outer diameter than the shaft to the front of it. This does not fit a 1979 Fiat center support bearing, which presses onto a shaft of identical diameter to the splines OD!
But it is NOT gouged or galled,...it is factory turned to that diameter (no wonder that the driveshaft seemed to be "flopping around")! But it did not previously,...as if something broke loose,...??
I do not understand, but this is a GOOD forward driveshaft,...it just is NOT for a 1979 with auto. And I'm stealing the yoke for the flexible joint. I've got some investigating to do,...
Thank you both for your responses!
Todd.

[wetminkey]

Naw! I was wrong. With the magnifying glass, I can see the variation in the shaft diameter. I've got it all figured out, now.
The shaft should be 25mm to accommodate the center support bearing, but the old, seized bearing ground this to 22 - 21mm before the rubber tore, allowing the center of the driveshaft to "wallow" around.
Anyway, this forward shaft is toast (without some repair) and the new driveshaft I have coming is complete, other than the flexible joint yoke. I'll reuse mine, with a new rubber seal.
I'll have to recycle the rear of my old driveshaft to Aspen Import Autos in Denver. It would be the best place for the parts that are good,...
Got the call from my driveline service at 9 this morning,...I'm just glad to not be in a panic anymore.

[wetminkey]

So, what do ya do when all else fails? PUNT!
I have my tranny yoke nicely cleaned and painted black, ready for installation on the new automatic transmission driveshaft that should ship on Monday. Also coming is a new seal for the yoke (I doubt that I can get this old one off of the short shaft intact!).
With my old yoke (plus new seal) and new guibo, my Spider will have a completely new, balanced driveshaft from tranny to differential. A little more expensive than rebuilding the old shaft,...
It was such a great pleasure scraping the underside of the driveshaft tunnel and car,...but I got a couple of pounds of a material that's pretty much a combination of grease and dirt out of there! Wee!
Cleaned and polished my crossmembers to factory black (and replaced some fastener details on them) so they are ready to re-install,...just waiting for delivery, now.
I was kinda hoping to be driving it again, by now. Soon,...
All enjoy your weekend!

[wetminkey]

Driveshaft arrived today, is correct, and has all new parts.
The new seal that arrived is for the front end of the yoke,...and goes behind the tranny output shaft bolt. Mine is fine, so I'll not mess with bolt removal and re-installation.
The seal I was after is the one on the rear of the yoke,...it goes on the short shaft's front end and keeps the grease inside the sliding joint. Didn't think I could get my old one removed and placed onto the new driveshaft, but I wrapped a piece of thin, stiff plastic (postal sealing tape folded and stuck to itself) over the ends of the splines to expand the seal, and it slid right off with a twist. A little grease on the end of the new driveshaft's splines, and the plastic sleeve did a great job of re-expanding the ancient seal so that I could slide it over them! HA!
Re-installing the yoke has a bit more difficulty than just the "fiddle factor" I had been told about. First step of yoke installation gets you to about 1" insertion. I managed it once, and never got past that before pulling too far and it was off again. Decided to smooth the sharp edges of the new driveline splines and the end of the shaft, as they seemed to be catching the yoke. Sure enough, managed the first step pretty quickly (compared to my first try!) after filing, and with some wiggle and downward force by hand, the yoke advanced past 'step one' and onto the driveshaft end. The assembly will install easily now,...with the new guibo. Once I've greased the yoke's joint, I'll snap the old seal into place.
This should do the trick!

[wetminkey]

51ftlbs on the guibo bolts, 25 on the flange bolts. Crossmembers back in, guibo installation strap removed, and wow! A clean, tight, quiet, drive assembly!
Hope all of you are having an enjoyable, and safe, holiday weekend!
Todd.