Warren928

Thanks for answering that. If we could change out for stronger or modify/forge harden the splines so they could handle it, maybe that's a possibility?
I've seen similarly shaped splines on a Range Rover Classic front driveshaft,with 155k miles, no wear and no play, just grease now and then thru the fitting and it's good to go.

The style I have seen has no clamping needed, the housing has no clamp gashes on the sides, it's simply a spline housing that is slightly larger than the shaft, enough to compensate for heat expansion and lube.
Holds the torque just fine and allows for in/out motion so no thrust bearings get damaged.

atb

Regarding the Range Rover V8:

The final version, used in the Range Rover, produced 222 hp (166 kW) at 4750 rpm and 300 ft·lbf (407 N·m) at 2600 rpm.

What would cause the most stress in daily driving, pullng out from a stop or hard acceleration from a roll? The HP is down on the Range Rover, but the torque is definitely there. Maybe a slip fit system would work?

Warren928

I am hoping that some good idea of mine will result in someone else making them and saving a whole bunch of 928's from engine failure. I wouldn't want the responsibility of setting up something like this for production. There are many good men on here who can and maybe should think about it.

Machined from high strength steel or Titanium and then swap out the old style for new.

Could the flex plates keep twisting until it fails, if the torque shaft is not locked into place? If that is true, that complicates things. But maybe some type of flex plate reinforcement exchange product may help keeping that from happening.

Mrmerlin

Maybe this might be an option .
If you think about German engineering they have a tendency to over complicate things.
That said I wonder if making a solid female slip fit collar would be a viable option,
they do have sliding splines in truck and car driveshafts but the splines are considerably different.
IE more square in profile

BrianG

For sure, walking splines are different than clamping splines in profile, and quite likely in metallurgy as well.

Z

I don't know about the paint on there, but to me it looks like the shaft has pulled out of the clamps. All of the ones that I've seen had less length of splined area showing when there was no pressure on the flexplate.

Here's a picture from Tony Harkin:
http://members.rennlist.com/v1uhoh/pinch.htm

Here are a couple from Bill Ball:
https://rennlist.com/forums/928-foru...xperience.html

All of the ones that I've seen in person looked basicaly like those pictures of Tony's and Bill's in regards to the amount of splined area showing when there was no pressure on the flexplate from the shaft having pulled out of the clamp. The pictures in the first post of this thread appear to have more splined area showing, and look like all of the ones that I've seen that had pressure on the flexplate, before the clamps were loosened to allow the clamp to slide back on the splines and relieve that pressure.

The ones that I've seen have all been on S4s. Maybe the '85 is different? Based on my experience, a quick glance at how much splined area is showing would have me immediately thinking that the shaft pulled out of the clamp(s).

PorKen

In the 'before' shot (first pic), it looks as if there is too much spline showing. As if the fast shaft was pulled too far back before it was tightened. Or the rear clamp was released long ago with a preexisting preload at the front. Perhaps the rear clamp had trouble holding in this position?

I think this is typical:

Landseer

Looks like my 85 & 86 in terms of length of splines visible. Both are using PKlamps. Normally aspirated though.

Cosmo Kramer

Now that I think about it, I think I may have loosened the rear clamp without relieving the preload. If this was the case, then the shaft could have moved forward a few mm in the slot once some torque was applied.

Z: The front did not move for sure. I spray painted it and it was the exact same spot as when I put it together. I followed Ken's directions for the front.

I am going to pull the rear pinch bolt to see what is going on back there and report back.

Mrmerlin

make sure to remove the front pinch bolt first before you remove the rear bolt

Cosmo Kramer

OK, removed the front clamp bolt completely and then took out the rear bolt. Came out nice and easy, after I wrenched it I was able to take it out with my fingers and it fell right out. It had to be pre-loaded last time I torqued it because last time it was binding in there really bad, I couldn't even pull it out.

Going to get 2 new bolts and torque them to spec and see how it goes. Any recommendations on the rear? Just put it in and torque it and then follow the PKlamp procedure on the front?

Mrmerlin

When you go to install the rear pinch bolt ( do this one first), make sure the drive shaft is centered in the input shaft of the trans.

Note the rear clamp will turn on the input shaft so you may have to stick a screwdriver up to position it.
If the new bolt doesnt thread in cleanly then use a tap to chase the threads of the clamp,
Then install the new bolt with some blue loctite torque to 66 ft/lbs.
Once this is done then proceed to the front clamp,
you want to pry the crank to the rear of the car first.
Then install the clamp bolt with the loctite and TQ to 66ft/lbs
Follow PK clamp install procedure .

blown 87

You guys are playing with fire, a very expensive fire.

Cosmo Kramer

I know I did, definitely shouldn't have loosened the rear bolt when it was loaded up. Now that I know how to do it properly, won't happen again. I am just glad I only had a few mm of preload, when I first checked the car in the spring it had double that. Thank god the thrust bearing is still on the tight side of spec.

How do I know when it is centered? Can I tell by looking through the bolt hole in the clamp? The bolt threaded out nice, so the clamp threads are good and the bolt is sliding freely inside the rear groove in the shaft.

Bolt is straight but has a couple of scars. The shaft definitely slipped in the rear clamp and the bolt stopped it from moving further.

Gregg K

I know this is OT, but I just want to chime in and say how much I appreciate what you all are doing here on this forum.

I bought my 89 GT several years ago, and have put almost zero miles on it. I've also been quite inactive as a mechanic for some time. Only backhoe repairs, which are limited to hydraulics mainly.

So as I have my oil pan off, I did a quick look at crankshaft play a week ago. But it wasn't until I started reading this thread that I remembered the dreaded thrust bearing issue. And a special thanks to Merlin for his thorough understanding of the 928 driveline system. I now know about the clutch force on the bearing. Well, I just freaked out because I was sure the play I saw last week was at least 20 thou. So I just crawled back under the GT with a mag base and dial indicator. 0.007 inches. Yaba daba doo!

I now return you to the thread at hand. Carry on...