Driveshaft Design Problem

pokeyl

Now that I "made you look", Nissan has boned me (us) again. The 370 has IRS and as such no movement in the relation from the trans to the differential. The result is you only use a very small number of the bearings in the "U" joints.

If you remove your drive shaft and inspect it; you will find a flat spot as you move the bearing around; it should be smooth as you move it; it will not be. I have no play in my shaft at this time but it is the start of failure.

Also the drive shaft is "Not Re-buildable" you have to pay Nissan $1500 for a new one. I am working with a master tool and die maker (friend) to see if the factory shaft can me made re-buildable. The cost, TBD, but after I will be able to change the "U" joints like any other car. I will out of town for the next 4 months, so the project will start in Nov-Dec.

We may be able to lower the aft trans mount and induce some movement in the drive shaft and allow the bearing to function normal, same at the differential mounts. It only takes 1 to 2 degrees and the flat spot issue should go away. The trade off is a very small power loss?

This is why some cars need drive shafts after only 12-15K miles and the harder you hammer the drive line the sooner the failure.

Please let me know if you have had to replace your drive shaft or have a noise/vibration the dealer has not been able to pin down.

You can check the rear "U" joint by removing the 4 bolts at the differential and slide the shaft forward into the trans as far as you can. Now you should have room to move the rear bearing and feel for the flat spot.

I found all this during my triple disk clutch install, along with some calls to drive shaft shops. I have been looking at after market custom shafts as well. I am at 65K miles now, 40K are SC 480-500 RWHP.

Thanks for reading.

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