360 Axle Shaft for Differential - HOLLOW or SOLID? Which one do you have?

Just coming back from my usual 200 mile weekly trip in my 360 Spider, I felt a thump as I backed up into my garage. I put it into first (to test if it was my imagination) and it thumped again. I've always had a shudder on slow corners and various noises I've previously diagnosed as clutch or diff related, but after 12K miles this year, this one felt different. The next morning I decided to test drive the car to duplicate the issue and found myself stranded with no gears.

After placing the car on stands, I noticed the passenger side wheel was completely free spinning, indicating maybe a broken diff or inner shaft. A quick tear down of the CV and inner flange quickly revealed that the inner axle shaft connecting the diff to the flange (CV) was completely SHEARED! Snapped in two, right at the diff carrier!

In my typical "get my car back on the road by the weekend" style, I made some calls and found two part numbers (185013 and 199055), both requiring a special order and a 3 week wait. Luckily FerrParts said they have a low mileage one they will overnight to me. When it arrived, I noticed an interesting difference between the otherwise identical parts - the one installed in my car was a hollow shaft and the one sent to me was a solid shaft!

Turns out that two parts were manufactured for use in the 360 - one 185013 which was hollow and 199055 which was solid and used in 360, Maserati and the Ferrari Enzo. In fact, although no TSB or even an official supersedence was found, the area that sheared on mine was a weak point where the hollow steel tapers into the diff, whereas on the new one, it has solid steel at least another two inches out, giving it more structural integrity at such a critical point.

Getting the broken piece out proved to be a challenge, as it was likely cracked and deteriorating for quite some time. The piece was rotating slightly and digging it's own channel into the carrier just outside of the splines and as a result was acting like a ring clip, preventing me from pulling it out. After a week and a half of drilling, tugging, and sitting in the drivers seat making engine noises with my mouth, I finally followed the initial advice of Dominick (Flash), and pulled out the diff. After that it was smooth sailing (compliments of a small sledge hammer) since removing the diff allowed me to knock it out from the other side. This also allowed me to examine and clean the internals and reassemble with the new and IMPROVED shaft!

So now the car is back on the road and feels better than ever with more confidence on turns and launches.

Two things I learned through this debacle that I felt necessary to share with the FC community:

1. This is an obvious and widely unknown weak area for the 360. I'm not sure when the transition of part numbers occurred (my car is a 2001 Euro spec), but the change happened for a reason. If anyone has unusual bouncing, thumping etc., even on left hand turns, I'd check it out. Had it not snapped, it would have been a 1 hour swap - easy peasy. I'll post pics shortly showing the differences as they typically don't have part numbers on them.

2. If Dominick makes a suggestion, just take it. I was stuck on the idea of removing the broken axle without the removal of diff and while supportive, he continued to give me confidence that I could do it the right way and be a step in the right direction in repairing the car. He was right. Thanks again to Dominick for the continued help. He saved me an easy $30K over going to the dealer!

 

Here are the differences between the new and the old shaft. The old shaft is clearly hollow, while the new one is solid steel. Image Unavailable, Please Login Image Unavailable, Please Login

 

Haha never too much of that! Thanks again!!

 

Not sure where the part number is - I did not see one engraved and they had no factory stickers. If you remove the right CV, you'll see the depth of hole in the center without removing the shaft itself.

The really odd part is simply ordering this part is confusing because both part numbers correspond to the same location and transmission build numbers. The hollow one is around $500-$600; the solid one being double that, around $1,200.

 

The bearing will need to be pressed off. The "U-channel" seal will need replaced along with the o-ring. Both inexpensive parts.

Removal:
1. Remove CV/axle from the flange and push aside;
2. Remove the CV heat shield. The forward bolt is accessible from below while the other two are easily reachable via the engine bay.
3. Remove the Flange bolts holding the inner axle to the gearbox. These surround the Flange on a floating ring. I believe there are 4 or 6 10mm bolts.
4. Connect a universal slide hammer to the Flange and hammer out. This may require you to unbolt the upper control arms of the passenger rear wheel. Just 4 small nuts and no re-alignment is necessary as the bushings remain intact and in place.

Installation:
1. Slide in the new shaft, slowly rotating until the splines line up. This will slide right in easily except for about 1-2 inches. Then use weighted rubber mallet to hammer in the new shaft until there's about 1/8" space between the Flange floating ring and the gearbox. Then, align the floating ring holes with the holes in the gearbox and use the flange bolts to bring it in the rest of the way by tightening each in a cross pattern.
2. Reverse all steps in the removal process tightening to spec.

 

I don't believe there is much difference in weight, and any additional weight will be at the point of rotation so there really won't be a change in rotating mass.

You're car is likely already updated being such a new model and a US model. If you're ever down there, just remove the CV and stick your finger in the hole in the middle of the flange. If you can touch steel with the tip of your finger, you're good! If there's an endless abyss of space, then you have the old shaft.

Again, you have a newer car in production at the same time as other cars using the updated part, such as the Maserati and Enzo. So, you're likely in the clear.