My 944 is F'ed.... how bad? Diff? Axle? Bueller?

Tishabet · 11-21-2008, 04:06 PM

Hi Guys,

Comedy of errors tonight, and now my 944 is broken down.

Driving on the highway tonight I heard a "pop" followed by the distinctive sound of something dragging. I pulled over immediately on the grassy shoulder of the highway, hopped out and took a look under the car. Sure enough, my exhaust had let go just after the connection with the cat. Fortunately I had seen this coming and had ordered a new Bursch cat-back last week, which should arrive next week. Pain in the butt to have the system let go, but not world ending.

I am well of the highway (all four wheels on grass) so I put the muffler our of its misery, and put the rusted hulk in the trunk. I start up the engine (dang that's loud!) and get ready to pull into traffic.

Here's where things go pear shaped

I see a break in traffic, gun the engine a bit, and begin to pull into traffic. I am really accelerating because it's rush hour and the gap is not big.

BOOM!

I lose power to the rear wheels (I am now going about 10-15MPH) and I pull back to the shoulder about 50 feet from where I began.

I am in first. The clutch is out. The engine is running. No movement.

I put the car in neutral and shut it off, then take a look. My passenger half shaft has sheered close to the diff, and it's hanging by the CV from the wheel. The driver's shaft appears fine.

75 minutes later I have the car in my sister's apartment's parking lot (I don't have a garage of my own and live in an urban area). Aside from the obvious broken half shaft, nothing appears wrong... but like I said, the car won't budge in any gear. If I put it in, say, 5th gear and let the clutch out there are no scary noises (or at least nothing discernable above the blasting exhaust) and the speedometer is indicating that I am moving at about 25MPH at idle. So I guess the driveline is complete to at least the speed reference sensor...

Does anyone have any idea what I should do now? I am confused by the other axle not driving the wheel... did I trash something in the diff?

I am seriously bummed right now. I have almost 60k miles under my belt with this car, and this is the first time I've ever broken down.

Thanks in advance to the Pelican brain trust!!

phoenix_iii · 11-21-2008, 04:27 PM

You're fine. If you had LSD you might have been able to get home.

If you have the open diff, which most do, the only wheel that spins is the one with the least resistance. That would be the one WITHOUT the axle. =)

Lastly, my volvo would about 15-20 in first in gear with the wheels off the ground. You're doing the same thing, except don't have the drive wheel connected.

[I am sure others will want pics/give you tests to perform]

Tishabet · 11-21-2008, 04:51 PM

I do not have an LSD... so this is normal for an open diff? i.e. I should be able to just buy a new half shaft for $200, install it and hit the road?

I know about body work, brakes and engines... that's about it

HondaDustR · 11-21-2008, 05:05 PM

Yeah, they'll do that when one side has no resistance. (didn't you have a radio controlled car when you were a kid?

)

Did the bolts shear or the actual shaft?

A new one should fix it right up. You'll just need a good 8mm (I think) 12 point internal socket tool to remove and install the bolts. It looks like a big torx bit, only with 12 star points, and don't try to get them out with an appropriatly sized allen wrench, which will fit, and will strip the head...don't ask me how I know. They strip too easily as it is with the correct tool.

Tishabet · 11-21-2008, 05:15 PM

It appears (from the light of the tow-truck) that the shaft itself let go... I think I can feel the other end inside the boot still attached to the diff.

I'm about to order a new complete axle from partsamerica. You guys are making me feel much better!

Dantilla · 11-21-2008, 06:27 PM

Why not order one here at Pelican?

http://www.pelicanparts.com/catalog/shopcart/944M/POR_944M_SUSaxl_pg1.htm#item0

Dougster · 11-21-2008, 06:46 PM

Wow, sorry to hear that, but not as sorry as I am to say I will be replacing mine as well...However I didn't lose mine in the dramatic fashion that you did. Mine is just giving me the clicking noise from the rear.

Yes HondadustR is correct its a 12 point hex head deal.

Two 89 944's as well...Lets hope they are both back on the road soon!

Dean924s · Dean924s's Garage

Quote:

Originally Posted by Dantilla

Why not order one here at Pelican?

http://www.pelicanparts.com/catalog/shopcart/944M/POR_944M_SUSaxl_pg1.htm#item0

Unfortunately I had to do this a while back and this is one part where Pelican needs to sharpen there pencil. I will typically get things here even if they are a little bit more. Calling up and talking to a human that actually knows my car is an intangible that is very important. BUT This particular item can be had for way under $100. I get them rebuilt locally returned to me in under 24 hours and some times the same day for between 35-80 depending on the car. Last time I checked for a 944 they were $68 with lifetime warranty. Unfortunately he will not be able to do a core return so his options are probably much more limited and a bunch more expensive.

I would also like to mention that it is very important to measure the overall length of your shafts. There are two sizes and things got really weird with my 924s as it was not what it was supposed to be according to one of the largest suppliers of rebuilt units..

Schumi · 11-21-2008, 08:31 PM

Good ole' open diffs. It will just spin one side, not the other. Replace that halfshaft and be on your way, be lucky it wasn't the ring ad pinion in the tranny going POP.

Pretty impressive that you snapped a halfshaft. Running some extra wide sticky tires?

Tishabet · 08:59 AM

Quote:

Originally Posted by Schumi

Good ole' open diffs. It will just spin one side, not the other. Replace that halfshaft and be on your way, be lucky it wasn't the ring ad pinion in the tranny going POP.

Pretty impressive that you snapped a halfshaft. Running some extra wide sticky tires?

Nah, running 225 4-seasons all around.

I'm guessing that I had the wheel spinning on the grass of the shoulder, then it hit the asphalt and that was all she wrote.

I decided not to order the shaft from Pelican after seeing several other posts mentioning that they were available elsewhere much cheaper... $165 vs $281. I have over $500 in parts (including the Bursch muffler) from Pelican currently in a UPS truck somewhere, so I don't feel too bad about it

Tishabet · 12-09-2008, 01:28 PM

Thought I would follow up to tell you that the 944 is back on the road with a half-shaft from George at 944 Ecology. Here is the carnage from the broken half-shaft:

Dougster · 12-09-2008, 01:33 PM

Glad to have you back on the road!

legion · 12-09-2008, 02:10 PM

For future reference, you used to be able to get rebuilt axles from Advance Auto Parts, Pep Boys, and the like for around $100 a pop. Not sure if that is still the case.

JonA · 12-09-2008, 04:28 PM

Be careful, I ordered rebuilts for the 924s two or three times until they finally got it right. Part numbers were really screwed up. Keep the old one as a sample so you don't bring home the wrong part.

Jon

HondaDustR · 12-09-2008, 05:52 PM

I'm surprised it broke the shaft and not the ring and pinion! Or does the 89 have the strengthened transmission...but still!

Tishabet · 12-10-2008, 05:02 AM

Quote:

Originally Posted by HondaDustR

I'm surprised it broke the shaft and not the ring and pinion! Or does the 89 have the strengthened transmission...but still!

I was quite surprised as well. I've never been able to ascertain all of the "one year only" changes on my 89, the only one that is well documented is the 2.7 engine. It is possible that it also has the beefier trans... it definitely has a short 5th gear.

emoore924 · 12-10-2008, 05:32 AM

It is kind of hard to tell from the pics but could it be that the halfshaft has a defect in the metal -- I wonder if that little egg-shaped bump is an indication of an impurity, air bubble, casting/forging defect or other latent weakness where the failure began. Maybe one of our more metallurgically-educated folks could chime in on what might cause this to happen...??

Then again, it might have just rusted out

kdjones2000 · kdjones2000's Garage

Looks like a pretty clean shear failure. Must have been hit with a pretty big load all of a sudden.

No real fatigue crack initiation, other than the obvious stress concentration due to the narrowing of the shaft and milling of the splines.....

Just my professional opinion :P

PS: In regards to the question above, the void in the middle probably did not overly contribute to the failure. If the defect were further out radially, it may have been the cause. I don't see too many fatigue marks around that area, so it doesn't seem to be the main issue. There does seem to be an outer ring of fatigue cracking that may have been there, and when hit with a large shear load caused it to fail.

Cheers,

Keith

emoore924 · 12-12-2008, 08:25 AM

yeah, what he said