I think I broke my diff.....

I'm really starting to think my 850 does not like me.
so far 2012 has been a disaster.

1.st my passenger seat is broken by a box of drying salt tipping over during winter, I have not fixed this yet.

2nd my Gearbox needs a complete rebuild, this was just done last week.

3rd. I get a new exhaust system fitted and it sounds crap and needs further modification.

4th, I accidently hit a pole and scratched my front during the Swedish meeting last week, this is more or less fixed by mounting the CSI kit, but a few small scratches and a small crack in the nose cone part under the left intake.

And now I think I broke my diff.
Visited a friend, and as I drive off I was going to show off a little so I floored it from stationary, hear a loud bang, and I'm not going anywhere.
Initially thinking gearbox, but that's rebuilt and reinforced a week ago.
The car can be rolled in P, or any other gear.
Jack up the car and see no obvious damage or leaks. there was also no smoke or smell.
Start the car, put it in R, hear a clunk, my friend said that came from the rear, not the gearbox.
Put the car in D and now there is a continuous clunk/slip sound from the rear, as if something like a gear or something is stripped and slipping.

I have a diff from a 750 so it looks like I will have to do the swap earlier than expected, if it's not one of the drive shafts or the prop shaft that is broken.
Though the diff is the prime suspect at the moment.

Zitat von SmileitsMe;100660

Hey!! it´s an old but amazing Car..
I also swapped my Diff and further things..
The Lady needs our attention

Does the drive shaft move when jou roll the car in P?
so you can find the fault easy!

My Bang.. broken Screws @ rear Drifeshaft.. cause i didnt thigten them correct..

I will get under the car later today and have a look, the drive shaft was down last week my the tranny shop, so it's entirely possible that it was not installed correctly.

I got under the car and the diff housing is cracked.
There was a huge puddle of oil under the car today, and this is what it looked like under the car.

Guess the 3.15 LSD will be installed within a week.





And what it looked like when the oil was wiped off.

Zitat von wokke;100696

I wonder what it looks INSIDE the housing

Since I need to use the back cover for the other diff.... I will post pictures

Well.. I did break it.

Replaced it with a 3.15 LSD from an e32 750i the other day and had to use the back cover.
When I emptied my old diff of oil these parts fell out.
This is one of the planet gears, and the shaft that is between the gears.
The other planet gear was wedged in the front and did not come out, and is probably what cracked the diff housing.

Sadly my gearbox was also damaged, and only works in 1st and reverse.
Will take it back to the shop that did the rebuild when they get back from holiday next week.

Zitat von anguswolfendale;101768

What on earth were you doing to cause this damage???

Standing stationary, and just stepped hard on the throttle in D.
Car moved 1 meter, huge bang and it was not going anywhere.

Though this may have been a looming damage, the gear has wear marks, and the magnet chip detector looked like a hedgehog with all the metal shavings.
the big part of the gear has another 5 ! cracks in it.
I suspect the diff has been in a sorry state for a while, the whole casing was covered with grime, so I think there has been some sweating possibly for years, I guess the oil level may have been a little low for some time, but not dangerously low.
The diff holds 1,9 liters of oil, I must have poured a little over a liter when I did the swap the other day, 1,2-1,3liters I guess. The day after the incident there was a puddle under the diff, probably a good 0,2 liters, so I would assume the diff had 1,5-1,6l in it before the incident, low, but not low enough to prevent lubrication.

Zitat von 8Harry8;101772

one meter - 38 seconds after beginning?

I told you I was not on the brake..... I was in D, held the car on the brake, let the brake go and just floored it with the same foot. car jumped, big bang and engine was bouncing of the rev limiter.
At first I thought the gearbox slipped out of gear, so I did what the guy in the video did, tried to cycle the shifter but nothing, then realized the car could be rolled in P.
Question is, did the gearbox break my diff, or did the diff break the gearbox.
this happened 1500km after the gearbox was rebuilt and reinforced, the rear tires had 750km on them so I was not interested in a big burnout to ruin my new tires.

Zitat von Timm;101793

I reckon the supercharger broke both of them!

I doubt it, I have had the supercharger on the car for a few years, and I have done a few burnouts in the past without any problems.
I've heard that the gearbox should handle 600hp stock with no problem.

The diff had signs of wear, so I suspect it's been slowly eating away until it finally failed.
The gearbox was completely rebuilt and reinforced because of the supercharger just 6 weeks ago, and it too was a bit worn before this.

I believe that the diff had weakened over time, and the completely rebuilt gearbox put more stress on it and it broke.

I'm no gearbox expert, but I don't understand how 2nd, 3rd and 4th gear broke but not 1st when the gearbox was in 1st when the failure occurred.
It would make more sense to me if 1st broke, and the other gears still worked.