Dirty Differential

[glmoore0001]

Hello to all..

The bottom of my 1971 250c is clean everywhere except for the differential. The differential is very dirty with road grime.

I don't believe this is from a leaking seal or the diff cover which is for sure leaking. There is no oil or dirt anywhere else. Not on the u-joints, axles or on the drive shaft.

It appears to me that a differential was swapped and not cleaned before doing so.
Why someone would do that is a mysterie to me.

I am going to drop the differential, change the mount and clean it up. Then pull the differential cover,clean it and seal it.

I will be looking for the differential part number but I was also wondering if I could determine the ratio by counting the teeth on the ring and pinion? If the gear ratio has changed I'd like to know.
Thank you
Gary

[Frank Reiner]

The ratio is stamped into the lower left corner of the case, looking from the rear.

[glmoore0001]

Thank you sir!

[Mike D]

Just as a "head's up", the differential number is stamped using the metric numbering system, e.g., 3,45 as opposed to U.S. standard 3.45

[meltedpanda]

Id be surprised if it is not leaking, they are notorious for that as they age , check the drain plug and dif seal once you clean it up . It does not take much of the heavy weight oil to make a mess

[glmoore0001]

Are you talking about leaking past the seals or the cover? The cover is for sure leaking, wet at the seam.

The fluid came out clean, a deep maroon color.

What's odd is that everything except the differential is really clean. The lid of the vent at the top of the diff is caked on, the sheet metal above it is is perectly clean.. Nothing on the axels, ujoint or drive shaft.

Nice black paint under grease.

[glmoore0001]

The grease was so old, it came off in ribbons, like stripping heavy paint.

[meltedpanda]

pictures would help us help you

[glmoore0001]

Too late.. I have already cleaned it up. I am pulling the back cover tonight and sealing with an anaerobic sealer. Then refilling and moving on.
Thanks.. Gary

[t walgamuth]

good!

[meltedpanda]

Good idea and good luck. Keep us posted. Like to hear good story endings

[glmoore0001]

When I bought the car it would idle, but wouldnt take fuel. I pulled the filter and fuel coming from the tank was orange. I had the tank boiled then painted and installed. Replaced all fuel hoses.
The fusebox was a mess, little pieces of burnt fuses lying across terminals deep inside. I disassembled it all, used Deoxit and cleaned all the connections. Installed new ceramic fuses.
I didnt have a battery so I bought a group 49 Interstate (the only place that had one) andI am painting the Rusty Battery tray this weekend.
The diff cover is going on tonight and the fluid with it.
If I get away without rebuilding the carbs, I will try to drive the car Monday evening.

[glmoore0001]

I am looking for the bolt torque for the differential cover plate to the differential mount.
The cover torque (45nm) and the mount body to chassis torque (25nm) I have found.
I cannot find the cover to mount bolt torque.
My MB Workshop Manual only lists the torque for the cover end mount which is not the same mount as mine.
I have included a pic of the mount in question. The bolt is a single 14mm Hex Head Bolt.
Thanks.. Gary

[glmoore0001]

Everything for the differential was cleaned and ready to go.
I was really impressed with the Hylomar Anaerobic Sealer. I applied it to both surfaces with my finger, let it set for about 15 mins per instructions. When I put the parts together, without any bolts at all there was no movement of the cover when I removed my hands. Sticky Stuff! Torqued to spec, wiped off the squeeze out and done.
I still am unsure of the torque of the 14mm hex bolt holding the diff to the mount on the chassis. I ended up putting 60 ft lbs on it only because I had no idea of the actual figure. I have a MB Technical Data Manual coming, maybe it will be listed in there.
1 bottle of Lucas 80\90, and topped off with Lucas Heavy Duty Oil Stabilizer per a Pierre Hedary video.
I am going to have to wait to replace the boots on the axels, I expect snow to be flying at anytime here in Northern Illinois. Gary

[Todd Miller]

Nice work. I'm sure 60ft/lb will be just fine on a bolt that large. You can also use blue loctite on bolts like this, for a little added piece of mind, and it won't make it difficult to remove in the future.