4-Prong Output Flange Socket/Tool
 

I have the engine and transmission out of the '74 for cleanup. The transmission output flange still has the original style 4-notch nut on it and I cannot find one of the special sockets to buy anywhere or borrow locally. I thought I had it worked out locally but it is not to be. Nobody I know has one of these sockets. The new nuts do not require the special tool.

Do any of you have this tool, and can I use it? I'd be happy to pay for shipping and a rental fee. Couldn't find it in the tool rental section.

The one-time removal approach that is often employed is to bend back the lock tab with a chisel, and then use the same chisel to loosen the nut.

Tried but the chisel was tearing up the nut without moving it and I don't want to make it more difficult to remove than it already is.

Let's see what turns up. If no tool is to be had anywhere in a reasonable amount of time I will look for another option.

Not sure on your year but in later years the nut is replaced with one that works with a normal socket. Obtain the replacement nut first before damaging the original.

I have the new 12-point nut in hand. It's the same as used on other chassis including W123.

Will it work on your transmission output shaft?

Some old threads but not for your exact year. It also needs a washer.

http://www.peachparts.com/shopforum/diesel-discussion/310185-transmission-flange-nut.html

An old member said it takes a 30mm 12-point socket but a normal socket due to the shaft protrusion may not allow the square of the drive to go in all the way but if you hold the wrench on it when you torque you can do it.

Yes. I have replaced the flange nuts before on W115 and W123 (it is the same part), and back then I knew someone who had the 4-pronged tool. That was more than 10 years ago, though, and that person is long gone and I have no idea where his tools went.

Just to be sure I trial fit my new nut to the output shaft of a junk transmission I have and it threaded right on. This particular transmission is an older unit than what it is in the '74.

Made a tool and got it done.

http://www.peachparts.com/shopforum/...1&d=1720286449

These nuts are the same functionally:

http://www.peachparts.com/shopforum/...1&d=1720286463

Part number for the new nut = 123-990-00-60.

Great job.

Thanks. When I found that piece of pipe in my scraps I knew I had something I could work with. And I'm not one to beat on things when I don't have to.

Nice job on the tool! I'm kind of surprised it came off with the tool when it wouldn't with the chisel.

On the rare occasion that I actually had one of those proper tools available, in the proper size for the nut that suddenly appeared inside a gearbox, I usually found the damn nut was torqued hard enough that I had to attack it with the chisel anyways.

I've cursed those things for at least a decade and still don't know what they're actually called. Some sort of castle or lock nut?

My old printed Spare Parts List refers to it as "nut, grooved".

I'm glad M-B changed the design so that a standard socket can be used. One of the things that bothers me about working on these cars is all the danged special tools that are required.

Good to know. Looks clean!!