W123 Pinion Seal

[Guest987]

On replacing the pinion seal was wanting to know, if it takes a special socket to remove the flange nut? If you use an air wrench, is it necessary to hold the flange or not, as well?

[SD Blue]

From what I've read and researched, you have the possibility of different nuts for the pinion flange:

M0026 (41.5mm dia. )
M0029 (38mm dia.)
M0032 (35.25 dia )
30mm 12pt

[Diesel911]

If the Self-locking Replacement Nut is a 12 Point Nut one of our Members but on anther Forum suggested using a Punch and Hammer to knock the Slotted Nut loose and remove it. There by avoiding the use of the Special Tool and replacing that Slotted Nut with the 12 Point one (if it is available).

I have never done the Seal Replacement so I don't know if that is feasible or not.

I think there is some of the Slotted Nut Tools in the Tool Rental Program.

[Guest987]

This is probably a dumb question, but wondering why there was so many different nuts used on this particular differential?

[greazzer]

On the W123, there's 2. The 4 slotted deal and the 30mm 12 pt deal. The 4 slotted is an older version I believe since you cannot buy that type (or at least I could not find it). Also, you need to measure the torque - drag before you remove. You will need a decent inch-pound torque wrench, e.g., 0-12 range or 0-20 range. They come up on Ebay for around $75 bucks for the Snap On Torqu-Ometer. I suggest a machinist since if it's too tight or too lose, you will have problems. A few inch pounds is nothing to measure. I myself punted on this one when I replaced the seals. Well worth the few bucks.

[Diesel911]

The Torque Wrench needs to be a Dial Gauge type or a Beam Type and it has to have a small range.

There is instructions in the DIY on how to avoid the Torqe issue:
DIY Repair Links
DIY Links by Parts Category - PeachParts Mercedes ShopForum
PeachPartsWiki: Do It Yourself Articles - Mercedes Vehicles

[Guest987]

Yikes! I don't have an inch/lb torque wrench with a dial gauge on it. However, I do have a very high quality one. I viewed a pictorial on doing one, and it emphasized the marking of the flange and the nut precisely. In doing this and with my testing procudures with the torque wrench, I feel I should not have any issues. There is an actual torque for the pinion bearing. I ran on to it searching on someone else doing the project several months ago. First, I need to verify if the bearing is good or not. If it is not, I will not attempt the project until this fall. I don't like to tackle a 3rd end in the summer heat!

[Diesel911]

Originally Posted by Rebe

Yikes! I don't have an inch/lb torque wrench with a dial gauge on it. However, I do have a very high quality one. I viewed a pictorial on doing one, and it emphasized the marking of the flange and the nut precisely. In doing this and with my testing procudures with the torque wrench, I feel I should not have any issues. There is an actual torque for the pinion bearing. I ran on to it searching on someone else doing the project several months ago. First, I need to verify if the bearing is good or not. If it is not, I will not attempt the project until this fall. I don't like to tackle a 3rd end in the summer heat!

There is no specific Torque on the Nut because you are supposed to squash a Sleeve similar to the ones in the Picture. You tighten down on the Sleeve a bit and then take the inch pound torque wrench and rotate the Pinion Shaft and see what type of resistance you get in inch pounds.

What you are doing is pre-loading the Bearings inside and there is no end play that can be checked like on the Rear Wheel bearings that also use a Crush Sleeve.

I did this on My Chevy Van over 1 Year ago but have never done it on a Mercedes. The pic of the Crush Sleeves are the ones from My Van.

The idea is that before you take the Pinon Shaft nut off you take the inch pound torque wrench and see what the bearing preload is. You make the position of the Nut on the shaft, count the exposed threads and even measuer the exosed threads if you can. But, that is only helpful if you use the same Nut again.
The above is a good idea to do even if you have the little Torque Wrench.

So you are trying to return the Nut to the exact same position and the theory is that that should preserve the Bearing Preload. And, that may be so.

I don't know about with Mercedes but on the Van there was a New Bearing Preload and an excepted limit Preload for used Bearings.

[charmalu]

You need to see what the Friction Pre-load is before removing the nut.

Pinion Seal Replacement - How to determine Friction Load

Here is a good thread with pictures explaining it. Found this on a Jag differential while looking for a picture of a Torque O-Meter.

Replacing a pinion seal on a Jaguar IRS! - Restorations and Projects by any description - The Garage Gazette


Here is a good picture of one.





Yellow Bullet Forums - View Single Post - Inch pound torque wrench?



Charlie