Excellent pictorial willydigger, thanks for taking the time to do it. Really helps with the visualization of the fix that FOG came up with. Question, with the OPDA housing being aluminum and the grubs screw hardened steel, do you think that the screw would 'self tap'?
It is very easy for a tap to cut it. I wouldn't risk not using a tap. I would hunt for a cheap tap and do it right.
Is the 1/4-28 grease fitting a taper or straight thread?
Loctite on grease fitting?
What do you think about a "flush" grease fitting that uses a ball end grease gun coupler to minimize the "load" on the OPDA when the grease gun is removed? OR
A button head grease fitting?
I think I may put on a flush fitting instead. I don't like forcing the grease gun onto an extended fitting tapped into aluminum. It is on there hard and "relatively" tight, but there is clearance for a needle so that might be a better alternative.
What do you mean by feeling the drill bottom out? Is that when you hit the outside of the bushing? Why isn't drilling into the bushing an issue? Does the bushing rotate? If you are drilling through the bushing through the factory hole how does the grease get to the hole there when the zerk is 1/4 turn away?
Below is a cut-away view of the actual OPDA. Looking at the below image, the red line on the right is the factory hole. This is were you actually drill through the bushing. The bushing will not turn, it is pressed into the aluminum housing. The yellow circle on the right is the hole in the bushing that you will drill. There is no other hole already in the bushing. It is solid.
On the left side, the green line is the hole you will drill to mount the grease fitting. When the drill gets through the aluminum housing, you will feel the drill bottom out (red arrow). Imagine drilling through a piece of wood. As you press the drill down there will be resistance. When you get through the wood the drill will go through easy. This is the same feeling you will have when you penetrate the aluminum housing. When you feel this release of resistance, you know to stop drilling. This will prevent you from putting a hole in the left side of the bushing (blue arrow). It is aluminum so you don't have to push hard. The drill bit will easily cut through it.
Here is a cut-away with a top view. The green line is where the zerk is located. The actual position will vary. You can put the zerk anywhere that is comfortable for you.
The green arrow is where the grease will enter the reservoir. The yellow area is the grease reservoir that surrounds the outside of the bushing. You will drill the hole in the bushing through the factory hole. The red arrow shows where the grease will enter the bushing and contact the shaft.
FOG, can you comment of Castrol PD2 Longtime or Mobil SCH 220 as grease alternatives? I have easy access to both, but I don't know what to look for for a quality grease in this application.
What about Green Grease?
What is the key element to look at for grease?
Finding Moly % is difficult. How about Dropping point Temp as an indicator?
I got the bit and tap, but I couldn't find the 'bottom tap'.
Try Grainger. I assume there is one is TX. I used a 8mmx1.25 grub screw. A bottom tap from grainger is $8.21. That is a little high. You can use a plug tap, but you'll have to drill the step in the factory hole. Plug taps don't have threads in the front. Notice in the pic below that the threads on the bottom tap start right away, while the plug tap goes in 3-4 threads before it starts cutting. With the space in the factory hole you will hit the step before you cut a thread with a plug tap.
Another question related to replacement gears, do the gears reuse the factory hole and roll pin? I think this was covered in this thread somewhere that you had to re-drill a hole. Have we found a gear that is a direct replacement?
Our Wal-Mart has Rotella T6 5w40 oil for 19.50 a gallon. Any opinions on this oil? I can't get Mobil1 5w40 locally and thought the Rotella might be a good replacement.
The Rotella 5W-40 is a ACEA E9 and SM/SL rated oil and from what I can find does have good ZDDP levels. From what I've read its a really good oil and wouldn't hesitate to run it if Mobil One 5W-40 wasn't available.
The below oils are acceptable for the 4.0 and prevent the gear wear IMHO.
Mobil One 5W-40 "Turbo diesel truck" Good for all around weather.
Rotella T6 5W-40 Also good for all around weather.
Mobil One 0W-40 For freeze your nibbs off kinda cold.
Mobil One 10W-30 High Mileage SL rated also going all around oil.
If you live in a place where none of the above are availbe then a ACEA rated oil is OK but not preferred.
Once again all this is just my opinion unless you happen to share it then it becomes our opinion such as then I cannot call it my opinion and I don't know what I think about someone taking my opinion.
Here is where someone did an analysis of a virgin sample of 5W-40 Rotella T6. The levels of ZDDP (Zinc and Phos) where very high). It also has a Total Base Number (TBN) of 11.7 which means it has a very robust detergent package in it.
Honestly for the price of $20 bucks a gallon I think its a pretty good deal and maybe try it next oil change.
In memory of Samantha Sue 1998 to Dec-16-10 at 2:15PM. She may have had 4 legs and a tail but she was the best friend I ever had and helped me through some really tough times. I hope to see her again one day.