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Odd diff pinion nut
Odd diff pinion nut
My car has this very strange looking pinion shaft "nut". Can anyone shed any light on what it is? I am looking to replace the diff oil seal.
1965 3.8S Automatic. Light blue, dark blue interior. J65P1B77162BW. Acquired 2019. Being refurbished. Now running and drivable, but not ready for prime time. 
1974 MGB roadster, Dark garnet.
1974 MGB roadster, Dark garnet.
Re: Odd diff pinion nut
It look like a cover over the top of the nut like a locking device. Have you tried prising it off the nut. Can you see the nut underneath this cover section?
Rob.C. P1B8973BW
1968 S Type 3.4 Auto. Old English White.
1993 Yamaha FJ1200 Yellow
1966 Ford Anglia 1760 cross flow (still being built)
2012 Old English sheep dog. Grey and white.
http://torbayweddingcarclub.co.uk/?page_id=57
1968 S Type 3.4 Auto. Old English White.
1993 Yamaha FJ1200 Yellow
1966 Ford Anglia 1760 cross flow (still being built)
2012 Old English sheep dog. Grey and white.
http://torbayweddingcarclub.co.uk/?page_id=57
Re: Odd diff pinion nut
Rolly
That is the standard pinion locking nut. The steel wings on the nut lock into the pinion threads, steel is used instead of nylon as the latter is apt to melt under influence of heat.
Firstly, ensure absolutely that there is not the slightest movement in the pinion bearings.
Before moving the nut, take a very, very accurate measurement from the end of the pinion to the face of the nut. If necessary, peal back one of the steel wings to access the face of the nut to accomplish the measurement. Take at least six measurements, call the average of the six measurements, distance “A”.
Your image of the flange tells me that the flange has not been seated correctly against the propeller shaft. Therefore, the flange needs refacing on a lathe, concentric with the seal facing. Before that is done measure the depth of the flange locating spigot from the flange face, it will be about 0.100 inch, we will call it measurement “B”. That spigot is the section that extends forward of the main flange face in your image.
Once the flange face has been machined true, then machine the face of your locating spigot so that it is measurement “B” less 0.015 inch. In essence if your original measurement “B” was 0.100 inch, then machine to now make it 0.085 inch. This ensures that the spigot is not fouling (bottoming) in the prop shaft mating face. At the same time have the machinist take about 0.002 inch off the circumference of the spigot. You will also find it advantageous to take about 0.002 inch off the flange oil sealing contact face to present the seal with an unworn running facing.
Many of the axle drive flanges have been bolted up to the prop shaft off square and the machining described above will ensure good contact facing once again. To complete the picture, you need to check the appropriate facings of the prop shaft. This can be done best if you strip the rear universal joint. At the very least check the face with engineering blue using the re-machined pinion flange as the master unit.
Beware of the current genuine Jaguar oil seals being too deep for the differential casing and fouling the pinion flange right on the radius of the flange, so tearing away at the seal.
When assembling tap the face of your pinion nut wings so they will foul the thread and after replacing the nut tighten it to achieve distance “A” again PLUS 1/20th of a turn. If necessary fit a new nut but ensure the depth is identical to your original nut.
Jack up the front of the car slightly higher than the rear, this will prevent axle oil flooding forward while you are working. Coat the axle casing oil seal locating groove and the inside of the drive flange splines (NOT the pinion splines) with sealer that will withstand EP oils.
Norman
That is the standard pinion locking nut. The steel wings on the nut lock into the pinion threads, steel is used instead of nylon as the latter is apt to melt under influence of heat.
Firstly, ensure absolutely that there is not the slightest movement in the pinion bearings.
Before moving the nut, take a very, very accurate measurement from the end of the pinion to the face of the nut. If necessary, peal back one of the steel wings to access the face of the nut to accomplish the measurement. Take at least six measurements, call the average of the six measurements, distance “A”.
Your image of the flange tells me that the flange has not been seated correctly against the propeller shaft. Therefore, the flange needs refacing on a lathe, concentric with the seal facing. Before that is done measure the depth of the flange locating spigot from the flange face, it will be about 0.100 inch, we will call it measurement “B”. That spigot is the section that extends forward of the main flange face in your image.
Once the flange face has been machined true, then machine the face of your locating spigot so that it is measurement “B” less 0.015 inch. In essence if your original measurement “B” was 0.100 inch, then machine to now make it 0.085 inch. This ensures that the spigot is not fouling (bottoming) in the prop shaft mating face. At the same time have the machinist take about 0.002 inch off the circumference of the spigot. You will also find it advantageous to take about 0.002 inch off the flange oil sealing contact face to present the seal with an unworn running facing.
Many of the axle drive flanges have been bolted up to the prop shaft off square and the machining described above will ensure good contact facing once again. To complete the picture, you need to check the appropriate facings of the prop shaft. This can be done best if you strip the rear universal joint. At the very least check the face with engineering blue using the re-machined pinion flange as the master unit.
Beware of the current genuine Jaguar oil seals being too deep for the differential casing and fouling the pinion flange right on the radius of the flange, so tearing away at the seal.
When assembling tap the face of your pinion nut wings so they will foul the thread and after replacing the nut tighten it to achieve distance “A” again PLUS 1/20th of a turn. If necessary fit a new nut but ensure the depth is identical to your original nut.
Jack up the front of the car slightly higher than the rear, this will prevent axle oil flooding forward while you are working. Coat the axle casing oil seal locating groove and the inside of the drive flange splines (NOT the pinion splines) with sealer that will withstand EP oils.
Norman
Re: Odd diff pinion nut
Thanks gentlemen. Norman has all the info. Thanks heaps for that. As a novice at this it was a bit like Greek at first, but with a second read and a bit of thought it is crystal clear. I am lucky to have a car club friend who is a retired engineer with a workshop full of lathe type equipment. He will relish the opportunity to use his machines and demonstrate his skills I'm sure. Do I check for play in the pinion bearings by just pulling on the flange, or is there a better way. And, of course, what should I do if there is some play? At this point I just want to get the car mobile and at some time in the future (when I get my new garage 
) I intend to take out the rear end setup for overhaul. So diff overhaul would be part of that.
) I intend to take out the rear end setup for overhaul. So diff overhaul would be part of that.1965 3.8S Automatic. Light blue, dark blue interior. J65P1B77162BW. Acquired 2019. Being refurbished. Now running and drivable, but not ready for prime time.
1974 MGB roadster, Dark garnet.
1974 MGB roadster, Dark garnet.
Re: Odd diff pinion nut
Help! Can anyone point me to where I might find one of these pinion nuts? My searching of the Internet hasn't turned up anything like it. I don't even know what it is called. If I remove this one and destroy it in the process I would like to be able to replace it with the same nut, to maintain the same distance specifications.
1965 3.8S Automatic. Light blue, dark blue interior. J65P1B77162BW. Acquired 2019. Being refurbished. Now running and drivable, but not ready for prime time.
1974 MGB roadster, Dark garnet.
1974 MGB roadster, Dark garnet.
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