Topic: unpainted machined surfaces on differential

[johnboy]

I lost a couple of points on this at a recent MCA show and have since consulted several books and walking "experts" but still don't have any idea exactly what I'm looking for.  I attached three photos of the diff in my '66 convertible. Pic #1 is passenger side, pic #2 is driver's side and pic #3 is my guess at where the natural finish machined surfaces might be.

Can anyone clear this up for me?  Maybe photos of a correctly painted diff?

Also, I'm pretty sure there are several other "mistakes" that will show up in the photos.  Feel free to comment.  I want to get it right and appreciate all the constructive help I can get!

Please see the attached photos:

[bryancobb]

How bout this?

[johnboy]

Thanks for the quick reply Brian.  However,I think we have different model diffs.  I can clearly see the same small machined concave areas on the bottom on both your unit and mine but there are no obviously machined surfaces on my center section.  Any thoughts?   

[J_Speegle]

This help

Purple and blue surfaces should be machined





Green arrow area should be machined (picture from first original post in this thread). Yoke was not apparently

[johnboy]

Thanks, Jeff!

I examined the yoke surface (your purple arrow) with a magnifying glass and could see no evidence of machining.

This helps a lot.  I really appreciate the fantastic support on this forum.

John Kelsey

[CharlesTurner]

This is a 9", but might help explain the machine areas better:

http://www.early-mustang.com/charles/K_vert/5_31_10/5_31_10%20010.jpg

[petersixtfive]

Hi Jeff
Any chance of reposting the pics showing the machined surfaces.
What method or technique are you using to achieve the machining of the 3 areas
Would a machine shop re-machine these
Just wondering what type of shop to take it to?
Currently have everything apart, blasted the pumpkin and painted it in an epoxy red primer
Ready to re-assemble once the machined surfaces are taken care of
Thanks
Peter

[johnboy]

Peter,

I used an abrasive wheel on a Dremel tool and carefully made "machine marks" on the appropriate machined surfaces.  I made the marks parallel with the axis of the axle. This is a bit crude but has served me well (no points deducted and no negative judges' comments) at several MCA Concours Trailered class judging events since 2011.

Some purists might scream about this method but none have screamed at me!

Hope this is of some value to you.

John K.

[CharlesTurner]

I usually take care of cleaning the metal in the original machined areas before paint, then after paint, use 80 grit sandpaper in straight lines to simulate the machine cut marks.

[J_Speegle]

Hi Jeff
Any chance of reposting the pics showing the machined surfaces.

Done - thanks for understanding and bringing it to my attention


I prep the surface like Charles before I paint often tapping out the center of the surface or protecting the surface other ways but not out to the edges. Then once paint is set go back over the complete area since there are often fingers of castings that are at the same level as the machined surface that I want to catch with the"machining" on the final product. Protecting the center of the area just saves some time and doing the final process produces a believable final look that does not look tapped off

[Bob Gaines]

This help


Green arrow area should be machined (picture from first original post in this thread). Yoke was not apparently

I have some observations that indirectly apply to the topic. I thought I would mention a couple of details while this picture is up . Hopefully this can be done before the center section is installed.  This is so much easier to accomplish before the center section is installed and the reason for mentioning it here. The threaded studs were not installed when the rear end housing was painted .They were a darker heat treat type gray finish. The ones in the picture were painted .You have to push them back through with a brass hammer ,piece of wood or something that will not deform the end of the thread. When you are ready to install the stud it is placed so the spline section of the stud matches the splines made in the metal of the rear end housing when they were first installed. You have to pull them in place with a washer and few sacrifice nut (it will be ruined after a few uses) . Use a non locking type fine thread nut with a wide flat washer for this effort . You tighten down the nut with a impact effectively pulling them through until seated.  The face of the rear end housing (where center section is installed) is machined steel. This is best down with the studs taken out. It can be down with them in but it is easier to do with them out. There are some sections of the surface that are not covered by the rear end gasket where you can see the machined surface once center section is installed. Also don't forget to use a correct rear end gasket . Most aftermarket ones are different in shape then Ford ones. I don't have a picture to show in comparison but maybe others do.