I am think about a trick we used to do on VWs.   When we did take apart the rear wheel bearings, similar set up to our vettes, we instaled a "Cheat".   With the bearings apart we drilled a 1/8 hole in the center of the hub, cleaned it, and installed a grease fitting on the outside.  Once reassembled just one squirt from a grease gun kept plenty of grease in the rear bearings.  Neat trick.

 

My concern is someone overgreasing the rear bearings and blowing out the seals, creating more problems that what was solved.   I don't know if there is room for the fitting on the rear of the C3s, but when I do mine I am going to look at this and think about it.   No recommendation for this at this time until I get into mine and check it out.

 

If you use the tool and only grease the one bearing, which is the case,  it is still leaving the other bearing to chance until the grease evens out during use,  If you have enough grease in there to do that.

 

Some greases will migrate over if there is enough there, without causing a problem.  Don't use a grease to thin so it will move, but not supply enough pressure and heat support to protect the bearings.

 

But for migrating, you need a smooth grease.  Pay close attention to the drop point.  The drop point is the temperature where the grease will thin out and start to flow, and drop off of device.   A really good grease has a drop point of 500 deg F.   IF the drop point is too thin (low deg F.) the grease will run out of the bearings, and perhaps through seals and leave what ever it is you are trying to lube lacking grease.   Too low of a drop point will allow disc brakes to heat the hub and empty it.   Drum brakes could use a lower drop point than disc.

 

So you don't really want it to migrate due to a low drop point.  It defeats the purpose.   You want it to migrate from flow caused by volume, rotation, and centrifical (sp?) force.   Most quality wheel bearing grease will do this.   Do not use conventional chassie grease.   It's water resistance may be excellent, but the drop point is too low for bearings.  It is possible to get a grease to do both jobs, but be carefull selecting them if this is what you want to do.  I prefer to use two different greases.

 

Most synthetic greases work quite well, but still pay attention to the specs.  Some are specfic purpose, and are not sutable for bearing use.   Let me clarify, high speed, high pressure bearing use.  Some bearing grease works very well at low rpm even under severe load, but won't do for a wheel bearing.  Perhaps a truck 5th wheel.   Read the labels.

C4s: 1986 C4 coupe (SCCA road race car), satin black, 4+3, Z51 package, L-98;  & 1993 C4 coupe, white, 6-speed, LT-1.

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