Thanks for the advice. I know that I need a differential because I think I
messed it up. Last fall I lost the front seal and the bearing went taking
the seat in the font of the housing. I thought I had it polished out enough
to go back together without a housing replacement. I was wrong. The seal
failed and the bearing is dry. Now I don't have time to rebuild again before
summer grad. school and I need to get back on the road so my wife can have
her car this summer. I'll check the axle shaft bearings per your
instructions when I get it apart.
Tim Wilcox
tw1@muw.edu
BWN wrote:
> Tim
>
> Good to hear from you.
>
> I have a 79 and a 65 Spitfire. On each car I have done major
> differential and real axle work. Partly needed on account of their age,
> and partly needed on account of DPO neglect and abuse.
>
> Rich is right, and I ran into the same problem: If you are getting a
> growling noise, it could be one or other of the axles. The inner
> bearing on the axle hub behind the brake plate is prone to failure. It
> is poorly designed where the bearing runs directly on the axle shaft,
> not a true bearing surface. This arrangement really isn't so bad, since
> it functions more for alignment than weight bearing, however, there is
> no grease fitting to service it. Instead the cars were built with
> little plugs you had to remove, then install a fitting, then grease,
> then replace plug. Dumb. Without the presence of a grease fitting or
> extensive knowledge of the fine print in the service manuals, one would
> never know to grease those bearings. Disassembly of the hubs to replace
> the bearings is almost impossible on your own. The forces required will
> bend and damage the lug flange unless you have the right shop tools.
> Again, these parts to so small they don't survive well when serviced
> improperly.
>
> Also, you may have universal joint failure on the inner end of the
> shaft. Since the Spit uses comparatively microscopic u-joints, there is
> no room for grease fittings, so they don't get serviced. If they are
> old, they may be very troublesome to remove from the yokes. I left the
> last set a a machine shop to remove. It was worth the 35 bucks.
>
> Now, as far the differential unit itself is concerned, these cars came
> with three different ones over the years (aside from the ratios). You
> need to check for number of splines on the output shafts and input
> shafts, and also the size of the flanges. The Victoria British catalog
> has good illustrations of the different units.
>
> If you swap one out, it should bolt into your car just fine, but the
> driveshaft flange may not be the right size to match your driveshaft.
> Also, the fore/aft location of the front flange plane may be slightly
> different as well. This may be what some people run into problems with
> the drive shafts not being the right length. The correct shaft
> according to the book may not actually fit if someone has already
> changed the differential.
>
> The cost for differential bearings and seals is about $120 and
> installation and setup is about the same. If your gears are OK,
> replacing these parts is the way to go. If the bearings are OK too,
> just replacing the seals is fine. The output shaft bearings should be
> replaced with the seals, since the bearing removal necessary for seal
> replacement can be quite abusive on the bearing. Those bearings are
> standard size and inexpensive. BTW, it is almost impossible to get the
> bearings off yourself. You should take them to an automotive machine
> shop that has a small enough pinch clamp to do the job. Otherwise the
> shafts can be ruined. On the earlier differentials, the pinion shaft
> seal can be replaced successfully with just retorquing the pinion nut to
> its exact location prior to removal. I have done this with success on
> three on three different units. On the later differentials with the
> collapsible spacer I don't think you will enjoy such easy results.
>
> A third source for your noise could be the driveshaft. On my 65 the
> driveshaft showed no external signs of failure such as lateral play in
> the u-joints or broken u-joint cups, but when I dismantled it, the rear
> joint was very dry and many of the needles were disintegrated causing
> terrible noise and balance problems. On both cars I have replaced the
> drive shafts with custom built units. Any good local driveshaft shop
> can do this. The cost is a fraction of the catalog replacement price,
> and you get a better result. On the later cars the front carden joint
> is non serviceable because of the rubber boot. Just replace the drive
> shaft with a custom built one. I think I paid about $100 for a custom
> built shaft with the ujoints installed. Although I had to bring in some
> flanges.
>
> All the best,
>
> Brian
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