[DeTomaso] Axle Nut Torque

[F&D Terry]

Mike,

The GTS bearing is not a double row bearing. The outer bearing remained 
a single deep groove ball bearing but with an increased size and the 
inner bearing was changed to a non tapered roller. The axle had a step 
on the outboard end to accommodate the larger bearing. They were still 
installed with improper tolerances and a spacer which did absolutely 
nothing to remedy the problem of failing bearings. The spacer in both 
early and late cars is a mild steel and squaring the ends will do 
nothing to prevent future problems. As originally installed, the spacer 
ends were square and failure always occurred. Because of the improper 
fit of the bearings to the axle, fatigue starts when the bearings start 
to squirm or rock on the undersized axle. This rocking spalls the ends 
of the spacer as you say, making it shorter and total failure is 
inevitable. Perhaps hardening the spacer may have acceptable results but 
will do little to a improve the inherent poor design.

The remedy used to be installing tapered bearings but this is an 
expensive endeavor without a good suitable method of sealing. I 
 recently have found  one of the modern "cartridge" type bearings that 
is an easy and excellent replacement for the outer bearing requiring 
minimal machining to install. It is much wider and should remedy the 
problem even when used with the undersized stock axles. If I find time, 
I'll try converting an upright  so I can verify everything will work.

Fred T.

MikeLDrew at aol.com wrote:

>In a message dated 4/10/07 18:00:18, tonydigi at optonline.net writes:
>
><< A remaining question for me:  What was the purpose of the 450 ft-lbs in the
>original bearing set up? >>
>
>  
>
>>>>I can't find the original reference, but I seem to recall that the 
>>>>        
>>>>
>original torque was 275 lbs.  Panteras started to develop "loose axle nuts", so the 
>fix was to make them tighter.
>
>What was actually happening was NOT that the nut was loosening by itself.  
>Instead, the spacer between the bearings was fretting and wearing as the axle 
>wore.  The spacer effectively became shorter, which reduced the preload on the 
>inner faces of the two bearings, and the nut then became loose.  That's why 
>it's critical that when the axles are replaced, that the face of the spacer is 
>restored to a perfectly flat condition (or it's replaced with a new one).  A 
>spacer that doesn't have flat surfaces touching the inside of the bearings won't 
>do its job properly, which is a contributor to axle wear (or is the axle wear 
>a contributor to the spacer going bad?  I don't know for sure, but know that 
>if you are taking the time to take everything apart and rebuild it, you need to 
>take the time to look after the spacer too).
>
>The actual length of the spacer isn't really that important.  There is plenty 
>of room in the hub carrier to support the inner bearing in a variety of 
>locations (and in fact, some people fit the so-called "GTS" bearing which is 
>actually a double-row bearing; this is easily accomodated by shortening the spacer 
>to account for the added width of the bearing).
>
>Mike<BR><BR><BR>**************************************<BR> See what's free at 
>http://www.aol.com.</HTML>
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