[DeTomaso] Upgrade List
JDeRyke at aol.com
JDeRyke at aol.com
Sun Sep 16 16:52:35 EDT 2012
In a message dated 9/15/12 5:46:27 PM, steve at snclocks.com writes:
> But, in searching I read "One of the very week points of the Pantera is
> the rear axle bearings. Ball bearings are use to support the axle and are
> not very well suited to carry the loads that our big fat sticky tires can
> exert on them. A ball bearing is just not a good bearing for handling heavy
> side loads. On the Pantera, the single outside bearing carries most of the
> side load forces. Roller bearings are a much better solution for handling
> side loads and the big fat sticky tires."
>
Absolutely wrong. What IS critical is the press fit of the outboard stub
axles into the ball bearings; the OEM factory fit was too light or
non-existant in many cases and was due to undersized AXLES made of low-grade mild
steel, not to a weakness in the bearing type. Replacement factory axles available
today have the proper 0.0007" interference fit and are made of 4130 or
300-M alloy steel- both far stronger than original stock axles. They are
suitable for any imaginable use of a Pantera including Pro-racing.
Ball bearings run cooler and with less power absorption than roller
bearings, which is why ball bearings are used in most racing cars starting with F-1
and Indy cars and work down from there. The LeMans Gr-4/GT-4 Panteras also
ran ball bearings and today, perhaps 90% of the Panteras on the road run
ball bearings including the big-block conversions with monstrous power and
torque & super-sized rear tires. Roller bearings are made to carry heavy side
loads found mostly in the front end, not the back. The single advantage of
tapered roller bearings is, they will tolerate a sloppy fitting axle. A good
press fit is unnecessary, so its easier to tear down the upright.
To verify this a couple of decades ago, I converted ONE of my '72s rear
uprights to roller bearings in my shop since there were no commercial
conversions that met engineering standards. I left the other upright with stock ball
bearings, with a proper press fit on the axles. Today after some 50,000 more
miles including many high speed runs, open track events, autocrossing etc,
they are both still back there in good shape- no difference that I can
detect except the tapered-roller side cost much more for parts and machining. I
run 12" wide 295-50 x15"s on optional 10" Campy wheels.
Boittom line: check your stub axles for looseness via the 'hip-test' and if
any is detected, you likely need new AXLES, not a change of bearing type.
IMHO, It really depends on what you expect from your car. What you need to
do for 21st century upgrades in a Pantera has been covered in many, many
articles published in the POCA Newsletter and in the currently-dormant PI
magazine over the last 20 years. The list runs to over 300 illustrated, multipage
articles that have been vetted by engineers as true improvements. They
cover handing, brakes, tires and wheels, aerodynamics, interior and a host of
other topics. I suggest you join POCA; e-mail Judy McCartney <
JPOCA2 at hotmail.com> for more info. Good luck- J Deryke, POCA Tech Editor
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