In reply to a message from mouton sent Wed 3 Feb 2016:
Hi Guys,
I am still on and off the forum from time to time. I am
helping my friend Scott with his 1970 OTS.*****************
Thank god for old email. I have all of mine since 1993
Here is the old email I sent to Bill and Jason.
Tuesday, October 20, 2009
Subject: Jaguar XKE Independent Rear Suspension Lower Inner
Control Arm Tubes (C17168).
Bill Terry and Jason Len:
After several discussions with bearing engineers that
inspected several original XKE bearing tubes (C17168) a
general consensus is that the Jaguar XKE independent rear
suspension lower inner control arm tubes which act as
the �inner race� of the needle bearings in the control arms
often show false brinelling.
The major reason often cited for the brinelling is the lack
of angular motion of the control arm which results in a
lack of proper lubrication.
On examination of the tubes, several engineers asked the
question as to if the tubes did in fact have the proper
heat treating.
The manufacture of the Torrington bearings (Timken)
specifies that the tubes, acting as the inner race, have a
hardness between 58 and 64 HRC with a case depth = (0.07 to
0.12) * Dw where Dw is the diameter of the rolling element
which is 7/8�. They recommend higher multiplier (0.12) on
low core strength materials and/or heavy loads. The minimum
recommended depth is 0.015 and based on a 7/8� diameter
bearing and the 0.12 multiplier the recommended case
hardening depth should be 0.105 inch.
Two original Jaguar tubes, one new early 3.8 (long) tube
from Terry�s Jaguar, and new one short tube from XK�s
Unlimited were taken to a San Francisco Bay Area heat
treatment business for analysis. The tubes were tested in
the center of the tubes. The tubes showed the following:
Jaguar Original #1: 53 RC
Jaguar Original # 2: 63 RC
Terry�s Jaguar: 55 RC
XK�s Unlimited: SOFT (This tubes showed no case hardening
after several tests)
In addition, several hardness scales were tested and the
depth of all samples was under the manufactures
specifications.
Conclusions:
Although the false brinelling of the tubes is no doubt in
part due to a lack of proper lubrication, the fact that the
tubes fall short of the manufacturer�s specification for
hardness may be a major contributing factor. The tube that
tested out at 63 RC showed the lest amount of brinelling or
general wear of all the used tubes.
It is recommended that the suppliers of these parts revisit
their suppliers and see to it that they are selling tubes
(inner races) that are within the specifications of the
manufacturers of the bearings they are supplying for this
assembly. Based on the results I recommend that the tubes
be heat treated to RC 64 with a minimum depth of 0.105 Inch.
Respectfully Submitted,
James Douglas
San Francisco.
–
James
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