| [GMCnet] Axle and steering knuckle [message #227204] |
Sun, 27 October 2013 11:20  |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
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In the last few months. I've gone both ways on two different 78 Royales. One was in need of so much that putting in the one ton was the best way to go without a doubt. The other one only needed the bores for the bearings reworked. A grease fitting was installed so that the grease can be changed at 30 to 40,000 miles. I do like that feature with the original knuckle. GM missed the boat by not having a grounded finish in the bearing bore. That has been the root of the front bearing problems. After I completed the installation of the one ton unit. I drove that coach on a 250 mile trip to Wis. I'm not crazy about the A frame geometry of the one ton unit. But we were able to get the proper wheel alignment, and the coach handled very well. So I have reservations that the geometry of the A frames with the one ton is a real issue. We are fortunate to have choices. Thanks to the vendors that we have. The original unit has served us well. I think the one ton will also do the same.
Bob Dunahugh 78 RoyaleAnd 4 Yenko'sIowa
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| Re: [GMCnet] Axle and steering knuckle [message #227216 is a reply to message #227204] |
Sun, 27 October 2013 13:19  |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
Thought I'd take a minute and explain what Bob meant by "grounded finish in the bearing bore."
The bore in knuckle was machined using a tool steel cutter with a sharp point. It leaves a surface that looks like this under
magnification:
wwwwwwwwwwwwwww
The bearings are supported by the "tips" of the w's which is less than the full ID surface. Over time those tips get "hammered" down
while driving and the bearing fit gets loose.
A ground finish does not have the "w's" and is completely flat so the bearings are supported by the full ID surface which is mo
betta!
When Dave Lenzi rebuilds hubs and knuckles he grinds them so that the bore of the knuckle and the OD of the hub are completely flat
then they are flame sprayed followed by finish grinding to a very tight spec. I have over 30,000 miles on mine and I've only greased
the bearings once. IIRC Dave has over 100,000 miles on his bearings without any problems.
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: Bob Dunahugh
In the last few months. I've gone both ways on two different 78 Royales. One was in need of so much that putting in the one ton was
the best way to go without a doubt. The other one only needed the bores for the bearings reworked. A grease fitting was installed
so that the grease can be changed at 30 to 40,000 miles. I do like that feature with the original knuckle. GM missed the boat by not
having a grounded finish in the bearing bore. That has been the root of the front bearing problems. After I completed the
installation of the one ton unit. I drove that coach on a 250 mile trip to Wis. I'm not crazy about the A frame geometry of the one
ton unit. But we were able to get the proper wheel alignment, and the coach handled very well. So I have reservations that the
geometry of the A frames with the one ton is a real issue. We are fortunate to have choices. Thanks to the vendors that we have.
The original unit has served us well. I think the one ton will also do the same.
Bob
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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