CRG Discussion Forum
Camaro Research Group Discussion => Maintenance => Topic started by: jmcbeth on August 08, 2006, 01:42:57 AM
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I recently had my '69 Z/28 transmission (M20) rebuilt by a very reputable Camaro expert. He recommended I use a needle type pilot bearing (GM Part # 14061685) instead of a solid bearing.
In doing some research on the web, I came across the following statement:
"GM has changed their part numbers several times and are currently referring to the bearing (part #14061685) to be used. We strongly suggest NOT using this bearing as it is a needle type bearing designed for 6.2L diesel trucks which have a limit of only 4,000-4,500 rpms. You can imagine how fast those little needles will turn at over 7,000 rpms. We have seen some failures which were quite interesting. The ideal bushing replacement is a bronze type with three grooves (or flutes) spiraled inside and is available under the GM part number 10125896."
(From http://www.zr1netregistry.com/ZR1_troubleshooting.htm.)
So, I have conflicting recommendations. Can anyone shed some light?
Confused... ???
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I've used the GM needle roller bearing in several project cars (after dialing-in the bellhousings) with no problems at all. Gotta love the comment above about the needles at 7,000 rpm - there's no relative motion between the needles and the input shaft unless the clutch pedal is depressed; how often does anyone free-rev the engine to 7000 rpm with the clutch pedal on the floor?
The correct oilite bronze bushings work fine too, but take a magnet with you when you buy one, and don't take it if it's attracted to the magnet; there are lots of Chinese counterfeit bushings out there that are mostly iron, and they'll score the input shaft.
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Thanks for sharing your good experience with the needle bearings. As you point out, there is very little relative difference in rotation. I don't think my Z will spend that much time at 7,000 RPMs anyway. Off to install!