[DeTomaso] My little repaint project is growing....

[JDeRyke at aol.com]

In a message dated 10/10/09 8:46:20 AM, charlesmccall at gmail.com writes:

> Can someone educate me regarding the difference? Are they (bronze 
> bushings vs needle bearings) interchangeable?
> Is one more durable than the other?
> 
They are interchangeable but needle pilot bearings are arguably not healthy 
to use in a normal Pantera. The pilot bushing/bearing runs in one of the 
most hostile areas in your car for bushings or bearings, with high heat from 
the clutch and engine, pulsating loads, complete lack of external lubrication 
and abrasives from clutch wear. A self-lubricating bronze bushing is a 
sliding-friction unit while a needle bearing is a less tolerant rolling-element 
assembly. A soft bushing will wear out in maybe 30,000 miles. A sealed 
needle bearing will not wear but it may seize from the adverse conditions. If it 
seizes, the hard bearing race will gouge the nose of the softer clutch-input 
shaft of your ZF- or thrash out the holev in the crankshaft, and you really 
don't want to know what THOSE cost to replace. I've replaced clutch input 
shafts in U.S made transmissions from this defect and they were 'only' $125, 
not including the tranny removal and a complete tear-down. In cars that get 
frequent maintenence and inspection, needle bearings would work. But on a 
normal 'hasn't-been-touched-since DeTomaso-built-it' Pantera, they can lead to 
tears and much expense. Some trucks do use needle bearings in that 
location, but they are almost always low rpm engines, and being work trucks they 
usually get frequent maintenence- and I suspect the needle bearings are still 
changed each time the engine or transmission is removed, just like the 
cheaper bushings. Most pro race cars don't use needle bearings there, either... 
and if they were 'better' or had any advantage, one would think professional 
teams would use them.
So, bottom line- it's a personal choice with some risk involved. Neither 
can be installed and forgotten. LLoyd Butfoy of RBT Transmissions could 
probably give you real numbers on gouged and replaced ZF input shafts and their 
costs. For the rest of us, its an insurance thing. To paraphrase Clint 
Eastwood's Dirty Harry Callahan, 'how lucky do you feel today, Charlie?'
Good luck- J Deryke