[Shotimes] rod bearings

[Donald Mallinson]

Lots of questions but the shorter answer is that auto trany 
vehicles don't lug, because you can't hold it in high gears 
at very low rpm's and high throttle openings.  Unless you 
have it modified for full manual shifting, and NOBODY makes 
one like that from the factory.

Towing almost always is in a lower gear all the time, or the 
tranny downshifts.  In any case, lugging is usually 1500 rpm 
  or lower at high throttle positions.

Even todays super overdrive tranny's usually don't run much 
below 1800 rpm at very low throttle openings.

Only on manual trans cars can you get serious lugging going 
on below 1500 rpm.

Yes EVERY stroke on ANY engine does put a lot of stress on 
the entire system, but they are designed for this "normal" 
stress.  As explained very well, lugging puts a huge hammer 
effect on the bearing at TDC at low rpms.

Trust me, and thousands of mechanics over the years,.... big 
throttle openings at very low rpm's are not recommended.

Yes you do see a lot of dump trucks and other delivery 
trucks (gas engines) lugged and a lot of them have early 
engine failures.  These drivers don't usually give a darn 
about engine life, and quite often have no idea how to 
properly drive the vehicle anyway.  Using these vehicles 
(along with other things like taxi drivers) as examples for 
proper operation of a vehicle just indicates a lack of 
understanding of the industry.

Still don't believe lugging hurts an engine?  then go ahead 
and do it!  :)

Don Mallinson

James F. Ryan III wrote:
> 
> What about pick-ups that tow a heavy trailer, or driving up a long hill, or
> driving up a long hill while towing a trailer, or cars with auto trans (that
> are notoriously in the wrong gear - esp torque conv lock-up)?  Why do I
> never hear of rod bearing problems with these vehicles?  What about the big
> diesel rigs?  They have high commpression engines AND pull heavy loads.
> Wouldn't every compression and power stroke put tremendous pressure on the
> rod bearings?  What about dump trucks?  Those guys seem to always lug (and
> buck) their engines yet I see an awful lot of very old Mack and Autocar dump
> trucks on the road every day.
> 
> Also, why don't we hear about Mustang 5.0 owners and their rod bearing
> failures?  If what you're saying is true wouldn't a higher horsepower/torque
> engine put more pressure on the rod bearings esp if you lug it?
> 
> 
> Jim Ryan
> Wayne, NJ
> '91 PLUS - all white/mocha with fiberglass hood, rod shifter, & rear spoiler
> 
> 255 Lph fuel pump, SHO Shop can & horn, 80mm MAF, S&B cone filter, SHO Shop
> HiFlow Y-pipe & cat-back exhaust, SHO Shop LPM, SHO Shop underdrive pulleys,
> SHO Shop HiRevs Jr clutch & steel billet LiteWeight flywheel, reinforced
> engine & trans mounts, SHO Shop TQ limiters, SHO NUT aluminum SFBs, FPS '96
> SHO front brakes, Carbotech F brake pads, Nook's full-body SFCs, Koni adj
> struts, SHO Shop linear springs, 24mm FSB, 26mm RSB, SHO Shop steel f&r
> STBs, Bridgestone Potenza RE-730 225/55-16, CATZ MSP fog lights, police
> grille
> 
> 
> 
> 
>>-----Original Message-----
>>From: shotimes-admin@autox.team.net
>>[mailto:shotimes-admin@autox.team.net]On Behalf Of Justin Schick
>>Sent: Wednesday, August 13, 2003 11:15 AM
>>To: shotimes@autox.team.net
>>Subject: Re: [Shotimes] rod bearings
>>
>>
>>Trying to accelerate from too low of an RPM, rather than downshifting to
>>raise the RPMs.
>>
>>
>>Justin Schick
>>silver 92 SHO in KC MO
>>194k and counting quickly
>>
>>
>>>>>"Carl Prochilo" <gr8sho@prochilo.myserver.org> 08/13/03 10:11AM
>>>>>
>>>>
>>What does "lugging" the engine mean?
>>
>>Cheers,
>>Carl Prochilo
>>92 Ultra Red Crimson
>>
>>
>>> Not everyone believes that lugging the engine kills the rod
>>
>>bearings.
>>
>>>Lugging the engine on a worn
>>>engine will sometimes make the oil pressure light flicker at near
>>
>>stall
>>
>>>speed, but that's just showing you the condition of the lubrication
>>>system.
>>
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> 
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