[AT] ATIS Holifday Charity Auction

Sun Dec 5 15:09:17 PST 2004

Steve,  I think ZF has built lots of automotive transmissions as well.  It 
is more likely that they built the units to a spec drawn by GM and it just 
wasn't tough enough.  As for loads on boat drivetrains a boat run in a rough 
sea or in any type of commercial application takes a pretty good beating and 
yes the loads do vary rapidly and dramatically at times.

Charlie

 Original Message ----- 
From: "Steve W." <falcon at telenet.net>
To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>
Sent: Friday, December 03, 2004 8:21 PM
Subject: Re: Re: [AT] ATIS Holifday Charity Auction

> The problem is similar to many other marine items folks try to use on
> the street, and vice-versa. Marine transmissions see constant torque
> loading for the most part. Street transmissions on the other hand have
> constantly changing loads. That was what caused the problems with the ZF
> units. They were fine in trucks and cars that were not really used
> heavily. Most of the ones used in trucks that actually hauled real loads
> or towed a lot failed because of the shock loading of the internals.  GM
> then ordered heavier units for the next generation of trucks. The real
> heavy duty transmission to use in a GM is the SM456 with granny low for
> trucks up to about 88. For newer trucks and for folks who are ordering
> new the manual of choice is the NV4500 5 speed. It is actually a 4 speed
> with OD in the 5th hole. The SM 456 is cast iron and is HEAVY duty. BUT
> you don't have a lot of gear choice. Of course if you could pair it with
> a 2 speed rear it is a great rig.
>
> I was actually looking at a 50's cabover GMC and thought about a 383
> stroker motor built for pulling with the SM456 behind it and a 2 speed
> Rockwell in the rear. Maybe toss a gear venders overdrive in there and
> putting a 15 foot bed on it and it would be a great tractor hauler and
> get better mileage. The cabover is up for sale about 10 miles away.
> Needs work but looks to be complete and not badly beat up, if anyone is
> interested I could get a few shots of it and send them to you.
>
> Steve Williams
> Near Cooperstown NY
>
>
> ----- Original Message ----- 
> From: "charlie hill" <chill8 at cox.net>
> To: "Antique tractor email discussion group"
> <at at lists.antique-tractor.com>
> Sent: Friday, December 03, 2004 5:27 PM
> Subject: Re: Re: [AT] ATIS Holifday Charity Auction
>
>
>> That is interesting in that ZF is probably the world leader in Marine
> (boat)
>> transmissions and clutches.  There stuff is usually excellent.
>>
>> Charlie
>> ----- Original Message ----- 
>> From: "Steve W." <falcon at telenet.net>
>> To: "Antique tractor email discussion group"
> <at at lists.antique-tractor.com>
>> Sent: Friday, December 03, 2004 1:25 PM
>> Subject: Re: Re: [AT] ATIS Holifday Charity Auction
>>
>>
>> > Yep those transmissions were German made ZF units. Marginal for use
> in a
>> > car and VERY poor for use in a truck that actually was used as a
> truck.
>> > The main reason for them was the fact that GM closed down the
> Saginaw
>> > plant and started buying manual trans from other suppliers. Now if
> you
>> > could find one of the old cast iron monsters it would bolt in
> without
>> > problem.
>> > Steve Williams
>> > Near Cooperstown NY
>> >
>> >
>> > ----- Original Message ----- 
>> > From: "Grant Brians" <gbrians at hollinet.com>
>> > To: "Antique tractor email discussion group"
>> > <at at lists.antique-tractor.com>
>> > Sent: Friday, December 03, 2004 10:00 AM
>> > Subject: Re: Re: [AT] ATIS Holifday Charity Auction
>> >
>> >
>> >> Actually the 1980's GM 4 speed truck tranny's are notorious for
>> >> self-destruction. Everyone I know locally with one had to replace
> it
>> > at
>> >> least once in the first 100K miles - one friend replaced his three
>> > times,
>> >> the first time under warranty! His case was not one of abuse, just
>> > use. The
>> >> reason is that sometime in the late 70's (date is hazy) GM
>> > "re-engineered"
>> >> the manual transmissions to save weight and money.... They ended up
>> > making
>> >> them too weak as a result, with the consequent explosion of repairs
>> > and
>> >> replacements. Shaft breakage, premature bearing failure and case
>> > cracking
>> >> all became common. This was one of the reasons for GM's precipitous
>> >> commercial track sales decline in the 80's. Additionally it
> cemented
>> > the
>> >> reputation of Ford for reliable light duty trucks because Ford kept
>> > the
>> >> heavy duty components in theirs.
>> >>     Having said all of the above, GM has returned to better Trannys
>> >> since....
>> >>         Grant Brians
>> >>         Hollister California
>> >> ----- Original Message ----- 
>> >> From: "Jim and Lyn Evans" <jevans at evanstoys.com>
>> >> To: "'Antique tractor email discussion group'"
>> >> <at at lists.antique-tractor.com>
>> >> Sent: Friday, December 03, 2004 4:04 AM
>> >> Subject: RE: Re: [AT] ATIS Holifday Charity Auction
>> >>
>> >>
>> >> > Those 4 speeds were just about bulletproof (I thought)  What did
> you
>> > tear
>> >> up
>> >> > to warrant a transmission replacement?
>> >> >
>> >> > Jim
>> >>
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