[DML] Re: Questions on automatic transmissions

["David Teitelbaum" <jtrealty@xxxxxxxxxxx>]

Thanks for the comment but you are not completly clear either on how
an automatic transmission works. Yes, it does have hydraulics inside
but they are ONLY used for control. The power flow is EXCLUSIVELY
through planetary gearsets and clutches. The shift computer controls
the hydraulic control systems which control the clutches. The
particular combination of clutches is what determines the gear ratio.
The hydraulic system also cools and lubricates the internals. This is
NOT a hydrostatic transmission, ie, the fluid is NOT used to transmit
motive power. This transmission "at it's core" is a bunch of
planetaries and clutch packs. The failure point is usually the C1
clutch pack, it is the smallest one so it is the weak link. When it
goes it can do other damage so if the transmission is slipping the
*best* advice is to not drive on it anymore until you can correct the
reason for the slippage. If it slips even with full line pressure you
are "in deep do-do". You have removed the friction materiel from the
friction plates and now they are slipping against the steels. No
amount of pressure is going to help you until you replace the
frictions and steels inside the clutch packs. In the course of the
general rebuild you replace all of the internal seals, exterior seals,
clutch plates, gaskets, and shim all the clearances back to spec. If
you do decide to drive the transmission to destruction you will wipe
out all of the bearings, the fluid pump, possably the gearsets, and
usually the case. At that point it is not economicaly reasonable to
rebuild. Now you HAVE to replace it and the old one is garbage. I have
rebuilt many kinds of transmissions, from many different kinds of
cars, the transmission in the Delorean is not so unique except in it's
construction. It requires special tools, the Workshop Manual and of
course replacement parts. Most places today no longer do internal work
on transmissions. They don't have the time, training, or the tools.
They will yank it out and send it somewhere. Even many transmission
shops now just yank them out and send them to a central shop where
they are done on an assembly line basis. Builders (transmission
mechanics as they are known in the trade) are few and far between.
They are like gold and shops are very possesive of them because good
ones are hard to find and keep.
David Teitelbaum
vin 10757


--- In dmcnews@xxxxxxxxxxxxxxx, "endotex23" <endotex23@xxxx> wrote:
> 
> 
> >
> > 
> > I don't know who to believe or who to trust, some people have
> motives to sell me a transmission, others are just trying to sound
> knowledgeable. So far no one is willing to make any gaurantees.<
> 
> I can't say I blame you. This list continues to offer some of the
> worst information I've ever seen. If you want to wade through all the
> nonsense you must not lose sight of fundamentals. An automatic
> transmission is at it's core nothing more than a hydraulic system. As
> such all the basics about hydraulic system maintenance apply. Dirt,
> moisture, oxidation, acidity, heat, and other contamination of fluid
> is the greatest single killer of hydraulic systems and this applies
> to auto trannys as well.
> 
> Of all the advice given David T's is the most valid. Shift timing is
> 








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