2nd Gen Non-Engine/Transmission reliability

[Jar Head]

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I know a guy who is a consultant to the transmission industry. He states that the only reason transmission fluid would ever need to be replaced is because of overheating, it does not wearout. Toyota recommends the fluid be changed at 60K miles if you tow, (meaning possible overheating). The only reason I would change the fluid at 45K miles and (I would want to do an exchange) is that I have a 60K mile warranty and would want to observe the result of the exchange while under warranty, incase of failure. Also I plan on trading at around 90K miles before the expensive timing belt service so I figure 45K would be an ideal time to change fluid.

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Posts: 43 | From: SW Missouri | Registered: Aug 2003 | IP: Logged |



Now that's reliablity!

 

[Lsfarm]

$1000's vs $50

I don't understand why you would want to save old ATF when it costs so little? You can buy ATF3 at auto supply stores for around $2. 50 a quart, you don't need the dealers ATF 4. Actually you don't need the ATF 3 either,[dexron3 works fine] but that is another subject.



Automatic transmissions wear some with every shift, the transmission clutches or the 2nd gear band pull the engine speed down to match the road speed for it's given gear ratio. With a stick shift truck, unless you are trying to wear out your clutch [or squawk the tires] the driver backs off the throttle when he/she shifts, and matches the rpms as the clutch is re-engaged. This reduces clutch disc wear and heat on a manual trans. .



When an automatic trans shifts the engine continues to make power and torque, and the clutches or band have to pull the engine rpm down to match the road speed/ratio's rpm. When this happens a great deal of heat is created at the clutches or band, and this heat can be great enough to cause ATF breakdown for a small quantity of ATF with every shift. This heat is absorbed by the ATF and shed to the trans coolers. So the quality or the condition of your ATF deteriorates with every shift.



With every shift some of the clutch material is worn off the clutch discs or the band. As this clutch material accumulates in the trans, some of it is filtered out, but some is so fine that it stays in the ATF, this is one reason why ATF gets darker after some miles.



If you drive nothing but city miles, the ATF deteriorates faster than highway miles [lots of shifting vs very little shifting per mile. ] Towing heavy increases the wear rate too.



So a good trans service includes dropping the pan, cleaning the magnet, cleaning the pan, adjusting the 2nd gear band, replacing the filter, and changing the ATF.



Why gamble a $3-4000 transmission for a $50-$150 service??



Just my experiences and opinion. Greg L

 

[nixter]

Simple and informative stuff Lsfarm. Lot of common sense. Could you mix in some technical jargon and stuff so us laymen are left in the dark?



Nixter

 

[Gary - K7GLD]

Only problem with most AT fluid servicing, is that they usually only drain the transmission pan - usually leaving the majority of the fluid still in the valve body and torque converter - a complete flush of ALL fluid is provided by many transmission shops, and is worth the extra $$$ in my opinion...

 

[HoleshotHolset]

"a complete flush of ALL fluid is provided by many transmission shops, and is worth the extra $$$ in my opinion... "



EVERY transmission I have ever heard that had a flush done... had issues not much longer down the road. Flushing them causes all the neat little built up particles to go where they're not supposed to go... and cause problems.



Some transmission shops LOVE flushing transmissions... they're almost guaranteed a rebuild after they flush it.



Now, if they're just draining all the flud... then that's okay...



Matt

 

[kstehnacs]

trans fluid

I understand that atf3 loses its ability to deal with heat at 30k under normal conditions. Atf4 is supposed to retain its ability to deal with heat much longer.

 

[RustyJC]

Originally posted by nixter

Simple and informative stuff Lsfarm. Lot of common sense. Could you mix in some technical jargon and stuff so us laymen are left in the dark?



Nixter

How about shearing of the long-chain hydrocarbon molecules? This will lead to changes in the kinematic viscosity and, thus, to performance degradation.



Oil (and ATF) does wear out. Molecules get sheared between gear teeth, in tight bearing clearances, between clutch plates, etc. Additive packages get depleted. There's far more than just heat to be considered.



Rusty

 

[Gary - K7GLD]

"EVERY transmission I have ever heard that had a flush done... had issues not much longer down the road. Flushing them causes all the neat little built up particles to go where they're not supposed to go... and cause problems. "



HMMMmm - "normal" flushing should involve merely circulating NEW ATF thru the system as the old stuff is drained - usually until the operator starts seeing new clean ATF flowing - not much reason in that scenario that "built-up particles" should be "stirred up" any more than normal transmission operation would do...



NOW, I suppose it IS possible to try that with a gazzilion pounds pressure, THEN you might create problems...

 

[scotmartin]

Here lies the real problem..... Most shops that flush, don't change the filter. And, a simple filter change, does not replace all the fluid.



Thats why, you must request both. Flush it first, then immediately drop the pan and change the filter. Thats what I did on my 93.



Scot