Transmission Q's

[tahoedriver]

Hey all, I got a 1997 Tahoe 5.7L 4x4 with 186,000 miles, all original parts. I'm changing the transmission fluid and would like to know whether or not to switch to synthetic fluid. As of now I've been using the high mileage fluid for the past 40,000 miles. Is it a good idea to switch fluid types in a high mileage transmission or should I keep to the fluid I've been using? Also, I've always changed my own fluids and was wondering whether I should take it in to have the transmission bands adjusted as I've never done it myself? What are the transmission bands, what purpose do they serve? One more thing...transmission flushing? Good idea or not? Would like to hear or past experiences or technical advice. Thanks a bunch.

[Blue Bowtie]

TD,

Frankly, while the synthetic will perform very well, it is probably better to change the trans oil more frequently than to try to extend the service intervals. Even the synthetic will eventually get contaminated with friction material and metal fines, not all of which will be trapped by the magnet in the pan.

Take the time to install a drain plug in the trans pan to make this a more controllable and cleaner task.

As for any adjustments, there truly are none. The older Hydramatics had adjustable band anchors which set the relaxed point of the band. Newer transmissions are designed with more than adequate overtravel in the actuator pistons to automatically adjust for any band friction material wear.

Incidentally, your trans has only one band, and it is used to clamp the input drum into position and force the input shaft to drive through the planetary gearset rather than directly, providing the necessary reduction ratios for the Reverse and Low ranges.

It's a little like this (pardon my mess):

[j cAT]

Originally Posted by tahoedriver

Hey all, I got a 1997 Tahoe 5.7L 4x4 with 186,000 miles, all original parts. I'm changing the transmission fluid and would like to know whether or not to switch to synthetic fluid. As of now I've been using the high mileage fluid for the past 40,000 miles. Is it a good idea to switch fluid types in a high mileage transmission or should I keep to the fluid I've been using? Also, I've always changed my own fluids and was wondering whether I should take it in to have the transmission bands adjusted as I've never done it myself? What are the transmission bands, what purpose do they serve? One more thing...transmission flushing? Good idea or not? Would like to hear or past experiences or technical advice. Thanks a bunch.

dexron III is not to be used..GM found that it was costing them too much in warrantee costs...this is now a synthetic dexronVI , which is the new replacement...

I stopped using dexron III back in 1998...soon after buying my vehicles [new] I replaced the fluid with mobil synthetic tranny fluid ...

on any vehicle that has your age replacing the complete fluid is best...flushing with a power flusher is BAD...the best way is to replace fluid/filter as usual then before starting disconnect the tranny line start engine and as the fluid comes out of the cooler line replace with new fluid.. you will need about 12 qts total...also have someone at the ignition switch...

[Blue Bowtie]

As for the flush, don't even consider it. Normal fluid changes are sufficient. I've rebuilt a few of these shortly after someone decided to take the advice of their mechanic and flush the trans and cooler. Unless it is done correctly, using ALL brand new fluid, and using a lot more fluid than any of the automatic flush machines have the capacity to hold, just forget it.

Shops which don't specialize in transmission building will listen to the equipment salesmen, purchase a flush machine because they don't know any better, then try to get as many services as they can run through it to justify its purchase.

It's not their fault. The salesmen mislead them, and since most of them don't have transmission training and experience, nor a transmission qualification on their ASE certificates, they really shouldn't be consulted for transmission advice.

I happen to have a little of that:

[tahoedriver]

Thanks for the info everybody, as far as the dexron III goes I've been using that forever. I've decided to go with dexon VI full synthetic. I make it a point to change the filter/fluid every year mostly during summer. As for the adjustment if I understand, I won't even bother with that. If I can recieve more info about the correct procedure in how to do it and what NOT to do I would appreciate it. Again thanks for the help.

[j cAT]

[quote=Blue Bowtie;6111647]As for the flush, don't even consider it. Normal fluid changes are sufficient. I've rebuilt a few of these shortly after someone decided to take the advice of their mechanic and flush the trans and cooler. Unless it is done correctly, using ALL brand new fluid, and using a lot more fluid than any of the automatic flush machines have the capacity to hold, just forget it.

Shops which don't specialize in transmission building will listen to the equipment salesmen, purchase a flush machine because they don't know any better, then try to get as many services as they can run through it to justify its purchase.

It's not their fault. The salesmen mislead them, and since most of them don't have transmission training and experience, nor a transmission qualification on their ASE certificates, they really shouldn't be consulted for transmission advice.

[quote]

what you forgot to mention is they sell this power flush telling the owners that replacing the filter and cleaning the pan is not necessary...

this is where the tranny is doomed to failure...Its just a scam . they are charging a large amount for the minimal time spent to maximize profit... its always about the money not the quality of service !

[consultIII]

to jcat and blue bowtie:

just wondering why machine flushing so bad? Have seen some machines that pressure pulse the line and probably loosen debris that could clog something internally but what about exchangers that don't pulse and just exchange.

thanks in advance.

[j cAT]

Originally Posted by consultIII

to jcat and blue bowtie:

just wondering why machine flushing so bad? Have seen some machines that pressure pulse the line and probably loosen debris that could clog something internally but what about exchangers that don't pulse and just exchange.

thanks in advance.

if the fluid is injected back into the transmission line from a machine this may loosen particles...the 100,ooomi tranny has lots of debris in it...

I don't have access to the various types of equiptment that does this...what many that do this service state is,,,," the machine flushing does not require the transmission to be opened or filter replaced" ...this is where the typical owner gets screwed...they leave it up to these so called "experts "...


too many have had to get transmissions repaired/transmission re-builders report many failures after these so called flushings...

if you would rather replace the fluid 3X with in 5ooomi , and that would be safer..

[transman618]

Automatics need to be serviced every 25-30k miles regardless..... Drop the pan, examine it real good for debris, change the filter, reinstall pan and tighten pan bolts to 95" (INCH) pounds. Refill using Dexron VI, it should take 5 quarts to refill on a pan drop.


transman