92Annie

I have removed my driveshaft to replace the U joints and drained a bunch of tranny fluid. When discussing my car with an "old guy" he advised AGAINST dropping the tranny pan and replacing filter citing once a transmission found a "happy spot" replacing filter and putting in new fluid would result in disturbing seals/gaskets and promote leaking. This sounds a bit far fetched but the guy knows an awful lot. Myth?

paulo57509

I've been doing it all wrong all these years.

Why would GM ever recommend servicing the transmission (fluid and filter change) every 15k to 100k miles if doing so was harmful?

92GTA

iTrader: (11)

Sounds like the old man was just trying to avoid the inevitable lol. No matter what, the 700R4 seems to barely last past 100K miles each rebuild anyway. I'm on my 2nd rebuild at 23x,xxx miles. At 105,000 the 2nd gear was slipping. About 100,000 after that rebuild the planetary exploded, literally. Have about 30K after that rebuild now.

I change my trans fluid and filter by dropping the pan every 40-60K miles, always have. Be sure you remove the magnet on the inside of the pan and clean it super well too.

I have a nice tranny cooler tho so I have no problem going to 40-60K miles. The hotter your tranny runs, the more often you need to change the fluid.

edpontiac91

iTrader: (2)

I changed mine at 49,000 (now have 62,000) and also at the same time, bought an aftermarket aluminum pan that had a drain plug and also held an extra QUART. It still sits about the same distance, so driving over speed bumps hasen't scraped the bottom as of yet.

92GTA

iTrader: (11)

Yeah I was gonna go that route but having the tranny cooler and lines adds a couple extra quarts and I like removing the pan to inspect the large square magnet and look carefully at what's on the bottom of the pan. Plus I think it's super important to change the filter, I see them break often. To each their own :cheers:

someone972

iTrader: (2)

I installed a drain plug on my stock pan just so I could more easily drop the pan without making a gigantic mess. Which by the way, it's almost impossible to find fine pitch nuts for the drain plug at any local hardware store.

I've heard of changing the fluid causing slipping if the transmission is very worn, but never heard of it causing leaking around gaskets

blacksunshine'91

iTrader: (10)

I wish the aftermarket tranny pans put the drain plug in a similar position as an oil pan. I like how the oil pan plugs are on the side of the pan in a horizontal position at the low drain point. Whereas every tranny pan I've seen has the drain plug on the bottom of the pan in a vertical position with the head of the bolt being the low point. So if anything is going to catch on a speedbump or anything it will be the drain plug. That is the main reason I've always kept my stock tranny pan but added an external tranny cooler.

92GTA

iTrader: (11)

Exactly ^^^^

someone972

iTrader: (2)

<off-topic-rant> I agree. I installed mine on the side of the pan for that very reason. With the curve of the pan I had to install it a bit higher than would be ideal, but it's enough to drain it down for removal of the pan. If I were to install one for actual draining I'd probably have to weld together a flat surface lower down. </off-topic-rant>

paulo57509

I failed to mention that I did have a transmission failure two years and 7k miles after a fluid and filter change in a 4L60E (essentially an electronically controlled 700R4) - the 3-4 clutches burnt up. This was not a neglected transmission either.

I'm still not drinking the cause and effect Kool-Aid.

If the OP is going to do a fluid and filter change, I would stick with an ATF that's spec'ed to Dexron III (or Dexron VI) only and avoid combo fluids like Dexron/Mercon. Don't try to out think GM's Hydra-Matic Division.

RBob

iTrader: (1)

I do the same, place it on the side where it won't catch on anything. I usually let it drain overnight as that reduces the ATF rainforest mode. Then put the plug back in and drop the pan.

RBob.

John in RI

iTrader: (167)

If a tranny is run up with real high mileage before the fluid is changed ( say 120K or more ?? ) than many tranny shops will tell you not to change the fluid. ( probably cause' they know your gonna' have to re-build it in a year or so due the lack of maintenance anyway ! )

It's one thing to change the fluid in a maintained tranny,.... but when there's high mileage, low/no maintenance, clean fluid could very well cause the crud & grit ( that was helping to provide band application, ect.... ) to get washed out and thereby cause the tranny to fail. Another thing the 'old timers' warn about is that loose grit in clean fluid getting jammed/stuck inside the Valve body passages. I've never had this problem myself,..... but all the tranny guys I know have described it.

dmccain

iTrader: (2)

John ive been told the same thing.

92Annie

This is exactly what I had been warned of. The previous (original) owner had been unable to care properly for (what is now) my car and pretty much no maintenance has been done for literally years. I will not mess with the tranny for now but I suspect this winter would be a good time for a rebuild during hybernation. Until then i will be gentle with it!

John in RI

iTrader: (167)

Knowing that I would say this,...... Base your decision on the fluid that's in the tranny right now. If the fluid is brown/burnt than leave it be !! If it's nice and red it might not have been changed - or driven - much in years and changing the fluid might not be too risky. If it seems kinda' pink/dirty than you could plan for the fluid change till right before putting it away for the season. If it caused problems it would happen when the car is expecting down-time and you could deal with rebuilding over the winter if needed.

I regularly seen 200+ from factory 700R4 trannys. Had a few fail around 170K and have seen them last over 300K. The last GM Tranny that failed on me was in a 2004 (4l60E, so not a 700 !) It had 220K or so and then lost 4th,... then second.

Bob88GTA

iTrader: (2)

I ran mine for 20 years in the hot Mojave Desert....100+ in the summer. Changed fluid and filter every 50k or so miles. The trans at 191k shifts like day one. I never had a problem.

Lurbie

iTrader: (3)

I just experienced the same thing myself. I had parts ordered from Dana @ ProBuilt, but wanted to see what was in the bottom of the pan because I already had a mild 1-2 slip, a nasty 2-3 flare and a soft 3-4 shift. So to see if I would need any more hard parts, I decided to pull the pan and put a new filter in while I was there. ALL I did was drop the pan, new filter, gasket, and fluid. Went to drive it afterward and it was near impossible to get it into 4th gear, then seemed to either be stuck in 1st or second, but manual downshifts still had engine braking. So I could say that my transmission was already ruined, but adding new fluid did create some immediate additional symptoms.

Brando5641

iTrader: (-1)

Its all hydraulics. Yes the fluid will break down and loose its lubricating effects but changing the fluid is not going to put material back on the frictions. If the transmission has a problem, 99% of the time changing the fluid and filter isn't going to fix anything. I personally dont change transmission fluid.