Automatic transmission maintenance

"My bird IS the word" (mybirdistheword) 11/21/2016 at 22:26 • Filed to: Transmissions, maintenance

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A thought just occurred to me: I haven’t paid the slightest attention to my transmission.

Now I did check the fluid level after I bought the car. It also seemed pink on the dipstick. I assumed the guy I bought it off of must have changed it, I figured I would still do new fluid and filter for sanity’s sake. I have not had the chance to do that yet.

That being said, when I go to do my engine, is there any maintenance items (aside from the above) that I should take a look at for the transmission? That would be a GM turbo 350 for those of you wondering. It shifts fine, and due to the complexity and expense a rebuild for shits and giggles is completely out of the question. I don’t plan on touching this box full of magic and demons if I don’t have to, but it seems odd that my engine needs all kind of refurbishing but my tranny doesn’t.

atfsgeoff > My bird IS the word 11/21/2016 at 22:34

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How much hooning are you going to be doing in the car?

gogmorgo - rowing gears in a Grand Cherokee > My bird IS the word 11/21/2016 at 22:39

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The transmission is a bunch of oil sitting in a gear box. The oil is very carefully engineered to not change in density or viscosity as it breaks down. The only way it can collect contaminants is by clutch bands wearing (high detergent levels in the fluid prevent this from becoming an issue) or by foreign materials entering via the dipstick tube or breather vent.

Check the level of the oil at every engine oil change interval. If it doesn’t look burnt and the level hasn’t dropped and you haven’t noticed any other issues, it’s fine, leave it alone.

Sure there are intervals where you’re supposed to replace the fluid (look them up) but most people end up ignoring them because they’re so big they don’t always realize it needs done. Like 100,000 miles big or something. I don’t remember.

Unlike engine oil that fills with combustion by-product and is exposed to high temperatures, most other automotive fluids stay pretty clean and stable.

Sovereign, Purveyor of Coupes > My bird IS the word 11/21/2016 at 22:49

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This is what I did to mine, which had probably been very neglected considering the awful smell of the fluids I drained the first time.

•100 miles of driving. making sure to hit all gears at least at 4000 rpm.

•change with cheap Walmart Dex III

• repeat two more times, changing filter if your Trans has one.

•Switch to full synthetic valvoline. and royal purple in the diff.

•absolutey 0 problems ~20k miles later. and I’ve done a few neutral drops which is a big no-no on the hp24 due to burning out clutches. I certainly don’t baby it, and it works great.

lone_liberal > My bird IS the word 11/21/2016 at 22:52

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Shifts are good, color’s good, and the level is good? I say leave it be.

camaroboy68ss > My bird IS the word 11/21/2016 at 22:54

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Doesnt hurt to give the dipstick a good sniff, if it starts to smell burnt then the clutches are going.

My bird IS the word > atfsgeoff 11/21/2016 at 22:55

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It is pretty much exclusively for hooning- is what I want to say. Some certainly though. not planning on racing or autocrossing on a regular basis.

My bird IS the word > Sovereign, Purveyor of Coupes 11/21/2016 at 22:58

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I’m real curious to see what the fluid inside looks like. I didn’t get the full story, but it is clear the guy I bought it from dragged it out of a yard or field, swapped the fluids and did some welding. I still am not sure what’s all been changed, its clear my power steering fluid needs some attention. Ill give that a try.

JGrabowMSt > My bird IS the word 11/21/2016 at 22:59

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I would change trans fluid around 50-75k miles. Brake fluid every two years, coolant about 2-3 years. My oil gets done ever 10k miles roughly, and diff fluid about 50k (now that I have a Wavetrac, and it’s broken in).

Beyond 100k miles, trans fluid is a hit or miss kind of thing unless you’re having the trans rebuilt.

atfsgeoff > My bird IS the word 11/21/2016 at 23:00

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Find a speed shop with some old timers, they can probably recommend someone who has mastered the black art of auto transmissions who will rebuild the thing stout enough to survive a heavy right foot for years to come, for a couple hundred bucks if you bring the transmission to him.

Birddog > My bird IS the word 11/22/2016 at 01:55

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The Turbo 350 is a hard trans to kill. I would consider changing the vacuum modulator if the PO hasn’t. It’s a neglected part that gets overlooked.

If max hoonage is your goal look into a good “Shift Kit”. Fairbanks and TransGo are about the best. They will, believe it or not, help extend the life of the trans. A good auxiliary trans cooler and temp gauge are worthwhile investments too. Eventually you may find a stalled torque converter a fun investment too. A TCI “Saturday Night Special” is a good choice there.

My bird IS the word > Birddog 11/22/2016 at 02:03

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Ahh, Thanks! That’s more what I was looking for. I was looking to someday swap to a TKO 5 speed but the TH350 is growing on me and I might keep it. I figured the shift kits would beat the crap out of it, that’s good to know. If I end up keeping it I will definetly upgrade the torque converter. I will look into the modulator, guaranteed this car has never had a serious service in it’s life.

Birddog > My bird IS the word 11/22/2016 at 02:16

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The modulator is so often overlooked it’s aggravating. It’s a $15 part and it’s held in by 1 bolt and a clip.

The “full race” shift kits will kill an unprepped trans. All you’re looking for is to kill some of the overlap during gear changes. It can lower temps and reduce wear. And if that gets a little bark of the tires on the shifts? All the better.

If you find an “old timer” trans shop they may be able to do the same thing without a kit too.

A good T350 can be fun. Especially in the stoplight commando game.

jordang1028 > lone_liberal 11/22/2016 at 02:19

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I massively second this. Add in a smell check for anything burnt and if it’s good leave it be. I had an Expedition with 280k on the clock on the original transmission (insane, I know) that had never had a fluid change. The mechanic who has worked on my parents cars for 20 years and mine for 5 explicitly told me not to touch it if there was no problem.

My bird IS the word > Birddog 11/22/2016 at 02:29

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TBH the entire vacuum system needs replaced. hot/cold cycles have destroyed the lines and diaphragms so that is something that will probably break when I start driving regularly. good to catch it rather than scratch my head later.

Sovereign, Purveyor of Coupes > My bird IS the word 11/22/2016 at 02:35

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Switching a few times in quick succession is the key. too many horror stories about guys stirring up old crap, and having it ruin everything. looks like a very nice car btw.

Sovereign, Purveyor of Coupes > My bird IS the word 11/22/2016 at 02:36

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Fwiw mine sat outside a barn 20 years before the PO got to it, hence why I was extra cautious with fluid changes. sounds like you might be in the same boat.

Birddog > My bird IS the word 11/22/2016 at 02:41

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Now I have to go back and read up on your Bird.. If your brief up top is an indicator I’m sure there will be a lot of nickel and dime work. That’s all stuff that takes more time than money. It all has a good payoff though.

My bird IS the word > Sovereign, Purveyor of Coupes 11/22/2016 at 02:43

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Thanks. The tri-five looks nice as well, I love total resto jobs.

My bird IS the word > Birddog 11/22/2016 at 02:47

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The trouble is going to be what I can do next summer with little to no money. Once I get settled I really won’t mind throwing money at it but right now I just want to drive the damn thing. This car is more a labor of love than a sound financial decision.

Birddog > My bird IS the word 11/22/2016 at 03:01

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Maintenance items like hoses/tubing, fluids, detailing and small hard parts like brakes, wheel bearings and tune up stuff are all relatively cheap. Mods can wait. It took me years to learn that. Too many years.

I’ve sold more than one unfinished project car because I went too far, too fast and ran out of time/money/ambition.

My bird IS the word > Birddog 11/22/2016 at 03:16

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I only have a few more roadworthiness things (tires, choke) to worry about. my plans for next summer are brake lines, an engine “overhaul”, subframe connectors with new bushings all around (the connectors are neccessary, the bushings aren’t but it drives like a camry right now) and maybe an inexpensive sound system upgrade so I can jam to some tunes. thats pretty much it unless I can secure some more money. I will have slightly powerful car with a sound system but no carpet or functioning door locks.

Birddog > My bird IS the word 11/22/2016 at 04:21

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I miss the days when you could go down the street to a local parts store to buy a choke pull off or a ballast resistor. Good times.

I’d recommend leaving the engine for last. Get the chassis right then put an engine together for it. That’s just me though.

My bird IS the word > Birddog 11/22/2016 at 05:22

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I just want to tool around in it till I can get the money to have the body professionally done. the engine is only really getting freshened up with new seals, timing chain, ect.. I am not touching the performance aspect or anything I can get away with.

19JRC99 > My bird IS the word 11/27/2016 at 10:46

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Shift kit? Or a Hurst Quarter Stick.

My bird IS the word > 19JRC99 11/27/2016 at 12:18

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The trans am comes factory with a ratcheting shifter. The shift kit I might do but I really don’t want to drop the whole thing if I don’t have to.

19JRC99 > My bird IS the word 11/27/2016 at 18:51

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I don’t think you have to drop the trans for one. Can’t remember.

My bird IS the word > 19JRC99 11/27/2016 at 23:06

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They say that you don’t but it is a pain in the ass that way. I am not really feeling it this year considering my budget, but if more money opens up I will.

19JRC99 > My bird IS the word 11/27/2016 at 23:27

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I see. I’ve never installed one.

Chan - Mid-engine with cabin fever > My bird IS the word 12/22/2016 at 15:16

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Drive/drain/fill 3 times

My bird IS the word > Birddog 08/09/2017 at 20:56

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hey, I just posted on the front page, but I wanted to thank you, look how bad my modulator was:

good lordy