Automatic Transmission Servicing, '73 2002

[jd_sims6]

Hi,  I'm servicing the automatic transmission on my '73 2002.  I'll replace the fluid, filter and pan gasket. There are three pan bolts broken so I'll have to tap them out.  I'm assuming I drain the fluid by removing the pan as I don't see a drain plug.  Any recommendations on things to watch for or avoid?  Also, any recommendations on which type of Dextron to use?

 

thanks, John

[Buckeye]

useful information for auto trans

 

 

[jd_sims6]

Thanks.  This is good.  Any recommendations on which DEXTRON to use?

[mmichalik]

Hi JD, couple of things.

 

1) No straight dextron ATF.  I have a 76 automatic, a ZF3HP, and it uses DEX/MERC.  I personally put in the Valvoline brand.  Verify that your's is, or is not, the same but, I believe you'll find it will be.

2) When you put the filter back in, it screws in directly to the valve body so be careful when tightening.  The specs call for inch pounds, not foot pounds, of torque.  Over-tightening of the filter "might" cause issues.  Just snug it up in there.

3) The pan has a gasket you should be able to buy from Worldpac.  I would suggest that, since these pans are pretty beat up after 40+ years, you use some properly spec'ed out ATV around the bolt holes at a minimum in conjunction with the gasket.

and most importantly,

4) If you have the opportunity, I would suggest buying a spare parts transmission for future need.  I just had to rebuild mine and some of the parts were so hard to get (even ZF didn't have them any longer) that we had to harvest parts from two donor transmissions.  (the two we grabbed were about $250.00 a piece so, not a big commitment)

 

Hope that helps.  Have fun with it!  They are certainly not as popular as the manual transmissions but, it sure is nice to be able to drink your coffee while driving in traffic. 

 

Mike

Edited March 17, 2017 by mmichalik

[jd_sims6]

Mike,  Great input and super timing. I'll finish the tranmission tomorrow.  How would I find out if it's a  ZF3HP.  Does the different fluids vary and affect the transmission that much?  Also, what is ATV, a sealer?  Thanks again, John

8 hours ago, mmichalik said:

 

 

[mmichalik]

John,

Sorry, that should have been RTV (I guess I had ATF on the brain when typing that).  Permatex black RTV will help seal up the pan and is only a few bucks for a small tube of it.

 

The ATF fluid will impact the performance of the transmission incredibly.  Here's what's listed for stock transmissions of ours https://www.amazon.com/Valvoline-Merc-Automatic-Transmission-Fluid/dp/B00DJ4FF0E?th=1

 

I'll see if I can find out anything about the transmission but, I believe all of the auto's were ZF3's

[jd_sims6]

Got it together and sealed up.  Gasket wouldn't seal so I used super grey permitech and it worked great.  Thanks for all the advice... 02 is back on the road!

[percy]

22 hours ago, mmichalik said:

The ATF fluid will impact the performance of the transmission incredibly.  Here's what's listed for stock transmissions of ours https://www.amazon.com/Valvoline-Merc-Automatic-Transmission-Fluid/dp/B00DJ4FF0E?th=1 

 

What do you mean by "incredibly" and what is your basis for that conclusion?

 

I would agree that when the transmission was first produced, the manufacturer recommended ATF, Type "F" which was used primarily by Ford in its transmissions (some of which had clutch material that contained bronze).  The majority used GM's Dextron fluid.  Type F or Type F compatible fluid, as you note, is still available, although not as widely stocked by retailers due to reduced demand.  However, modern transmission lubricants have made great strides in the past 40 plus years and that even includes the fact that whale oil is no longer an ingredient.  Now the current trend is a blend of additives trending toward cross-compatibility with other fluids and I would venture to guess that there are many ZF3HP's currently using Dextron/Mercon variants without issue.  But maybe you have additional information?

[mmichalik]

Not being a hydraulic expert, I just know that lubrication, fluid pressure, and cooling are the primary functions of ATF.  I was always told that the correct type of ATF for the transmission will keep the fluid pressure at the right levels to activate the transmission bands and clutch plates, etc, in order to change gears, and provides the proper cooling capacity to prevent overheating.

While you're right in saying that it could use a wide variety of products, that's just the one that I was recommending based on what we have put into the car for the past 10+ years and our mechanic has recommended that we use. 

 

 

Edited March 20, 2017 by mmichalik

[percy]

42 minutes ago, mmichalik said:

I was not trying to start a debate about which type of ATF was better.

 

Nor was I.  Your response suggested that the difference between fluid type F and Dextron was critical, and that caught my attention.  I thought you were hinting at some personal experience with having used the non-recommended Dextron fluid.  Now curious about PatA's experiences.

 

I would not ordinarily advocate deviating from the factory recommendations and am not doing so now.  But I question whether the differences between these two general "types" are significant enough to notice.  Type-F ordinarily came without friction modifiers and it tended to have a higher viscosity than Dextron.  Dextron had friction modifiers that essentially made the oil slightly more slippery that the Type-F.  The Type-F therefore promoted crisper rather than smoother shifts.  (It is debatable whether one fluid type promoted longer transmission life.)  For any number of reasons, Dextron became the predominant fluid since Ford and (I think) Toyota eventually moved to their own version of Dextron, aka, Mercon.  But consider that the factories did not recommend synthetic lubes either, when they produced and serviced the cars under warranty in the early '70s.  That doesn't necessarily mean, however, that they would advise against using them today.  Same reasoning might apply to using the longer-life "blue" or "gold" antifreeze, but that is a topic for another thread.

 

FWIW, a friend has an E3 with a ZF 3HP-20 that has been a daily driver for more than 35 years.  He uses a Dextron variant almost exclusively without any problems.  In fact, he has used a lot of it since his transmission (which has never been removed from the car) has a slight leak that he chooses not to fix.  He routinely replaces the trans filter, and the fluid is always bright red.  Since he routinely tops up the trans fluid level, he buys the fluid in bulk and stores some with me, which is how I came to use some of it.  Although my daily drivers are not specifically ZF 3hp-12 automatics, two once were, and I never noticed any differences in transmission performance or deleterious shifting effects due to using non-F type fluid.  Of course my experience may be the exception to the rule, so mind the adage: "your mileage may very."

 

Not that long ago, another fluid "Type" question arose in connection with another vehicle and the owner mentioned a TSB that suggested all modern grades were compatible.  Another acquaintance noted that although the owner's manual for his E9 also has a list of recommended "F Type" brands, just like the 02's manual, a contemporaneous Autobooks manual actually mentions using Dextron!  (It does also mention using the correct fluid, but that may be to distinguish it from motor oil or mineral oil, otherwise why mention Dextron and not Type F?.).  The page is printed below.  Read paragraph opposite dipstick that reads "Do not overfill transmission."   SInce I do not have the same manual handy for the 02, I will leave it to others to research this.  Maybe it is a printing mistake or maybe not. 

 

Redline currently appears to offer six different types of automatic transmission fluid, including "Racing Type F"  which they describe as  "Similar to a Type F fluid.  https://www.redlineoil.com/product.aspx?pid=52&pcid=9   I suppose I would choose that fluid for my early ZF3hp transmissions, although other available information suggests that in the long run, the distinction might not be that different than the difference between various brands of the same weight synthetic motor oil.  Yes, JimK, has told us that certain oils have better lubricating properties than others, but often those qualifies far exceed the needs of the average daily driver, whereas the added benefits are nice to have but often go unappreciated.

 

Like it or not, no matter what fluid type is used, if the transmission gets used too - internal wear is inescapable.  Wear can be minimized by maintenance and avoiding problems that you hinted at, including overheating, contamination and maintaining proper fluid levels.

 

 

[peteri]

If you want a spare tranny let me know. I swapped my 73 auto to 5 speed. It was in excellent shape with no leaks or grinding when I removed it

[mmichalik]

Percy,

 

That's an awesome response.  Thanks for sharing that.

I actually removed the line that you ultimately ended up quoting because I did not want to sound arrogant or condescending.  I hope you didn't take it that way and if you did, you're response was elegant enough that it was not noticeable.

I learned a lot today just reading that and, I appreciate the post.

 

Mike

Edited March 21, 2017 by mmichalik

[percy]

Thank you Mike.  I've been around the block one or two times, but I also recognize that there are always new (and even old) things to learn and occasionally better approaches to tried and true methodology.  This is why I took interest in your comment. 

 

Something I recall hearing years ago (from more than one source that worked on transmissions) was that mixing the two ATF types was a bad idea because one of them (Dextron?) was potentially incompatible with so-called yellow metals, e.g., bronze or brass, presumably used in some friction materials e.g., Ford clutch packs.  Your post rekindled my memory and the fact that I was never able to confirm (to my own satisfaction) that this notion was true.  As you know, Getrag manual transmissions used in our cars do have brass/bronze synchronizers, and for that reason, it is recommended that only (non corrosive) GL4 lube be used in them.  The sulfur-laden extreme pressure additives used in most GL5 lubes are potentially corrosive to yellow metal.  It has been a long time since I carefully examined an original clutch pack for the 3hp-12 and I honestly can't recall whether there was any specific or obvious use of brass/bronze/copper in the friction materials, so I am still at a loss on this rumor, as it might apply to clutch materials originally used in 3hp-12's.

 

FWIW, I had an almost-stock 02 auto that provided well over 150,000 + trouble free miles using mostly Dextron III variety fluid.  I kept a spare 3hp-12 in the garage, thinking that some day it might come in handy.  That day never came due to an inattentive driver who failed to notice a stop sign.  I did give the spare transmission away, but I quietly contemplated replacing the original with a 4speed automatic (4hp-22) from another model (E30).  For all I know, the transmission may not have ever developed problems, but I tend to be optimistic.

 

I don't recall this forum devoting much, if any time to the early automatics.  The pre '73s that did not have any exterior cooling lines and a remote trans cooler.  If I remember correctly, the torque converter had integrated external cooling fins, that probably consumed extra power at high engine speeds.  That transmission performed just as well as our '75 - equipped with the cooling hoses and heat exchanger (incorporated in the radiator) or any other auto-equipped '02 I have driven.  Primitive but durable.  Maybe it was the Dextron and clean living. 

 

(Not one of mine)

Edited March 21, 2017 by percy

[Esteban Auto]

If any of you Automatic owners or previous automatic owners want to separate themselves from the interior selector parts, think of me!  The display and horsehair has gone to another place.  Would love to make it look better as I have no plans on switching to manual.

[OldRoller]

On 10/6/2024 at 12:22 PM, Esteban Auto said:

interior selector parts

The shifter housing in difficult to find. Possibly place an want-to-buy in the Classifieds... but likely any housing would need a serious refurb. You can get the brushes in a strip from McMaster Carr, cut trim and glue them in place. The 'selector' graph is another matter, but someone with a 3D printer could make a suitable replacement. 

There was a gent in Oregon that planned to make repo's of the housing, not sure if he ever progressed on the project. I'll try and find his contact info. 

On with the hunt!