If You’re Really Going to Service 8HP70 Trans on Your Driveway ...

[Funkychateau]

Nick14, good point, an air inlet helps it drain a little faster.

 

[Nick14]

Yes it will drain faster but, more important, if the plug is stripped, rusted, cross threaded and can't get loose, there would be no way to fill it. Nick

 

[Funkychateau]

Yeah, jack the rear axle up 8-10” and you’ll get another quart and a half in there. Take it easy on shifts until then so you don’t slip your C/E clutches.

Tim, I just finished topping off with the rear jacked up to level the pan. The actual difference in fluid taken was only a little over one-third of a quart.

As expected, this required about nine inches of rear-axle elevation above level.

My sump gun has a 2-inch bore and 8-inch stroke, so it holds about 25 cubic inches, or 0.43 quarts. I fed a full barrel into the transmission, but it was flowing pretty freely out the fill hole. I estimate that two or three cubic inches came back out by the time I sealed everything up at 115 degrees F.

 

[alpinegreenneon]

The FSM video:
https://drive.google.com/open?id=1b4bU8_t8f3c5cEqiSdQTWx4e2IZsdr7v
It's missing the part about the pan rails being level.

 

[Funkychateau]

The FSM video:
https://drive.google.com/open?id=1b4bU8_t8f3c5cEqiSdQTWx4e2IZsdr7v
It's missing the part about the pan rails being level.

Yes, it was missing in the resources I used as well.

Since so many of the videos omit it, I’m wondering how necessary it really is. Especially considering how small the actual difference (1/3 quart) in fluid fill turned out to be.

Maybe the acceptable fill range is fairly wide. After all, capping anywhere between 86 and 122 degrees would be “in spec”, and this represents some difference in acceptable final fill. I wonder if the allowed temp range might have a more-significant impact on volume than leveling anyway.

 

[chrisbh17]

Yes, it was missing in the resources I used as well.

Since so many of the videos omit it, I’m wondering how necessary it really is. Especially considering how small the actual difference (1/3 quart) in fluid fill turned out to be.

Maybe the acceptable fill range is fairly wide. After all, capping anywhere between 86 and 122 degrees would be “in spec”, and this represents some difference in acceptable final fill. I wonder if the allowed temp range might have a more-significant impact on volume than leveling anyway.

Could be an interesting experiment.....fill a beaker with some known volume of the trans fluid, take its temperature, then heat it up and see how the volume is affected. ATF does expand when warm/hot, but Im not sure we know for sure just how much (and just how much for our unicorn blood fluid)

Its possible that the volume increase with temperature AND a slight underfill (if the pan rail was not level when refilling) could combine to lead to a bigger issue. Ive heard/read that the 8HP is very sensitive to fluid level, so maybe even just 1/3rd quart makes a difference.

 

[Funkychateau]

Chrisbh17, are we sure that fluid expansion alone is responsible for temperature-related level changes? I’m only guessing here, but could there be components or assemblies that retain less fluid when hot, “giving it back” to the reservoir?

I didn’t notice a drivability difference from the 1/3 quart I added after leveling the pan, but the difference with clean fluid and filter vs 184,000-mile stuff was like night and day. Especially concerning the shudder and grabbing during upshifts under light acceleration. That issue had been steadily worsening for three years. Clean fluid and a new filter turned the clock back at least 100,000 miles.

 

[PoMansRam]

Great work and awesome write up. I've seen replacement pan kits for as little as ~$40-50 shipped. I wonder how those measure up to the doorman?

Great call on the Maxlife ATF. That's been my plan all along, but I never got around to changing the pan and ATF on my 2017 Ram as I traded it for the lightly used 2019 classic recently.

Sorry if I missed it, but did you compare the amount of fluid you drained out with the amount that went back in? Just curious if there was a difference.

Again.. great call on the Maxlife ATF. Just goes to show you, you don't need the unicorn tears $20/qt OEM fluid.

 

[Funkychateau]

Great work and awesome write up. I've seen replacement pan kits for as little as ~$40-50 shipped. I wonder how those measure up to the doorman?

Great call on the Maxlife ATF. That's been my plan all along, but I never got around to changing the pan and ATF on my 2017 Ram as I traded it for the lightly used 2019 classic recently.

Sorry if I missed it, but did you compare the amount of fluid you drained out with the amount that went back in? Just curious if there was a difference.

Again.. great call on the Maxlife ATF. Just goes to show you, you don't need the unicorn tears $20/qt OEM fluid.

Though I was certainly curious regarding how much fluid I would actually get out of the unit, I decided upfront that I wouldn’t attempt to measure the drained volume. There were several reasons for this, but the main ones were that I wanted to use my old trusty large oil drain pan which I can never seem to empty completely, plus the fact that I would have no idea how much fluid was absorbed and retained by the discarded filter.

I did, however, collect and save a small jar of the fluid somewhere mid-drain, in case I become interested in an analysis.

Other issues prevented precise measurement of the fluid that I put back in. First off, I didn’t buy individual quarts, instead opting for the economy of gallon jugs of Valvoline. I also “topped off” three separate times, each time losing an unquantified amount that ran or dribbled out the fill hole. Plus, I was reusing a sump gun that had been previously used to transfer diff lube. I disassembled and cleaned it carefully, and then used maybe a cup or more of my Valvoline ATF in a throwaway container to “purge” the sump gun 5 or 10 times.

So the best I can do is guess. I have about 1/2 of my second gallon remaining, so the amount I put in is maybe six quarts minus waste. I’m guessing a little over five quarts was actually replaced in my transmission.

As I noted in the original write-up, I may do a second fill-and-drain (without pan removal) in the future. This should further dilute the unknown quantity of 184,000-mile fluid I left behind in my transmission.

 

[PoMansRam]

I know this has gotten kicked around a lot here and I wanted to confirm it's actually possible, but is it possible to use the drain plug on the pan of the 8spd to drain fluid for a simple spill and fill?

It's been surmised that the drain plug on the plastic 8spd pans can't be reused and is a once and done thing.

I never thought this was the case given parts diagrams I've seen of it.

 

[Funkychateau]

I know this has gotten kicked around a lot here and I wanted to confirm it's actually possible, but is it possible to use the drain plug on the pan of the 8spd to drain fluid for a simple spill and fill?

It's been surmised that the drain plug on the plastic 8spd pans can't be reused and is a once and done thing.

I never thought this was the case given parts diagrams I've seen of it.

I did notice a quirk in the “feel” of the stock drain plug. It “clicked”, somewhat in the manner of a gas cap being tightened, whenever it was turned in either direction. Don’t know whether this has any significance regarding it’s reusability.

I opened it a turn or two (not complete removal) and the fluid drained out. When I re-tightened it, the flow stopped. I can’t say whether the seal would have been durable. I threw the pan away.

For an aftermarket pan (such s the Dorman) with a replaceable filter, it is obviously designed for multiple re-uses. This plug did not “click” when turned, but that may just be a design manifestation with no particular significance regarding durability.

 

[Rader]

I know this has gotten kicked around a lot here and I wanted to confirm it's actually possible, but is it possible to use the drain plug on the pan of the 8spd to drain fluid for a simple spill and fill?

It's been surmised that the drain plug on the plastic 8spd pans can't be reused and is a once and done thing.

I never thought this was the case given parts diagrams I've seen of it.

It is reusable. While camped in a remote area hunting I had the misfortune of having a stick flip up and crack the plastic pan, overnight the fluid leaked out enough that the truck would not move. There was no pans of correct fluid in the only town within 150 miles so at a small town O'reillys I picked up acetone JB weld MaxLife and a pump.

I removed the plug and finished draining the pan then cleaned the area and patched the pan with JB plastic weld. The original plug came out with some resistance but screwed back in and sealed fine. After some miles the repair was solid and at that time the pans were about $350 so I decided to wait until 30,000 miles to change the pan. After I got home I decided to drain and refill again to up the ratio of Max Life so used the drain plug again and again it screwed back in and sealed just fine.

 

[Marshall]

Sounds like what you need is a kid with gloves and a heavy shirt, old towel , you look at gauges , and yell, he pumps oil and install the plug.
My suggestion , never get the wife involved in stuff like this, the yelling gets BAD. Learned that 50 yrs ago.
But as others have said , great write up . I can get down good and fast , the getting up part can be a problem.

 

[Snaggletooth]

Great thread. Am very interesting in doing this soon to my newly purchased 2016 Ram 1500 with 92k miles on it. What’s holding me back, for the most part, is the damn weather here in Phoenix, AZ. I’d have to do this at like 4:30 AM and it’d still be around 90F ambient haha. So I’ll just use the weather as an excuse to wait a couple months.

 

[Snaggletooth]

I wasn't happy with low speed downshifting either and finally took mine in this week. There is actually a reprogram for the transmission, here is a link to the TSB they updated it under. It's dated February 2020.

So far seems much better, we'll see as the trans learns.

My issue is the slight “bump” from 2-1 when coming to a complete stop. It happens right around 3 MPH however does not do it when in tow/haul. Leads me to believe an update, such as the one you posted in the TSB may fix my issue.

 

[Dodge 1500 4X4]

I think the bump is the Backlash in the rear end, and the slip joint spline on the drive shaft, my new Ram is doing this at times if I give it a little throttle and have to stop or slow down i get a clunk, I'm going to grease my spline to see if it takes some of this away.

 

[MRFREEZE57]

great write up and good detail. which flavor of the maxlife did you use?

 

[Ramdy]

If I read all of this correctly, you must have the rear wheels off the ground so that you can accelerate enough to shift from first to second gear?

 

[chrisbh17]

If I read all of this correctly, you must have the rear wheels off the ground so that you can accelerate enough to shift from first to second gear?

Yes, but more importantly while filling and checking the level, the transmission pan rail needs to be parallel to the ground, which requires lifting the rear end fairly high (8-10" off the ground IIRC).

 

[Wild one]

If I read all of this correctly, you must have the rear wheels off the ground so that you can accelerate enough to shift from first to second gear?

Here's ZF's instructions for servicing the 8 speed.The first highlighted paragraph is very important. You need a fairly tall floorjack and jackstands to lift the rear tires high enough to level the transmissions pan rails