underwaterphoto

Hi, I just purchased a used 2001 Winnebago Brave RV at a great price. However, I was told it had an allison transmission in it. That turns out to not be true. I decided to buy it anyway. The transmission that is in this RV has these numbers on the side. P/N 24208421 GM-B8. I did a quick search on and it came up with several different types of transmissions. Can anyone give me more info on this transmission? I want to change the fluid on it and the filter. What fluid? Filter? While I am at it. I need to change the differential fluid as well. Any advice?


Thanks!

strutaeng

Transmission or axle?

That's a 4L80e. It actually has it cast on the case. What engine does it have? Is it gasoline? 8.1 liter perhaps?

Can't tell on the axle...🧐🤷

underwaterphoto

Gas. 8.1l Vortec. 81,000 miles.

RDF1

Right above the part number..... 4L80-E


That is a standard depth pan so it will take a WIX 58608 Filter. And it will take about 8 quarts of ATF. Id use some Dex VI fluid.

underwaterphoto

Do I have to drop the pan to change the filter?

strutaeng

Dexron VI is the correct fluid. You can disconnect one of the transmission cooler lines at the radiator or external cooler and hook up a clear vinyl tubing into a 5 gallon pail. Start the engine with a helper and wait until the fluid starts spitting, then shut the engine off. That will pump out most of the old fluid from the converter.

Remove the pan (now almost dry), clean the magnet and remove the filter and the little metal seal inside the transmission. The new filter for your transmission (late model) has the little feet on the bottom. Install new metal seal, filter and reuse the original thick pan gasket. Torque pan bolts to spec.

Dump about 5 quarts of new fluid and start the engine and add another 5 quarts while engine is running (have them ready.) Shift through the gears and add more as necessary.

That's the procedure I've done. Sounds kinda scary at first, but it's not once you do it the first time.

underwaterphoto

Ok.. thanks for the info! I am an electrical engineer so transmission is out of my pay grade. LOL

FFDP

iTrader: (2)

That pan has a drain bolt too, do that before removing the pan.

My opinion is just measure the amount of fluid you take out, that way you roughly know what you need to put back in. Have enough fluid on hand but just don't go dumping 10 quarts in the thing right off the bat. Fill, check with dipstick and repeat.

strutaeng

I now see you have a drain plug on the transmission pan 🧐. You can do a drain and refill. No problem.

Can you count the number of bolts on the differential? I'm thinking you have a Dana 80? It's probably an open differential, so any spec gear oil will work. Pop the cover (actually, pop the fill plug first to make sure you can actually remove it), drain fluid, use brake clean to wash any grit out. Clean the magnet and reinstall cover. You need a little hand pump to pump new fluid in until full to fill plug level.

someotherguy

From what we can see in the pic, shape doesn't look quite right to me for a Dana 80. But it is important to correctly identify as that wants different fluid than your typical 14 bolt. Dana 80 wants 75w140 synthetic, instead of the usual 80w90 GL5 spec'd for the lighter stuff. Anyway from the pic it looks more like a 14 bolt to me.

Richard