"How-To" RDU Fluid Exchange - glock-coma

[SHOdded]

Originally posted by glock-coma

Changed RDU fluid today
#1
04-14-2013, 08:40 PM
Just thought I would post some pics

Here are some DIY 2"x12" car ramps I made.
Found these over @ evolutionm forum
http://forums.evolutionm.net/evo-x-g...bout-40-a.html


I used a Hydro-Turf oil extractor and a quart fluid pump both found on amazon.
http://www.amazon.com/Hydro-Turf-Oil...sim_sbs_auto_1



Pic of RDU fill plug....I used a 3/8 drive ratchet to remove it. The hole is pretty shallow, so the ratchet will not go completely in. Anyone know why that exhaust hangar is there?
There is not a bracket on the pipe below it


Drain plug before cleaning, and after. Some metal filings, but nothing to worry about



I couldn't completely warm up the fluid for easier extraction, I didn't want to deal with a hot exhaust while under the car. It was moving very slowly through the tube.


I got out as much as I could, about 32 ounces by weight.
The fluid was pretty nasty. It was the consistency of syrup, maybe a little thicker


Here is a side by side of old fomoco "lifetime" fluid and new redline 75-w90


Wasn't that hard of a job, the pump just took awhile because of the thickness of the fluid.
While I was waiting, I also changed the spark plugs to the new updated part number CYFS-12Y-3. Probably going to do the PTU fluid next week.

Last edited by glock-coma; 04-14-2013, 10:49 PM.

12/4/2015:  Thanks for the re-linked images, glock!  Much appreciated

[IHeartGroceries]

Lovely how-to. How'd that extractor pump work? I think I'll pick one up.

So, to be clear...

The RDU has a fill plug only. No drain. Thats where a pump or suction device comes in.

How about the PTU? Aux cooler (Perf. package) equipped SHOs have a fill AND drain on the PTU, correct? Both accessable by removing one or both primary cats. But those without the aux cooler do NOT have a drain, thus require a suction device as well. Is that correct?

[ZSHO]

I purchased a cheap but pretty descent suction gun along with an 3/8 hose extender,can probably do the CAC or maybe other applications as soon it gets warmer out.   http://www.amazon.com/gp/product/B000MD4YNY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

[AJP turbo]

I just popped the cover when I changed mine. Just have to buy some RTV and you can wipe out more old fluid with a towel.

ALso meant to add awhile back when I changed my PTU the fluid looked ok but it was only at about 5K miles. People were wondering what relatively new fluid looked like since people were seeing bad fluid at 20k. I wanted to change mine before it had a chance to turn bad.

And I'm not sure but I don't think it would do any good to drive the car to try and heat up the Rear diff because I think the clutch pack that activates the rear is in the PTU and only comes on when needed. I don't think the driveshaft spins until needed.

[SHOdded]

I would think the driveshaft would spin as long as the engine is running/ trans is not in neutral or park to avoid the startup inertia, no?  Should still take longer to warm up the RDU though.

[AJP turbo]

I would think the driveshaft would spin as long as the engine is running/ trans is not in neutral or park to avoid the startup inertia, no?  Should still take longer to warm up the RDU though.

Now that I think of it I think you are right, the clutch packs in the PTU just engage to link the 2 when needed.

[crash712us]

That not correct. The clutch is a part of the RDU. The PTU is always engaged and the drive shaft is alway spinning. The electronically controlled clutch engaged RDU when needed.  There is no clutches in the PTU what so ever.
electronic clutch circled in red.



Sent from my iPhone using Tapatalk

[Gray Brick]

Pictures are not showing up...

[joe raptor]

No picture !!!!

[metroplex]

How did y'all stick that ratchet in there? My standard 3/8" drive ratchet won't fit because of the exhaust hanger and that IRS cradle. I'd have to get a really slim ratchet in there?

[pmezo33]

How did y'all stick that ratchet in there? My standard 3/8" drive ratchet won't fit because of the exhaust hanger and that IRS cradle. I'd have to get a really slim ratchet in there?

You need to go from the top and fish the ratchet down and into the plug.  It's tight, but it will fit. 

[glock-coma]

I used several 3/8" extensions through the passenger side wheel well maybe a crows foot wrench with a 3/8" adapter would work

[metroplex]

I tried going from the top, it almost fit. I have a Gear Wrench pass-thru wrench set that I should have thought to try, it's like 1/4" thinner than my normal ratchet.

Is the RDU just an open differential? Is there any merit in using some Lubegard Gear Fluid additive (which is supposed to help reduce temperature and reduce friction) to help out the RDU and the PTU given that we don't have a lot of oil to work with?

[slurppie]

The RDU uses a electronically controlled clutch so I wouldn't use anything that reduced friction.

sent from my speak n' spell using tin cans and string

[metroplex]

So the electronic clutch mechanism is in contact with the RdU gear oil?

It doesn't seem to be actually part of the differential fluid system: http://www.shoforum.com/index.php?threads/how-does-the-awd-work.119781/