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Changing the rear diff fluid

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So I was under the car today changing engine, tranny (Royal Purple Synchromax...took about 2.8 QT's), and the diff fluid. When I got back to the diff I hesitated because I wasn't sure if there was a gasket required when I pulled the cover off? Also, can I get the cover off without removing the panhard bar? I have an aftermarket Steeda bar. I am thinking about buying the 2013 diff cover because it has the drain plug. I have heard of people taping the 12 diff cover. If anyone has done this and has feedback I would appreciate it.

The car has 3500 miles on it and still has the stock diff fluid. Of that I'd say it has about 3-4 hours of track duty and I'm gonna be heading to the track again next weekend. The Nurburgring isn't as hard on cars as conventional tracks because it only takes me about 8 minutes to do a lap and then I take a break for at least 30 minutes between laps. Anyways, am I good to do another track day without changing the fluid? I know the manual says to change it after the first 4 hours on the stock fluid. Thanks to all in advance.
 
Personally, I have not changed my diff fluid yet, so I'm not 100% sure if what I'm about to tell is correct. But I had started reading threads to get ready for my diff fluid change.

- I believe you do need to drop the panhard bar at one side to get enough room to remove the diff cover. recently, someone had a thread about this. not sure about steeda bar, if it's thinner or mounts differently compared to stock bar.
- You will need to clean and reapply RTV sealant/gasket maker on the diff cover to seal it back up.
- I think ford recommends you change the the diff fluid pretty quick the first time because of metal shavings. So, I would recommend you replace it as soon as you can.

someone who has done this will soon chime in and assure you with what you need.
 

steveespo

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Sako has it right. Panhard bar needs to be swung down to remove cover. You can tap and plug the '12 diff cover but for $100 buy the '13 GT500/Boss cover, comes with magnetic plugs already done and a port for a temp sensor if you are so inclined, (I was). The fill location is on the drivers side front of the diff housing. 3/8"square drive to remove and replace use some teflon paste to re seal. The rear cover I use Permatex Ultra Black RTV, follow the directions to let it set before final torque and you will have no leaks, also use plastic razor blades (look on Amazon) to get all traces of old sealant off the cover and housing then wipe with brake clean or alcohol before new seal. I use the Ford specified gear oil and add 4 oz of Ford friction modifier. Even though they say Torsen doesn't need it I think it helps the helical gears slip better and reduces the Torsen groan in tight turns. When filling I use the Cool Tech pressure fluid pump and it is great at $39 bucks. Excellent for both diff and trans fluid changes. There are probably other versions out there but Cool Tech is a great supporter of our community. When filling try and level the rear axle to normal ride height and fill through the front plug until the fluid dribbles out. Stop filling and let it settle in whil rotating the wheels a few turns. Then pump in some more till it dribbles out again. Re install front plug with telflon paste and tighten to 25 ft/lbs, wipe every thing clean with brake cleaner and you are good to go. I change mine every season which is about 14-18 hours on track or about 2000 track miles.
Steve
 
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Where did you buy your new diff cover? I saw Lethal and Steeda sell one but it doesn't have the diff vent on the top like the stock one does.

Am I good to hit the track this weekend with 3500 miles and 4 track hours on the stock fluid? I'd like to get the new diff cover and do the oil change all at the same time.

steveespo said:
Sako has it right. Panhard bar needs to be swung down to remove cover. You can tap and plug the '12 diff cover but for $100 buy the '13 GT500/Boss cover, comes with magnetic plugs already done and a port for a temp sensor if you are so inclined, (I was). The fill location is on the drivers side front of the diff housing. 3/8"square drive to remove and replace use some teflon paste to re seal. The rear cover I use Permatex Ultra Black RTV, follow the directions to let it set before final torque and you will have no leaks, also use plastic razor blades (look on Amazon) to get all traces of old sealant off the cover and housing then wipe with brake clean or alcohol before new seal. I use the Ford specified gear oil and add 4 oz of Ford friction modifier. Even though they say Torsen doesn't need it I think it helps the helical gears slip better and reduces the Torsen groan in tight turns. When filling I use the Cool Tech pressure fluid pump and it is great at $39 bucks. Excellent for both diff and trans fluid changes. There are probably other versions out there but Cool Tech is a great supporter of our community. When filling try and level the rear axle to normal ride height and fill through the front plug until the fluid dribbles out. Stop filling and let it settle in whil rotating the wheels a few turns. Then pump in some more till it dribbles out again. Re install front plug with telflon paste and tighten to 25 ft/lbs, wipe every thing clean with brake cleaner and you are good to go. I change mine every season which is about 14-18 hours on track or about 2000 track miles.
Steve
 

steveespo

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I got mine from Tousley Ford, here is a link to the part
http://www.roushyatesparts.com/ford-racing-differential-cover-p/frp-m-4033-ka.htm

It has the port on top for the vent, just have to swap it over.
You are fine to run another day, gear oil is tough stuff, especially synthetics.

Have fun on the Ring, I drove it in '07 when I picked up my 335i. Wish I can go back.
Steve
 
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Thanks for the info...I'll go ahead and order the new diff cover. I wish Ford hadn't cut this corner but it's worth not having to pull the cover off every time. One more question I have is about installing a breather. I have seen the turkey baster and another that hard mounts to the chassis. Do you have one that you recommend?

As for the ring...I love taking the Boss on the ring. It's so much fun passing all the M3's and Porsche's. I'll have to post a video of the Boss on the track after I head out there this next weekend. In Europe the Boss is an exotic car and I get a lot of attention. Not looking forward to bringing her back to America where I have to go 75 on the freeway :( I'll be convoying up there with a Z06, M3, and a Mustang GT.

Thanks
 
Flyboygsxr said:
As for the ring...I love taking the Boss on the ring. It's so much fun passing all the M3's and Porsche's. I'll have to post a video of the Boss on the track after I head out there this next weekend. In Europe the Boss is an exotic car and I get a lot of attention.
Quote of the day! 8)
 
steveespo said:
When filling try and level the rear axle to normal ride height and fill through the front plug until the fluid dribbles out. Stop filling and let it settle in whil rotating the wheels a few turns. Then pump in some more till it dribbles out again. Re install front plug with telflon paste and tighten to 25 ft/lbs, wipe every thing clean with brake cleaner and you are good to go.

Steve, the correct oil fill level is 1/4 to 9/16 inch BELOW the fill hole. Do not fill to the bottom edge of the fill hole. If the diff is filled to the bottom of the fill hole, there is much more of a chance of oil coming out of the breather/vent in the top of the cover, at least for those of us who still have them.
 

steveespo

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06mach1 said:
Steve, the correct oil fill level is 1/4 to 9/16 inch BELOW the fill hole. Do not fill to the bottom edge of the fill hole. If the diff is filled to the bottom of the fill hole, there is much more of a chance of oil coming out of the breather/vent in the top of the cover, at least for those of us who still have them.

I guess you're right, I run the bobs remote reservoir with vent, no blow off anymore. Stock I had the typical vent wash after a track day, went to the turkey baster and that worked but got melted so finally went with the bobs. The level is not the issue but the high temp causes heated vapor to expand and there is not enough relief with the stock vent so the whole thing pressurizes. I have seen the overflow but also rear axle seals start to leak too. This also why I went for the differential cooler setup for the track, now I can keep it right around 235 degrees through a whole 20 minute session. It also gave me an additional .75 quart of lube to help draw of the heat.
Steve
 
I am about to do the same today, and have the axle up on jack stands. I have never touched a RWD suspension before. If I detach the panhard will the car shift and become dangerous without it present or put strain on the control arms? The driveway is not perfectly level. The drivers side might be lower by 1/4".
 
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Flyboygsxr said:
Is there any fabrication required for this or is all bolt on?

IIRC the two bolts used are 148 lbs/ft of torque so no small task.

BTW here's some pics of my fluid change. http://forums.themustangsource.com/f813/first-diff-fluid-change-pics-497224/

No friction modifier required if you have the Torsen. 8)
 

drano38

Wayne
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Flyboygsxr said:
Is there any fabrication required for this or is all bolt on?

None as already posted.
But those bolts have blue locktite on them and are a b*!# to get out. I used long extensions to get the ratchet below the diff and added a pipe to the ratchet. If you have a lift, it will be so much easier. Jackstands are doable.

Can't find Pete's install thread. Here's one from another board. You can run the hose to the axle or top of the diff cover. The stock diff cover vent goes to the top of the catch can.
http://forums.themustangsource.com/f813/ls-rear-differential-vent-500746/
 
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I've got a new adjustable third link and relocation bracket to install from Steeda and I started to do the work but those bolts were so hard to get off I thought maybe I was doing something wrong so I retorqued them and left that job for another day. It was 2AM and I had been working on the car for over 12 hours!

One other question...well, probably more than one but can I just pump the fluid out of the rear diff without removing the cover? My pump line fits in through the hole and I'm pretty sure I can get 95% of the fluid. At least until I get the new cover with the drain port I was thinking this would be better than nothing before I hit the track next weekend. Last question, can anyone who has installed a Steeda third link with relocation bracket do a "How to thread"? There are so many holes to choose from on the new bracket that I'm not sure which one to use to set the suspension up properly. I know these questions are off topic so if someone has experience and wants to start a new thread that would be nice.

Thanks guys
 
How much fluid is the 13 boss supposed to take? I pumped in 3 qts and its still not not registering w my dipstick.

Car is level.

On the 13 there is a fill hole in the diff cover and that's where I was filling from
 
I think that's a common mistake.

I too thought my '13 diff cover had a super-cool "fill hole" and "drain hole". But that's not correct... those holes are for a bolt-on diff oil cooler. Right guys?

The proper fill hole is on the main diff housing, not on the diff cover. Look for it above a "ledge" on the front, driver's side, upper half of the diff housing.

It's lower than the top hole on the diff cover.... so when you take it out you'll probably get some spillage.
 

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