Changing oil in 7.5'' axle (may contain stupid questions)...

Topic: Changing oil in 7.5'' axle (may contain stupid questions)... (Read 1587 times) previous topic - next topic

Changing oil in 7.5'' axle (may contain stupid questions)...

February 20, 2006, 05:56:30 PM

Hello!
I have a little more free time now and I think it's time to change the oil in my T-bird's axle. It was always getting a little noisey at about 40mph, but I think it may be caused by the SAE 75W90 oil somebody used there, so I'm gonna change it to correct SAE 90.
I've never changed axle fluid so I want to ask you a few questions.
Please take a look at this photo:

-What is that "something" marked as #1? Can I unbolt it to fill in the axle without any risk?
-Is the plug (#2) a fill in plug? I always thought it should have higher level of oil (like over the middle of axle housing)?
-Are there any things I should take care of while changing the fluid?
-Can I put the cap back after drianining the axle on the silicone only?
-I can't find SAE 90 oil here for conventional axle, can I use the one for limited slip?
Thanks in advance for your comments!
Mariusz...

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #1 – February 20, 2006, 06:13:08 PM

Quote

What is that "something" marked as #1? Can I unbolt it to fill in the axle without any risk?

It's a harmonic dampener for the rearend so it doesn't make noise. They are matched for certain gears, so if you have changed your rearend ratio, it is useless weight. It is not necessary either way and you can grenade it if you wish. The side effect would be some noise.

Quote

Is the plug (#2) a fill in plug? I always thought it should have higher level of oil (like over the middle of axle housing)?

That's the plug. Fill till you can't anymore....

Quote

Can I put the cap back after drianining the axle on the silicone only?

Not sure what you mean. If you're talking about the cover then I would advise against it.

Quote

I can't find SAE 90 oil here for conventional axle, can I use the one for limited slip?

The only difference is that the limited slip has an additive. You can use it.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #2 – February 20, 2006, 06:20:11 PM

Quote from: Paul Flockhart

Not sure what you mean. If you're talking about the cover then I would advise against it.

Yup, I wasn't sure how to call it. What kind of gasket should I use? The silicone I thought about is the black one used by some guys to seal valve covers, oil pans etc.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #3 – February 20, 2006, 06:55:04 PM

I use black RTV. Most any kind will do.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #4 – February 20, 2006, 10:20:19 PM

Quote

They are matched for certain gears

huh..guess ya learn something new everyday....

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #5 – February 20, 2006, 11:22:28 PM

By itself 75W90 should not be enough to make a noisey rear end. IT's possible but not likely.

While you've got the diff cover off, remove the differential pin, slide the axles in, remove the C-clips and slide the axles out of the housing. With the axle out of the housing inspect the "neck" of the axle shaft (where the starts) for wear, grooves, pitting, etc. If your axle is making noise this is most likely the problem - the bearings wear into the axle shafts, and the only cure is to replace the bearings. The axle shaft should be replaced as well, but if you can't find any in Europe you might be able to get the axles "sleeved" at a truck shop. IN any case, if you have wear on the axle it would do no good to simply replace the bearings without replacing or sleeving the axle shaft.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #6 – February 22, 2006, 01:50:45 PM

you shouldn't even have to unbolt the dampner... all you need to remove the fill plug is a half inch drive extension/ratchet. the half inch drive extension goes into the hole without a socket thingy. you probably already knew that, but anyway, screw it, i'm done. uh, get the quart size bottles of fluid and shove it up there and cut a hole in the bottle to let the fluid drain out so you don't have to squeeze it. plus it should fit in there if you jack the frame up.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #7 – February 22, 2006, 02:21:27 PM

Thanks for all your ideas and comments. It's snowing here again and it got a little colder so I'll wait another few days until it gets back to normal (over 32F).
There is a good thing about the worse weather... I'm spending more time at home and I found out that Ford is using SAE 90 oil in all Ford Transit vans axles and it's available at the dealers here :)
I was wondering if you ever used any gear oil additives in your cars or trucks? I found a German stuff called MOS2 ANTIFRICTON FOR GEARS by Liqui-Moly. They are famous from using MoS2 in their oils. Here is a short manufacturer description:

- reduces friction and wear
- improves gear change performance
- stable under continuous high loads
- boosts operating reliability
- reduces transmission noise
- increases smoothness and limp-home properties
- secures optimum transmission operation

This additive has been specially developed for manual and differential transmissions. The product significantly reduces wear and reduces temperature peaks which means quieter running, softer gear changes and energy conservation. The transmission runs more quietly generating less heat. Even older transmission run more quietly with increased efficiency due to the smoothing effect on tooth surfaces. The product increases operational reliability and provides emergency lubrication properties due to the MoS2.
Operational area: Suitable for the rearaxle and manual transmissions of vehicles and particularly where the running temperature and wear is high. Because of the reduction in friction caused by MoS2, this product must not be used in fully automatic transmissions or self-locking differential transmissions. Depending on load or noise, sufficient for 1 -- 2 litres of gear oil.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #8 – February 23, 2006, 08:23:33 AM

i think additives are a waste of money. i think just keeping oil in the thing is good enough. for a while there i can remember all my differential fluid leaking out, and i ran it for almost a few weeks before filling it back up. invest in a 8.8 with quad shocks and calipers then put the expensive stuff in there.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #9 – February 23, 2006, 10:11:37 AM

My rearend has always had an annoying whine, since brand new. No place ever knew why it did it, but its got 199,800 miles on it now without a problem. I'm hoping a swap will get rid of it all (can hear it well over road and wind noise combined). Just a heads up, as it might not get rid of your "problem".

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #10 – February 23, 2006, 12:36:37 PM

Quote from: Shevretti

Thanks for all your ideas and comments. It's snowing here again and it got a little colder so I'll wait another few days until it gets back to normal (over 32F).
There is a good thing about the worse weather... I'm spending more time at home and I found out that Ford is using SAE 90 oil in all Ford Transit vans axles and it's available at the dealers here :)
I was wondering if you ever used any gear oil additives in your cars or trucks? I found a German stuff called MOS2 ANTIFRICTON FOR GEARS by Liqui-Moly. They are famous from using MoS2 in their oils. Here is a short manufacturer description:

- reduces friction and wear
- improves gear change performance
- stable under continuous high loads
- boosts operating reliability
- reduces transmission noise
- increases smoothness and limp-home properties
- secures optimum transmission operation

This additive has been specially developed for manual and differential transmissions. The product significantly reduces wear and reduces temperature peaks which means quieter running, softer gear changes and energy conservation. The transmission runs more quietly generating less heat. Even older transmission run more quietly with increased efficiency due to the smoothing effect on tooth surfaces. The product increases operational reliability and provides emergency lubrication properties due to the MoS2.
Operational area: Suitable for the rearaxle and manual transmissions of vehicles and particularly where the running temperature and wear is high. Because of the reduction in friction caused by MoS2, this product must not be used in fully automatic transmissions or self-locking differential transmissions. Depending on load or noise, sufficient for 1 -- 2 litres of gear oil.

Lucas makes a good additive/gear oil if you can find it were you are located.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #11 – February 23, 2006, 07:38:32 PM

Quote from: Seek

My rearend has always had an annoying whine, since brand new. No place ever knew why it did it, but its got 199,800 miles on it now without a problem. I'm hoping a swap will get rid of it all (can hear it well over road and wind noise combined). Just a heads up, as it might not get rid of your "problem".

Haha!! That is becuase Ford ring and pinion sets suck, and the people building them at the factory have no idea what the hell they are doing. I have had cars with 10,000 miles on them come in with
.022" of back lash on the ring gear. Spec is .008-.013"! That anoying whine comes from a bad wear pattern on the ring gear. Doest do any damage, just a pain.

Changing oil in 7.5'' axle (may contain stupid questions)...

Reply #12 – February 24, 2006, 08:48:03 AM

i'm working in a factory making Honda headlights... it's true that no one knows what they are doing. It's through a temp agency and there turnover rate is incredible!!!!! not only that but the inspectors are supposed to do way to many parts to even catch something wrong, and there are days when the press molds are broke or something and they've made 24 hours worth of bad parts! So it's true, lots of manufactoring issues are at hand. Just thought i'd ramble. Sorry.