Rear diff fluid change
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From: Wisconsin
Rear diff fluid change
hey guys,
i was wondering what weight oil these rear ends take? its a 4:10 limited slip on a F-350 dually.
i just replaced the VSS on the diff and some little pices of metal fell inside so i wanna change it ASAP.
so what brand are all of you guys running and what weight? ohh and how much does it hold?
thank you very much
Mitch
i was wondering what weight oil these rear ends take? its a 4:10 limited slip on a F-350 dually.
i just replaced the VSS on the diff and some little pices of metal fell inside so i wanna change it ASAP.
so what brand are all of you guys running and what weight? ohh and how much does it hold?
thank you very much
Mitch
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Joined: Aug 2004
Posts: 3,948
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From: SHELTON, WA
it holds about 4 qts.
just clean up the cover really well and the diff and use rtv to seal er up.
the book calls for premium 80w-90.
i run royal purple max gear synthetic. 75w-90. already has the friction modifier in it. although i have an open diff.
dont forget to take a rag and wipe out on each side of the ring gear. it has some pockets on each side of it that hold a little fluid in there.
just clean up the cover really well and the diff and use rtv to seal er up.
the book calls for premium 80w-90.
i run royal purple max gear synthetic. 75w-90. already has the friction modifier in it. although i have an open diff.
dont forget to take a rag and wipe out on each side of the ring gear. it has some pockets on each side of it that hold a little fluid in there.
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From: Wisconsin
should i flush it out first? since i live on a farm i have gear 80w-90 that i could use for a flush. should i drain the old stuff, but the 80w-90 in there and then i was thinking of putting RP synthetic 75w-90 or the amsoil. i am a fan of amsoil so im leaning tward that. but im gunna go shop around a bit to see prices and such. so what do you guys think about the flush? and also what is this friction modifier???
thank you for the help guys!
Mitch
thank you for the help guys!
Mitch
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Joined: May 2001
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From: Cabot, Arkansas
Frictrion modifier is the stuff that makes the gear oil more slippery. If you use too much the limited slip will become a limitless slip. I run Amsoil 75w-140 in mine without modifier.
I wouldn't bother with a flush. Pull the cover while the oil is hot and the majority will drain on it's own. Then use a rag to wipe out the crap in the bottom of the pumpkin.
Servicing the rear diff is much easier if you remove the VSS and pour the lube in from the top. The fill plug on the side is at a funny angle for a bottle, unless you use a pump.
I wouldn't bother with a flush. Pull the cover while the oil is hot and the majority will drain on it's own. Then use a rag to wipe out the crap in the bottom of the pumpkin.
Servicing the rear diff is much easier if you remove the VSS and pour the lube in from the top. The fill plug on the side is at a funny angle for a bottle, unless you use a pump.
Last edited by cookie88; May 27, 2006 at 06:54 PM.
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Brett Foote
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From: Cabot, Arkansas
Originally Posted by jcab
Pardon me for butting in but what is the VSS? I need to do rear diff. fluid change also. jcab
Pull the sensor from the top of the housing and the fill plug from from the side, then just pour in from the top until it runs out the side.
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From: Wisconsin
Originally Posted by jcab
Pardon me for butting in but what is the VSS? I need to do rear diff. fluid change also. jcab
-------------------------------------
Frictrion modifier is the stuff that makes the gear oil more slippery. If you use too much the limited slip will become a limitless slip. I run Amsoil 75w-140 in mine without modifier.
I wouldn't bother with a flush. Pull the cover while the oil is hot and the majority will drain on it's own. Then use a rag to wipe out the crap in the bottom of the pumpkin.
Servicing the rear diff is much easier if you remove the VSS and pour the lube in from the top. The fill plug on the side is at a funny angle for a bottle, unless you use a pump
------------------
i went to Bumper to bumper and bought amsoil 80w-90 and then he gave me a little tube of that limited slip oil. its pretty small and told me to dump in the whole thing. i bought a gallon of that 80w-90 and he told me to dump in like 3.5 quart. is there any way to tell when to stop??? and he told me to pull off the rear diff and spray brake cleaner in there to get anything chunky out of there.
thanks
Mitch
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
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From: Southwest Georgia
First, be very careful if you use brake cleaner, you do not want to shoot it down the axle shaft and it will degrease everything that it touches, ring gear, spider gear, bearings, etc. I don't use it in a rear diff. I just remove the rear cover, be sure and clean the outside good before you pull it off or you will get dirt in the diff. Have a large drain pain under the diff to catch the fluid, then use paper towels and long needle nose pliers or a screw driver to wipe out the diff. This will remove all of the "chunky stuff".
After cleaning the inside of the diff. reinstall the cover using RTV. Remove the fill plug (halfway up the diff.) remove the VSS (top front of the diff.). Pour fluid in through the VSS hole until it comes out the fill hole. Replace fill plug, replace VSS. Your done.
Friction modifier is used to make the limited slip "slip". with out it you could have full time positive traction, which is very hard on very thing in a turn.
After cleaning the inside of the diff. reinstall the cover using RTV. Remove the fill plug (halfway up the diff.) remove the VSS (top front of the diff.). Pour fluid in through the VSS hole until it comes out the fill hole. Replace fill plug, replace VSS. Your done.
Friction modifier is used to make the limited slip "slip". with out it you could have full time positive traction, which is very hard on very thing in a turn.
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From: Wisconsin
posi track any one not add this? what would happen if i did not add this. would it do any damage besides to the tires? muahahah i like, i think.thanks guys!!!! your a big help!!! saved me so much time and i appreciate it!
Mitch
Playing in the Dirt
Joined: Oct 2005
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From: Southwest Georgia
Originally Posted by 79f-250custom
posi track any one not add this? what would happen if i did not add this. would it do any damage besides to the tires? muahahah i like, i think.thanks guys!!!! your a big help!!! saved me so much time and i appreciate it!
Mitch
FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
Likes: 6
From: Cabot, Arkansas
The vast majority of lubes on the shelf today say they are safe for use with limited slips without additional friction modifier.
If you are getting tire scuff on low speed turns or any type of chattery noises from the rear then I would recommend adding the modifier in 1-2oz. increments, using only the minimum amount necessary to quiet it down. Dumping the "recommended" amount of modifier will make your L/S act like an open diff.... It will be useless.
If you are getting tire scuff on low speed turns or any type of chattery noises from the rear then I would recommend adding the modifier in 1-2oz. increments, using only the minimum amount necessary to quiet it down. Dumping the "recommended" amount of modifier will make your L/S act like an open diff.... It will be useless.