How do I know if I have LS Diff?
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How do I know if I have LS Diff?
New to FTE. Thanks to all of you folks for what I have learned from you in a couple of hours reading your posts.
I am preparing to replace the oil in my rear diff ('97 F150 4x4 w/ 4.6L Winsdor). I have read in several posts that I need to use a synthethic oil, but what weight?
Also, how do I determine if I need/have limited slip differential. Is this a function of the diff itself or the oil required or both?
Lastly, the reason I am doing the oil replacement is the first step in troubleshooting a weird noise that has developed. When I accelerate from a stop, I hear two short, low squeaks coming from the rear end. It almost sounds like a spring or something, but it only makes the noise when accelarating from a stop. I have intentionally hit some pretty big bumps to hear if I have something loose back there, but I never hear anything. I have checked the fluid level in the rear diff, and I am okay there, but I do not know if it is the correct fluid. I bought the truck used last year and have not made any changes since. I did have to tighten up the bold on the rear diff cover when I bought the truck to stop a slow leak.
I am preparing to replace the oil in my rear diff ('97 F150 4x4 w/ 4.6L Winsdor). I have read in several posts that I need to use a synthethic oil, but what weight?
Also, how do I determine if I need/have limited slip differential. Is this a function of the diff itself or the oil required or both?
Lastly, the reason I am doing the oil replacement is the first step in troubleshooting a weird noise that has developed. When I accelerate from a stop, I hear two short, low squeaks coming from the rear end. It almost sounds like a spring or something, but it only makes the noise when accelarating from a stop. I have intentionally hit some pretty big bumps to hear if I have something loose back there, but I never hear anything. I have checked the fluid level in the rear diff, and I am okay there, but I do not know if it is the correct fluid. I bought the truck used last year and have not made any changes since. I did have to tighten up the bold on the rear diff cover when I bought the truck to stop a slow leak.
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From: Maine
Originally posted by ranger88a
If there is no tag saying it, raise the rear end up, in neutral, turn one wheel if the other one rotates with it it's limited slip. Use 75/140 synthetic lube.
If there is no tag saying it, raise the rear end up, in neutral, turn one wheel if the other one rotates with it it's limited slip. Use 75/140 synthetic lube.
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Are some F150s limited slip and others aren't, I guess?
As for the replacement fluid, I read in Haynes last night that a friction modifier should be added to the synthetic oil. BTW, Haynes also confirmed the 75W140 grade (thanks ranger88a). I guess I should have checked there first before posting that part. Anyway, I have read elsewhere on this board that no additives are required if you use a synthetic oil. Additive or no additive, that is the question?
As for the replacement fluid, I read in Haynes last night that a friction modifier should be added to the synthetic oil. BTW, Haynes also confirmed the 75W140 grade (thanks ranger88a). I guess I should have checked there first before posting that part. Anyway, I have read elsewhere on this board that no additives are required if you use a synthetic oil. Additive or no additive, that is the question?
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If you have a tag on the rear axle housing cover bolt. It will have the letter L in the gear ratio. 3.73 will be 3 L 73, 4.11 wil be 4 L 11
There should be a tag on other side of cover that says synthethetic or abreviated synth if it has synthetic oil in it.
There should be a tag on other side of cover that says synthethetic or abreviated synth if it has synthetic oil in it.
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Help Deciphering Diff Tag
I checked the tags on my diff cover. As expected, one of them stated that I should use 75W140 Synth Oil Only. The other is a bit of a mystery. It reads:
S862B
55 88 6H07
Can anyone break this down to let me know what my gear ratio is and if I have LS or not?
Thanks.
S862B
55 88 6H07
Can anyone break this down to let me know what my gear ratio is and if I have LS or not?
Thanks.
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Junior User
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Additive w/ Synth Lube
Still wondering about whether or not to put a friction modifying additive in with whatever synthetic lube I end up with. Does the answer to this depend on the LS answer?
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From: DC
I think some synthetic lubes already have the friction modifier in them. Check the label and see what it says. Regarding the LS, look on the drivers door jamb, the tag there should have a code next to the word "axle". See what that says and post it here. I'm pretty sure that if it has a letter and a number i.e. H9, it's an LS. If it's 2 numbers i.e. 19, it's not.
Logistics Pro
Joined: Jul 2002
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From: South Dakota
Synthetic gear lube is not needed, unless you are topping off the factory fill. Dino 85-140 will perform quite nicely for 1/4 the cost, but in either case you still need to add the proper amt of friction modifier (unless you have an open rearend). But do make sure that you use an 140 weight oil, as I have found out the hard way that 80-90 leaks out of the seals like water in a strainer.
The squeaks that you talk about sound Identical to the ones that my F-150 had, it would squeak on acceleration, from 5mph to 20 mph, then shake the whole truck on deacceleration from 70mph to 40 mph.
Turned out to be those wonderfull sealed ujoints that Ford (and others) are now famous for. The ujoint on the Diff end had 2 cups that dried up and turned the needle bearings into powder.
Upon trying to move the drive shaft side to side and up and down, I could not get the shaft to move suggesting that the ujoints were infact okay. It was only the small ring of rust around 2 of the opposing end's cups that gave the ujoint away.
I put 2 NAPA ujoints on with grease fittings for a grand total of 20 bucks and one busted shop vise.
Sorry for the long winded post.
BTW, welcome to the forum!
The squeaks that you talk about sound Identical to the ones that my F-150 had, it would squeak on acceleration, from 5mph to 20 mph, then shake the whole truck on deacceleration from 70mph to 40 mph.
Turned out to be those wonderfull sealed ujoints that Ford (and others) are now famous for. The ujoint on the Diff end had 2 cups that dried up and turned the needle bearings into powder.
Upon trying to move the drive shaft side to side and up and down, I could not get the shaft to move suggesting that the ujoints were infact okay. It was only the small ring of rust around 2 of the opposing end's cups that gave the ujoint away.
I put 2 NAPA ujoints on with grease fittings for a grand total of 20 bucks and one busted shop vise.
Sorry for the long winded post.
BTW, welcome to the forum!
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From: NE TX
'Bout the u-joints, sometimes you have to jack up the wheel or better, drop the back of the driveshaft. It doesn't take long to check. I've even watched from a safe distance as someone went forward/backward rocking and seen the u-joint get loose. Generally, it's the back one at the pinion that goes out. Doesn't cost much or require expensive tools to replace so sometimes I just go ahead and change it.
As rear end. The door jamb tag gives the code and IF the rear hasn't been changed, a letter designates LS. Auburns and others are inexpensive though and many people, especially 4x4 owners go to other LS. So if the truck is used I'd look at both tags. And if I ever drain the fluid, I add the friction modifier. If not you have no LS. If I'm just adding fluid, I don't worry about it unless it's really low, then I look for where it's leaking. No more fluid than the diff. holds, price difference doesn't matter to me for synthetic. I just don't want the diff. to fail. Welcome and good luck.
As rear end. The door jamb tag gives the code and IF the rear hasn't been changed, a letter designates LS. Auburns and others are inexpensive though and many people, especially 4x4 owners go to other LS. So if the truck is used I'd look at both tags. And if I ever drain the fluid, I add the friction modifier. If not you have no LS. If I'm just adding fluid, I don't worry about it unless it's really low, then I look for where it's leaking. No more fluid than the diff. holds, price difference doesn't matter to me for synthetic. I just don't want the diff. to fail. Welcome and good luck.
Postmaster
Joined: Jul 2001
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From: South Kitsap County, WA
cwgoff, since nobody did a thourough job of addressing your question, you have a 3.55 open rear so the friction modifier is not necessary.
The "3" for 3 55 is under the bolt head and not the "B" as mentioned before.
The U-joint would be a good place to start, especially with the problem under acceleration.
-Kerry
The "3" for 3 55 is under the bolt head and not the "B" as mentioned before.
The U-joint would be a good place to start, especially with the problem under acceleration.
-Kerry
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Thanks to all of you folks for this info.
BTW, this is my first truck, so the whole concept of limited slip is new to me. It seems odd that some stock F150s would have LS and some not. Is this an option that the original owner would have specified at purchase? Is it that the diff might have been changed with an aftermarket product since original purchase?
I would just think that all '97 F150 XLT 4x4s would have the same rear diff specs. Is that not case, I guess?
On a related note, what does "open differential" mean. Does that just mean non-LS?
BTW, this is my first truck, so the whole concept of limited slip is new to me. It seems odd that some stock F150s would have LS and some not. Is this an option that the original owner would have specified at purchase? Is it that the diff might have been changed with an aftermarket product since original purchase?
I would just think that all '97 F150 XLT 4x4s would have the same rear diff specs. Is that not case, I guess?
On a related note, what does "open differential" mean. Does that just mean non-LS?
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From: NE TX
Open is non LS and all that is required to move your truck. In some circumstances (I log and ranch where there is mud) you need both tires to pull or just one will sit there and spin. The factory LS is not a true positive traction or locker differential so I tire can spin at different speeds than the other which is useful turning corners, especially on pavement. The open diff. will turn sharper, make less noise and has less pressure on it to do the required job so it fails less. LS needs more maintenance and depending on use/abuse can fail more often. Open suits majority of the owners and is cheaper so it is standard. LS comes on certain 4x4 packages and as an option for people like me that drive off road quite a bit. They are usually $200-300 higher. The Auburn aftermaket LS is similarly priced+labor. If you don't risk getting in bad situations off road open is all you need. On ice open is more predictable but lacks traction that LS has.
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