Noticed the other day when I got stuck, only one rear wheel was spinning. Yesterday changed out the 75-90 valvoline synthetic for 75-140 amsoil. Jacked one wheel off ground, put it in gear, still spinning freely with no power from the traction wheel. Added a tube of friction modifier, still no LSD. Any ideas? Is there something in there that could have peter'd out? 100k mi now. .
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2nd Gen Non-Engine/Transmission No More LSD
- Thread starter LStanphill
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(sigh)
Yup - get the Amsoil outta there, get the RIGHT stuff from DC - if the LS chatters, add a bottle of the friction modifier - if it still chatters, add a half bottle at a time 'til the LS acts the way you like - for ME, that is at the ragged edge of chattering, but not quite. Loss of LS action when using synthetics is not a new phenomena... REGARDLESS of what the synthetics lovers will now try to assure you...
BEEN there, DONE that - didn't even get a T-shirt...
Yup - get the Amsoil outta there, get the RIGHT stuff from DC - if the LS chatters, add a bottle of the friction modifier - if it still chatters, add a half bottle at a time 'til the LS acts the way you like - for ME, that is at the ragged edge of chattering, but not quite. Loss of LS action when using synthetics is not a new phenomena... REGARDLESS of what the synthetics lovers will now try to assure you...
BEEN there, DONE that - didn't even get a T-shirt...
Dan_69GTX
TDR MEMBER
The friction modifier is just that - it modifies the friction. How it modifies it is that it makes it slipperier.
The chattering is the clutches not wanting to slide over each other, by making it slipperier, they do not chatter anymore.
It is a common misconception that when both wheels do not spin, well - add the modifer. Unfortunately this actually only makes the problem worse.
Yes, based on my experiance, if you have a marginal limited slip and switch to synthetics, the limited slip will only get worse.
But as with anything - why did you change to synthetics? Was it based on the pros/cons of adding it or just because?
I run synthetics because of the pros - if the limited slip doesn't work as well - that is fine with me. However, I've never had the limited slip work any differently after changing to synthetic oil.
If your limited slip worked fine before you changed to synthetics and you want the best you can get w/o taking the rear apart - switch back to a fluid that is designed NOT for limited slip diffs - either conventional or synthetic. Now your rear should chatter. Do what Gary recommended and slowly add the modifier till you are not annoyed with the chatter and you will have the best of both worlds - minimal chatter - and a decent limited slip.
Dan
The chattering is the clutches not wanting to slide over each other, by making it slipperier, they do not chatter anymore.
It is a common misconception that when both wheels do not spin, well - add the modifer. Unfortunately this actually only makes the problem worse.
Yes, based on my experiance, if you have a marginal limited slip and switch to synthetics, the limited slip will only get worse.
But as with anything - why did you change to synthetics? Was it based on the pros/cons of adding it or just because?
I run synthetics because of the pros - if the limited slip doesn't work as well - that is fine with me. However, I've never had the limited slip work any differently after changing to synthetic oil.
If your limited slip worked fine before you changed to synthetics and you want the best you can get w/o taking the rear apart - switch back to a fluid that is designed NOT for limited slip diffs - either conventional or synthetic. Now your rear should chatter. Do what Gary recommended and slowly add the modifier till you are not annoyed with the chatter and you will have the best of both worlds - minimal chatter - and a decent limited slip.
Dan
Last edited:
From reading your post is says that your LSD was not working before you swapped to Amsoil. I don't know much about them but I think they do wear out. I'm also not sure, but I think they can be rebuilt. I also think that putting in synthetic oil is filling the whole diff with friction modifier. That will make a LSD a full slip Diff. JC
I also have to agree with Gary. One more thing that I noticed is that you have Amsoil ATF IN your NV5600. 
It sure seems like you are spending a ton of money to mess things up. Sorry.
It sure seems like you are spending a ton of money to mess things up. Sorry.
Dan_69GTX
TDR MEMBER
I have no experiance with AMZOIL, but I do with Red line oil.
Here is their website:
http://redlineoil.com/whyredline.htm
Taken from their site"
75W90 GEAR OIL - recommended for most street driven and racing differentials. Excellent performance in conventional and limited-slip units. Also for limited-slip manual transaxles which require a 90 WT oil. Contains limited-slip friction modifiers.
75W90NS - recommended for manual transmissions and non-limited-slip transaxles that recommend 90 WT oils. Can be used in racing limited-slip units to increase lockup and reduce wheel spin. Street-driven rear-wheel drive cars should use regular Red Line 75W90 or 80W140. "
Notice what they say regarding the second one. All oils are not the same - even within a specific brand. It would be as if someone said you need to run 370 injectors because it works for them. It will work only if your truck is set up for them.
rolltideram - your right - I didn't catch that his didn't work before hand - changing the oil (with anything that has a modifier in it) will only make it worse - cause now you are adding new modifer - meaning it will slip more - dino or synthetic oil.
Gary - from your experiance - has the synthetic oil you've used had the modifier in it already or do you add your own? I've never liked it when you can't control the amount of modifier - who knows how much they have put in it.
Dan
Here is their website:
http://redlineoil.com/whyredline.htm
Taken from their site"
75W90 GEAR OIL - recommended for most street driven and racing differentials. Excellent performance in conventional and limited-slip units. Also for limited-slip manual transaxles which require a 90 WT oil. Contains limited-slip friction modifiers.
75W90NS - recommended for manual transmissions and non-limited-slip transaxles that recommend 90 WT oils. Can be used in racing limited-slip units to increase lockup and reduce wheel spin. Street-driven rear-wheel drive cars should use regular Red Line 75W90 or 80W140. "
Notice what they say regarding the second one. All oils are not the same - even within a specific brand. It would be as if someone said you need to run 370 injectors because it works for them. It will work only if your truck is set up for them.
rolltideram - your right - I didn't catch that his didn't work before hand - changing the oil (with anything that has a modifier in it) will only make it worse - cause now you are adding new modifer - meaning it will slip more - dino or synthetic oil.
Gary - from your experiance - has the synthetic oil you've used had the modifier in it already or do you add your own? I've never liked it when you can't control the amount of modifier - who knows how much they have put in it.
Dan
I really wanted a heavier, EXCELLENT lube for towing - went with a heavier than stock synthetic - up in the 140 wt spec'd by DC for towing use. TOTALLY, INSTANTLY lost all LSD action, and it HAD worked perfectly prior to the switch. I still wanted a 140 wt class lube that provided SOME of the advantages of a synthetic, and was willing to do some experimenting, so next went to Valvoline 90/140 semi-synthetic, and right out of the bottle, it has worked PERFECTLY - for ME!
I learned early on, in both the LS differentials AND the syncros in the manual trannies, what works for ONE guy often does NOT for another due to widely varying quality control and manufacturing tolerances. I have no doubt the pure synthetics ARE far better lubes in both trannies and differentials, but I am not willing to sacrifice the shifting of my transmission (yes, had trouble with synthetics THERE too!), or the LS action of my differential to obtain that slight improvement (maybe!) in the gears - so far the semi-senthetic in the differential fills BOTH expectations nicely.
As far as the synthetic I tried in the differential, no FM was included or added to it...
I learned early on, in both the LS differentials AND the syncros in the manual trannies, what works for ONE guy often does NOT for another due to widely varying quality control and manufacturing tolerances. I have no doubt the pure synthetics ARE far better lubes in both trannies and differentials, but I am not willing to sacrifice the shifting of my transmission (yes, had trouble with synthetics THERE too!), or the LS action of my differential to obtain that slight improvement (maybe!) in the gears - so far the semi-senthetic in the differential fills BOTH expectations nicely.
As far as the synthetic I tried in the differential, no FM was included or added to it...
It's my understanding DC recommends 90/140 in heavy-use situations such as towing - they have such a lube they sell in addition to the lighter stuff last I knew... I like the synthetics, but ALSO like my LS because of some of the RVing sites we must pull into from time-to-time that require backing steeply UPhill, with one tire in loose dirt and the other on pavement...
One time on that same campsite with the old '91, I had unknowingly snagged the emergency brake lanyard and pulled it outta the 5er - couldn't figure WHY I was having so much problem backing the trailer up - fortunately, all wheels were on pavement at the time. After a couple of tries and not lots of progress, I see the lanyard loose, check back at the trailer wheels, and I had been SLIDING all 4 locked-up trailer wheels uphill with my mildly bombed truck... Do these trucks have POWER or what!
One time on that same campsite with the old '91, I had unknowingly snagged the emergency brake lanyard and pulled it outta the 5er - couldn't figure WHY I was having so much problem backing the trailer up - fortunately, all wheels were on pavement at the time. After a couple of tries and not lots of progress, I see the lanyard loose, check back at the trailer wheels, and I had been SLIDING all 4 locked-up trailer wheels uphill with my mildly bombed truck... Do these trucks have POWER or what!
OK here's what happened to me last week.
My limited slip never did work right from the beginning. Not as tight as I had in the past. I put in Amsoil Series 2000 about 2 years ago. No change. No chatter. LSD acted the same. NOT worse.
Just changed it again at 52K miles. It sure is nice having the Mag Hytec diff cover! Easy to drain and refill. NO mess.
Within 50 miles my LSD was chattering like crazy! Even just a slight turn, I'd feel and hear a rumble. But my LSD was working like I'd always wanted! One tire on dirt and one on pavement, it will spin both! Wouldn't do that before. It would only spin the tire on the dirt.
My guess is that DC adds a LOT of additive to the rear axle so they will not get any complaints. Too much will make the LSD not work correctly. Too little and it will chatter.
So far I have added 3 oz of additive, one ounce at a time. Again it is nice to have the Mag Hytec. Just crawl under the truck, unscrew the dipstick/fill and pour a little in. So far 3 oz and it doesn't chatter much. Just a little if any. I don't want to overdo it because then the LSD won't work right again!
That's my theory on the subject. It's a free country and we can run what we want. I'm just trying to dispell the myth that synthetics mess up the LSD action!
TOO MUCH additive/friction modifier will make the LSD work like crap! Remember that.
As I said in another post on this subject in a different thead, dino or synthetic, either is fine. Synthetic has a much better heat threshold and if you tow VERY heavy loads at highway speeds you'll be better off with a synthetic. If you don't tow, then run dino lube or synthetic.
Hope that helps.
My limited slip never did work right from the beginning. Not as tight as I had in the past. I put in Amsoil Series 2000 about 2 years ago. No change. No chatter. LSD acted the same. NOT worse.
Just changed it again at 52K miles. It sure is nice having the Mag Hytec diff cover! Easy to drain and refill. NO mess.
Within 50 miles my LSD was chattering like crazy! Even just a slight turn, I'd feel and hear a rumble. But my LSD was working like I'd always wanted! One tire on dirt and one on pavement, it will spin both! Wouldn't do that before. It would only spin the tire on the dirt.
My guess is that DC adds a LOT of additive to the rear axle so they will not get any complaints. Too much will make the LSD not work correctly. Too little and it will chatter.
So far I have added 3 oz of additive, one ounce at a time. Again it is nice to have the Mag Hytec. Just crawl under the truck, unscrew the dipstick/fill and pour a little in. So far 3 oz and it doesn't chatter much. Just a little if any. I don't want to overdo it because then the LSD won't work right again!
That's my theory on the subject. It's a free country and we can run what we want. I'm just trying to dispell the myth that synthetics mess up the LSD action!
TOO MUCH additive/friction modifier will make the LSD work like crap! Remember that.
As I said in another post on this subject in a different thead, dino or synthetic, either is fine. Synthetic has a much better heat threshold and if you tow VERY heavy loads at highway speeds you'll be better off with a synthetic. If you don't tow, then run dino lube or synthetic.
Hope that helps.
The above example is why I hate to make "absolute" statements where transmission/differentil lubes are concerned - results vary all over the map!
So is that why I have had absolutely no problem with the Amsoil. The rear end has 294K miles with Amsoil and 1 bottle of friction modifier. I do change it every year, and that would be around 35-45k miles. So far no trouble at all. I even ran this truck on the drag strip. I just don't understand how our trucks could be so different. I tow 15K lbs add the LS has worked great. Just lucky I guess.
. . Preston. .
. . Preston. .
Preston, not to put you on the spot - but HOW do you determine YOUR'S "works great" - how do you test it for proper operation?
LOTS of guys THINK theirs works great - but few have actually tested them in situations for which they are made... And THEN get a big surprise when they find it really DOESN'T work!
LOTS of guys THINK theirs works great - but few have actually tested them in situations for which they are made... And THEN get a big surprise when they find it really DOESN'T work!
See a pattern.....
Ever notice it is almost never a pre-99 truck that posts a LSD problem. Some posted a while back the the clutch packs were changed in the newer model years (99+ ???).
If anything, back in 96 - 97 you read more about LSD setups being to grabby or barky tires when turning.
Makes me wonder if DC asked DANA to softenup the LSD setup in late 99. Thus the sensitivity to LSD additive or "slippery" synthetics.
Here is what my 96 LSD does with Amsoil 75W90 and TWO bottles of Mopar LSD additve... . leave a mark (inside tire) when turning on any gravel road, twin marks with spinning on snow, gravel, blacktop or dry concrete. I have never felt mine slip... EVER.
I have grabbed a sample every 40 - 60K when I change. Things run very clean with only the first sample being nasty. Back when my truck was new, I called DANA and asked about the best fluid to run when towing heavy and yet running in cold climates. THEY said back in 96 that 75W90 full synthetic would be the best.
Onther then a one rear wheel seal, my rear diff is still totally factory. And it reacts like it did the year is was new.
Pre-98 trucks most likely need to add additive to the best synthetics sometimes more then 1 bottle.
Post 98 trucks should only add additive as needed. If you can not run a full synthetic (including Amsoil) w/o LSD addtive withou have the LSD slip, I would question if everything is work properly.
jjw
ND
Ever notice it is almost never a pre-99 truck that posts a LSD problem. Some posted a while back the the clutch packs were changed in the newer model years (99+ ???).
If anything, back in 96 - 97 you read more about LSD setups being to grabby or barky tires when turning.
Makes me wonder if DC asked DANA to softenup the LSD setup in late 99. Thus the sensitivity to LSD additive or "slippery" synthetics.
Here is what my 96 LSD does with Amsoil 75W90 and TWO bottles of Mopar LSD additve... . leave a mark (inside tire) when turning on any gravel road, twin marks with spinning on snow, gravel, blacktop or dry concrete. I have never felt mine slip... EVER.
I have grabbed a sample every 40 - 60K when I change. Things run very clean with only the first sample being nasty. Back when my truck was new, I called DANA and asked about the best fluid to run when towing heavy and yet running in cold climates. THEY said back in 96 that 75W90 full synthetic would be the best.
Onther then a one rear wheel seal, my rear diff is still totally factory. And it reacts like it did the year is was new.
Pre-98 trucks most likely need to add additive to the best synthetics sometimes more then 1 bottle.
Post 98 trucks should only add additive as needed. If you can not run a full synthetic (including Amsoil) w/o LSD addtive withou have the LSD slip, I would question if everything is work properly.
jjw
ND
Gary:
The way I tell is on a dirt spot, road, drive way, any spot I happen to be, and spin the rear tires. Both spin and chew up the dirt. The last time I changed the lube, I didn't install any stink oil. I was told the Amsoil didn't need any. Well mine did. Every time I turned, the darn thing sound like the tires were scrubbing and really making a racket. Kinda like a popping noise and scrubbing the tires. I bought 2 bottles of stink oil and put in one. Drove some figure 8"s and it went away. It is true I haven't gotten off on wet grass but the LSD to me seems to be working from what I've described.
What do you think?
. . Preston. .
The way I tell is on a dirt spot, road, drive way, any spot I happen to be, and spin the rear tires. Both spin and chew up the dirt. The last time I changed the lube, I didn't install any stink oil. I was told the Amsoil didn't need any. Well mine did. Every time I turned, the darn thing sound like the tires were scrubbing and really making a racket. Kinda like a popping noise and scrubbing the tires. I bought 2 bottles of stink oil and put in one. Drove some figure 8"s and it went away. It is true I haven't gotten off on wet grass but the LSD to me seems to be working from what I've described.
What do you think?
. . Preston. .
According to my 01 Service manual the acceptable breakaway torque for the LSD in a 70 or 80 axle is a minimum of 30 ft lbs up to 200 ft lbs. Basically you lift one rear wheel, leave the other on the ground and using a torque wrench measure the amount of torque required to spin (breakaway) the one wheel.
It's a wide range, but I would imagine it a warranty thing.
Another interesting deal is the stack up of the steel and friction plates. It's as follows:
1. Install dished disc on side gear.
2. Install one disc on side gear.
3. Install one plate on side gear.
4. Install one disc on side gear.
5. Install one plate on side gear.
6. Install three discs on side gear.
7. Install three plates on side gear.
So that about 50% of the holding capacity of the LSD clutch pacs that is lost due to stack up. My guess is it was a quick way to eliminate excessive chatter and warranty claims for noise.
I currently work at a Ford dealer and we get a fair number of chattering clutches is LSD's. Between playing with friction modifier cocktails and sometimes reducing shim thickness to get them to quiet up. It's kinda comical, pay extra money for a LSD then complain it's noisy when it actually works. So we make it "better" by making it not work. Funny deal.
Through extensive therapy I can type and occasionally say Ford now. But at least at the end a busy day making the world a better I can get I my Cummins and it jumps to life and I drive away.
Later,
Wayne
It's a wide range, but I would imagine it a warranty thing.
Another interesting deal is the stack up of the steel and friction plates. It's as follows:
1. Install dished disc on side gear.
2. Install one disc on side gear.
3. Install one plate on side gear.
4. Install one disc on side gear.
5. Install one plate on side gear.
6. Install three discs on side gear.
7. Install three plates on side gear.
So that about 50% of the holding capacity of the LSD clutch pacs that is lost due to stack up. My guess is it was a quick way to eliminate excessive chatter and warranty claims for noise.
I currently work at a Ford dealer and we get a fair number of chattering clutches is LSD's. Between playing with friction modifier cocktails and sometimes reducing shim thickness to get them to quiet up. It's kinda comical, pay extra money for a LSD then complain it's noisy when it actually works. So we make it "better" by making it not work. Funny deal.
Through extensive therapy I can type and occasionally say Ford now. But at least at the end a busy day making the world a better I can get I my Cummins and it jumps to life and I drive away.
Later,
Wayne
Sounds good to me! Congrats on actually TESTING it, rather than ASSUMING it is working OK, as many do...
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