Bad Rear End Chatter?

[Emeraldage]

I've had this issue for awhile I bought a 3.73 LSD from another member here, he had to ship it dry. I originally put Castrol 80-90 (http://www.oreillyauto.com/site/c/d....oap?ck=Search_N2367_-1_-1&pt=N2367&ppt=C1985) in it. As I drove it the first time when turning the inner wheel always was locked up. So after a bottle in a half of motorcraft friction mod it's mostly gone. But in parking lots tight turns or loose gravel the inner wheel will still skipp about or leave tire marks on tar. I added another bottle (After draining some) and it got better but still definitely has this issue. The oil that came out was black and goopy thick.

Should I just drain and add lots more modifier maybe try redline's? Was the original oil bad and I should replace it with something else like 75W-140 since it already has the modifier applied? Or is this rear end just need servicing and clutches replaced?

 

[Emeraldage]

That chatter also decreases quite a bit after the car warms up and it's been moving for a bit.

 

[Bogwon]

I used redline 75w90 in my 3.73 with about 1/3rd of the motorcraft friction mod and my chirping is now only when the car is cold and I take a tight (full lock) corner.

If after a whole bottle of friction mod and then some and you're still having issues, that sounds to me like a mechanical problem and not an oil or additive problem.

I also had mine rebuild with a weir performance kit, new seals and bearings for around $300 (not including parts). Good luck!

 

[3p141592654]

Try some synthetic Mobil 1 gear lube. My experience with it was that the clutches did not lock up enough with it, but yours seems extra tight so it may work better. I am a bit confused though, how did black goo come out if it was shipped dry?

 

[IndigoMKII]

Try some synthetic Mobil 1 gear lube. My experience with it was that the clutches did not lock up enough with it, but yours seems extra tight so it may work better. I am a bit confused though, how did black goo come out if it was shipped dry?

Probably got shipped dry and it was just installed, not cleaned out and looked over before installation.

 

[Emeraldage]

I've read it's a very tight diff because it's actually air tight which contributes to it apparently, kind of impressive opening that cap after weeks and hearing air pressure blow out. I've also read that the ford gear oil and additive do magical things for our diffs. I don't understand how the clutches being old and worn out would grip more to me I think it would mean they slip more but I don't have really any experience with clutch LSDs. My original 4.30 one was leaking and I added same castrol stuff and it was fine. Granted I didn't replace all of it I don't know what was really in it. Would like more opinions I'm thinking about trying the mobile stuff. I remember someone mentioning that in another post about this about it being too slippery.

 

[Emeraldage]

Probably got shipped dry and it was just installed, not cleaned out and looked over before installation.

Was shipped dry. I thought it would just take time to soak as when I went to the ford dealer they say they soak their LSDs for about a month before they install them. But no I did not take it apart or anything I knew nothing about them.

I was looking at this forum post. (http://www.supramania.com/forums/showthread.php?157104-LSD-fluid-recommendations/page2) And they said Royal Purple is the brand that is too slick.

 

[IndigoMKII]

There's your problem, you went to a ford dealer asking for help to repair a vehicle.

I'd get the diff pulled and find out why an 'worn out diff' it grabbing harder than they did from the factory.

 

[Emeraldage]

Naw I got it from someone on here. I just asked them at ford when I was getting the modifier about it. Unless the previous guy did something to them, I mean when I add modifier it still makes it better. Just a pia to work on them and I don't have the money to rebuild or get a new clutch pack at the moment anyways.

Oh just remembered something. Can too much oil be a problem? I know when my friends installed it he just filled it up till it was spilling out which was just a bit over 2 quarts.. Rather than the 1.3 the TSRM calls for.

 

[Bogwon]

First of all, the LSD in our cars are not air tight. There is a small valve at the very top of the housing that allows for expansion of the oil once operating temperature is reached and pressure relief, if that valve was blocked with road grime then you pop a seal.

Second, if you want to read about LSD oils do a quick search in the "oil/lubicant" section, there are a ton of topics on which oils perform well. I will say that the motorcraft and redline oils are among the favorites but you'll have to add the friction mod as stated in prior posts. Also you don't want the synthetic version as it's too slippery for the clutch packs.

Lastly speaking of clutch packs, check out the weir performance website and read about their findings on the rebuilds they have done over the years. Spence said he hasn't seen any stock LSDs from our supras with worn out clutch packs because the pinion preload spring was too weak and Toyota used a crush sleeve to preload the pinion gear. This made it so we don't wear out the clutch packs and in most cases the car turns into a "one tire fire" after a couple hundred thousand miles or so...

 

[Emeraldage]

So in your opinion what do you reccomend me doing? Does too much oil make it worse? Should I just drain more oil and add more friction mod? Or start over with a quart of oil and a bottle of friction mod? That oil from my ford dealer is 20$ a quart.

 

[3p141592654]

The pinion preload issue has nothing to do with the clutch plates and plate wear.

 

[Bogwon]

So in your opinion what do you reccomend me doing? Does too much oil make it worse? Should I just drain more oil and add more friction mod? Or start over with a quart of oil and a bottle of friction mod? That oil from my ford dealer is 20$ a quart.

I would take it out and have it looked at by a shop but you could try some different gear oil if you think it's still an oil issue. If you want to try to start over, you might try the redline LSD oil and you won't have to mess with the modifier. It's really up to you but if it were my car, I'd pull the diff and looked at by a reputable shop at the very least but I tend to over do things.

You also might drain it in a clean oil catch and see if you get any sparkles (shavings) in the bottom. If it's good you can reuse the oil you drained.

Too much oil is probably not good. I imagine you are more likely to blow a seal if you're over filled and run it that way.

 

[Emeraldage]

I would take it out and have it looked at by a shop but you could try some different gear oil if you think it's still an oil issue. If you want to try to start over, you might try the redline LSD oil and you won't have to mess with the modifier. It's really up to you but if it were my car, I'd pull the diff and looked at by a reputable shop at the very least but I tend to over do things.

You also might drain it in a clean oil catch and see if you get any sparkles (shavings) in the bottom. If it's good you can reuse the oil you drained.

Too much oil is probably not good. I imagine you are more likely to blow a seal if you're over filled and run it that way.

Okay. Maybe I'll just drain mine. Get a quart of redline, and recycle a bit of my old oil back in? It's been about 5 months now and it hasn't leaked any but yeah I'll try to get it back down and closer to the 1.4 quarts the TSRM wants.

 

[3p141592654]

Sometimes those capacities can be off. I know the A/T fill is off by 0.5 qt.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=MA&P=11

 

[Emeraldage]

http://www.redlineoil.com/product.aspx?pid=133&pcid=4 <-- This is what I want then? or should I get the 75w85?

Which is (http://www.amazon.com/Red-Line-5010...414798119&sr=8-4&keywords=75W85+GL-5+Gear+Oil) I think? I wish red line would put the part number on their site or at least make their bottles squeeze bottles!

 

[Bogwon]

75w90 iirc is what you want. The first one you linked is what you want.

 

[Bogwon]

The pinion preload issue has nothing to do with the clutch plates and plate wear.

I beg to differ sir.

Quoted straight from the weir performance web site:

"This LSD is known for its lack of performance, this is for the most part caused by sloppy assembly at the factory. We have opened up many of these units and have not seen one yet that was worn out. Unfortunately these LSD units do not have clutch members or pressure rings to apply clamping force to the clutch plates. In order for these LSD units to function properly for performance applications they need to be correctly shimmed and the spring pressure increased."

 

[Emeraldage]

Well I just have amazon prime and I need it before a week so I'm assuming the 75w-85 will do okay?

 

[3p141592654]

I beg to differ sir.

Quoted straight from the weir performance web site:
[.........]

There's nothing there that contradicts what I said i.e. pinion preload is a separate issue. The clutch preload is set by the springs and shims selected. The Weir MAX GRIP LSD kit is just a spring that goes inside the stock spring that applies pressure to the outer spider gears and clutches. The pinion preload is set separately and has nothing to do with the clutch plate preload.

In a nutshell you are confusing pinion preload with clutch pack preload.

If you want to learn more read this treatise:
http://www.supramania.com/forums/showthread.php?203766-HOW-TO-Rebuild-the-MK3-Rear-Differential.