14 replies to this topic

[WilsonSteele]

All,

    Just got a 4.3 for my car, and it was pretty well worn out at 176,000 from the donor.  I had it completely rebuilt at UniTrax in Anaheim (SoCal area).  They did a great job, and seem to know exactly what they are doing.

    However, they give a sheet of paperwork that has some interesting advice on it, which seems to go against the tribal knowledge of many SpecMiata racers that I respect, and who have components that don't seem to blow up...

 

    And I quote:

 

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"After installation, fill you Miata IRS Torsen diff with only a premium GL-5 hypoid gear synthetic lubricant.  Approved lubricants are Synergyn Syngear II, Motul Gear Competition 75w140, Motul Gear 300 75w90, and NEO Synthetics 75-90 RHD or 75-140 HD.  The Torsen ATB diff dosen't require friction modifiers.

 

**** Special Note: DO NOT USE Redline Shockproof or similar lubricants that contain microscopic soild particles in immersion to "cushion" differential components"

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Anyone ever hear of issues using RedLine products?  I ask cause I just bought a bunch and was about to fill the diff and trans with them.  And I know a LOT of people using these lubes who rave about them.  Anyone know why shockproof is specifically called out as not recommended?

[G.Obadia]

They are specifically talking about the shockproof line of products made by redline and not redline from the way I read it. Look up the products and you will see why.

[Ron Alan]

+1 above. Have always used redline 75-90...never had a problem. But not the shook proof product...

[ChrisA]

I used Shockproof in my Torsen for a few seasons without any problems until recently... and this may not be a true problem. I typically change the Diff fluid the beginning of each season, however last season didn't happen for me, so the fluid was about 2-yrs old. Appearently, Shockproof does not react well with moisture and will congeal. When I went to change the fluid, it was thick and lumpy and I actually needed to scoop/pull the clumps out with a popsicle stick to continue the flow. I now have Mobil-1 75-90 in there to clean out the rest. After dyno tuning I'll drain it again and likely put regular Redline 75-90 back in there. I can say the Shockproof has wonderful cling properties.

[FTodaro]

I would like to hear from some others, I have used the shock proof oil in my diff and have never had problems with it, but i do change it often.

 

I have seen people use it in there transmission, and it does come out lumpy. I have never used that in a transmission i normally use MTL ot MT85.

 

you might go back to those folks and ask them what is it that causes them to recommend NOT using it. I think however when the Shock proof stuff gets warm it thins out again.

[Johnny D]

It would be good if you included how often you change it so somebody reading it doesn't think you leave in all season or something.

 

J~

[marcusmazza]

After a ring and pinion failure with a 1.6L Mazdacomp diff., I switched over to the redline shockproof oil. I run the lightweight. I have not had any issues with it, and so far, no failures. I do change the fluid every 2-3 weekends, and it has been 2 seasons since the re-build.

 

From redline's website: Avoid use with pumps, coolers, and filters as unique medium and affinity for metal can cause clogging.

 

I assume this is what is causing it to get lumpy if you don't change it often enough, especially since diffs produce a fair amount of metal particles. I have never had mine get lumpy, but again, I change it often. Trying to keep from having to do another diff. re-build.

 

Also from their website: Not recommended for most synchro applications due to the product's extreme slipperiness.

 

My guess is this is why they recommend not using it in the Torsen Diff., since the Torsen relies on the friction produced at the thrust bearings/washers in order to control the torque bias. If the shockproof stuff is really that slippery, it may effect the Torsen's performance. I would assume the viscous limited slip would also have issues with the shockproof oil. The Mazdacomp diff., as I understand it, is more like a Detroit locker so it doesn't really care, plus keeping the ring and pinion alive is more important. The Torsen is pretty bullet proof, especially since it has a larger ring and pinion. Really no need to run the shockproof oil in it IMO.

 

Marc

[Bench Racer]

The Mazdacomp diff., as I understand it, is more like a Detroit locker so it doesn't really care, plus keeping the ring and pinion alive is more important.

 

Marc

My Madza comp L/S works well using Mobile 1 diff grease. Agree with the 6" ring and pinion. Change every two race events. The internals are quite different between a Mazda Comp and a Detroit locker. The Mazda Comp is clutches and the detroit locker is more like gears of a transmission dog box that get ramped out of engage. Never drove a Detroit locker, but would guess it's more instant open type diff to one wheel. Dave Wheeler??? 

http://www.youtube.c...h?v=FYBOoljH-qE

[marcusmazza]

I don't know why I had it in my head that it was similar to the locker. You are right Bench in that it is a clutch pack style diff. With that being the case, I would think that the shockproof oil might be an issue for it as well, but I haven't had any issues, and I know a few other people that run it without issue. I also take back my comment on the viscous limited slip. Not sure if the shockproof oil would really effect it or not.

 

Marc

[davew]

Lots of mis-information in this thread.

 

I am a Redline dealer, also sell Royale Purple, Schaeffer and sometimes Mobil 1.

 

I use and recomend Redline 75-90 or Schaeffer 75-90 for our diffs.. Depends upon which I have more of on the shelf!!!! I have no real issue with any quality, synthetic gear lube in our cars.

 

Any Redline Shock Proof fluid is designed for non-syncro gear boxes and locker style diffs. It is not recomended for syncro type gear boxes (Spec Miata) or clutch type differentials (torsens do have clutches inside). Therefore you should not be using shockproof in our transmissions or diffs. It wiil lubricate just fine, but does not have the correct additives to work with parts that must slip in operation (syncros and diff clutches).

 

The viscous part of the OEM 1.6 limited slip is a sealed unit, that does not use the lubricant in any way. So Shock Proof would have no effect on the performance of the VLSD.

 

Detroit Lockers are open on the straights and "lock" on corners. They are terrible in low horsepower cars, especially on big sweeping turns. Also called a "ratchet" by the southern circle track crowd. With the right amount of power and grip, you don't notice the locking action. Not enough power, or too much grip make them a real handfull. I tried a locked (welded) diff at Road America and thought I was going to crash at ever corner. At Blackhawk it was a lot of fun, but a totally different driving style.

 

Dave

[robertcope]

I thought that the Torsen was a completely mechanical LSD. In fact, I thought that was one of the big selling points. This paper on how it works seems to confirm that, although I will be honest and say that I have not read the entire thing: http://www.torsen.co...rol_Article.pdf

 

I've run ShockProof in my diff for about three years and ~125 days on track now without issue. I change it once a year. I guess I should consider trying something else and seeing if it acts any differently.

 

robert

[davew]

Do not try this at home....

 

If you take a Torsen apart, you will find a set of friction discs inside. Something has to slip otherwise it would simply lock (like a Detroit locker). Metal on metal does not lock very well.

 

The original question was why these fluids and not these others? SO we answered.

 

Dave

[marcusmazza]

First off, to Dave's comment, all the mis-information came from my post. I don't see any issues with the rest of the thread. It is pretty bad that I run a MazdaComp and have no idea what type of diff it is. I did go back and do some research on it after Bench set me straight.

 

Although my credibility in regards to diffs is probably shot as this point, I will comment anyway. I may not be up to speed on clutch or viscous type diffs, but I know quite a bit about Torsens, both type 1 and type 2. I have disassembled examples of both and designed and machined custom housings for them for use in formula SAE cars. Robert is correct in that they are completely mechancial, i.e. it has no clutches. What they do have are thrust washers between the housing and the sun gears. I have heard people refer to these as clutches, but they are in fact just smooth metal washers. This is true for both type 1 and type 2. The difference between the two diffs is that the planetary gears on the type 2 rotate along the same axis as the sun gears. This was done, at least in my opinion, to reduce maching and overall part costs. The majority of the Torsen's torque biasing comes from the gear set and the friction between the gears, however, the friction between the sun gear and the housing can change the torque bias of the diff. to an extent. I have seen people run thrust washers of varying materials, including carbon fiber, in order to tune the torque bias of the diff. I have also heard of people replacing the thrust washers with needle bearings to take the torque bias the other way.

 

A few other interesting points on the Torsens. The torque bias drops after the diff breaks in. Again, the Torsens rely on friction. Friction goes down after the diff breaks in. Second, in general (may not be the case for the Torsens in the Miatas), the Torsen type 2s have a slightly lower torque bias than the type 1s.

 

All that said, I would imagine that running the slippery shockproof oil in the Torsens would most likley reduce the torque bias of the diff, given that it would reduce the friction between the gears, and between the sun gear/housing and the thrust washer. The shockproof oil is however lighter weight (al least the lightweight and super leightweight stuff) than 75-90. You may be able to make up for the loss in torque bias with the power increase from running the lighter fluid? I would imagine this would be very track dependant.

 

I have not felt (subjectively) any performance loss with my MazdaComp diff running the shockproof oil, nor have I seen any change in lap times. I will continue to run it. As I stated earlier, with the small ring and pinion, I am more worried about keeping it alive than I am of any torque bias loss.

 

Marc

[WilsonSteele]

All,

    Thanks for the great insight and feedback.  Quite a lot of useful info here, glad it is now up for public consumption.

 

    I am also one of the few who have completely disassembled a Torsen unit, for F-SAE use, though I will admit I've never reassembled one sober, and might not be able to do it without the aid of my friend Jack.

 

    So, that being said, we remade half the steel shim washers, or washer stacks, out of brass for our car, to get it to loosen up it's biasing (helical gears rotating more freely).  The F-SAE cars didn't weigh enough, or have enough torque compared to their grip, to use a stock Torsen properly.

 

    So, also totally on board with there being no "clutches" in a Torsen, just thrust washers.  Which, in effect, are just plain bearings, and in this application, hydrodynamic plain bearings.

 

    So my basic question remains, and the reason I bought the lubricant I did:

 

    Why would a plain bearing, or helical gear teeth, not appreciated a lubricant with microscopic shock proof additive particles in it?  To me, shock proof sounds like a wonderful idea in this application.  I expose it to a lot of shocks!

[FTodaro]

My opinion, it will work just fine, but it may be overkill for this type of diff and this application, you might be further ahead just using a standard GL-5 synthetic gear oil which may be more slippery and not have those free suspension partials flowing around. but either choice would work.