no, nothing had been cryo treated.

quote Originally posted by pontiacjeff: That's a knock-off Torsen (Zexel). Not a real limited slip b/c it goes full-open in a turn.

The application remains the same. Lets just call it funny names, ok? Looking at this and a Torsen, this is the simpler, cheaper, and seemingly more robust, of the two.

Compare:

Torsen B


Truetrac


http://www.rangerpowersport...wthread.php?t=205575

quote Originally posted by Zac88GT: no, nothing had been cryo treated.

would cryo treatment have helped? thanks

------------------
1986 Silver 5 speed Fiero 3.4 DOHC
Bored .30, Fully balanced and blueprinted
13.93@101mph as it is on the street.
... ... !
350ci 400hp/tq SBC, 4 bolt main
Spec Stage 3, Nitrous Oxide, many extras.
87 GT 5-speed Getrag, power everything.

quote Originally posted by AP2k: My suspension might be worn the eff out, but torque steer IS caused by unequal length axles and LSD's solve the torque steer problem provided the clutches grip enough.

No, it doesn't. Unequal CV joint angles cause torque steer in FRONT wheel drive cars. They don't in a Fiero because the toe links are anchored to the cradle, not to a steering rack.

What passes for torque steer in a Fiero is the ENTIRE rear suspension twisting in worn out cradle mounts because of the torque creating by having the dogbone brace mounted off center on the engine.

quote Originally posted by flames4me: would cryo treatment have helped?

Most likely, though there's no way to tell whether it would have prevented Zac88GT's problem. Cryo treatment increases the metal's wear resistance and like I said, I would hesitate to simply drop a clutch pack (the PG unit) in to a differential whose components were never intended to be used that way.

quote Originally posted by Will: No, it doesn't. Unequal CV joint angles cause torque steer in FRONT wheel drive cars. They don't in a Fiero because the toe links are anchored to the cradle, not to a steering rack. What passes for torque steer in a Fiero is the ENTIRE rear suspension twisting in worn out cradle mounts because of the torque creating by having the dogbone brace mounted off center on the engine.

And you will get equal torque on both sides of the transmission if you *GASP* have equal length axles. Changing the angular displacement of the transmission is going to change the absolute torque applied to each axle. Thats why you cant drive a CV joint when its got a 90* bend.

I have poly cradle bushings, so my cradle isnt going anywhere. I DO, however, have the old tranny and engine mounts and a poly dogbone.

quote The Torsen pictured is a type II-R, which is a parallel axis helical LSD with a CLUTCH PACK in the center. The helical LSD delivers torque by ratio. That is, it will deliver to the wheel with grip (torque bias ratio) times the amount of torque it delivers to the wheel without. If one of the wheels is off the ground, it can absorb zero torque, so zero torque goes to the other wheel as well. With the clutch pack in the center, the diff always has something to push on. With one wheel off the ground using one of those diffs, it will still deliver (torque bias ratio) * (clutch pack preload torque) to the other wheel.

I was showing the differentials that were closest to each other in construction. The Eaton isnt a knockoff of the Torsen.

[This message has been edited by AP2k (edited 05-02-2007).]

I have been in contact with the Gr8grip represntatives, and apparently if you put the wrong fluid in the tranny after you install a LSD of any kind Gr8grip or Phantom Grip you will get the results the original thread starter had gotten (A LOT of wear and metal shavings). BUT if you use LSD friendly trans fluid there will be very little to no wear on the LSD itself or the contact points. Does anyone know what specific fluid would work best with LSD's of this kind? (Royal Purple, Lucas, Syncromesh, etc?) thanks.

------------------
1986 Silver 5 speed Fiero 3.4 DOHC
Bored .30, Fully balanced and blueprinted
13.93@101mph as it is on the street.
... ... !
350ci 400hp/tq SBC, 4 bolt main
Spec Stage 3, Nitrous Oxide, many extras.
87 GT 5-speed Getrag, power everything.

You mean to tell us you were on the phone with GR8 Grip reps and they told you that this miraculous mystery fluid would prevent the problem, but didn't tell you what this fluid is or where to get it? I'm no physicist, but fluid viscosity aside, these "LSDs" still work the same way and are going to put the same pressure and wear on the components. I really find it hard to believe that just switching lubricants will make a night and day difference.

since these limited slip units pretty much rely on friction to work, putting an oil in that reduces the friction pretty much would render it a few hundred dollar piece of junk, which they are anyway. And this magical fluid definatly isn't syncromesh because thats what i was using.

[This message has been edited by Zac88GT (edited 05-02-2007).]

quote Originally posted by flames4me: I have been in contact with the Gr8grip represntatives, and apparently if you put the wrong fluid in the tranny after you install a LSD of any kind Gr8grip or Phantom Grip you will get the results the original thread starter had gotten (A LOT of wear and metal shavings). BUT if you use LSD friendly trans fluid there will be very little to no wear on the LSD itself or the contact points. Does anyone know what specific fluid would work best with LSD's of this kind? (Royal Purple, Lucas, Syncromesh, etc?) thanks.

I remember seeing LSD-friendly text on the back of some tranny fluid bottles. Wouldnt hurt to go around town to auto parts shops and checking them out.

Remember, oil isnt always oil. The chemical makeup of the fluid might make the clutch plates wear easier and not grind up like that. Compare this to little things like engine oil and enigne oil with ZDP. There IS a difference, even though its not printed on the bottle.

i always wondered about the whole concept of jamming metal to metal until its grips. on most LSD (saying rwd cars, they use fricton plates to allow for slipage) the phanton grips simpliy forces metal to metal surfaces, which in sense equals wear at an accelrated rate. now if they used a friction disc this would be a more practical concept.

i might try going with a Lincoln locker....lol.

quote pontiacjeff said: Every limited slip differential from every auto manufacturer from the first in the 1950's up til 2007 has friction discs or cones in it! (except the viscous units in Mitsu and some other Japanese cars)

Just to clarify, I was referring to clutch-pack type LSD's... like the Phantom Grip one featured in this thread.

I'm not surprised at the pictures. I had a feeling of this sort of thing occurring from the first time i saw the Phantom. Heat, lack of lubrication and incompatability of metals took their toll. Plate types like the Eaton have multiple drive and driven plates. The steel ones (they can also be carbon fiber) have a checkered finish to retain oil to keep from galling. They're also very hard. The drive plates are keyed into the iron carrier so the don't spin. Consequently the side differential gears never rub the case like the Phantom. The driven plates have splines that fit over the splines on the gears. Again, no wear on the gears. The drive and driven plates take all the wear and can be replaced. wear is not a great issue unless you road race or something. In the Phantom, you don't have enough surface area for what it's being asked to do either. The Limited slip in my F150 has 6 large diameter plates per side. The ones in my old Eaton in my previous 70 Z28 camaro had 11 per side.

Don't expect an LSD specific lubricant to fix this situation. And Cryo treating can't change the metal enough to resist what's being done to it.

I didnt talk to the Gr8grip reps over the phone, I have been emailing them. last email I sent to them I asked which fluid would be best so I havent heard anything back from them yet (just emailed them today, so I'm expecting to hear back next day or two).

I am also thinking that since Gr8grip uses twice the contact points as PG, they might use less spring pressure? or at least need less spring pressure to do the same job.

I agree that using friction from metal-to-metal contact points isnt the best for the metal pieces in contact with eachother and there will be wear nomatter what, that is just common sence and not a debatable issue. But, I am just trying to get a few answers on how to extend that wear so it will last longer and not have the dammaging effects as shown earlier in this thread. Under the right conditions how many miles can this type of limited slip be used before it gets to the point of unuseable? 10k, 25k, 50...100?? and what are those conditions?

anyway, just my ranting and raving, maybe we can come to a conclusion that using a PG or Gr8grip will wear out faster then an open diff but what can a person do to help extend the mileage and reduce the wear to as minimal as possible if that person does want or need to install a LSD unit.

------------------
1986 Silver 5 speed Fiero 3.4 DOHC
Bored .30, Fully balanced and blueprinted
13.93@101mph as it is on the street.
... ... !
350ci 400hp/tq SBC, 4 bolt main
Spec Stage 3, Nitrous Oxide, many extras.
87 GT 5-speed Getrag, power everything.

The only wear factor for the PG type LSD are the number of turns you take. Take no turns and it will never wear out, autocross like the OP, and it will die in no time.

The only thing you can do to make them wear longer under normal driving is take it easy in the corners.

quote Originally posted by Zac88GT: since these limited slip units pretty much rely on friction to work, putting an oil in that reduces the friction pretty much would render it a few hundred dollar piece of junk, which they are anyway. And this magical fluid definatly isn't syncromesh because thats what i was using.

The clutches and bands in an automatic transmission are bathed in oil, yet they still hold.

quote Originally posted by Will: The clutches and bands in an automatic transmission are bathed in oil, yet they still hold.

but clutches and bands are different material than the phantom grip

What has the manufacturer said? Have you gone back to them?

Bob

They choose not to respond. Surprise surprise.

have you called them and forced them to talk to you?

Hmm, well, I have a PG in my car (somewhat modded 3800) and just happened to have everything out to do a new clutch. Did a quick check of it over the weekend and I have no appreciable wear or problems (yet). 30,000 miles or so since install. But. I pretty much baby my car, more of a top end runner than anything else when I do get on it, plus maybe 15 or so stoplight "yeah screw you and your Mustang/Eclipse/BMW/whatever" starts, but other than that just running up and down the interstate. So it will probably be very dependent upon how you treat it through the corners (as previous poster stated). For how I drive, it has been no problem, and I left it in (for as rarely as I use it, I do like having both tires go when it comes down to it).... But it is good to know it is something to watch for. Will check it again in another 15,000 miles or so.

Thanks for the update on the potential problem though.

David

^ wow, 30k and no apparent wear, do you by any chance know what tranny fluid you where using? Zac88GT said he only put about 5k (km's not miles) on it when it did all of that dammage. but Zac was also autoXing a few times during that mileage. can you still take any pics of your diff assembly with spider gears and LSD MP5Na3? or is it already in the car again? thanks

that definatly brings up how much driving style affects the wear. might it be safe to say this style LSD might be safe for drag racing? and straight line acceleration where there is very little movement of the spider gears (if one tire doesnt go spinning out of control), but a differant style locker or other mensioned above would be better for autoXing and other forms of racing where there are many corners to come out of while being hard on the throttle?

I have heard that the Phantom Grip does destroy the transmission after awhile from a performance guy recently, since my friend is doing a citation notchback L67 Swap. He had one of these installed:

http://www.engineered.net/eplsd.htm

[This message has been edited by thebaron (edited 05-03-2007).]

yea, those are very good diff assemblys, but they cost $599. and the PG and Gr8grip's are under $300. i guess you get what you pay for though. If I could afford one of those I would buy one in a heartbeat but I have already stuck to much into my tranny and am running out of funds.

quote Originally posted by Zac88GT: but clutches and bands are different material than the phantom grip

Yes, but they're bathed in oil. Not everything that's bathed in oil slips. Not every oil that bathes things causes them to slip.

quote Originally posted by pontiacjeff: Every Every limited slip differential from every auto manufacturer from the first in the 1950's up til 2007 has friction discs or cones in it! (except the viscous units in Mitsu and some other Japanese cars) With a friction disc, you won;t get galded washers like the pictures above. And, when the plates are HEAT-TREATED (like the EP-LSD) they won;t waer the plates or the gears... a little R&D is always a good thing and I worked on mine for over a year before I sold the first one. PG has been breaking in Hondas since I went into business formally back in 2001.

What are your friction plates made out of?

Thanks,
JG

quote Originally posted by Zac88GT: I just thought i'd give people some fair warning about using a phantom grip. I bought one for my getrag last year when i had the trans fully rebuild and have put only 5,000km's on it and it's destroyed my transmission. I now need all new bearings and syncros aswell as an entire new carrier assembly. The whole trans was full of metal particles and the phantom grip was worn ~.040 inches down on either side. The side gears are also super worn where they press against the carrier. I would not recommend the phantom grip to anybody unless you want to change tranny fluid every 1000km's and rebuild the trans every 5000km's. POS!!!!!!!!!!!!!

I don't know what PG says, but I think Bud's Outback, who makes the GR8 Grip recommends a posi-traction additive for the transmission oil to go along with their insert.

GM has a special version of its synchromesh designed for transmissions with LSDs. It's called "Synchromesh Friction Modified". The part number is 12377916.

quote Originally posted by Steven Snyder: GM has a special version of its synchromesh designed for transmissions with LSDs. It's called "Synchromesh Friction Modified". The part number is 12377916.

GM also specifies the modified oil in their factory LSD diff's, which are also clutch-pack based. I used to work in a shop that did a great deal of work on diffs, due to specializing in 4WD trucks. You could tell the people that put 'standard' hypoid gear oil in thier LSD's as when they would turn the corner into the shop, the tires would chirp every few feet. Adding the friction modifier would eliminate the problem.

We typically installed three types of LSD's: Clutch pack type (as with the phantom grip), Detroit 'lockers', which have a clutch pack, as well as a centrifugal mechanism to give 100% lock, and finally the torsen unit, which had no clutch packs, but was a gear only solution, but expensive.

If I had my choice, it would be for a torsen style.

phantom grip never said or hinted anything about using a different fluid or additive with their product so i didn't.

quote Originally posted by 2feido: I might try going with a Lincoln locker....lol.

I see the lol after the statement.

Since some may not understand that comment I will elaborate for the fun of it.

A Lincoln Locker is when the spider gears in the differential are fully welded (Lincoln welder) to each other so there is no slippage at all.

Just so there is no misunderstanding from anyone, and a little fyi, there is no way a Lincoln Locker is streetable. I have one in the Getrag on my Formula and it is a serious challenge going slow and making tight turns. The inside wheel keeps hopping and the car always wants to go straight.

On the other hand when road course racing it is awesome. During turning on a race track, as the inside of the car gets light from weight transfer, the power would normally start spinning the now lightened wheel. The Locked rear allows full power to go to the fully loaded outside wheel which helps to launch the car off the turns better. Also when doing high speed braking 120 to 50 or so, the locked rear keeps the compressional braking even on both sides so the car does not become more unstable than it already is. This is a HUGE differance when racing in rain when traction is reduced.

In regards to the trans failure, just because the trans was rebuilt does not mean everything was measured and installed correctly. I wonder if the new bearings were properly set up when it was assembled as it might have been too tight causing metal to metal interference. I am no expert on rebuilding them but when I rebuilt mine IIRC there are specific procedures to measure and adjust the carrier bearing preload. They may have simply pressed in new bearings and bolted it back together. Just thinking about it a bit.

Saed made a great LSD for the MG-282. It was a "detroit locker" style but I wouldn't recommend it for the street even if you could find one. It clicked on turns. GREAT for racing though!