GregBBRD

Truthfully, I've never been able to tell the difference between a Quaife and an open differential. I tried one, very early on, in my own 911 rocket ship and it "lit" up the inside tire at virtually every turn that I was able to put the power down. I have had the great opportunity to drive quite a few cars, over the years, with all kinds of differentials. To this day, I can't say that I've ever felt a Quaife do anything....at all.

I also ran several of them in one of my customer's 951's. It was virtually impossible to "keep" the gears from self destructing and we virtually always had one back to Quaife for them to warranty (which they did, without any complaints.....always sending us back a brand new unit.) To keep the vehicle running, we actually had 3 of the units for one car...to be certain that we always had a "good" differential to use. However, the problem became so absurd that we finally gave up, had them redone one more time, and the customer sold all of the units.

I also was "involved" with the people that used to be the exclusive US importer for the Quiafe units and was able to see the unit that they had sent to Porsche for testing come back from Porsche. Was not very pretty. Looked as though they ran it for extended periods of time without any gear oil. Needless to say, Porsche never bothered buying them...or bothered to use any of that technology.

I used the one that I had in my own 911, for years, to keep the front door of the shop from blowing closed, when the wind blew.

That was a job that it was able to do.

GregBBRD

Carl:

This is great news. If you read your first post, it appeared that you were trying to sell these units without testing....something that you've done before, unfortunately.

Come up with an idea, have a prototype built, test that with multiple vehicles (if possible), correct as required, then build and sell pieces for others.....can't hardly go wrong. "There never seems to be enough time to do it right, the first time, but plenty of time to redo it" is probably one of the best things that you can ever try to remember.

My adaptation of the carbon/carbon clutch is the perfect example of this. Although this is a "proven" technology in all kinds of different vehicles (much like this differential) and the first prototype has been installed and thoughly tested (and works very well,) I'm still waiting for a second test to be performed on another vehicle. I specifically selected this vehicle to be one that I was completely removed from and would not be present to help with the install. I want to know what the problems are...before I send these clutches out to others.

Yes, it hurts that I'm sitting on a small fortune worth of clutches and flywheels, but that is the price we need to pay to make sure that our customers get the best product possible.

I'm happy to "see" your change in approach! There might be hope, for you, after all! I hope this project works out great....I'm very interested in an "improved" differential for these vehicles....and it saves me the grief of developing something else....my "plate" is stupid full.

Aspkiller

Gosh, I must have said something that supported Carl.

IcemanG17

an interesting bit of stock 928 LSD info I found out yesterday......my new 79 racer has the G28-03 trans (early with 8 plate LSD), but the LSD is quite worn...so much so that in neutral with both wheels off the ground they spin in OPPOSITE directions, just like an open diff..... I have been having issues with it spinning the inside tire just like an open diff..... So I loosened the rear sway bar, & it got better.....I lowered the rear end & it got better......then I disconnected the rear sway bar and it got better, but still slipped.....last thing I tried yesterday at Thunderhill was to add "slip lock additive" to the gear oil....I was running Amsoil Severe Gear 75-90...& the additive helped A LOT....barely any slip now and I can actually use power to rotate the tail, vs a 1 tire smoke show I got before.....

Its VERY fun taking turn 2 at Thunderhill at over 1.4+G just barely sliding the tail...... :>)

brutus

Correct suspension tuning and setup are so important and so easy to miss. Now that you can throttle steer you are going to like the 5 speed a lot more than the auto , a LOT more ! Slow corners under braking lifting off the gas may rotate the car as well. Assuming you heal and toe the amount of control you have of the rear drift is AWSOME !

Carl Fausett

There is no change in my approach. Only an improvement in your understanding. It was always going to be tested in my 928. It still is.

If I was less than clear about that in my initial post, then the fault for your mis-understanding is mine. I'll be more direct in the future.

Ad0911

After reading all of this I think I want an LSD Now that the gearbox is out of the car. Until now I thought this was a job to hard to tackle. How hard is it to fit a LSD into a manual gearbox? Mine is '78 so this one won't fit...

blazing928

Be nice, I'm a bit diff dumb, SO, would this diff bolt straight into an 87 auto? What other set up & adjustments are needed?
In a car thats 99% road use, [1% local club track days], will there be a standard diff set up. "Plug and play" so to speak?
I don't feel the love in spending a lot of time adjusting plates etc.

brutus

Any time you swap parts in the differential? ring and pinion YOU MUST reset the mesh of the ring gear to the pinion gear using dial indicators as described in the workshop manuals. While Porsche specs are rather consistant for dimensions there is always a + -_in all tolerances. With aftermarket parts there can be more variance or not depends on how well engineered and made they happen to be. So I would not consider it to be "plug and Play". Most will want an experienced trans guy with proper tools to do the setup or you will have a noisy ring and pinion or reduced gear life or both !

Rick Carter

Subscribing for updates.

Ad0911

Anyone have experience with Phantom Grip LSD?
http://www.phantomgrip.com/

Dave928S

If you look at the setup it's basically two plates, with captive springs within, exerting pressure on the flat machined face of the spiders. They say in their FAQ that if there are machining ridges or a lip on the face this ... "can be done with patience on a bench grinder/table saw,mill or a lathe if you have access to one" ... this gives a clue to the 'engineering' of this 'product'.

Basically it jams up your spider gears until the spiders and/or plates grind themselves to nothing. It would have such minimal bearing surfaces that with any sort of duty they would have to overheat and start destroying metal.

You would not want to put this in a diff, let alone a transaxle where the ground metal would destroy your gearbox as well.

Phantom would seem to be an appropriate name ... here one minute ... gone the next.

Carl Fausett

Brian, the friction plates in your 8-disk LSD may just need replacement. They are a consumable item - meant to wear and wear out. Not to hard to replace and put back the performance it should have.
I have them here: http://www.928motorsports.com/parts/...lip_plates.php

You can see in the photos below that the new disks have "wear indicators" in them, sort of like tires do. They are actually meant to flush fluid across the face of the disk and wash out the worn particles. But, when you were the disks down to the "bars" its time to replace them.

Carl Fausett

I agree with Brutus somewhat, but not entirely. Yes, the tooth contact between ring and pinion will need to be checked - he is absolutely right. Given variables in machining, there is little chance that the new diff is exactly the same dimension as the old one. Very true.

But does it have to be done by a transmission pro or can you do it yourself? A small can of Prussian Blue machinists dye will go a long way to help you get your ring gear setup. Then you just adjust your shims to get the tooth contact patch where it belongs and you're good to go. IMO - its not that hard.

That being said - each of you know best what your level of comfort with tools is. If you are uncomfortable with setting up a new ring gear, then by all means, take it to a pro and have it done.

Ducman82

great to see an option is being made/discussed. lots of work for sure.