time for Quaife or AutoTech's new diff

 

^looks like that is in the future.

 

Quaife wouldn't be a bad way to go for a car that sees a lot of street use like my G. Quaifes are basically a Torsen-style diff like used by Honda on their performance models. Definitely a step up from a VLSD in terms of effectiveness and longevity (torsen diffs can last a very long time), but not as aggressive in torque transfer characteristics as a clutch-type diff. Not sure which will be best for the G, but I think I'll probably go clutch-type since I'm ok with a bit of chattering on tight slow corners (like when you're pulling into a parking spot) in exchange for some kickass torque transfer at the track.

What's the deal with the AutoTech diff? I'll have to look into that option!

EDIT: Just checked out the AutoTech diff. It's a torsen or helical-type diff, just like the Quaife. Looks like a solid design that'll be very durable, zero maintenance, and more effective than the factory VLSD.

3.9 FD might not be a bad idea either, since I don't do as much highway driving as I used to.

 

Auto Tech is Quaife America... its difficult to obtain Quaife domestically anymore - Auto Tech is developing their version of ATB diff “wave track”... If I didn’t already have Quaife I would absolutely be looking into their product... I don’t think it's available yet, but I've talked with them a couple of times and it will be soon. They are addressing the one major issue Quaife has which is open diff characteristics when one wheel is entirely off the ground.

Shorter gears are definitely worth doing!!! I went from 3.3 to 3.7 (AT of course) it is a VERY good bang for the buck mod!!! *note – for daily driving it might not be a good option these days with gas prices – I’ve noticed considerable loss in mpg… but I rarely drive the car and when I do it’s 85% spirited driving… I suppose if someone tried real hard to drive conservative mpg would be better than I’ve seen… but I only drive the car for fun so I rarely get enough conservative driven miles to get decent mpg.

 

Oh yeah, I forgot AutoTech is Quaife. LOL. Good stuff. That would explain the similarity between the designs

 

actually Quaife is in the UK (as you probably know)... AutoTech is/was the US distributor of Quaife - their design is similar though (however from talking with them and seeing a bit of the design it looks like theirs might be better).

 

Hmm, sounds like a lawsuit for patent infringement could be looming. LOL. Hopefully Quaife and AutoTech can play nicely together. Or maybe Quaife doesn't hold any patents since OBX has knocked off their diff design without any lawsuits that I know of, and quite a few OE's use torsen-style diffs as well. So maybe this technology isn't easily patented or the patent is open due to age or something. *shrug*

 

I don’t think there is any animosity between the companies... and Quaife has provided diff for many manufacturers - I'm not sure which "OE" you are referencing but I don’t know of any that have made race quality differentials in house... AutoTech’s “WaveTrack” is amicable to Quaife from what I understand.

 

Many of the OE's use Torsen or torque-sensing LSD's including all the hot version Hondas (NSX, S2000, Type R's, some Si's, etc), most of Audi's performance models from the A/S4 thru thte A/S8, Subaru STi, Toyota Supra, Mazdaspeed3, etc., etc. Very common style LSD for OE's to use because it's a very durable design that requires no maintenance.

Of course there are different types of Torsen diffs, some using helical gears like Quaife and Honda, and some using planetary gears like the center diff on WRX's, STI's and Audi Quattro models, but the basic concept is the same. I'm assuming since this type of gear-based LSD has been around a long time and is used widely by many different manufacturers, that AutoTech is able to make their own without infringing on any patents.

In any case, I wouldn't really call a Torsen-style diff "race quality". Most race cars use clutch-type LSD's because they transfer torque more aggressively and their lockup rate can be adjusted.

As far as OE's making race quality LSD's, performance divisions like TRD and Nismo both offer very high quality clutch-type LSD's for specific vehicles. I can tell you from personal experience that the TRD clutch-type LSD's are absolute works of art compared to most of the aftermarket LSD's I've taken apart.

 

Engineers use BMEP [positive torque] and IMEP [negative torque = friction, exhaust back pressure, intake reversion, and contaminated charge from backpressure] sum the two and you get net torque.

The coast down dyno/road test is an example of testing a portion of IMEP.

Exhaust work [from exhaust valve to muffler output] is almost entirely IMEP related.

Engines are driven to peak rpm by an electric motor [no ignition but hot coolant and oil] to measure IMEP and friction. Obviously corrections for cold air output are required.

 

Wrong. All Dynapacks read different from each other, so this one can read different then say the world famous Dynapack at Churchs' in Cali lol

Dynojets are the closest thing to reading the same between any random dynojet country or worldwide. Why? Because unlike Dynapacks its a very cheap and simple dyno, in that it doesnt have many shiney bells and whistles to mess with that can also skew the numbers, but is better at emulating real world driving than a dynojet.

Anyone get that? Just wanted to clear some stuff up in this thread.



Modified dave, was there any tuning done or just a swap of the headers? And are you still using the stock ECU?

 

Dave(Modified, not B) can you elaborate a little on the break-down of the VLSD fluid?

 

Did you ever get a video...maybe two?

-Sean

 

Bolivian - no tuning yet. Stock ECU, but about to have a TS L-spec reflash done to fix the throttle-by-wire issues and install a Haltech Platinum to adjust the fuel, ignition and cam timing. Once the tuning is done we'll really see what the group of bolt-on mods I've done are capable of, including the headers and cats.

VLSD and fluid breakdown - this type of diff is fairly simple in design. They use a cylindrical chamber of fluid filled with a stock of perforated discs that rotate with the drive wheel axles. These discs do not come in contact with each other, but instead move through a silicone-based fluid. The faster these discs spin, the more the fluid thickens and resists this motion. SO if one wheel loses traction and begins to spin, the viscous fluid on that side of the diff will try to catch up with the faster moving discs on the other side. This transfers more torque to the slower moving wheel, which also happens to be the wheel that is not slipping and is therefore better able to put the power to the ground. This type of LSD has pros and cons, pros being the gradual engagement and torque transfer qualities that make it very street-friendly and almost invisible to the driver, but it's less efficient at transferring torque than a gear-type or clutch-type LSD.

Just like engine oil or damper fluid, over time the fluid is put through many heat cycles, which breaks down its composition and reduces its thickening (and therefore torque-transferring) properties. Generally speaking, after about 60,000 miles a VLSD loses its modest limited slip characteristics and behaves more and more like a standard open diff. And since the VLSD is a sealed unit, there's no easy way to replace the fluid, so it's at this point that going with a Quaife gear-type LSD starts to make a lot of sense of drivers who want/need some LSD action in their life.

Sean - no video yet, but will put something together soon.

 

^^^ Intersting. THe G i just bought has 63k, i might look into a quaife LSD. They make ones for G's?


Also Haltech.... EXPENSIVE STUFF! How much coin is that costing you?