Orpheus

Hi guys,

This isn't for my Corvette, as it already comes with one of course. But I am setting up another car for track racing, and I can't find any material on which LSD type is typically used in racing applications. Apprently the two main high-performance LSD types would be Helical and Clutch. And Clutch comes in 3 variants: 1, 1.5, and 2 way.

Anyone know which LSD type is preferred for track racing? If you like clutch, should I get 1.5 or 2 way? (Thanks guys... I've been googling this subject for an hour and there are no solid opinions!)

UstaB-GS549

Try Torsen or Quaife. Torsen is supposed to put power to wheel with most traction. No personal experience, just what I have read.

jlucas

Need more car details before advice can be given.

Orpheus

well, it's going to be a highly modified 1984 Corolla, RWD. Probably looking at ~250-300rhp. Skinny tires (205-225 width, 15"), but DOT racing types. The rear is a solid axle. All suspension parts will be aftermarket. target car weight = ~ 1800lbs.

My goal is to have the fastest time around the track.

Looked at the Quaife website--they claim to have suported all types of cars including F1. Sounds good... but cannot confirm their claim.

Another brand I've looked at is the Kaaz clutch type, which I think is offered in 1.5 and 2 variants. These are mostly recommended by import tuners and drifters. My goal though isn't to make a car that slides the best, but a car that will make the best time.

I guess at this point, it's between Quaife, Kaaz, and... (is Torsen a brand or a type? seems like there are other brands calling themselves torsen as well.)

Solofast

I used to run first gen RX-7s and the best thing was a clutch type LSD. I was in a stock class but built them tight and that helped keep the car pointed in the right direction. Under trail braking they keep the car from getting loose. With a car like the Corolla the a tight clutch type LSD will keep you in line and still let the car rotate under braking. Off the corners you will be shot from guns. The tight LSD will add power to the outside rear tire and it will push you around the exit. Small light cars can get away with this kind of setup, where heavy cars will just push with a tight LSD or a spool. You have to set up the car to work that way, if the LSD goes away the car will be loose, but it can be a very fast way around the track for a small light car. The disadvantage of the Torsen or Quaife is that it isn't as "tight" and under heavy braking the car won't be as stable.

All of this is personal opinion and others swear by the Torsen/Quaife, but they are generally a lot more expensive than a clutch type system, and if you can get the clutch or spool to work it is cheap way to go.

I always liked those RWD Corollas, they were neat cars....

Orpheus

hmm, so i also looked at this thread:

http://sccaforums.com/forums/thread/233925.aspx

guess another problem with Quaife is that if i corner hard enough to lift the inside wheel, the diff goes open too.

so many opinions! well, thanks solo--let's say that i get a clutch... should i go with 1.5 or 2? or maybe even a 1? sounds like 1.5 is the way to go then for road racing?

yeah, it does seem like Quaife is more expensive than the rest. but personally, i don't mind paying a little extra if it's going to make a difference. after all, it's already costing a fortune to build up an antiquated car like the Corolla to be formidable.

AMERICANMUSL

Quaif is stronger than clutch driven...very similiar design as Detroit Tru-Trac...I have it and so does my friend Oli in our Corvettes and we get a better charge coming out or mid corners with out back end skipping sideways...only thing is for optimum performance, both tires need to be planted. My 2 bits! They alsp are standard in most P-Cars.

Ed

jlucas

That is one of the reason I was asking about the car. You can usually solve this if your class allows you to run any spring & sway bar combination you want. If a type of car is prone to lifting, some guys will run no rear bar at all and go up a little on rear spring rate instead. If that's not allowed, then definitely go clutch pack.

Do you understand the function of 1 vs 1.5 vs 2 way? 1 only applies clutch action under acceleration, 2 applies both ways, and 1.5 applies full action under accel and partial under decel. In my experience, 2 can be very difficult to drive but then again that depends on the type of car. Some cars may need that to get them rotated -- think trail braking with only the rear wheels when off throttle. With out knowing more (or talking to other experienced Corolla owners) I would lean toward the 1.5 way clutch pack type when choosing a clutch type.

Quaife is pretty bullet proof/reliable/zero maintenance but if all out speed is what your looking for it's usually hard to beat a properly setup & maintained clutch pack. However they will require maintenance like more frequent fluid changes (depending on how hot your getting it) and clutch plate wear inspection/repacking (could be annually depending on how much you use the car).

If streetability is an issue, go with the quaife. Clutch packs typically make more noise and your going to put more wear on the plates. ATS diffs with the carbon plates (as opposed to KAAZ) are a little quieter and engage more smoothly but even they make noise.

You'll never have to do anything for a Quaife, other than make sure the wheel is not lifting.

Hope that helps.

Orpheus

yeah, it helps a lot! thanks man.

i'm not really planning to run this in any class though. this is purely a "how fast can i make this car go" kind of experiment. so, i'm not limited by anything except my pocketbook.

that said, it sounds like the clutch pack might be the way to go. what i'm thinking is that the car is super light (like i said, ~ 1800lbs, and that's not a typo.) the center of gravity seems high too--wasn't originally a real sports car after all, and it's quite tall. i do plan on running sway-bars though just to keep the car from rolling so much--it feels very soft stock. if it's running really grippy tires, it's quite possible the side will lift is what i'm thinking. do you agree?

but on a technical note, i was thinking it isn't possible for the clutch type to divert more than 50% of the torque to the outside tire right, as the mechanism simply locks the left and right axles together? how 'bout the quaif?--can it actually put more power out to the right tire? would that not make the quaif superior?

(oh btw, i love those LOUD diffs! i think the sound is cool. you should check out my vette, which used to be my daily driver. fixed racing seat, stage 2+ clutch, hurst, exhaust, corner-balanced, etc. was insane! and i drove it in 3 hours worth of stop and go traffic every single work day.)

jlucas

If I were you, my next step would be to find some people who have built up Corollas already and see if there are issues with lifting and such.

edit: I have no solid axle experience so that's why I can't really comment further.

Solofast

As somebody noted above, if you totaly lift the inside wheel, some of the Torsen/Quaife type units won't stop the one wheelerpeelers... As noted with a short tall car you are going to be lifting the wheel up if you are on really sticky tires...

The diffs I had made equal locking in each direction, thus by your nomenclature they would be a 2 way, you want the 2 way because when you are trail braking the relatively short tall car you will unload the inside rear tire. If you have the 2 way the car won't lock up that tire as badly under trail braking. Also, with a short tall car the inside tire will unload under braking, so it won't be hard to rotate the car with the diff working...

The Mazda stock Lsd had two driven plates and two drive plates on each side, they were grooved radially, and had a 45 degree wedge angle on the spider gear cross. The Mazda racing diff was the same, but had smooth plates and a 30 degree ramp angle. It tended to lock and unlock a lot and wasn't as streetable, but it didn't wear out as often as the racing diff. The hot setup was to mod the stock diff to get a better ramp angle and get more wedge action to keep the diff locked most of the time. It really didn't change the diff action much, but when it locked it stayed locked and didn't wear out for years...

Clutch type LSD's are great until they start to wear. Once they start slipping, they go soft in short order and it is then time for a new clutch pack. Still,for car control, I like them better than the Torsen.

Orpheus

Hmm, interesting theory..... never thought about braking locking up the tire that's unloaded.

But what about the claim that 2-way clutch diffs are hard to drive with? (I was thinking 1.5 until you posted your comments, which made me think even more )

Solofast

In looking at the SCCA forums on the Quaife, they end up setting the car up from more understeer and by increasing the front roll stiffness, it keeps both rear tires on the ground so that the Quaife works and they go fast with that setup.

With a tight LSD, you set the car up for a more netrual balance (which helps cornering), and the aligning moment created by the rear axle being close to locked up tames any transient oversteer. Basically it adds what chassis engineers call stability margin. That allows you to trail brake deep into the corners without loosing the back end of the car. Then as you transition to high cornering load, you have a car with a netrual balance, and since the inside wheel is lightly loaded, the self aligning effect really doesn't come into play. At high lateral g's, as you power out of the corner, the outside rear wheel pushes the car thru the exit.

Where you run into trouble with the tight diff or a spool is if the car is heavy, has a long wheelbase, and if you have huge meats on the back. Then the car is going to be hard to rotate and get turned in. There is just too much aligning torque being applied to the rear of the car, and the load on the rear wheels never goes away. In your case, you have a tall, light, short wheelbase car that is going to unload the inside rear tire under braking big time. It isn't going to have any trouble turning in since there won't be much weight on the inside tire anyway. More typically, you will be locking up the inside rear tire under heavy braking and the LSD will tend to cure that. The tight diff just adds some stability margin, but lets you run a cornering setup that gets around the corners more quickly.

Since these cars have been around a long time there is a good bit of knowledge that I would tap into before you go wild on the mods. Getting the suspension in line is a good place to start. Since this is a pretty tall narrow car, lowering it a LOT is probably one of the biggest things you can do with it. I saw this article in Sport Compact Car:

http://www.sportcompactcarweb.com/pr...e86/index.html

Lowering the rear a lot will likey require a relocation of the longitudinal locating links to keep squat under control. We had the same problem with the RX-7's when going to SP classes, when you lowered them a lot the rear link location went off and that caused some issues. It looks like the parts to lower the front and correct the geometry are readily available...

I also saw this web page where some folks were building a serious autocross AE86, they went with the 2 way KAAZ... http://www.pdm-racing.com/features/AE86_buildup.html

I would also look around for guys that are road racing these things and see what they did for lowering, rear suspension relocation and other items. Always remember that there are a lot of ways to go fast and one persons setup isn't necessarily yours.

1bdasvt

I'll be installing My heavy duty diff. w/3.15 gears and "Quaife" next week on My A6!!
Can't wait!!
Should pull like a frieght train!!

Orpheus

Thanks for all your advice guys. I appreciate it! After evaluating all the opinions and notes, I think it is best for me to try the Kaaz 2-way at this time. I think there are many merits to the Quaif, however in the end it's all about fun, and I think the Kaaz probably wins in that department. Also, the Kaaz seems the safest bet, as it covers all the bases adequately. The Quaif might be a little faster given all the same variables, but I think the Kaaz is the best choice for the way I drive.

And special thanks to Solofast. Lots of good information there! (those links also talk about other useful mods too.) Still trying to absorb anything. Anyway, appreciate it!

OKsweetrides

I swear by Quaife... it takes a bit to get used to, but it's all I'm accustomed to. You have to get accustomed to a different driving style, and the suspension MUST be setup properly for it, otherwise, say hello to the uneasy feeling!

That said, my roommates FD has a Kaaz 2-way, I'm kind of jealous of the clicking, it's a good unit as well.