I track my FD quite often now and still have the stock torsen. In my opinion the stock torsen is "OK" but isn't very durable even in non-drag track racing. I have 50K miles on my car and have ridiculous amount of diff slack (kinda feels, sounds like I have bad pillowball bushings) VERY clunky at this point.

Another thing I have noticed is that the torsen doesnt do an excellent job putting power down without getting too greasy. This may be subjective but the torsen def is scary once locked compared to some other cars/lsd's ive experienced. Its live-able but with my diff slowly decomposing this just adds more cause to go for a different setup.

For those who do see track-time and are looking for the same grip setup (not the aggressive drift setup) how can one compare the s4 clutch type LSD to the torsen? Its cheaper, stronger but I need to know if it is beneficial to my handling. Of course Kaaz is another popular option but ive seen how clunky they can be and I am just not too attracted to them. cusco, or the beautiful os geiken diffs are the choice for me but they cost half a motor.

--Feel free to give your opinions and perhaps recommend other options since i am no way an expert in diffs. I know theres a lot of diff talk scattered through this forum but my goal is to gather all the info into one thread.

 

I run the Carbonetics Carbon 1.5 LSD in my 20B FD, it has silent operation and a beautiful lock up. We have installed this is numerous customers' cars as well, drag racers to street racers, everyone has been happy with it.

http://banzai-racing.com/store/93+_r...ferential.html

 

if you feel clunking, check your differential first before automagically thinking its your diff.

even with 50k miles, the ujoint/yoke on the drive shaft can have enough wear to give a clunking sound.

if your DS is in good order, thats when i would look into the diff's Banzai have mentioned.

I can side with the Carbonetics 1.5.... excellent diff

 

thnx for info.. lol if I can find a used one for cheap i will DEF pick one up!

All i know is that when the car is up in the air and I spin the DS left to right there is A LOT of play before it begins to rotate the wheels thus Im thinking its the diff itself correct?

 

anyone have input on T2 LSD's on track driven FD's?

 

I'm pretty sure your current diff is fine and the space between each wheel reacting is normal.

I don't know much about diffs but I think a torsen diff is gear driven and unless you've sheared a gear or something the usual failure are the bearings. If you infact damaged a gear it won't be long before the whole thing comes crumbling down so I'd investigate that if you think it's truly acting weird.

No doubt there are some quicker reacting diffs that would smooth things out but they are expensive and require some maintenance along with setup and besides this is a decent diff for road racing.

If you've already invested heavily in coil overs, sway bars, brakes, wheels and tires etc.... then maybe a diff is your next step but if you don't have all the other pieces of the puzzle nicely sorted there's likely a better place to spend your money.

 

a S4 diff and rebuild is another option..... i believe mazdatrix still sells all the parts necessary

 

there is def something wrong with my drive-train. Its NOT my pillowballs, ive checked them. If I go on-off throttle or if the motor bucks the slightest bit my rear end (diff) sounds like its gonna break. There is so much play that it sounds like someone has a sliding hammer and is hitting my rear end repeatedly as the bucking happens.

It didnt do this this 2 years ago as the symptoms gradually began.

Obviously if I find a used Cusco or Carbonetics LSD for sale ill jump on it. But worse case If I have to buy a new LSD I am wondering how the T2 clutch type LSD compares to the stock torsen??.... which nobody has clearly answered yet.

 

You may of already checked them but some bad diff bushings will really make each gear change and on and off throttle feel terrible.

The one place solid or delrin bushings are good is in the diff. If you need a set shoot me a pm.

 

You mention diff slack. I interpret that as the same thing as backlash in the ring and pinion. That would be an issue of gear wear and wouldn't have much to do with whether the ring is mounted to a torsen, open, or clutch pack diff.

That said, if one diff puts the power down more smoothly it should create less shock load on the gearing and that will reduce gearing wear. Smooth engagement = less gear wear. Anyway, I digress.

David

 

i use an FC Cusco lsd @ the moment in my FD. Its a bit noisy when turning out of car parks/driveways etc...but in terms of control, way better than the torsen type. i'm putting out 400hp /345tq and it helps out alot especially from 1st - 2nd gear. I hated it @ first with the noise and all but it's like music to my ears now.....

 

I think this is a shimming problem because I experience the same thing when I rotate my axle back and forward. My problem 1st became noticeable ever since I started solidifying the rear end. I have solid diff mounts and a differential support brace that I made in place of the PPF for my 20b conversion. I have zero wheel hope but that clunk is really annoying. I have another axle at my disposal but it has the same play also. I think there is so much movement with the stock drivetrain that most don't feel the clunk with everything rotating at the same time. The movement kinda absorbs the shock. With a more solid rear end, the cluck makes itself more known because you have no more rotation back their. I wanna install the Turbo II stuff myself but I'll do all that and the shimming when I put in 4.3 gears.

 

Thanks for the info. When you say control are you talking about straight line traction or in turns?

And for shimming, that may be a likely suspect to my issue as well. But when I check for play, I checked my actual drive-shaft, not the axles. Ill check the axles too next time.

 

anyone have thoughts on the mazdaspeed unit?



The carbonetics also sounds intriguing... whats the difference between the carbon and the metal unit? I guess the goal is max power to the ground in straights as well as curveys i'm just not sure what dictates that. Also lets not forget the cobra conversion which seems to be popular for high HP applications.

This link seemed interesting, and has explanations of the different diff types http://mazdarotaryclub.com/forums/sh...82&postcount=1 Though he seems to draw different conclusions, saying that the torsen provides the best traction (if im reading this correctly) .

 

^Not sure how those Mazdaspeed diff for the FD measure up compared to other options but I do know the Spec Miata guys routinely break the Mazdaspeed LSD.


Grassroots Motorsports did an article a while back comparing (and testing) the different types of diffs on an S2000. Might be worth finding that article since the S2000 also has a Torsen and the diffs they tested are from the same companies that make them for the FD.

 

there's nothing wrong with the TII diffs, the biggest issue people run into with them is that most are tired after being on the road for ~20 years now.

the nice thing about the clutch type TII differential is that you can preload it how you want to get better lockup characteristics out of it, the drawback to this is that you have to disassemble the whole diff and mill the case to pre-load the clutch pack how you want it. milling the case sandwiches the clutches tighter versus rebuilding it with $700 worth of parts and getting only a stock reacting diff(which usually is fine depending on your suspension and grip characteristics of the car). no noise and no slack in engagement.

but that aside, it sounds like you have ring/pinion gear wear issues versus the LSD being worn out, when the torsen goes it GOES!

 

sorry this is obviously a totally diff-newb question:
The point of being able to lock the diff is..... ?

I was under the impression that for max grip, you'd want the diff to be constantly adjusting the power to each wheel (whether in a corner or straight). Now obviously I understand why locking is desirable for drifting as you are TRYING to upset the car with snap oversteer, being able to spin the wheels etc, but for street and road courses isn't the goal simply max grip? I always thought of a LSD as a rudimentary form of traction control

 

if i was talking about full lock i would have suggested a spool over any LSD. my point is and was that you can adjust the clutch pack stiffness on the S4 clutch type differential for either harsher or softer engagement at a fraction of the cost of aftermarket LSD units... clutch types will adjust power to each wheel but it is a more even rate, not quite ideal but it is an alternative. generally it is a drag car upgrade(while still keeping the car streetable) but not so much for tracking since the torsen distributes power more universally, where the aftermarket units are generally clunky harsh engaging units.

there is also a cheap alternative to the clutch type which is the phantom grip which is similar to a clutch type LSD but they are a bit on the grabby side so i would rate them more of a drift type LSD.

 

Well, I have not put a S4 clutch type in my FD (and will not).

I did however, replace my TIIs S4 clutch type with an FD Torsen.

From what I have seen of the Clutch type S4 rear ends in both NAs and TIIs is that they don't wear out after 20 years of commuting- they survive that just fine then wear out with a season or two of Auto-X.

FD Torsen does not have to be rebuilt every season or two.

The S4 clutch type (any clutch type LSD) also has the handling disadvantage of locking up.

In low speed Auto-X situations this causes understeer accelerating.

It also causes less traction on the inside tire in all turning situations as this tire is forced to rotate at a higher rpm (Locked to rpm of outside tire) and is therefore operating at a higher slip angle.

The only possible disadvantage I have noticed to the Torsen was on the hill climb exiting a certain slow turn crossing over the road crowning it allowed one tire to spin- though still biasing enough torque to the other tire to allow for great acceleration.

This actually seemed be an advantage as it would raise the engine rpms into the powerband if you kept your foot in it and let the tire burn. Though, if there had been many turns like this (thinking lapping on a circuit) and I kept doing this I am sure I would have overheated the tire.

Finally, there is the cost factor. I priced out the S4 clutch type rebuild kit through MazdaMotorsports and it was cheaper to buy a complete used FD 3rd member and have the Torsen swapped into the FC.

If you do decide to go clutch type use something aftermarket as they have more friction disks so it lasts longer between rebuilds and if you choose right it should cost less to rebuild as well.

 

I have a Mazdaspeed 2-way clutch type, housing looks just like the one pictured above ^...I've also noticed the same housing on TII LSD's, Re-Amemiya units, etc...I believe they're all made by the same company GKN Driveline (formerly Tochigi Fuji Sangyo) but with different internals.

I really like my Mazdaspeed unit, puts down the power nicely and I don't notice harsh engagement. Biggest reason I changed from Torsen is because I broke 2 of them, the spider gears literally sheared off! I'm thinking over time all those little spider gears start to develop excess slack (gear against gear) ... This made my drivetrain feel very sloppy especially modulating the throttle on the track while cornering hard around a corner. Then finally one day after a sudden burst of torque (usually in a lower gear) BAM it breaks! FYI, I also have superpro diff busings and a diff brace...

By the way, I think the Miata Mazdaspeed LSD mentioned earlier is a different unit with different part#'s. http://www.ooparts-international.co....lsd/index.html

 

^All Miata diffs after 99 are Torsen

I used to own a mazdaspeed miata fwiw

 

So regarding your previous comment, you probably meant the Spec Miata guys break the Torsen diffs that happen to come with the Mazdaspeed Miata... Or did you mean the Spec Miata guys upgrade and break Mazdaspeed clutch type LSD's? Just want to make sure we're comparing apples to apples...at least torsen to torsen or clutch to clutch

 

I just stumbled on this info from Mazdatrix while looking for some differential mounts.

http://www.mazdatrix.com/g2.htm

"Transmission / Differential Troubleshooting

Symptom:
Really bad noises from drivetrain that change dramatically between acceleration, light throttle cruise, and deceleration.

Probable Problems / Solution:
Ring and Pinion are bad. The 3rd member must be rebuilt or replaced."


This sounds exactly like what I'm experiencing.

Anyone know what they mean by "3rd member must be rebuilt or replaced"?

 

I believe my problem, and maybe urs is caused by backlash issues. I dunno if I can get it fixed or if I need a new ring n pinion.

 

My main problem with a torsen is I keep one legging everywhere, it is hard to tell when both tires are going to grab or not.