ive been diving into lsd tech and deffinatly will shy away from the phantom grip/gr8 grip units due to the added stress and wear. clutch/spring type lsds seem to have their disadvantages outside of drifting(for rwd) as well as eventual wear issues. that leaves the much more expensive gleason-torsen diff which seems to be a 'lifetime' part as well as providing variable wheel speed but equal torque distribution. i can see this causing the back end to slide out should the wheels break free due to overpowering but that can easily be controlled. it should offer much greater off the line traction and acceleration for drag racing/street racing while also improving cornering by increased grip and less loss to wheel spin.

i plan on using this on an NA 3.4pr with the trueleo intake/exhasut, cam, rockers, ported head, balanced engine, dohc pistons, all of the good stuff. the power output will be low so the idea is to have too much grip, then i can spend more time accelerating(or keeping up as some might say). i like accelerating into turns and all the way through them but id rather not crash(but do want to go faster). im not building a race car but a strange combination dragster/track car that all street cars must be and this diff seems to be the right choice besides the 1500 price tag. the main thing is making sure i understand the downsides before deciding, its either this style diff or keeping the open diff which serves me well still. any comments would be very helpfull

Years ago they had a reputation for being fragile, not what you wanted to hear, but things may be different now. I've never
had issues w/clutch style, and they were used in applications such as you describe for your Fiero, only in FoMoCo, MoPar,
& BowTie instead.

Norm

[This message has been edited by gt88norm (edited 10-23-2008).]

quote Originally posted by megafreakindeth: i like accelerating into turns and all the way through them...

you might be interested to know that is not the best or fastest way through a corner

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87 Fiero GT 5sp with Vortec L35 4300 Turbocharged V6
Bully Stage 2 clutch
Syclone intake manifold and engine management with Moates adapter and chip burner
Air/water intercooler and Devil's Own progressive water/alky injection
50lb injectors, 3 bar map sensor, Walboro fuel pump and Jabasco Intercooler pump
LM1 wideband on custom manifolds and 3" stainless exhaust system
T31/T04B H3 turbo and a S10 caliper conversion.
Murphy's Constant Matter will be damaged in direct proportion to its value
Murphy's Law of Thermodynamics Things get worse under pressure.
Arthur C. Clarke "Any significantly advanced technology is indistinguishable from magic"

I have the Peloquin LSD in the VR6 Fiero and it does take a little to get used to, but the launch is much better. Daily driving is no problem. Turns are no issue. I don't really see any downside yet.
Dave

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1987 GT (my toy-see above), 1987 GT (daily driver), 1986 SE with a VW VR6, certified master technician/shop owner
www.njautobahn.com

Those appear to be similar to the G/Ts, but are VeeWee specific. Don't suppose he entertains different marques does he?

Norm

The main down side to a torsen is they multiply the torque the tire that is spinning faster and deliver it to the slower wheel. So if you are in a turn and just light up the inside tire, it is producing almost no torque, and nothing times anything is nothing.

Clutch type diffs have many applications other than drifting. Road racing being one of their main uses.

Some info:
http://auto.howstuffworks.com/differential.htm

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if you have a torsen you cant light up just one tire . the way they work it is impossible to have one wheel spinning and one wheel rolling like on an open diff .if you have the horsepower you will be able to spin both tires at the same time , but torsens generally limit wheel differential speed to 5 % or less .which is enough to go around a corner without upsetting the apple cart .i put a torsen in a 98 F150 and it was amazing ,especially in the snow .i dont know what they use now , but torsens were used for years in indy cars and F1 cars .

I checked mine by taking the car down a nice freshly paved deserted road and left a bunch of "impressions". In turns, if you break the tires loose too hard, you will wind up doing a 180. There is that fine balance to get the car to corner properly. This is one thing that is better to show you, so if you come up to the NJ area, I'd be happy to show you how it feels.
Dave

yeah ive messed with quaifes in mk4s but in the little ive read a fwd is a different set of requirements so the comparison doesnt work. tho in gtis its a much needed improvement, even that funny shim set for o2o trans is almost nessesary for vws. on the quattros they use a torsen diff for the center diff only, have to think about why

i know its not the fastest way around a turn but i cant lose my car on an exit ramp. or on some mountain road in the middle of nowhere. the extra traction to idiot proof the vehicle along with better drag characteristics seems to be a good idea. thats why i said i like to accelerate into and through turns, its fun not the best way.

if the inside wheel spins and produces no torque that would be a problem but is not the purpose of this diff to prevent wheel spin and modulate wheel rpm so there is no spin? is this what was mentioned as the diff only having a 5% difference so at most the left wheel can spin 5 percent more or less than the right wheel? if ou were to spin or slip the back end then the zero torque and zero traction that would occur wouldnt matter since all you do is back off the gas to regain traction where then both wheels would hook up and you can resume going. havent taken any racing classes yet so i dont comprehend much theory.

[This message has been edited by megafreakindeth (edited 10-24-2008).]

quote Originally posted by wftb: if you have a torsen you cant light up just one tire . the way they work it is impossible to have one wheel spinning and one wheel rolling like on an open diff .if you have the horsepower you will be able to spin both tires at the same time , but torsens generally limit wheel differential speed to 5 % or less .which is enough to go around a corner without upsetting the apple cart .i put a torsen in a 98 F150 and it was amazing ,especially in the snow .i dont know what they use now , but torsens were used for years in indy cars and F1 cars .

It is far from impossible.

From http://www.torsen.com

quote What happens when I have a wheel in the air? As mentioned above, the Torsen differential is a torque multiplier. The Torsen requires some type of resistance or friction in the system to function properly. A wheel in the air provides zero torque or friction on the system and as the Torsen multiplies the available torque, zero, by its TBR, the end result is still zero. In response to this, we developed the Torsen T-2R with pre-load to combat those wheel in the air situations.

From http://auto.howstuffworks.com/differential6.htm

quote However, if one set of wheels loses traction completely, the Torsen differential will be unable to supply any torque to the other set of wheels. The bias ratio determines how much torque can be transferred, and five times zero is zero.

If you are driving a car at its limits the inside tires are severely unweighted. On many cars they are in the air. In this situation it is very easy to produce almost no torque from the inside wheel. With no torque being made there is nothing to multiply.

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from the torsen website : AS SOON AS one wheel starts to lose traction ,the difference in torque causes the gears to bind together .this is probably why i never experienced the zero traction phenomenon you are talking about .and i drove my F150 in the snow for two years and it never gave me a problem .as far as one wheel in the air goes , i never experienced that in my truck so i cant comment .

so when the inside wheel breaks loose does it then cause the outside wheel to have no torque or is it still riding on its portion of the torque distribution? if you lose the inside wheel and the outside still has its power you should still be alright. i dont see how, if you lose one wheel to zero resistance(traction), you will also lose the other wheel.

when i contact the people to make one for me are there any specifics for a fiero that would help make it work with the car? the company makes them for cavaliers and cobolts and i know the needs of fwd are different.

what lsd does the cobalt 6spd use?

be carful with differentals. i drove my friends v8 vega and the if you dont break traction you will break something else it has a 555 and i know you wont be runing that kinda torque but he bent the entire car fram to a point where a window cracked and the doors dont open. so be careful there.
enough negitive i have more drag racing experience with this kind of thing then i do road course.
the race track near me most of the cars i work on are hondas ricers etc and thier wheight is over there drive tires giving them a great grip in a fiero your wheight is over your drive tires.
so the question is are you spining your tires enough to warrent a 1500 dollor part?

my opinon on that is that it looks so much better when you have a loud torquey car spinning both tires and not just one. My V8 gets picked on by my friends for only leaving one burnout mark. Trivial...yes.
Dave

I was very impressed with the friction LSD installed into one of my getrag based 3800 swaps.

It nearly broke both the passengerside axle when it broke the driver side axle (it blew the boots off it), and it handles without any obvious issues around corners when it was at the 25th waterford track day.

The wear issues are moot. There is no friction material that can be damaged in the manual gear box. You might spend a bit more time changing fluid, but GM makes friction LSD specific fluid that has a fairly lazy changing schedule if i recall.

the highest numbers i could run are max 220hp and 250-275 tq depending on how the heads turn out. in a quarter mile ive max hit 80 in 3rd gear but usually its like 70 because the wheels spin. in a corner i cant get enough slip to be benificial because the car keeps hooking back up(bummer right?) and it cant grip enough without slipping uncontrolled.granted alot of this probably has to do with my driving skills but theres only so much im willing to try on a policed road. i think by having two wheels pushing, with no transistion time like lsds, both of which have better grip than normal that i should be alright.

the money isnt an issue ill be getting all the money to wrap up the powertrain department of my car shortly and on the side so it wont really affect the official budget(thats why a 1500 dollar diff is kinda like 'why not?'). it looks like ill be going for it, ive contacted mantaparts and im going to see if they can return one for a rwd app and ill find another 5spd in the meantime to rebuild to minimize downtime.

on an unrelated note, with my stock 5spd if im roaring around an exit ramp(lets say going right) and back off the gas quickly, the back end swings right? id figure it would swing left towards the outside, for me it acutally pushes in. whats up with that?

quote Originally posted by megafreakindeth: ...on an unrelated note, with my stock 5spd if im roaring around an exit ramp(lets say going right) and back off the gas quickly, the back end swings right? id figure it would swing left towards the outside, for me it acutally pushes in. whats up with that?

You are in an alternate reality where physics don't apply?

The only way your back end could be moving to the right in a right hand turn at the limit of the tires traction upon lift throttle is if there is something majorly wrong with you back end's suspension geometry. An example of what I'm thinking is on lift throttle both rear tires are toeing to the right.

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My Car Site
www.flexyourrights.com
Just say NO!! to Automatic Transmissions!!

Drop throttle understeer? That's a new one on me, especially in a Fiero. It's a geometry issue, the dif. can't fix that, and
may make it worse. Find that problem first! Is your alignment up to spec.? I'm thinking that someone can fill in the blanks
for your setup from a performance angle, as opposed to an NHTSC "save the stupid" setup. Look to the Road course guys,
or the AutoXers.They've no doubt massaged the alignment spec.s for more neutral handling.

Norm

and do the bumpsteer mod anyway. Cheap and worth it.