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Author Topic: Mazdacomp vs Torsen diff?
W. Bonsell
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Region: NWR/Oregon
Car #: #26
Year : 1991
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Will soon be purchasing a limited slip for my 91... Searched the archives but can't really get a handle on which is the better way to go - Torsen or Mazdacomp. Interested in the reliability factor as well. Given that Torsens may become even more difficult to find in the future, would it be easier to "rebuild" a Mazdacomp?


Thanks...
Bill

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William Bonsell
SCCA/ICSCC #26
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Drago Verified Driver Made Donation to Website Series Champ
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Torsens are not hard to find and will be more readily available and less expensive than building a Mazdacomp. They are also far more reliable.
The only potential down side is Comp unit is better performance unit IMO and a little lighter. But we arent talking much time here, so if reliablity is factor, go with a torsen. if pure perforance and little budget concerns, build a comp unit.

Jim

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Jim Drago
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W. Bonsell
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Thanks JD. Is it my understanding all torsens are used rebuilts or is it possible to get a "new" unit? And are torsens then available as a completely assembled unit including half shafts etc which can just be bolted in replacing my oem viscous?

Also, estimate time and difficulty of swap out.

Bill

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William Bonsell
SCCA/ICSCC #26
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MPR22
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Bill,

Lay mechanic, like myself, with a helper can perform the swap in less than an hour, and that includes installing the VLSD back into my street donor. You need the driveshaft as well as the halfshafts for the swap.

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Michael Ross

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New is available as well. But torsens are gears, not clutch packs, so wear isnt really much of a factor. But you can get all new fom Mazda

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Jim Drago
East Street Auto Salvage
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davew Verified Driver Made Donation to Website
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I hate to disagree with Drago, NO I LIKE TO DIS AGREE WITH DRAGO.

There are clutches inside a torsen. The gears are what activates them, but there are clutches. They are not servicable, so what you get is what you got. Cause I took one apart!!!

I would not recomend a new Torsen. You need to put at least 1000 street miles on it before installing in the race car. You will burn the fluid every session on a new torsen. I know, I tried.

Dave

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David Dewhurst
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Not to argue with anyone, BUT, when you lift a rear corner of a Torsen it reacts just like an open. [Wink]

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Have Fun [Wink]

David Dewhurst
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d mathias Verified Driver Made Donation to Website
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I'll probably jinx myself but my rebuilt MazdaComp diff has lasted 4 1/2 years of abuse with only a bi-annual oil change. I was told that the ring and pinion were upgraded/more heavy duty.

Great, now mine will be done blow'd-up next race.

cboehly Verified Driver
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Denny,

I would recommend a fluid change after every weekend. Smell the fluid after a few events and it smells burnt. $8 for a quart of Redline every race weekend is cheap insurance. BTW, mine is that old too. Mine will probably blow up now. ;-)

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Charlie Boehly

Scottie
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Im a little confused on this. What exactly makes the mazda comp different from the torsen. Why would the torsen spin act like an open when a wheel is in the the air, vs. the mazda comp not.

Right now I have the stock LSVD, which is really an open after a couple laps.

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How do I fit this ls7 into my mia... nevermind.

hoverducky Verified Driver Made Donation to Website
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http://en.wikipedia.org/wiki/Limited_slip_differential

Scott

Scottie
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Thank you ducky!

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How do I fit this ls7 into my mia... nevermind.

Brian Newton
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AHHHHHHHH very interesting.

So what type is the Mazda LSD?

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W. Bonsell
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What is meant by "lifting the rear wheel"? Right now my VLSD spins a wheel in hard cornering. I presume the torsen will not let that occur but not as effective as a true limited slip such as the mazdacomp.

Reliability is always a part of the equation, but overall ability to dig hard out of a corner is the performance I want.

I want to be assured the torsen is a sustantial upgrade over the viscous. I am tired of spinning up the unweighted wheel.

Bill

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William Bonsell
SCCA/ICSCC #26
SM/ITA

Scottie
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Lifting the rear wheel is just what you are describing. In hard cornering, the inside wheel becomes unweighted. From what I hear, the torsen will cure your problem, but the mazdacomp will do it better.

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How do I fit this ls7 into my mia... nevermind.

JimEli Verified Driver Made Donation to Website
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Bill,

Here is my experience which will relate directly to you. I was generating wheel spin at Portland in 4, 7 and 12 with an open diff on my 1.6. The only place at Pacific I had wheel spin was in 3.

I purchased a MM LSD and had Greg B set it up (a real wizard with these things). Installation required swapping the stub axles (a 1 minute job) and about 1 hour to drop the exhaust, pop off the axles and swap the diffs. Air tools help break everything loose.

The diff has eliminated my wheel spin issues at Portland (only time on track at Pacific was in the rain so I canít tell). My lap times improved about 0.5 seconds with the LSD. I figure the LSD set me back $1500 for purchase, rebuild parts, setup and install (including buying a used diff for backup/axle swap).

My opinion is the Torsen will eliminate the wheel spin, is practically built-proof, but probably saps a little performance due to increased rotational inertia. You could easily install it and then forget about it.

There are mixed experiences with the reliability of the MM LSD. A few report absolutely no issues, while others tell horror stories. However, it seems most LSD users with good reliability are the meticulous maintenance types. At the very least, use good fluid and change it like your underwear.

See you at Pacific.

Jim

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Randy Thieme
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Bill,

When getting rid of my Open Diff (OD) I asked about Torsen vs the Mazdaspeed. I went with Torsen based on recommendations it would be more rugged and reliable. If best performance is priority at any cost the Mazdaspeed may or may not be the better choice.

I'm aware of the reputation Torsen's have for acting like an OD if one wheel is off the ground completely. I have not experienced a problem with that yet and I'm frequently upsetting the inside wheels by getting up on the curb at the apex of T2 at PIR. Once the wheel touches the ground again it should grab right away. The wheel spin issue really doesn't concern me since I figure if a rear wheel is up in the air long enough for wheel spin to be an issue the car has probably been upset so badly I've got much bigger problems on my hands. [Wink]

I spent under $1400 when all was said and done. That included a "Torsen kit" with used '99 Torsen, drive shaft, and axles. Plus buying new bolts which attach the driveshaft to the differential. The bolts for the '99 are different from the 1.6. Don't use hardware store bolts unless they're grade 8 (metric equivalent) or better. Best is to buy the correct bolts from Mazdaspeed. Installation was easy even for a lay mechanic like myself.

Also - I sent you a PM.

hoverducky Verified Driver Made Donation to Website
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quote:
Originally posted by Brian Newton:
AHHHHHHHH very interesting.

So what type is the Mazda LSD?

Clutch pack.

The reliability issue with the Mazdacomp LSD isn't really a problem with the diff, so much as the tiny ring and pinion. As far as I can tell, you can make them live if you change fluid a lot and replace the bearings every season. We run the piss out of our car, so I opted for the Torsen (which, of course, has the larger 1.8l R&P) when we shredded the original pinion.

I like the Mazdacomp better from a driving standpoint. I think it is more fun and noticeably quicker to accelerate in low gears. But I _really_ like not having to worry about the diff failing.

I do get wheelspin in turn 2 at Sears Point. I'm hoping to fix that by using 75W90ns instead of 75W90. The guys at Redline said that might help.

Scott

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Greg was nice enough to spend a good deal of time educating me on diffs when he replaced my R&P and while I couldn't do his explantion justice (or get more than about half of it right if I tried) I did take away some valuable insights.

Either diff will last a long time if properly assembled and serviced.

There are a few parts of the 1.6 diff that can cause it to go bad so it should really be overhaulled anualy. That involves replacing about $200 worth of nuts, bolts, bearings and at least one crush sleeve, plus another couple few hundred bucks in labor for someone to do it right each time. Improper assembly is the #1 cause of failure as evidenced by his shelf full of broken diffs.

The 1.8 is much beefier in several places so it doesn't get as stressed and should last forever if it is properly assembled and the fluid is changed periodically. (This could save the budget minded racer money over the long haul when you add up parts and labor for each overhaul.)

Even a 1.8 needs to be properly assembled. Mine was on the tight end of normal tollerances which when it heats up a few hundred degrees during race use makes all the clearances too tight.

Be careful when buying a used diff because there are a number of things that could be wrong with it making it a potentially expensive time-bomb/paper weight. If not assembled right, bolts will back out and chew the innards up. Chips in the R&P teeth can turn into cracks if not dressed up properly. There were several items where he talked me through the inspection process to determine if I in fact bought an expensive paper weight myself.

He wouldn't buy one without first carefully inspecting the innards and I probably wouldn't now either after that education.

--------------------
Keith Novak
(Will work for tires)

Frank Todaro
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quote:
Originally posted by hoverducky:
quote:
Originally posted by Brian Newton:
AHHHHHHHH very interesting.

So what type is the Mazda LSD?

Clutch pack.


I do get wheelspin in turn 2 at Sears Point. I'm hoping to fix that by using 75W90ns instead of 75W90. The guys at Redline said that might help.

Scott

75W90 "NS" What does NS stand for and why would this help if you know. I have the same issue a little wheel spin in a few spots at Mid Ohio I have been trying to play with the set up to get away from it, but I am willing to try anything at this point.

--------------------
Frank
Member: No Pain Racing

Rye
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NS = No Slip

It contains a friction modifier to reduce clutch slippage on LSD's so equipped. Works best with a clutch pack diff, but might have some effect on a Torsen as well. I believe the Torsen contains a clutch , but works on a different principle.

Richard

TillerTech
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The torsen -R version has a preloaded clutch pack.
Not legal in SM.

The friction modifier you speak is from the clutch type LSD, it is used to keep the disks from sticking together and smooth out the operation (street application).

John

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Frank Todaro
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I have a Torsen so I suspect that will not get it done. Still working with the set up. its either the set up or its me.

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Frank
Member: No Pain Racing

Z-MAN Verified Driver
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quote:
Originally posted by d mathias:
I was told that the ring and pinion were upgraded/more heavy duty.

Now, I believe that would be an un-authorized modification...

Not something to talk about - you should check on that... Only stock gears are allowed...

MZ

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They are the OEM gears, superceding previous part #. Order a 1.6 R&P from MazdaComp and that's what you get. Thanks for asking.

'Strongbad'
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Oops. wrong thread!

Maybe have the 99's run without the top! That should punch a bigger hole through the air and make the cars look better.

Anybody have real data on running the car with/out the top?

Joseph Strong
1.6

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quote:
Originally posted by Rye:
NS = No Slip

It contains a friction modifier to reduce clutch slippage on LSD's so equipped. Works best with a clutch pack diff, but might have some effect on a Torsen as well. I believe the Torsen contains a clutch , but works on a different principle.

Richard

It's the other way around. The NS doesn't have the friction modifier. The non-NS has the friction modifier.

Here's a blurb on the friction modifier Redline sells (and which are included in the non-NS gear oils):

"Limited-slip or Positraction units use plates or clutches to provide the proper amount of lock-up to the differential. Slippery lubricants are required to prevent chatter, but too much slipperiness causes excess wheel spin, reducing traction. For perfect traction, use Red Line 75W90NS and add the Red Line Limited-Slip Differential Friction-Modifier / Break-In Additive until the chatter disappears."

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Rob Gibson
RJ Racing
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hoverducky Verified Driver Made Donation to Website
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As a follow-up I tested at Sears Point last weekend with 75W90NS in the pumpkin and it seemed to do the trick. Granted, it was a different day with different conditions, but the setup was exactly the same as last time I was there.

Scott

   

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