3.42 open diff to 3.23 LSD.
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On The Tree
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From: Alabama
3.42 open diff to 3.23 LSD. I currently have a v6 that has an open differential with 3.42 gears. I found a LSD with everything but it's 3.23 gear ratio. What's better for my v6 keeping the 3.42 gears even though it's open or swapping to 3.23 just for the LSD? This LSD rear end is on 200 bucks and is right around my area.
Changing 3.42 to 3.23 will result in a 6% loss of torque to the rear wheels/tires,will you feel it,yes,is it significant,no.
But there exists two different scenarios.
1) Keep the 3.42s and change the carrier only. Since you wouldn't be touching/removing the pinion gear,it's already set for 'pinion depth'. You would just possibly have to be concerned only about setting/adjusting 'lash' but it should be close because carriers are basically interchangeable.
2) Use the 3.23 gearset/carrier. Since you'd be putting a different pinion in,pinion depth would have to be set. And then 'lash'. You would also need a gear change in the computer to correct the speedometer,it would be reading/indicating lower by 6%. At 54mph you'd actually be going 60mph.
If it was mine (and I work on rear ends),I'd be doing #1 because of simpler.
But there exists two different scenarios.
1) Keep the 3.42s and change the carrier only. Since you wouldn't be touching/removing the pinion gear,it's already set for 'pinion depth'. You would just possibly have to be concerned only about setting/adjusting 'lash' but it should be close because carriers are basically interchangeable.
2) Use the 3.23 gearset/carrier. Since you'd be putting a different pinion in,pinion depth would have to be set. And then 'lash'. You would also need a gear change in the computer to correct the speedometer,it would be reading/indicating lower by 6%. At 54mph you'd actually be going 60mph.
If it was mine (and I work on rear ends),I'd be doing #1 because of simpler.
You should ask yourself a few questions: How do you drive your car? Just daily/street? Autocross? Race? Do you have a lot of gravelly roads or curvy roads? Do you need a diff? If you don't really push the car hard in corners, or have a lot of traction-limiting issues, an LSD won't improve your car's overall performance.
The lower gear on the new rear will make your launch a little slower and seem like it saps some power from the car. Not a lot, but probably noticeable. It will change your shift points.
Lastly, how many miles on the LSD? What's it out of? All diffs wear out, in different ways. If it has a lot of miles, it could be worn out already.
The lower gear on the new rear will make your launch a little slower and seem like it saps some power from the car. Not a lot, but probably noticeable. It will change your shift points.
Lastly, how many miles on the LSD? What's it out of? All diffs wear out, in different ways. If it has a lot of miles, it could be worn out already.
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
Unless your V6 is significantly modified, I can't image that you have major traction issues even with an open rear (and if you do, it's probably just the result of poor tires), so an LSD isn't necessarily a "must have" in this instance. But, depending on your plans for the car, it might be a nice or necessary addition. As mentioned above, the concern would be that this replacement rear might not be in as good of shape as your current rear overall, and/or that the LSD is already at or near the end of its lifespan (which would leave you in a worse position - with a numerically lower gear ratio and still no LSD).
Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
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From: Alabama
Originally Posted by RPM WS6
Unless your V6 is significantly modified, I can't image that you have major traction issues even with an open rear (and if you do, it's probably just the result of poor tires), so an LSD isn't necessarily a "must have" in this instance. But, depending on your plans for the car, it might be a nice or necessary addition. As mentioned above, the concern would be that this replacement rear might not be in as good of shape as your current rear overall, and/or that the LSD is already at or near the end of its lifespan (which would leave you in a worse position - with a numerically lower gear ratio and still no LSD).
Last edited by BamaBird22; Oct 9, 2018 at 01:56 PM.
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
I do have traction issues but my tires are far from poor. I'm currently running 255/45/18 nitto nt555 tires. I have midtube headers, higher stall built Trans, aluminum driveshaft, koni struts and Eibach springs lowered 2 in. And soon to come is a cam and valve train upgrades and eventually turbo. So either way I'm gonna need lsd or posi. Open just isn't doing it. Also, if I can buy a carrier to swap the gears I have into, that isn't gonna cost much over all, I'm willing to do that because the gears I have are in fairly decent condition as I've just popped the diff cover off recently and peeked around in there. The lsd I'm looking at is a 99 off a trans am, if I'm not mistaken it the zexel Torsen unit but has 144k on it.
Sounds like you already have a couple modifications that would require a traction improvement, which would not be the case with a stock V6 car.
How high is the stall speed? If it's optimal for your setup, then the actual performance difference between 3.23 and 3.42 would be even less than with a stock stall speed (which is already just a marginal difference at best).
At 144k, the Torsen LSD could be fine or it could be very near its end. All depends on how those miles were accumulated. With a 3.23 ratio it would have been from an auto car, so perhaps less abused than an M6.
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Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
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From: Alabama
Originally Posted by RPM WS6
There are several important details here which you did not include in the original post.
Sounds like you already have a couple modifications that would require a traction improvement, which would not be the case with a stock V6 car.
How high is the stall speed? If it's optimal for your setup, then the actual performance difference between 3.23 and 3.42 would be even less than with a stock stall speed (which is already just a marginal difference at best).
At 144k, the Torsen LSD could be fine or it could be very near its end. All depends on how those miles were accumulated. With a 3.23 ratio it would have been from an auto car, so perhaps less abused than an M6.
Sounds like you already have a couple modifications that would require a traction improvement, which would not be the case with a stock V6 car.
How high is the stall speed? If it's optimal for your setup, then the actual performance difference between 3.23 and 3.42 would be even less than with a stock stall speed (which is already just a marginal difference at best).
At 144k, the Torsen LSD could be fine or it could be very near its end. All depends on how those miles were accumulated. With a 3.23 ratio it would have been from an auto car, so perhaps less abused than an M6.
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Verdad Gallardo Pre 1999 Auburns typically have a service life based upon when the clutch spiral cones wear out. There doesn't seem to be a 'service life with Torsens as they don't have clutches to wear out. They have a torque sensing gearset to direct the power flow. But they're have been catastrophic failures ( there are threads here on ls1tech) with Torsens in that the bolts holding the case together loosen and break and cause damage in the rear. Torsen became aware of the problem and the 3 series carrier as used in the F-platform is no longer available as a purchaseable part replaced by a heavy duty more expensive 3 series carrier.
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From: PDX-OR-USA
If its a Thorsen, its gear drive, so the internal bits should last about as long unless they were really abused,
its pretty easy to see the ends of the gears on the ones that fit GM axles. All your replacing really is the carrier,
I'd swap it, keep the older/deeper gears, reuse all the shims (Make sure you know where they go! as related
to the housing, I bet its dead on when it goes back together..
DONT get tricky with the lube, while you have it out, make sure you record the numbers off of it, then look up
the recommended lube on the thorsen page, they can be picky about the slip vs resistance to make the
gears cycle correctly. For instance I had one that did not work with full synthetic, It liked plain old gear lube.
Do not dismantle it,, if you want to clean it use a small brush and degreaser then rinse well with alcohol
and submerge in a bucket of lube, rotate the gears a few times to circulate the lube inside. Depending on the version it takes a
really special jig to reset the gears and align it if its dismantled.
Option: A Detroit true-track is cheaper than a thorsen, works the same way, are not priced too bad.
its pretty easy to see the ends of the gears on the ones that fit GM axles. All your replacing really is the carrier,
I'd swap it, keep the older/deeper gears, reuse all the shims (Make sure you know where they go! as related
to the housing, I bet its dead on when it goes back together..
DONT get tricky with the lube, while you have it out, make sure you record the numbers off of it, then look up
the recommended lube on the thorsen page, they can be picky about the slip vs resistance to make the
gears cycle correctly. For instance I had one that did not work with full synthetic, It liked plain old gear lube.
Do not dismantle it,, if you want to clean it use a small brush and degreaser then rinse well with alcohol
and submerge in a bucket of lube, rotate the gears a few times to circulate the lube inside. Depending on the version it takes a
really special jig to reset the gears and align it if its dismantled.
Option: A Detroit true-track is cheaper than a thorsen, works the same way, are not priced too bad.
Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
Likes: 1
From: Alabama
Originally Posted by pdxmotorhead
If its a Thorsen, its gear drive, so the internal bits should last about as long unless they were really abused,
its pretty easy to see the ends of the gears on the ones that fit GM axles. All your replacing really is the carrier,
I'd swap it, keep the older/deeper gears, reuse all the shims (Make sure you know where they go! as related
to the housing, I bet its dead on when it goes back together..
DONT get tricky with the lube, while you have it out, make sure you record the numbers off of it, then look up
the recommended lube on the thorsen page, they can be picky about the slip vs resistance to make the
gears cycle correctly. For instance I had one that did not work with full synthetic, It liked plain old gear lube.
Do not dismantle it,, if you want to clean it use a small brush and degreaser then rinse well with alcohol
and submerge in a bucket of lube, rotate the gears a few times to circulate the lube inside. Depending on the version it takes a
really special jig to reset the gears and align it if its dismantled.
Option: A Detroit true-track is cheaper than a thorsen, works the same way, are not priced too bad.
its pretty easy to see the ends of the gears on the ones that fit GM axles. All your replacing really is the carrier,
I'd swap it, keep the older/deeper gears, reuse all the shims (Make sure you know where they go! as related
to the housing, I bet its dead on when it goes back together..
DONT get tricky with the lube, while you have it out, make sure you record the numbers off of it, then look up
the recommended lube on the thorsen page, they can be picky about the slip vs resistance to make the
gears cycle correctly. For instance I had one that did not work with full synthetic, It liked plain old gear lube.
Do not dismantle it,, if you want to clean it use a small brush and degreaser then rinse well with alcohol
and submerge in a bucket of lube, rotate the gears a few times to circulate the lube inside. Depending on the version it takes a
really special jig to reset the gears and align it if its dismantled.
Option: A Detroit true-track is cheaper than a thorsen, works the same way, are not priced too bad.
Once a Torsen wears out, it's done. There is no rebuilding it. I autocross my car a lot - I've had an Auburn, which was pretty good and lasted ~5 years of racing before just wearing out an doing 1 wheel peel, and now I have an Eaton True Trac. Sam sells both and his recommendation is one or the other, he didnt have a big push one way or the other for me. Again, how you drive your car is the important aspect still unanswered - if you drag race, maybe a Detroit Locker is what you want but their engagement is pretty extreme. A True Trac will be good for street, twisties, and probably light drag passes(mabye?).
Thread Starter
On The Tree
Joined: Apr 2015
Posts: 145
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From: Alabama
Originally Posted by Chris Paveglio
Once a Torsen wears out, it's done. There is no rebuilding it. I autocross my car a lot - I've had an Auburn, which was pretty good and lasted ~5 years of racing before just wearing out an doing 1 wheel peel, and now I have an Eaton True Trac. Sam sells both and his recommendation is one or the other, he didnt have a big push one way or the other for me. Again, how you drive your car is the important aspect still unanswered - if you drag race, maybe a Detroit Locker is what you want but their engagement is pretty extreme. A True Trac will be good for street, twisties, and probably light drag passes(mabye?).
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
I see that the OP mentioned a turbo as future plans, so a bit less gear might actually be better (traction) and you could just swap to the complete 3.23 rear. Though, at that point you might want something stronger than the 7.5" rear depending on how much boost you're planning.
The factory recommendation for all OEM '99+ Torsen F-body rears is 75w90 synthetic with GM LSD additive. Many folks skip the additive (no friction modifier should really be needed for this style of LSD) without issue but, strictly speaking, the GM manual does call for it.
DONT get tricky with the lube, while you have it out, make sure you record the numbers off of it, then look up
the recommended lube on the thorsen page, they can be picky about the slip vs resistance to make the
gears cycle correctly. For instance I had one that did not work with full synthetic, It liked plain old gear lube.
the recommended lube on the thorsen page, they can be picky about the slip vs resistance to make the
gears cycle correctly. For instance I had one that did not work with full synthetic, It liked plain old gear lube.
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Joined: Oct 2016
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From: PDX-OR-USA
I just mentioned the lube because there are both factory and aftermarket versions, there are some
Racing Torsen diffs out there as well..
They used to sell them in several splits ,, but been a while.
I put about 80K on a Detroit/Eaton True Track ,, I had a housing let go and destroyed the whole assembly..
Was in a Jeep that was being used pretty hard crawling so no high rpm but a lot of High torque use..
Ironically,, the housing I broke was a D35 which is very close to the 7.25 GM housing in size..
In my Jeep, I use ARB lockers now, air activated switch from open diff to spool.
The E-locker is a little better if you need a bit more flexibility, its a limited slip posi
with a locking system so you get limited slip or spool..
I've wondered why nobody uses the select-able lockers on street strip cars,
spool function seems like it would be cool. And from the number of axles I've
seen broken off-road with a ARB in the diff,, they are very strong..
Racing Torsen diffs out there as well..
They used to sell them in several splits ,, but been a while.
I put about 80K on a Detroit/Eaton True Track ,, I had a housing let go and destroyed the whole assembly..
Was in a Jeep that was being used pretty hard crawling so no high rpm but a lot of High torque use..
Ironically,, the housing I broke was a D35 which is very close to the 7.25 GM housing in size..
In my Jeep, I use ARB lockers now, air activated switch from open diff to spool.
The E-locker is a little better if you need a bit more flexibility, its a limited slip posi
with a locking system so you get limited slip or spool..
I've wondered why nobody uses the select-able lockers on street strip cars,
spool function seems like it would be cool. And from the number of axles I've
seen broken off-road with a ARB in the diff,, they are very strong..