Drexler rear

[est8esq]

Here we are, in purgatory (between Christmas and New Years). Was hoping to have my new Drexler rear arrive and installed. Unfortunately, it won't be here in time for Winterfest, Sebring. So sad.

[Exhlr8n]

I'm supposed to have a new Drexler rearend in the spare parts that came with my Comp Coupe. I haven't checked it out yet. It is currently in a spare Gen 3 Batwing housing.

[est8esq]

Just ran Sebring with Suncoast PCA. Was supposed to run Friday (beautiful weather and day) and got stuck on Zoom call ALL DAY. So sad.


Ran one session Saturday morning before rain came in. I can NOT believe the difference this LSD made???? Literally, unbelievable. Anyone out there that has a Prefix package of any kind (heads and cam, 9.0 or 9.0 Extreme), you're wasting your your money and leaving all their enhancements on the table. It's physically impossible to put power down without this LSD.

I ordered mine back in October. Didn't arrive until last week. So, I'm not sure where they are with new orders, but I want to give a shout out to my tech, Steve (MGP Motorsports) who flew in to Sebring, from Ohio and installed it. He fabricated the flanges, altered this and that to make it all fit. Replaced seals that leaked (drove 2 hours north to Orlando to grab parts) and got me up and ready the day of...and my first run out I set my personal best, EVER at Sebring.

Literally, unbelievable.

[Whiskey]

How much are these Diffs? Ratio available?

How does it drive different than stock.

[Steve M]

How much are these Diffs? Ratio available?

How does it drive different than stock.

Price I saw was around $5,500...that was enough for me to bow out immediately.

[est8esq]

Price I saw was around $5,500...that was enough for me to bow out immediately.

I didn't disagree at first. But, after various upgrades and what I felt was solid horsepower/torque my limitation was a putting power down. It was just where this car was. I've repeatedly stated I'm not a tech and really marvel at all your mechanical savy on here, so I wasn't even sure what it was that could help til I spoke with my folks. I needed this LSD and Drexler was what was recommended.

I found a thread on here and ended up reaching out to Dana (Drexler's contact for U.S.). He was great at communication, but like I wrote earlier I'm still confused how one small, iddy-biddy part could take a company almost 5 months to fabricate and ship (COVID or no COVID)?? Regardless, this was the natural evolution for me and now it's all come together and feel the car is "balanced."

I received a quote (who's name I won't mention) for almost $8000 for the complete part. So, thanks to this forum I found Dana and my diff from him was around $4300. Only, you do need "flanges" that add about $1000? So, really you're looking out the door WELL UNDER the $8000 quote I first received (and that DIDN'T include the first quote's labor). There is apparently some modification work needed. It's not a simple plug and play. However, my tech "Steve" mentioned earlier did everything with absolutely no hassles nor issues and knew everything that needed to be done. (And he did it "in the field" as opposed to his shop, might I add).

As for performance difference, it does two things... under heavy brake as front load occurs it SIGNIFICANTLY reduces rear instability. From my understanding, whatever the diff does it must somehow keep both wheels in sync better than stock and allows BOTH wheels to keep their rotation/contact vs just one? Bottom line, as the car remains more stable, that stability carries as you release brakes and start your next turn.
Second, under acceleration and load the power transfer to the wheels is there. Before, I had to modulate and wait til I was able to go full throttle. Now, I can get on earlier without the rear wanting to step out.

Doing nothing different, it shaved 2 seconds at Sebring. Interestingly enough, I'm having to rethink turns and which gear to use since I'm able to carry more speed through turns and now I'm losing sleep whether to stay in 2 or go to 3, with 3rd being about 1000 rpm too low and out of the power band. Just can't win, lol.

[StrokerAce]

Price I saw was around $5,500...that was enough for me to bow out immediately.

Dang! Makes my Dana S60 for the SS seem like a downright cheapo......

[Whiskey]

I didn't disagree at first. But, after various upgrades and what I felt was solid horsepower/torque my limitation was a putting power down. It was just where this car was. I've repeatedly stated I'm not a tech and really marvel at all your mechanical savy on here, so I wasn't even sure what it was that could help til I spoke with my folks. I needed this LSD and Drexler was what was recommended.

I found a thread on here and ended up reaching out to Dana (Drexler's contact for U.S.). He was great at communication, but like I wrote earlier I'm still confused how one small, iddy-biddy part could take a company almost 5 months to fabricate and ship (COVID or no COVID)?? Regardless, this was the natural evolution for me and now it's all come together and feel the car is "balanced."

I received a quote (who's name I won't mention) for almost $8000 for the complete part. So, thanks to this forum I found Dana and my diff from him was around $4300. Only, you do need "flanges" that add about $1000? So, really you're looking out the door WELL UNDER the $8000 quote I first received (and that DIDN'T include the first quote's labor). There is apparently some modification work needed. It's not a simple plug and play. However, my tech "Steve" mentioned earlier did everything with absolutely no hassles nor issues and knew everything that needed to be done. (And he did it "in the field" as opposed to his shop, might I add).

As for performance difference, it does two things... under heavy brake as front load occurs it SIGNIFICANTLY reduces rear instability. From my understanding, whatever the diff does it must somehow keep both wheels in sync better than stock and allows BOTH wheels to keep their rotation/contact vs just one? Bottom line, as the car remains more stable, that stability carries as you release brakes and start your next turn.
Second, under acceleration and load the power transfer to the wheels is there. Before, I had to modulate and wait til I was able to go full throttle. Now, I can get on earlier without the rear wanting to step out.

Doing nothing different, it shaved 2 seconds at Sebring. Interestingly enough, I'm having to rethink turns and which gear to use since I'm able to carry more speed through turns and now I'm losing sleep whether to stay in 2 or go to 3, with 3rd being about 1000 rpm too low and out of the power band. Just can't win, lol.

That's all good things! Sometimes more power isn't the answer. If you could please share with me via PM the contact as this will be on my list of future mods.

[Steve M]

I didn't disagree at first. But, after various upgrades and what I felt was solid horsepower/torque my limitation was a putting power down. It was just where this car was. I've repeatedly stated I'm not a tech and really marvel at all your mechanical savy on here, so I wasn't even sure what it was that could help til I spoke with my folks. I needed this LSD and Drexler was what was recommended.

I found a thread on here and ended up reaching out to Dana (Drexler's contact for U.S.). He was great at communication, but like I wrote earlier I'm still confused how one small, iddy-biddy part could take a company almost 5 months to fabricate and ship (COVID or no COVID)?? Regardless, this was the natural evolution for me and now it's all come together and feel the car is "balanced."

I received a quote (who's name I won't mention) for almost $8000 for the complete part. So, thanks to this forum I found Dana and my diff from him was around $4300. Only, you do need "flanges" that add about $1000? So, really you're looking out the door WELL UNDER the $8000 quote I first received (and that DIDN'T include the first quote's labor). There is apparently some modification work needed. It's not a simple plug and play. However, my tech "Steve" mentioned earlier did everything with absolutely no hassles nor issues and knew everything that needed to be done. (And he did it "in the field" as opposed to his shop, might I add).

As for performance difference, it does two things... under heavy brake as front load occurs it SIGNIFICANTLY reduces rear instability. From my understanding, whatever the diff does it must somehow keep both wheels in sync better than stock and allows BOTH wheels to keep their rotation/contact vs just one? Bottom line, as the car remains more stable, that stability carries as you release brakes and start your next turn.
Second, under acceleration and load the power transfer to the wheels is there. Before, I had to modulate and wait til I was able to go full throttle. Now, I can get on earlier without the rear wanting to step out.

Doing nothing different, it shaved 2 seconds at Sebring. Interestingly enough, I'm having to rethink turns and which gear to use since I'm able to carry more speed through turns and now I'm losing sleep whether to stay in 2 or go to 3, with 3rd being about 1000 rpm too low and out of the power band. Just can't win, lol.

Good info...I had never even heard of Drexler until I saw the name pop up on the forum sometime late last year. That's awesome that it made that much of a difference for you.

For the axles: I'm assuming you are running the stock Gen 5 axles?

When I swapped a Gen 5 differential in my Gen 4 a few years ago, I had to swap out the stubs. The Gen 5 differential stubs use a flange to which you bolt the axles. My Gen 4 uses splined stubs that only accept splined axles. Bottom line: I couldn't use my Gen 4 axles with a Gen 5 differential until I pulled the stubs from the Gen 5 differential and replaced them with the Gen 4 stubs. The other option would have been to swap my Gen 4 axles for the Gen 5 units. The Gen 4 stubs were the substantially cheaper option.

From what you describe, it sounds like the Drexler differential stub axles might be able to be used with the Gen 3/4 style axles; the issue is that a good set of those style axles are ~$1,700, which is substantially more than what you paid to have the stubs modified to work for your application. If that's accurate, it might make the Drexler a bit more feasible for the Gen 3/4 crowd.

[Jack B]

Steve

I thought G4 was CV joints

Good info...I had never even heard of Drexler until I saw the name pop up on the forum sometime late last year. That's awesome that it made that much of a difference for you.

For the axles: I'm assuming you are running the stock Gen 5 axles?

When I swapped a Gen 5 differential in my Gen 4 a few years ago, I had to swap out the stubs. The Gen 5 differential stubs use a flange to which you bolt the axles. My Gen 4 uses splined stubs that only accept splined axles. Bottom line: I couldn't use my Gen 4 axles with a Gen 5 differential until I pulled the stubs from the Gen 5 differential and replaced them with the Gen 4 stubs. The other option would have been to swap my Gen 4 axles for the Gen 5 units. The Gen 4 stubs were the substantially cheaper option.

From what you describe, it sounds like the Drexler differential stub axles might be able to be used with the Gen 3/4 style axles; the issue is that a good set of those style axles are ~$1,700, which is substantially more than what you paid to have the stubs modified to work for your application. If that's accurate, it might make the Drexler a bit more feasible for the Gen 3/4 crowd.

[Steve M]

Steve

I thought G4 was CV joints

Yes, the Gen 3 and 4 axles both use CV joints.

For clarity, I'm going to define what I mean when I use different terms involving the differential/rear drivetrain.

This is what I consider a differential assembly (includes the housing, ring & pinion, differential/carrier, "batwing" cover, stub axles, seals, bearings, yoke, etc.):



More specifically, that is a 2013-2017 Gen 5 Viper Dana Super 44/Dana 44HD/Dana 226 differential assembly. That basic assembly pictured will fit any Gen 3/4/5 (2003-2017) Viper, provided you use the correct stub axles.

This is what I consider a differential (some call them differential carriers, or just carriers):



That is the GKN Visco Lok, which was the OEM differential in all Gen 4 and 5 (2008-2017) Vipers.

These are the most popular aftermarket differential options, including Drexler which is the topic of this thread:



This is what I consider an axle:



Those are Gen 3 (2003-2006) and Gen 4 (2008-2010) axles. As you can see, they both have constant velocity (CV) joints. It should be noted that some Gen 4 cars came from the factory with Gen 3 axles (like mine). The part numbers are different (Gen 3 = P05038200AA; Gen 4 = P05038200AB); you can easily tell them apart by looking for the "double hump" center shaft. The Gen 4 axles are supposedly stronger between the two.

These are Gen 5 axles:



They appear to use the same "double hump" center shaft as the Gen 4 axles, but they attach to the differential assembly differently.

Neither are to be confused with the Gen 1/2 half shafts:



These are stub axles (they slide into the differential housing, mating with the internal splines in the differential):



Specifically, Gen 5 (2013-2017) stub axles.

As you can hopefully see from the pictures above, the Gen 5 axles bolt to the stub axles instead of using splines:



And this is a Gen 3/4 stub axle:



It should be noted that Gen 3 and Gen 4 stub axles are not the same. The part that is outside of the differential is the same, but the part that goes in to the differential is not.

Backwards compatibility goes something like this:

Axles:

• Gen 3 and Gen 4 axles are interchangeable
• Gen 3 and Gen 4 axles can be used with either Gen 3 or Gen 4 stub axles
• Gen 5 axles can only be used with Gen 5 stub axles

Stub Axles:

• Gen 3 stub axles can not be used with the Gen 4/5 GKN Visco Lok differential due to the location of the internal retention ring grooves
• Gen 4 stub axles can be used in a Gen 5, but you would have to use Gen 3/4 style axles
• Gen 5 stub axles can be used in a Gen 4, but you have to use the Gen 5 axles
• Note: some aftermarket differentials are not compatible with the OEM stub axles, and will come with their own stubs

Differentials:

• Gen 3 (2003-2006) = Hydra-Lok (w/ 3.07 ring and pinion)
• Gen 4 (2008-2010) = GKN Visco-Lok (w/ 3.07 ring and pinion)
• Gen 5 (2013-2017) = GKN Visco-Lok (w/ 3.55 ring and pinion)

[GTS Dean]

^best post ever.^

[est8esq]

^best post ever.^

HOLY COW, "Steve M", you are AMAZING??!!!! Dang, brother. You and Ralph Gilles need to get together and craft the next gen Viper, lol?! Great gouge. Was amazing to read and learn. Thank you.

[Arizona Vipers]

Ummmm, this is an amazing post!
What does the Drexler do, exactly?

[Steve M]

Ummmm, this is a good post? LOL.
What does the Drexler do, exactly?

How exactly is a rainbow made? How exactly does a sun set? How exactly does a posi-trac rear-end on a Plymouth work? It just does.

Here are some very rudimentary basics:

• A differential allows the inner and outer drive wheels/tires to rotate at different speeds
• That functionality is only needed when you go around a turn, because the outer tire has to cover more ground than the inner tire
• If one tire loses traction, which is typically the inside tire due to weight transfer, an open differential (what most cars on the road have) will send all of the power to that corner, causing that tire to spin (the ol' one wheel peel)
• Spinning ain't winning

But Vipers don't have open differentials - the OEM GKN Visco Lok (stock on Gen 4 and 5 Vipers) is a clutch-type limited slip differential. You can read about how it works here (https://www.resyl.net/atvfiles/ViscoLok-engl.pdf).

You can tune a limited slip differential to either increase or decrease the amount of slippage allowed, but there's a trade-off:

• More slippage allowed = better performance in tight turns - think trying to park your car in a small parking lot
• Less slippage allowed = better power distribution to the driven tires, which should give you better traction overall (i.e. you can put the power down sooner coming out of a turn)

Car manufacturers want grandma to be able to park her Corvette at Wal-Mart without making a bunch of chattering/groaning/tire chirping sounds, which is what you would get with a limited slip differential that's too tight. Since cars have to work well everywhere, manufacturers are going to err on the side of a differential that allows a little more slippage, knowing that it will be at the expense of the one guy out there railing on his car at COTA where it is highly likely he'll spend at least some time with only one of the two drive wheels in contact with the pavement. The more slippage allowed, the more likely the differential is to unload its power to the tire without traction. See above (spinning ain't winning).

I don't know exactly how the Drexler works, but I'm pretty sure it is also a clutch-type limited slip differential. My guess is that it is set up on the tighter side, which should help you get power to the ground more evenly when you are going 10/10ths at the track. That aligns with this comment:

...under acceleration and load the power transfer to the wheels is there. Before, I had to modulate and wait til I was able to go full throttle. Now, I can get on earlier without the rear wanting to step out.

Everything has drawbacks, so I'm guessing that this differential might have some undesirable daily driving characteristics, specifically binding in tight turns. That would be of minimal concern for a race car though, and last time I checked, yours certainly qualifies.

My $0.02, until someone that actually knows what they are talking about decides to chime in.

[docwviper]

How exactly is a rainbow made? How exactly does a sun set? How exactly does a posi-trac rear-end on a Plymouth work? It just does.

Here are some very rudimentary basics:

• A differential allows the inner and outer drive wheels/tires to rotate at different speeds
• That functionality is only needed when you go around a turn, because the outer tire has to cover more ground than the inner tire
• If one tire loses traction, which is typically the inside tire due to weight transfer, an open differential (what most cars on the road have) will send all of the power to that corner, causing that tire to spin (the ol' one wheel peel)
• Spinning ain't winning

But Vipers don't have open differentials - the OEM GKN Visco Lok (stock on Gen 4 and 5 Vipers) is a clutch-type limited slip differential. You can read about how it works here (https://www.resyl.net/atvfiles/ViscoLok-engl.pdf).

You can tune a limited slip differential to either increase or decrease the amount of slippage allowed, but there's a trade-off:

• More slippage allowed = better performance in tight turns - think trying to park your car in a small parking lot
• Less slippage allowed = better power distribution to the driven tires, which should give you better traction overall (i.e. you can put the power down sooner coming out of a turn)

Car manufacturers want grandma to be able to park her Corvette at Wal-Mart without making a bunch of chattering/groaning/tire chirping sounds, which is what you would get with a limited slip differential that's too tight. Since cars have to work well everywhere, manufacturers are going to err on the side of a differential that allows a little more slippage, knowing that it will be at the expense of the one guy out there railing on his car at COTA where it is highly likely he'll spend at least some time with only one of the two drive wheels in contact with the pavement. The more slippage allowed, the more likely the differential is to unload its power to the tire without traction. See above (spinning ain't winning).

I don't know exactly how the Drexler works, but I'm pretty sure it is also a clutch-type limited slip differential. My guess is that it is set up on the tighter side, which should help you get power to the ground more evenly when you are going 10/10ths at the track. That aligns with this comment:



Everything has drawbacks, so I'm guessing that this differential might have some undesirable daily driving characteristics, specifically binding in tight turns. That would be of minimal concern for a race car though, and last time I checked, yours certainly qualifies.

My $0.02, until someone that actually knows what they are talking about decides to chime in.

quaife is a mechanical with no clutch packs from my understanding. The Quaife is a beast on the track on a VCC with gen 3 diff.

[Steve M]

quaife is a mechanical with no clutch packs from my understanding. The Quaife is a beast on the track on a VCC with gen 3 diff.

That is also my understanding.

The differentials I've listed above fall into basic two categories:

1. Limited slip (a.k.a. plated/clutch-type/posi-trac)
2. Torque biasing (a.k.a. Torsen/geared/helical)

Limited slip/clutch-type examples: GKN Visco Lok, OS Giken, Drexler

Torque biasing/geared examples: Wavetrac, Quaife

Both designs require compromises, so there isn't one that's going to necessarily be better than the others. It all depends on your application.

Clutch-type limited slip differentials (GKN Visco Lok, OS Giken, Drexler) can be tailored to suit the user's needs; you can vary the clutch material/friction plates, the number of friction plates, the amount of preload, etc. The downsides are that they are usually more expensive, can make more noise, and usually require a differential fluid with a friction modifier to allow the friction plates to work as intended. You will also likely end up needing to rebuild at some point, but that is an option.

Torque biasing/geared differentials (Wavetrac, Quaife) can not be tailored to suit the user's needs; once you settle on the worm/helical gear design, that's it. The upside is that they are generally lower maintenance, lower cost, and lower noise on the street. The downside is that both tires must be in contact with the pavement for it to work; otherwise, it will unload just like an open diff, leading to something that looks like this:



If your driving style is such that one tire may lift in a corner (like hitting the curbing hard), the clutch-type limited slip differential would probably be the better option.

What I've written is overly simplified, but I think it hits the high points.

[docwviper]

That is also my understanding.

The differentials I've listed above fall into basic two categories:

1. Limited slip (a.k.a. plated/clutch-type/posi-trac)
2. Torque biasing (a.k.a. Torsen/geared/helical)

Limited slip/clutch-type examples: GKN Visco Lok, OS Giken, Drexler

Torque biasing/geared examples: Wavetrac, Quaife

Both designs require compromises, so there isn't one that's going to necessarily be better than the others. It all depends on your application.

Clutch-type limited slip differentials (GKN Visco Lok, OS Giken, Drexler) can be tailored to suit the user's needs; you can vary the clutch material/friction plates, the number of friction plates, the amount of preload, etc. The downsides are that they are usually more expensive, can make more noise, and usually require a differential fluid with a friction modifier to allow the friction plates to work as intended. You will also likely end up needing to rebuild at some point, but that is an option.

Torque biasing/geared differentials (Wavetrac, Quaife) can not be tailored to suit the user's needs; once you settle on the worm/helical gear design, that's it. The upside is that they are generally lower maintenance, lower cost, and lower noise on the street. The downside is that both tires must be in contact with the pavement for it to work; otherwise, it will unload just like an open diff, leading to something that looks like this:



If your driving style is such that one tire may lift in a corner (like hitting the curbing hard), the clutch-type limited slip differential would probably be the better option.

What I've written is overly simplified, but I think it hits the high points.

Interesting. I push pretty hard at the track and go over curbing and never had this issue happen to me. Maybe i've been lucky. Now you will make me more paranoid

[Steve M]

Interesting. I push pretty hard at the track and go over curbing and never had this issue happen to me. Maybe i've been lucky. Now you will make me more paranoid

If it did happen, it would be very brief, especially at speed.

If I had unlimited cash, I'd love to be able to try each one of these. The reality of the situation is that any of these differential options are expensive, especially when you consider the labor required to install, which means someone is going to pick what they think might work best and likely live with it for a long time.

Seems like a good case for "if it ain't broke, don't fix it".

Similarly, "better is the enemy of good enough".

[Arizona Vipers]

How exactly is a rainbow made? How exactly does a sun set? How exactly does a posi-trac rear-end on a Plymouth work? It just does.

Here are some very rudimentary basics:

• A differential allows the inner and outer drive wheels/tires to rotate at different speeds
• That functionality is only needed when you go around a turn, because the outer tire has to cover more ground than the inner tire
• If one tire loses traction, which is typically the inside tire due to weight transfer, an open differential (what most cars on the road have) will send all of the power to that corner, causing that tire to spin (the ol' one wheel peel)
• Spinning ain't winning

But Vipers don't have open differentials - the OEM GKN Visco Lok (stock on Gen 4 and 5 Vipers) is a clutch-type limited slip differential. You can read about how it works here (https://www.resyl.net/atvfiles/ViscoLok-engl.pdf).

You can tune a limited slip differential to either increase or decrease the amount of slippage allowed, but there's a trade-off:

• More slippage allowed = better performance in tight turns - think trying to park your car in a small parking lot
• Less slippage allowed = better power distribution to the driven tires, which should give you better traction overall (i.e. you can put the power down sooner coming out of a turn)

Car manufacturers want grandma to be able to park her Corvette at Wal-Mart without making a bunch of chattering/groaning/tire chirping sounds, which is what you would get with a limited slip differential that's too tight. Since cars have to work well everywhere, manufacturers are going to err on the side of a differential that allows a little more slippage, knowing that it will be at the expense of the one guy out there railing on his car at COTA where it is highly likely he'll spend at least some time with only one of the two drive wheels in contact with the pavement. The more slippage allowed, the more likely the differential is to unload its power to the tire without traction. See above (spinning ain't winning).

I don't know exactly how the Drexler works, but I'm pretty sure it is also a clutch-type limited slip differential. My guess is that it is set up on the tighter side, which should help you get power to the ground more evenly when you are going 10/10ths at the track. That aligns with this comment:



Everything has drawbacks, so I'm guessing that this differential might have some undesirable daily driving characteristics, specifically binding in tight turns. That would be of minimal concern for a race car though, and last time I checked, yours certainly qualifies.

My $0.02, until someone that actually knows what they are talking about decides to chime in.

Ok, I want!!!!

[Nth Moto]

We use the Wavetrac in almost all of our builds, although we do have a Drexler here as well. It's a really pretty piece - we'll see how it functions compared to what we're used to. The tuneability is nice with clutch style diffs, but most every day users don't get into that really. For the hardcore track guy, sure thing, so long as the data/input info from the driver is valid to make adjustments off of.

[J TNT]

We use the Wavetrac in almost all of our builds, although we do have a Drexler here as well. It's a really pretty piece - we'll see how it functions compared to what we're used to. The tuneability is nice with clutch style diffs, but most every day users don't get into that really. For the hardcore track guy, sure thing, so long as the data/input info from the driver is valid to make adjustments off of.

Thanks for the heads up , and glad I went with WaveTrac !

[mjorgensen]

I had the stock diff, the Quaife and then the Giken in my old 08' the thing I liked most about the Giken (likely similar to the Drexler) is that mid corner it provides consistent and most of all predictable grip even if you are bouncing off the curbs a little. The power given, especially to the outside tire does not vary, other diffs search for optimal split in that moment. (think how the car reacts mid corner to on off throttle suddenly) this for sure makes you faster everywhere.

[Arizona Vipers]

I didn't disagree at first. But, after various upgrades and what I felt was solid horsepower/torque my limitation was a putting power down. It was just where this car was. I've repeatedly stated I'm not a tech and really marvel at all your mechanical savy on here, so I wasn't even sure what it was that could help til I spoke with my folks. I needed this LSD and Drexler was what was recommended.

I found a thread on here and ended up reaching out to Dana (Drexler's contact for U.S.). He was great at communication, but like I wrote earlier I'm still confused how one small, iddy-biddy part could take a company almost 5 months to fabricate and ship (COVID or no COVID)?? Regardless, this was the natural evolution for me and now it's all come together and feel the car is "balanced."

I received a quote (who's name I won't mention) for almost $8000 for the complete part. So, thanks to this forum I found Dana and my diff from him was around $4300. Only, you do need "flanges" that add about $1000? So, really you're looking out the door WELL UNDER the $8000 quote I first received (and that DIDN'T include the first quote's labor). There is apparently some modification work needed. It's not a simple plug and play. However, my tech "Steve" mentioned earlier did everything with absolutely no hassles nor issues and knew everything that needed to be done. (And he did it "in the field" as opposed to his shop, might I add).

As for performance difference, it does two things... under heavy brake as front load occurs it SIGNIFICANTLY reduces rear instability. From my understanding, whatever the diff does it must somehow keep both wheels in sync better than stock and allows BOTH wheels to keep their rotation/contact vs just one? Bottom line, as the car remains more stable, that stability carries as you release brakes and start your next turn.
Second, under acceleration and load the power transfer to the wheels is there. Before, I had to modulate and wait til I was able to go full throttle. Now, I can get on earlier without the rear wanting to step out.

Doing nothing different, it shaved 2 seconds at Sebring. Interestingly enough, I'm having to rethink turns and which gear to use since I'm able to carry more speed through turns and now I'm losing sleep whether to stay in 2 or go to 3, with 3rd being about 1000 rpm too low and out of the power band. Just can't win, lol.

What was your time at Sebring???

[Arizona Vipers]

Hey what fluid are you running in the Drexler? They recommend Ravenol. Did you use that? Or the factory Castrol Syntrax?