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Torsen differential for 700+ torque

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#1
Hello everyone,

What do you think the most likely weak links will be for the ST between 700 and 800 lb feet of torque? Does using the Torsen differential as a preventative measure for high torque (700+) make sense or are there still too many unknowns for this to be a rational decision? Is it correct to assume that the Torsen differential will hold significantly more torque than the open differential for road racing (no launches)?

The Torsen differential from the timerbline seems to be working well for several ST's but not flawlessly. Some ST owners, who made the swap, stated that they had increased tire noise during turns which makes it seem that the AWD system is making the transfer case go into a 4H setting for some reason. The Torsen diff seems like it would be able to handle much more power than the open diff, but no one has tested it on a high performance ST yet. One member mentioned that the Torsen diff would be great for road racing, but bad for launches.

Kathy, the current 1/4 mile record holder for the ST, is still tuned for 690 lb ft of torque on the street and that's likely not going to change soon since a driveshaft failure just occurred with HSF's ST, which is running significantly less torque. Once a custom driveshaft is on the market, we'll likely see higher torque numbers.

Attached is the last dyno pull from the ST. For now, no launches are planned for at least a year after it's built, but I was hoping to keep it out of the shop for as long as possible once finished.
 

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#2
Correct, the Torsen rear diff is for road racing, not drag strip use. The Torsten rear differential may in fact be weaker for our purposes. Torsens tend to not like being launched.

Also, what do you mean by “causing the transfer case to go into 4h setting.”
 

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bbbart
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Thread Starter #3
Correct, the Torsen rear diff is for road racing, not drag strip use. The Torsten rear differential may in fact be weaker for our purposes. Torsens tend to not like being launched.

Also, what do you mean by “causing the transfer case to go into 4h setting.”
Dirty Dan (That Racing Cop on YouTube) mentioned that his transfer case began to malfunction after the torsen differential swap. However, after taking it to the dealer, they determined that the differential was fine but the transfer case was shot.

He was experiencing tire noise during turning, which he figured was caused by the AWD system engaging all four tires equally. However, he also mentioned clicking/popping/grinding noises during turns as well so it could be an installation issue.

I'm hoping it was a defect or improper installation. Hard to say what went wrong exactly but it seems like there is a good chance the Torsen diff will work without any issues if setup properly. Seems like there are a lot of quirks with the swap, similar to the 10R80 swaps, possibly needs to be configured in the ECU to run properly...
 

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#4
Dirty Dan (That Racing Cop on YouTube) mentioned that his transfer case began to malfunction after the torsen differential swap. However, after taking it to the dealer, they determined that the differential was fine but the transfer case was shot.

He was experiencing tire noise during turning, which he figured was caused by the AWD system engaging all four tires equally. However, he also mentioned clicking/popping/grinding noises during turns as well so it could be an installation issue.

I'm hoping it was a defect or improper installation. Hard to say what went wrong exactly but it seems like there is a good chance the Torsen diff will work without any issues if setup properly. Seems like there are a lot of quirks with the swap, similar to the 10R80 swaps, possibly needs to be configured in the ECU to run properly...
Most likely had nothing to do with the Torsen. It’s a direct swap, no quirks or anything, and there is nothing that you could do programming wise.
 

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bbbart
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Thread Starter #5
Most likely had nothing to do with the Torsen. It’s a direct swap, no quirks or anything, and there is nothing that you could do programming wise.
Would an open diff failure cause serious damage to the axles, driveshaft, or transfer case?

Since it is a fully mechanical part that is also a direct swap, seems like a good idea. Might be good to swap it when the open diff eventually fails though. I believe I should treat every part of the drivetrain as a "wear" item that will eventually need to be replaced. If an open diff failure would cause serious damage to other parts, then it seems like it would make sense to swap it preemptively.
 



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