steady state understeer going into turns.

mike stevens

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among changing suspension parts, it was suggested that the ford limited slip has direct cause of this. Running a detroit locker would fix that phase of the problem. I understand the reasoning how that works. My question is, wouldn't a torsen t2r also work for that compaint? Would appreciate input on the differences.

Mike
 

white95

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I have a Detroit TrueTrack and a wealth of suspension mods. My personal car rarely understeers unless I majorly overcook my turn in point but it typically favors oversteer. It basically will go where you point it, even if that’s the through inside of a corner. Balancing throttle and steering inputs keeps it poised.

I have a friend who greatly prefers the T2R for autocross over the T2. I believe the T2R has a preloaded clutch pack and a greater bias ratio and reacts to torque much faster.

This may answer your question:


Today’s Ask Torsen question comes to us by email from James Stapleton. He asks:

(I) Have seen where you’ve stated that a T-2 might be better suited for open tracking than the T-2R. I do both open track and autocross currently on Michelin Pilot Super Sport tires, and maybe changing to a 200 treadwear type tire in the near future. Thoughts?
Well James, that’s a great question – and one we’ve been asked a lot over the years. However, it is highly dependent on a number of things: chassis set up, track conditions and degree of technicality, even driver preference, so there is no singular hard and fast answer. The basic essence of the answer, though, is that it’s a matter of what trade-off is best for the situation in question.

As a limited slip differential becomes more aggressive – with a greater degree of lockup (or torque bias ratio) – it has greater resistance to differentiation. This has two influences on the car in the context of what we’re talking about here. First, it affords better resistance to wheel spin, which of course means that the driver can apply more throttle and accelerate faster. Second, it has greater resistance to steer input, at least during turn-in and initial corner exit, because by resisting differentiation, it is also resisting the car’s need to rotate and change direction.

This initial understeer is somewhat mitigated, at corner exit, by resisting inside wheelspin. In so doing, more torque is allowed to go to the outside tire once the inside tire reaches its traction limit than would otherwise be the case. That, in turn, has the effect of generating an understeer-canceling yaw moment on the chassis, serving to actually drive out of the corner with greater authority. But you have to overcome initial understeer to get to that point. This effect is described in more detail elsewhere on this blog.

To boil that all down to the nuts and bolts of the matter, higher TBR can make the car “push” some in a corner, but allows a great deal of corner-exit traction. Lower TBR, on the other hand, can be more neutral-feeling, but potentially lack sufficient traction to prevent inside spin. So, as with any aspect of chassis set-up, it’s a trade-off. Cars with lower torque output (such as a Miata or BRZ) can be comfortable with a lower TBR because they favor nimble response and don’t have the torque to overwhelm the tires. Big-bore cars with big torque output may need the higher TBR of a T-2R model.

However, as noted above, venue plays into it as well. A track that is fast and flowing will probably favor the lower TBR of the standard Type-2. With less dynamic weight transfer in a corner, you don’t need to compromise handling balance based on corner-exit traction. The lower dynamic weight transfer means the inside tire doesn’t become unloaded and loose traction as readily. But a smaller, more technical course – especially in autocross – may force you into a more aggressive differential due to tight corners and high weight transfer. There is a much greater potential to lift an inside tire off the pavement. Frankly, the T-2R owes its existence to autocross. It was due to the complaints of wheelspin and Type-2 not being aggressive enough in that environment that we created the T-2R product line. But again, it comes down to what compromise makes most sense to you.

In your specific case, because you participate in both open track events and autocross, I would probably prefer using the T-2R. It is easier to make some chassis tweaks to compensate for a little extra initial understeer than it is to cope with insufficient traction at corner exit. At least, that would be the approach I would take. Best of luck!
 

MTRHDROB

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A good diff will help you put the power down coming out of the turn.
understeer is a problem with the front setup.
 

Gregomatic

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:cool:

My pleasure. I try to give informed answers based on personal experience and factual data or I’ll point ya in the right direction.
This could be a slight understatement, as I have found a wealth of information in your posts and links.
When I first joined, I spent an entire evening, seriously HOURS binge watching your youtube videos. Gained a whole different level of respect for you that night.
Besides enjoying seeing you progress and get better and faster, I have always been keen to pay close attention to what you have to offer.

And thanks for the torsen link, I just spent almost an hour perusing through that site, very eye opening.

I think we're pretty blessed you're eager to share what you know.

Your contribution to our collective knowledge is significant. It is appreciated buddy.
 

Gregomatic

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White, I've been back to that link to soak up some more knowledge about diff's.
The rear differential on my car is letting me know that replacement is becoming less of an option and more of a requirement.
Note: I believe the PO let it leak dry enough to damage it and just put more lube in instead of replacing it.

While I have a basic understanding of the open diff's function, I never grasped how the helical type LSD actually meshes the worm wheel/spur gear with the internal gearing.

Now that I have a better idea of what I want, now I can look into price vs. quality in which brands.
That's extremely helpful and I hope Mike shouts us back to acknowledge if he knows what he wants now too!

Thanks again bud!
G
 

mike stevens

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Thanks everybody for your inputs. First of all suspension changes are being made. But, I still see a problem with long decreasing radius turns. The stock limited slip has been pointed out that it is contributing to the problem. I had talked to Mike Meyer about it. He liked the detroit locker for that problem. After our conversation, I remembered about stories of abruptness in engagement, as you have mentioned. White95, that was a very nice reply addressing the problem.

I'm setting the car up for SCCA ITS class. 95 gt . class rules are a stock engine, less smog equip. free exhaust rules. SO not a lot of power.

What is the driving difference between a detroit locker and a truetrac? I'm concerned about the lockers abruptness.

would the t2 torsen handle driving out of a turn well with my stock engine?
 

white95

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This could be a slight understatement, as I have found a wealth of information in your posts and links.
When I first joined, I spent an entire evening, seriously HOURS binge watching your youtube videos. Gained a whole different level of respect for you that night.
Besides enjoying seeing you progress and get better and faster, I have always been keen to pay close attention to what you have to offer.

And thanks for the torsen link, I just spent almost an hour perusing through that site, very eye opening.

I think we're pretty blessed you're eager to share what you know.

Your contribution to our collective knowledge is significant. It is appreciated buddy.

Thank you sir. That’s what it’s all about.

White, I've been back to that link to soak up some more knowledge about diff's.
The rear differential on my car is letting me know that replacement is becoming less of an option and more of a requirement.
Note: I believe the PO let it leak dry enough to damage it and just put more lube in instead of replacing it.

While I have a basic understanding of the open diff's function, I never grasped how the helical type LSD actually meshes the worm wheel/spur gear with the internal gearing.

Now that I have a better idea of what I want, now I can look into price vs. quality in which brands.
That's extremely helpful and I hope Mike shouts us back to acknowledge if he knows what he wants now too!

Thanks again bud!
G

Thanks everybody for your inputs. First of all suspension changes are being made. But, I still see a problem with long decreasing radius turns. The stock limited slip has been pointed out that it is contributing to the problem. I had talked to Mike Meyer about it. He liked the detroit locker for that problem. After our conversation, I remembered about stories of abruptness in engagement, as you have mentioned. White95, that was a very nice reply addressing the problem.

I'm setting the car up for SCCA ITS class. 95 gt . class rules are a stock engine, less smog equip. free exhaust rules. SO not a lot of power.

What is the driving difference between a detroit locker and a truetrac? I'm concerned about the lockers abruptness.

would the t2 torsen handle driving out of a turn well with my stock engine?

The locker will absolutely be abrupt. My truetrac whines and clunks too.

Here are a few links to end users thoughts on both:



 

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