Posted By: Anonymous
Post deleted by moparts
Posted By: autoxcuda
Re: Sure Grips and Cornering - 04/01/12 09:22 AM
Given a choice most autox guys seem to like the Torsen (Tru-Track) limited slip. There's a factor of availability, price, and personal preference involved.
I have seen a 68 Mustang that used a Detroit Locker in autocross. But I don't know if he can't use a Torsen due to rules or if it's a choice. He's the original owner and he's been running a Locker before they had Torsen's for a 9". So he's got years of fine tuning his setup with the Locker. He did say you have to get used to it.
Because of the tight turns on a autocross, some people have problems burning up clutch type limited slips.
We run a Detroit Locker on our Circle Track cars. The drivers do have to drive them different than running a spool. The drivers have to get off the gas differently coming into the turn to unlock it. Many times there are rules to keep the cost down for racers that don't allow Torsens or Lockers. So running a certain type might be a rules thing more than a choice thing.
Torsen's are the most expensive of the three types.
I have seen a 68 Mustang that used a Detroit Locker in autocross. But I don't know if he can't use a Torsen due to rules or if it's a choice. He's the original owner and he's been running a Locker before they had Torsen's for a 9". So he's got years of fine tuning his setup with the Locker. He did say you have to get used to it.
Because of the tight turns on a autocross, some people have problems burning up clutch type limited slips.
We run a Detroit Locker on our Circle Track cars. The drivers do have to drive them different than running a spool. The drivers have to get off the gas differently coming into the turn to unlock it. Many times there are rules to keep the cost down for racers that don't allow Torsens or Lockers. So running a certain type might be a rules thing more than a choice thing.
Torsen's are the most expensive of the three types.
Posted By: David_in_St_Croi
Re: Sure Grips and Cornering - 04/01/12 01:33 PM
We have a tru-track in our 70 Road Runner with a Strange 60 rear. It used to have an 8-3/4 with a sure grip. The difference in how it drives is noticeable. There are some curves here that are sharp uphill steep curves. The sure-grip I could feel the inside wheel slipping and chirping on the turns (it was set up pretty tight for the drag strip). With the Tru-track it goes up the same curves like an open differential. At the drags trip it also locks up so an excellent device. The cornering question was a primary reason why we went with the tru-track over the Detroit Locker, as we use our car regularly on the street which includes our dirt road which can be slippery in the rain.
At the time we got the axle assembly from Dr. Diff the Detroit Locker was slightly more expensive (maybe $20-50, minor compared to the whole axle assembly, it was not the deciding factor by any means)than the Tru-track. Maybe that has changed? If you have the money and rules allow I would choose the tru-track. I think the tru-track is available for the 8-3/4.
At the time we got the axle assembly from Dr. Diff the Detroit Locker was slightly more expensive (maybe $20-50, minor compared to the whole axle assembly, it was not the deciding factor by any means)than the Tru-track. Maybe that has changed? If you have the money and rules allow I would choose the tru-track. I think the tru-track is available for the 8-3/4.
Posted By: Mattax
Re: Sure Grips and Cornering - 04/02/12 03:28 AM
Agee that the tru-trac seems to be the ideal. My understanding was that the version we're talking about may not be available for the 8.75, and there are also some assembly issues that come along with it.
I too found the tighter a limited slip is set makes it harder to drive (oversteer). The nice thing about the clutch (Dana) type sure-grip is you can replace the clutches and change how tight it is set. Mine was set tighter than I like but its not high on the todo list. Only chirps on tight corners on the street, not autocrossing. But, autocrossing and snow is where it's harder to keep the back from sliding than before It replaced a cone-type sure grip that I bought used and got roughly 70,000 miles out of it (and a lot of autocrosses).
I too found the tighter a limited slip is set makes it harder to drive (oversteer). The nice thing about the clutch (Dana) type sure-grip is you can replace the clutches and change how tight it is set. Mine was set tighter than I like but its not high on the todo list. Only chirps on tight corners on the street, not autocrossing. But, autocrossing and snow is where it's harder to keep the back from sliding than before It replaced a cone-type sure grip that I bought used and got roughly 70,000 miles out of it (and a lot of autocrosses).
Posted By: Anonymous
Post deleted by moparts - 04/02/12 09:13 AM
Posted By: autoxcuda
Re: Sure Grips and Cornering - 04/02/12 12:20 PM
Torsen diff are all gears inside. "Torsen" is for TORque SENsing. The design of the gears, gear arrangement, gear type determine the how it distributes the torque.
They are sort of complex in details. Read directly here: http://www.torsen.com/products/products.htm or find some other manufactures literature for a first hand expanation in plain english.
There are no clutches or cones that slips against something. Nor is it a ratcheting type like a Detroit Locker. Supposedly Torsens don't wear out.
They are sort of complex in details. Read directly here: http://www.torsen.com/products/products.htm or find some other manufactures literature for a first hand expanation in plain english.
There are no clutches or cones that slips against something. Nor is it a ratcheting type like a Detroit Locker. Supposedly Torsens don't wear out.
Posted By: 70Cuda383
Re: Sure Grips and Cornering - 04/02/12 01:13 PM
Quote:
Can someone explain the functionality of the "Torsen" type differential? I'd like to understand it better.
how does it work? it just does!
now, HOW does it work, or how does it drive?
with no load on the tires, it acts like an open diff.
in fact, I was scared when I first put one in, because when the truck was up in the air, I spun a wheel and noticed the opposite wheel spun backwards. I thought "oh crap, something is wrong with it...limited slips aren't supposed to do that!"
Turns out it's normal.
basically the torsen type can tell when both tires have good traction, and it locks up to deliver equal torque to both wheels. once the gears "slide into place" or whatever happens, it locks up and nothing slips, it becomes like a spool, zero slip! when torque is neutral the gears retract back into position, and it acts like an open diff.
on wet roads, where traction is limited or non-existent, mine acted like an open diff, and would not send the back end out sideways around corners, yet I could feel one wheel spinning.
Posted By: David_in_St_Croi
Re: Sure Grips and Cornering - 04/03/12 12:29 AM
Quote:
Agee that the tru-trac seems to be the ideal. My understanding was that the version we're talking about may not be available for the 8.75, and there are also some assembly issues that come along with it.
I was curious so looked it up and it appears that Detroit does list a true-trac for the 8-3/4. No idea on the assembly issues one way or the other.
http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_128302.pdf
Best, Dave
Posted By: 5spdcuda
Re: Sure Grips and Cornering - 04/03/12 01:36 AM
Torsen type diffs have been around for some time, but it's just been fairly recently that they have been available in the aftermarket for the typical hot rodder rear ends. The only downside I can see to them would be that if used on a long distance road course all those gears are bound to generate quite a bit of heat. Nothing that a good cooler shouldn't be able handle. As for the older sure grips, the plate types can be set up with varying degrees of torque transfer [ tighter or looser ]. A tight one obviously is better at keeping both tires pushing. This is really good when you're going straight or nearly so. Not so good if you get too eager with the throttle since it can actually induce corner exit understeer. The oversteer has already been noted. If you can avoid the oversteer but still use too much throttle exiting the corner you can cause the front of the car to "push" off the edge of the corner. Many a novice short dirt track racer has discovered this the hard way when they shoved the front of their car into the wall. A tight diff can also cause some degree of corner entry understeer. Torsens should be free of this problem.
As for NASCAR and oval racers in general, tire stagger is frequently used to get the car to turn left. In order for tire stagger to work you have to have a locked rear end. If the amount of stagger is too great it will affect straight line speed and handling since you're dragging the inside rear down the straights.
As for NASCAR and oval racers in general, tire stagger is frequently used to get the car to turn left. In order for tire stagger to work you have to have a locked rear end. If the amount of stagger is too great it will affect straight line speed and handling since you're dragging the inside rear down the straights.
Posted By: Moneypit6
Re: Sure Grips and Cornering - 04/03/12 02:00 AM
I believe the Torsen was originally called the Dual Drive many years ago. It's principal is that a worm gear can turn a worm wheel but a worm wheel cannot turn a worm gear.
Basically, it works by allowing one of the wheels to turn faster as long as it's an external force that's doing the driving, like the outside wheel in a corner. The inside wheel can drive slower only to the extent that the outside wheel is overdriving. In a case like this, torque is applied to both wheels equally.
If one wheel is off the ground and you try to go forward, the wheel without traction cannot drive faster than the wheel with traction because the no traction wheel is not being driven by an outside force. It is being driven by inside force (engine).
This type of differential is never 100% locked because their are compromises made to the angle on the gears. But it is an excellent differential for a road car because it allows equal torque to be applied to both wheels in a corner unlike friction clutches which need to slip to allow the difference, or a detroit locker which always drives the slower turning wheel.
Sorry for the wordy explaination.
Basically, it works by allowing one of the wheels to turn faster as long as it's an external force that's doing the driving, like the outside wheel in a corner. The inside wheel can drive slower only to the extent that the outside wheel is overdriving. In a case like this, torque is applied to both wheels equally.
If one wheel is off the ground and you try to go forward, the wheel without traction cannot drive faster than the wheel with traction because the no traction wheel is not being driven by an outside force. It is being driven by inside force (engine).
This type of differential is never 100% locked because their are compromises made to the angle on the gears. But it is an excellent differential for a road car because it allows equal torque to be applied to both wheels in a corner unlike friction clutches which need to slip to allow the difference, or a detroit locker which always drives the slower turning wheel.
Sorry for the wordy explaination.
Posted By: DoctorDiff
Re: Sure Grips and Cornering - 04/03/12 03:08 AM
The worm gears run in slightly elongated holes in the carrier. This creates an additional wedging action between the carrier and gear which causes the unit to "lock up".
Posted By: Mattax
Re: Sure Grips and Cornering - 04/03/12 03:09 AM
Dave, Did some digging in my files to see what my fuzzy memory was grasping at.
Torsen T2R was/is supposed to be their road race oriented unit. Back around 2001 it was not available for 8.75 and from their web site map it may still be true.
Tru-trac was available for a while in a full pre-load version but no longer is. That's the version I was thinking of. The preload insured some transfer of power when one wheel was spinning.
I vaguely recall the technical issue had to do with getting the axle bearings adjusted and the spacing between the axles. IIRC E-berg had to deal with this issue and covered it in an article and others may have come up with some work arounds. One solution involved using non-adjustable bearings, but a lot of us corner carver types insist on our tappered rollers. Hence the hunt for other work arounds.
Torsen T2R was/is supposed to be their road race oriented unit. Back around 2001 it was not available for 8.75 and from their web site map it may still be true.
Tru-trac was available for a while in a full pre-load version but no longer is. That's the version I was thinking of. The preload insured some transfer of power when one wheel was spinning.
I vaguely recall the technical issue had to do with getting the axle bearings adjusted and the spacing between the axles. IIRC E-berg had to deal with this issue and covered it in an article and others may have come up with some work arounds. One solution involved using non-adjustable bearings, but a lot of us corner carver types insist on our tappered rollers. Hence the hunt for other work arounds.
Posted By: DoctorDiff
Re: Sure Grips and Cornering - 04/03/12 03:14 AM
Eaton True-Trac differentials are readily available for 8 3/4" rearends. The design incorporates a center thrust block for use with OEM, adjustable wheel bearings.
Posted By: Mattax
Re: Sure Grips and Cornering - 04/03/12 03:18 AM
Was that (no thrust block) an issue at one time?
Posted By: DoctorDiff
Re: Sure Grips and Cornering - 04/03/12 04:14 AM
I don't think the thrust block was included when they were first released.
Posted By: Rick_Ehrenberg
Re: Sure Grips and Cornering - 04/03/12 05:15 AM
Quote:
Eaton True-Trac differentials are readily available for 8 3/4" rearends. The design incorporates a center thrust block for use with OEM, adjustable wheel bearings.
This is great news. Now there's no excuse for not using a TorSen (Gleason patent) all-gear diff in any 8-3/4" buildup.
Rick
Posted By: autoxcuda
Re: Sure Grips and Cornering - 04/03/12 07:14 AM
Quote:
Eaton True-Trac differentials are readily available for 8 3/4" rearends. The design incorporates a center thrust block for use with OEM, adjustable wheel bearings.
Which of the three? major types of Torsen types is that Eaton True-Trac version?
Posted By: DoctorDiff
Re: Sure Grips and Cornering - 04/03/12 07:31 AM
The 8 3/4" True-Trac is a worm gear differential stamped HT on the outside. I assume that means "half-tight".
Posted By: autoxcuda
Re: Sure Grips and Cornering - 04/03/12 08:10 AM
From http://www.torsen.com/products/products.htm :
From http://en.wikipedia.org/wiki/Torsen :
Quote:
Torsen differential products cover a wide range of torque biases and applications in the front, center, and rear of a vehicle!
T-1 (Type A)
This is the original differential that was introduced in the AM General HMMWV (Hummer®) and the Audi Quattro which has seen considerable growth in other worldwide applications. This is our crossed axis helical (Invex™) higher torque bias differential.
T-2 (Type B)
This differential is only a few years old and adds a wide range of torque bias coverage for the Toyoda-Koki Automotive Torsen North America, Inc. product line. This type of differential is referred to as our parallel axis helical (Equvex™) differential which was designed to accommodate Ford and GM C-Clip applications.
T-2R (RaceMaster)
The T-2R is a higher bias T-2 torque sensing parallel axis differential designed for the more performance minded driver. The higher bias found in the T-2R, like the T-1, allows the transfer of more available torque to the wheel that can better use it.
T-3 (Type C)
The newest differential style of the Torsen product line. The T-3 is currently offered in a single or Twin Differential configuration (The twin differential has an open differential surrounded by a Torsen differential!). This versatile unit is ideally suited for center applications and is designed for those hard to package all wheel drive systems. The design of the Type C allows for a torque split other than 50:50 with a majority of available torque designed to go to either the front or rear axle.
From http://en.wikipedia.org/wiki/Torsen :
Quote:
There are currently three types of Torsen differentials.
The original Torsen T-1 (Type A) uses crossed axis helical gears to increase internal friction. The Type I can be designed for higher torque bias ratios than the Type II, but typically has higher backlash and the potential for Noise, Vibration, and Harshness (NVH) issues, and requires a precise setup/installation.
The later Torsen T-2 (Type B) uses a parallel gear arrangement to achieve a similar effect. There is also a specialist application of the T-2, known as the T-2R (RaceMaster).
The latest Torsen T-3 (Type C) is a planetary type differential, in that the nominal torque split is not 50:50. The Type C is available as single or twin version; the Torsen twin C differential has front and center differential in the same unit.[2]
Posted By: DoctorDiff
Re: Sure Grips and Cornering - 04/03/12 12:08 PM
Looks like the Eaton True-Trac is similar to the original Torsen (Type A) differential.
Posted By: Rick_Ehrenberg
Re: Sure Grips and Cornering - 04/03/12 01:52 PM
Posted By: dangina
Re: Sure Grips and Cornering - 04/12/12 09:50 AM
For the guys who are autoxing - what rear diffs are you running? torsen, locker or the suregrip? I have a 3:55 suregrip right now, was wondering If it would be better to upgrade to the torsen or locker..
Posted By: Mopar Mitch
Re: Sure Grips and Cornering - 04/12/12 03:48 PM
I've done a ton of parking lot auto-x since the mid-70s, as well as some hi-speed road course solo events. I've used the cone-type (3.23, 3.55 and 3.91) and it will allow some slippage (one wheel will spin sometimes, but not always, under extreme corner exiting). I've also used the clutch-type (also with 3.23, 3.55 and 3.91) which I favor having a much less (if ever) slippage... set up on the tight-side of specs. My car is setup to the max for the SCCA Solo II class of E/SP.
My good friend John Sandberg races his AAR Cuda in the SCCA Solo II C/Prepared class (his car is featured in the current MCG magzn this month) and his car has a Detroit Locker... a very tight setup and he is pleased with its performance.
My good friend John Sandberg races his AAR Cuda in the SCCA Solo II C/Prepared class (his car is featured in the current MCG magzn this month) and his car has a Detroit Locker... a very tight setup and he is pleased with its performance.