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#2263888 - 03/05/17 04:41 PM LSD for Autocross?
Bob J Online   content
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Registered: 11/16/16
Posts: 116
Loc: Colorado
What is the best LSD for Autocross? I have a Power lok out of my 68 that I can rebuild and how well will that work? Does anybody know the ratio on a power lok vs what else is out there?
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#2263891 - 03/05/17 04:43 PM Re: LSD for Autocross? [Re: Bob J]
MuuMuu101 Offline
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Registered: 12/12/10
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I use an Eaton TrueTrac and have no complaints.
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#2264290 - 03/06/17 10:59 AM Re: LSD for Autocross? [Re: Bob J]
myduster360 Offline
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Registered: 01/20/03
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Loc: central IL
I'm definitely considering a helical diff like the Eaton TrueTrac, Quaife, Torsen,ect.

The fact that they always transmit torque to the wheel with the MOST traction(instead of the least) is what sets that design apart. Seems it would work great for corner exit.
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#2264528 - 03/06/17 06:20 PM Re: LSD for Autocross? [Re: myduster360]
Bob J Online   content
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Registered: 11/16/16
Posts: 116
Loc: Colorado
Originally Posted By myduster360
I'm definitely considering a helical diff like the Eaton TrueTrac, Quaife, Torsen,ect.

The fact that they always transmit torque to the wheel with the MOST traction(instead of the least) is what sets that design apart. Seems it would work great for corner exit.


Thanks that is what I'm looking for. Does anybody know the different lockup ratios for declaration between the units.
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07 Porsche C2 997.1 6spd DD and SCCA Solo II SS
68 Plymouth GTX Convert. 493cu Hotkiss Wilwood Classic air, Building for Solo II Cam
65 Chrysler 300 Convert. project
57 Desoto 2dr. Firesweep 392 Hemi,Wilwood Project with son
2003 Dodge Dakota R/T Wife DD

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#2264591 - 03/06/17 07:53 PM Re: LSD for Autocross? [Re: Bob J]
ahy Offline
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Registered: 01/22/07
Posts: 7395
Loc: IN
I run a clutch type sure grip for HSAX and it works quite well. Probably similar to your '68 unit. They can be set up with various levels of "tightness". Mine is "medium". Full tight might be good on a drag car but not a handling car per my understanding. Too tight can upset the car on corner exit.

The worm gear type are great in theory... but 8.75" versions have suffered quality problems and noise.

I would suggest clutch type.

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#2264610 - 03/06/17 08:19 PM Re: LSD for Autocross? [Re: ahy]
amxautox Offline
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Yes, I heard the Detroit Locker is too noisy, and locks up too quick and can break things. But the 'soft' Detroit Locker is fine for autocross.
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#2266410 - 03/09/17 06:16 PM Re: LSD for Autocross? [Re: Bob J]
CJD AUTOMOTIVE Offline
mopar

Registered: 09/08/08
Posts: 547
Loc: Florida
The Detroit Locker is going to be the best, providing you change the springs to accommodate what your doing and for the type of tires (slicks or treaded). For treaded tires, a #48 spring is what you'll want. Yes, it is a little noisy, but the abrupt lock and unlock is usually do to the unit having too high a spring rate, and once setup with the correct springs, you'll have a hard time finding a unit that can put the power down better with more predictability.
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#2268470 - 03/13/17 03:15 AM Re: LSD for Autocross? [Re: Bob J]
dangina Offline
pro stock

Registered: 11/19/08
Posts: 1391
Loc: Lethbridge, AB, Canada
eaton trutrac here no complaints, setup by dr diff

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#2268717 - 03/13/17 02:52 PM Re: LSD for Autocross? [Re: Bob J]
Mattax Offline
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Registered: 02/28/10
Posts: 949
Loc: Phila. Pa.
Bob. I've never had an issue or concern with the LSD as long as it was working. When the cone style was giving up during an evo school, I noticed because I was having an acceleration problem to the pivot cone. No one said anything 'til I asked because they thought cars like ours naturally spin tires. :LOL: I said "sure, two or one?" But it was hard for observers to see. There was only a single rubber mark laid down so that was the answer

When I got a replacement, went to the clutch style for the same price as the cone type. However, I did not like how tight he set it, either on the street or for autocross. It changed the balance especially cold/wet looser than I liked. One of these days I'm going to set it back.

OTH heck I rememeber guys showing up with Brit/euro sports cars with welded up rears 'cause LSD weren't available for them. Good ol days. smile

You'll need to decide how tight based on power level and tires as well as if you plan any street use. My guess is your power level and tires and going to put more load on everything than mine and other 'CP light' and ESP cars. Talk to Sandbergs and other people with national level CP cars - see what they've found over the years. Some of the new locking units mentioned are really nice design. Whether they will actually perform better than your clutch unit for your build harder to say. Another person to ask would be Sam Strano.

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#2268817 - 03/13/17 05:43 PM Re: LSD for Autocross? [Re: Bob J]
Bob J Online   content
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Registered: 11/16/16
Posts: 116
Loc: Colorado
Thanks Mattax I'm going to rebuild my clutch type for one reason. Money as it seams like I'm pissing money at the moment as I still need to drop 10k or so on the car. Wheels and tires 4-5k alone. I didn't think of Sam as he is so into front wheel drive at the moment. So I'm going to start looking to see how to setup the clutch pak since the last time that I did it was for drag racing and not turning. I ordered every thing from DrDiff yesterday for the rearend plus new gears and the green bearings that I need for my brakes. Dam I would like to get this done something this year so I can some seat time so I can get it dialed in this season.


Edited by Bob J (03/13/17 05:44 PM)
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07 Porsche C2 997.1 6spd DD and SCCA Solo II SS
68 Plymouth GTX Convert. 493cu Hotkiss Wilwood Classic air, Building for Solo II Cam
65 Chrysler 300 Convert. project
57 Desoto 2dr. Firesweep 392 Hemi,Wilwood Project with son
2003 Dodge Dakota R/T Wife DD

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#2275091 - 03/23/17 09:47 PM Re: LSD for Autocross? [Re: Bob J]
Bob J Online   content
member

Registered: 11/16/16
Posts: 116
Loc: Colorado
I was just looking at the factory shop manual on the LSD and they give you 4 way to pack the disk but don't tell what each will do. You can guess as 2 are 5 disk setup and 2 are 3 disk setups. Anybody know? I guess I can drop it 3rd member and change it later but I's a job that I never liked to do if I don't have to.
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07 Porsche C2 997.1 6spd DD and SCCA Solo II SS
68 Plymouth GTX Convert. 493cu Hotkiss Wilwood Classic air, Building for Solo II Cam
65 Chrysler 300 Convert. project
57 Desoto 2dr. Firesweep 392 Hemi,Wilwood Project with son
2003 Dodge Dakota R/T Wife DD

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#2275905 - 03/25/17 10:08 AM Re: LSD for Autocross? [Re: Bob J]
Mattax Offline
super stock

Registered: 02/28/10
Posts: 949
Loc: Phila. Pa.
Bob - Which Company and year is the Service Manual? The '68 Plymouth only shows 3 possibilities, one for each type of carrier, each side is 5 pieces.
Side Gear:
Flat Plate
smaller flat disk
Dished Plate (beville)
smaller flat disk
Flat Plate, thin

edit: illustration in tech archives
http://www.moparts.org/Tech/Archive/axle/13.html
and some rebuilding tips in this thread.

I think there was an article in one of the magazines way back about what it takes to make them tighter..



Edited by Mattax (03/25/17 10:27 AM)

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#2275936 - 03/25/17 10:54 AM Re: LSD for Autocross? [Re: Mattax]
Bob J Online   content
member

Registered: 11/16/16
Posts: 116
Loc: Colorado
Dana Power Lok
Here is the manual this is from Dana Corp. Spicer Axle Division. Thanks for the info I will read through the manual that you posted. I'm not put it together for a week or so as I'm prepping all the parts for the rear and painting and trying my hand at powder coating.
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07 Porsche C2 997.1 6spd DD and SCCA Solo II SS
68 Plymouth GTX Convert. 493cu Hotkiss Wilwood Classic air, Building for Solo II Cam
65 Chrysler 300 Convert. project
57 Desoto 2dr. Firesweep 392 Hemi,Wilwood Project with son
2003 Dodge Dakota R/T Wife DD

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#2276092 - 03/25/17 03:57 PM Re: LSD for Autocross? [Re: Bob J]
DoctorDiff Offline
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Registered: 01/20/03
Posts: 7797
Loc: Polson, MT
2 clutch packs are available for the clutch (power-lock) sure-grip.

I stock both. One is aggressive and one is smooth.
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#2282146 - 04/04/17 10:36 AM Re: LSD for Autocross? [Re: Bob J]
Mattax Offline
super stock

Registered: 02/28/10
Posts: 949
Loc: Phila. Pa.
Ran across this older thread with has some useful specifics on the different systems.
Sure-grips and cornering

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#2282218 - 04/04/17 12:10 PM Re: LSD for Autocross? [Re: Bob J]
Bob J Online   content
member

Registered: 11/16/16
Posts: 116
Loc: Colorado
Thanks Mattax that was a good read. I was ready to go to the 3 disc setup till I read Mopar Mitch's post in the thread that you posted. I will have to make a choice in the next week or two so I can put it together. All the parts are now prepped and painted.I working on removing the undercoating dam I hate that job as I can only do for so long. Dam it's a [censored] to get old.
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07 Porsche C2 997.1 6spd DD and SCCA Solo II SS
68 Plymouth GTX Convert. 493cu Hotkiss Wilwood Classic air, Building for Solo II Cam
65 Chrysler 300 Convert. project
57 Desoto 2dr. Firesweep 392 Hemi,Wilwood Project with son
2003 Dodge Dakota R/T Wife DD

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#2389726 - 10/19/17 07:24 AM Re: LSD for Autocross? [Re: Bob J]
MoJoe Offline
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#2389738 - 10/19/17 08:57 AM Re: LSD for Autocross? [Re: MoJoe]
Supercuda Online   content
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Originally Posted By MoJoe
I prefer brown micro dot, but a small dose of orange sunshine is nice too


Then go find a skyscraper to fly off of.
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#2389869 - 10/19/17 01:53 PM Re: LSD for Autocross? [Re: Bob J]
Sweet5ltr Offline
member

Registered: 04/02/12
Posts: 39
Loc: Florida
Originally Posted By Bob J
What is the best LSD for Autocross? I have a Power lok out of my 68 that I can rebuild and how well will that work? Does anybody know the ratio on a power lok vs what else is out there?


Why not give Dr. Diff a call? He builds a modern clutch type "Powr-Lok" limited-slip differential for an 8 3/4. Price is very reasonable.
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#2390029 - 10/19/17 07:33 PM Re: LSD for Autocross? [Re: Bob J]
Bob J Online   content
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Registered: 11/16/16
Posts: 116
Loc: Colorado
I bought a kit from Dr. Diff for my power lock with a 3.55 gear set. I'm going to leave the car on jack stands for a little while long as I'm thinking of going to the Magnumforce 4 link setup. So I will need to weld on tabs for the links first if I do it. I have been side tracked on working on the GTX as the wifes 03 Dakota R/T that we bought new was totaled when she was sitting at a stop light. She was pissed but she is happy now since we bought here a 07 BMW X5 loaded with the sport package. Guess what I get to do on a used car, Yes work on it so the GTX sits a little longer.
_________________________
07 Porsche C2 997.1 6spd DD and SCCA Solo II SS
68 Plymouth GTX Convert. 493cu Hotkiss Wilwood Classic air, Building for Solo II Cam
65 Chrysler 300 Convert. project
57 Desoto 2dr. Firesweep 392 Hemi,Wilwood Project with son
2003 Dodge Dakota R/T Wife DD

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#2390748 - 10/21/17 09:49 AM Re: LSD for Autocross? [Re: CJD AUTOMOTIVE]
Adobedude Offline
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Registered: 05/07/06
Posts: 1144
Loc: New Mexico
Originally Posted By CJD AUTOMOTIVE
The Detroit Locker is going to be the best, providing you change the springs to accommodate what your doing and for the type of tires (slicks or treaded). For treaded tires, a #48 spring is what you'll want. Yes, it is a little noisy, but the abrupt lock and unlock is usually do to the unit having too high a spring rate, and once setup with the correct springs, you'll have a hard time finding a unit that can put the power down better with more predictability.


http://shop.ronsuttonracetechnology.com/shopping/?k=detroit%20locker%20springs

I ordered the 110# springs to keep my locker from unlocking...Will put them in the winter
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#2399094 - 11/05/17 07:32 PM Re: LSD for Autocross? [Re: myduster360]
Magnum Offline
master

Registered: 01/24/03
Posts: 5582
Loc: Hamilton, Ontario Canada
Originally Posted By myduster360
I'm definitely considering a helical diff like the Eaton TrueTrac, Quaife, Torsen,ect.

The fact that they always transmit torque to the wheel with the MOST traction(instead of the least) is what sets that design apart. Seems it would work great for corner exit.


We are all traditionalist here and I personally still prefer the Power lock for street and strip drag racing but if you are going autocrossing a helical differential is the only way to go.
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#2399108 - 11/05/17 08:07 PM Re: LSD for Autocross? [Re: Bob J]
autoxcuda Offline
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Registered: 01/20/03
Posts: 25418
Loc: So Cal
At SEMA Richmond said they were comin out with a Torsten style mopar 8.75 setup and to check with Dr Diff.
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#2399111 - 11/05/17 08:22 PM Re: LSD for Autocross? [Re: autoxcuda]
ahy Offline
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Registered: 01/22/07
Posts: 7395
Loc: IN
The helical style is better in theory... but the 8.75 versions have had quality problems. Why I suggested the clutch type (which I run).

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#2399166 - 11/05/17 11:01 PM Re: LSD for Autocross? [Re: autoxcuda]
MuuMuu101 Offline
I got lucky at Woodward!

Registered: 12/12/10
Posts: 12122
Loc: Covina, Ca
Originally Posted By autoxcuda
At SEMA Richmond said they were comin out with a Torsten style mopar 8.75 setup and to check with Dr Diff.


That will be cool.
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