Trac Lok Vs detriot locker

[rhurley]

About to pull the trigger on my 9" 3rd member.

66 mustang that will be about 420hp weekend cruiser/ track car.

What would you go with and why??

Thanks

[Ron Sutton]

IMHO, it's a personal choice. it comes down to how hardcore you are about performance versus street manners & civility.

Lockers (Detroit, Yukon, G-force & other brands) are all about performance & lack street manners & civility. The locker does exactly what we need it to do on track (autocross or road course). It engages & drives both wheels equally when we're on the throttle. And it disengages completely when we're off the throttle & turning. Exactly what we need it to do ... when we need it to do it. Plus they're super tough. The down side for the street is they are noisy & rough. When turning tight at lower speeds, the locker clicks, clanks & bucks .. disengaging & re-engaging ... making the novice think something is broke back there. Backing & turning ... like out of a parking spot ... is worse.

Clutch type limited slips differentials (Posi, Positraction, etc, etc) are a compromise that offers less than ideal on track performance, but much better street manners & civility. As you probably know, there is spring pressure pushing on the clutch discs, and as the load form the inside wheel & outside wheels differ ... the clutches allow slippage. The down side on track, is the inside rear tire is not fully loaded or engaged equally when we're on the throttle. You have power to both wheels ... but only partially. And it does not disengage completely ... only partially ... when we're off the throttle & turning. Kinda what we need it to do ... but not exactly. They're NOT super tough. Beat on them enough & they break, plus they need to be rebuilt occasionally. More with serious use. But they sure are more civil on the street. You have power to both wheels. As long as you have the right gear oil & friction modifier to allow smooth clutch slippage ... you won't have clicking, clanking & bucking. You'll have a much tamer, nicer, pleasant street driving experience.

That's about all i can share. From here it's personal choice. Choose your weapon. Hardcore? or Civil?




.

[1BADBET]

You can get a nascar take out 3rd member on eBay for a smokin deal. I got mine with less than a few hundred miles and ultra high dollar parts for $725 shipped to my door. 5.14 gear and locker. There are a bunch of different gear ratios if you want something more "friendly" but be sure to get the soft locker springs from Ron, I did!

[andrewb70]

I can vouch for what Ron says about a locker. I have a Detroit Locker in my Cougar and when going around tight turns it sounds like the rear end is going to fall out. There is a lot of bucking and noise at low speed. However, at the drag strip, it's both tires, doing what they are supposed to do!

Andrew

[68Formula]

Eaton Truetrac is a limited slip that doesn't use clutches, yet also doesn't have the bad street manners of a locker. Have it on my truck and love it.

Here's some info.:
http://www.streetmusclemag.com/tech-...th-gen-camaro/

Stielow reportedly used it on the Red Devil, so seems to be pretty strong.

BTW, to function correctly, do not use synthetic gear oil or friction additives.

[mean buzzen half dozen]

How about one of these?

http://www.ebay.com/itm/190523633401...%3AMEBIDX%3AIT

[ssx]

I've got a Detroit Locker in my '65. As stated above its a little rough on the street (especially in reverse) but you get used to it. Peace of mind, knowing it's practically bulletproof.

[rhurley]

Well i am hard on stuff and want it to last, as well as i am not overly concerned with low speed parking lot driving. I believe a locker will be my direction.

I was about to pull the trigger on the used Roush yates 3rd members that are fully built for $899 , but they just jumper up $300 bucks!!

[Ron Sutton]

Every mechanical device has its pros & cons. Lockers & typical clutch type (& cone type) limited slip differentials definitely do.

I sell quite a bit of the Eaton/Detroit TrueTrac worm gear drive differentials for performance street use. They, and all worm gear drive limited slips have their pros & cons too:
* Con: If you completely unload the inside rear tire, it will spin & put no power to the outside tire.
* Con: The bias ratio (the percentage of torque split across the axle) is preset.
* Con: Whatever the bias, it is not zero where we need it o be, nor is it 100% where we need it to be. It is a performance compromise.
* Pro: But it is more civil on the street. No bucking, clanking, etc.

This is good reading to help you understand how both gear drive LSDs & the Wave-trac work.
http://www.wavetrac.net/different/

Wavetrac's have similar, but different, cons when it comes to track performance:
* Pro: Unlike clutch & gear LSDs, it will always provide power to the outside rear tire. So do lockers.
* Con: The bias ratio (the percentage of torque split across the axle) is preset.
* Con: Whatever the bias, it is not zero where we need it o be, nor is it 100% where we need it to be. It is a performance compromise.
* Pro: But it is more civil on the street. No bucking, clanking, etc.

Again, IMHO ... learn the pros & cons & choose what's important to you.

[AMC Racer]

Interesting read here:
http://www.taylor-race.com/pdf/under...ferentials.pdf

Truetrac generally works well as an all-purpose option.

[Ron Sutton]

Well i am hard on stuff and want it to last, as well as i am not overly concerned with low speed parking lot driving. I believe a locker will be my direction.

I was about to pull the trigger on the used Roush yates 3rd members that are fully built for $899 , but they just jumper up $300 bucks!!

If you can get the right gear ratio, these used NASCAR lockers can be an good deal.

BUT ... the locker springs in them are ALWAYS too stiff. On short tracks & road courses, most NASCAR teams run 85# springs. On the mile & half tracks, most NASCAR teams run 110# locker springs. On the Super Speedways the NASCAR teams vary. Some run 110#, some 125# & some 150#.

All of these spring rates are way too stiff for what we're doing here. Our rear tires do not have enough grip to unlock the locker ... if the springs are too stiff. So you end up with a spool in effect.

For Pro Touring Cars with grippy street tires ... for street, autocross & road course ... we need 40# locker springs.
For Pro Level Race Cars slicks on road courses, I like to use 55# ... unless they're 12" or wider slicks ... then we run 65# springs.

I offer these springs in a wide range of rates on my website here: http://shop.ronsuttonracetechnology....pping/?ic=9334

*Key Note: These softer springs do NOT make the locker stop clunking on the street. They simply make the locker disengage the inside rear wheel easier when turning. This does stop the tire squealing & jerking people experience if the locker won't unlock, from too stiff of springs. But it doesn't make the locker "civil" like a clutch or gear LSD.


Best wishes.

[rhurley]

If you can get the right gear ratio, these used NASCAR lockers can be an good deal.

BUT ... the locker springs in them are ALWAYS too stiff. On short tracks & road courses, most NASCAR teams run 85# springs. On the mile & half tracks, most NASCAR teams run 110# locker springs. On the Super Speedways the NASCAR teams vary. Some run 110#, some 125# & some 150#.

All of these spring rates are way too stiff for what we're doing here. Our rear tires do not have enough grip to unlock the locker ... if the springs are too stiff. So you end up with a spool in effect.

For Pro Touring Cars with grippy street tires ... for street, autocross & road course ... we need 40# locker springs.
For Pro Level Race Cars slicks on road courses, I like to use 55# ... unless they're 12" or wider slicks ... then we run 65# springs.

I offer these springs in a wide range of rates on my website here: http://shop.ronsuttonracetechnology....pping/?ic=9334

*Key Note: These softer springs do NOT make the locker stop clunking on the street. They simply make the locker disengage the inside rear wheel easier when turning. This does stop the tire squealing & jerking people experience if the locker won't unlock, from too stiff of springs. But it doesn't make the locker "civil" like a clutch or gear LSD.


Best wishes.

Great Info,

thank you very much,

Out of curiosity. What does a factory tru trac come with for springs.

[SSLance]

I just recently replaced my clutch type posi with an Eaton Locker outfitted with Ron's 40# springs after wearing out the clutches in several previous diffs. The clutch posi style just could not handle the abuse I was throwing at them. Right now I'm driving the car on 25 year old 215/60/15 tires and at times it will drag or spin a tire instead of releasing the locker, I expect this to change in a day or so when the fat sticky tires get bolted onto the car once again.

I'll be sure to chime back in to this thread once I get a little more experience driving with the locker and sticky tires. It HAS to be better than what I dealt with before, even with the clanky noises coming from under the car. I am so excited to feel what happens the first time I'm exiting a right hand turn on an autocross course and nail the throttle.

[andrewb70]

If you can get the right gear ratio, these used NASCAR lockers can be an good deal.

BUT ... the locker springs in them are ALWAYS too stiff. On short tracks & road courses, most NASCAR teams run 85# springs. On the mile & half tracks, most NASCAR teams run 110# locker springs. On the Super Speedways the NASCAR teams vary. Some run 110#, some 125# & some 150#.

All of these spring rates are way too stiff for what we're doing here. Our rear tires do not have enough grip to unlock the locker ... if the springs are too stiff. So you end up with a spool in effect.

For Pro Touring Cars with grippy street tires ... for street, autocross & road course ... we need 40# locker springs.
For Pro Level Race Cars slicks on road courses, I like to use 55# ... unless they're 12" or wider slicks ... then we run 65# springs.

I offer these springs in a wide range of rates on my website here: http://shop.ronsuttonracetechnology....pping/?ic=9334

*Key Note: These softer springs do NOT make the locker stop clunking on the street. They simply make the locker disengage the inside rear wheel easier when turning. This does stop the tire squealing & jerking people experience if the locker won't unlock, from too stiff of springs. But it doesn't make the locker "civil" like a clutch or gear LSD.


Best wishes.

Good stuff there Ron. How hard is it to replace those springs?

Andrew

[SSLance]

There are a couple really good videos about the different differentials in this link

http://www.onallcylinders.com/2016/0...differentials/

[Cobra 498]

You might want to check out the faster autox cars running Goodguys or SCCA. The majority use Tru-track or Torsen, the new Mustang GT-350R comes with a Torsen. A properly set up suspension will not spin the inside tire. If you want understeer in tight corners buy the Detroit locker.

This shows how well the Tru-Trac works on a very tight autox course

https://www.facebook.com/turnology/v...0969363690766/

[Get' er done]

There are a couple really good videos about the different differentials in this link

http://www.onallcylinders.com/2016/0...differentials/

While watching the video on the Eaton Detroit Locker at the 2:00 min. mark the narrator speaks of the outside wheel uncoupling from the driveline while turning. From my understanding it is the inside wheel that uncouples. Am I correct?

[Ron Sutton]

While watching the video on the Eaton Detroit Locker at the 2:00 min. mark the narrator speaks of the outside wheel uncoupling from the driveline while turning. From my understanding it is the inside wheel that uncouples. Am I correct?

It can be a little confusing. The load ... and therefore grip ... of the inside rear tire is the key factor that unlocks the locker. But it is the outside wheel that gets unlocked.

If the inside rear tire doesn't have enough grip to unlock the locker ... then both wheels stay engaged ... and this makes the car tight or pushy. In my experience, the factory 78# springs are way too stiff for the street tires we run ... and will cause a push condition. The used NASCAR lockers are worse, because all of them come with 85#-150# springs. So if you choose to go the locker route ... any off-the-shelf locker or used NASCAR locker needs to have the locker disengagement springs changed.

Detroit only offers one rate ... the standard 78# rate. But Aftermarket locker springs commonly come in rates from 55# to 150#. I added 40# springs to my product line a couple years ago, specifically for street tires. They work well for my clients & have won many autocross & track events from SCCA, Goodguys & optima/USCA.

[Monzsta]

I just recently replaced my clutch type posi with an Eaton Locker outfitted with Ron's 40# springs after wearing out the clutches in several previous diffs. The clutch posi style just could not handle the abuse I was throwing at them. Right now I'm driving the car on 25 year old 215/60/15 tires and at times it will drag or spin a tire instead of releasing the locker, I expect this to change in a day or so when the fat sticky tires get bolted onto the car once again.

I'll be sure to chime back in to this thread once I get a little more experience driving with the locker and sticky tires. It HAS to be better than what I dealt with before, even with the clanky noises coming from under the car. I am so excited to feel what happens the first time I'm exiting a right hand turn on an autocross course and nail the throttle.

How'd it do?

My experience with a locker was hateful. Mind you it was a stock car take out I rinsed off and chucked in my 9" under a '78 Monza weighing 2800 lbs so your results might vary.

On acceleration through a turn it would push like crazy as the inside wheel is the only one driving. If you lifted in the same turn suddenly the car would dive to the inside of the turn as now all your engine braking is on the inside wheel. Real easy to upset the car and spin it out. Whenever you're turning the outside wheel is just along for the ride.

Punching it from a standstill turning out on the road is a no no. Instant doughnut or "half turn". Leaving easy from a stoplight sometimes resulted in a shotgun bang from the rear that had me looking for parts and oil on the road the first few times because a dog was partially engaged and slipped out. Nothing broken or wrong but it sure felt like it. Real entertaining for passengers. Not to mention the helpful lady who gave me a card to a C.V. joint shop in town because her car was making the same noise as mine when I pulled up to the store.

Straight road driving with traffic the locker would tug the car from side to side as you were on and off the gas with each wheel locking and unlocking. This lessened with new tires but was still there.

At the drag strip I could bang 3 gears without touching the wheel, the car went dead straight.

I put a torsen differential in the car and couldn't believe the difference. It was a well worn unit that was chewing itself up so the locker had to go back in but when the car gets back on the road it'll have a Quaife in it. The best of everything.

[SSLance]

I'll update in the next day or so with a longer explanation and some video. We raced the car again today and the locker did great, the chole car did great really. The only time you can really tell there is a locker in the car is when it releases on some corner entries. It's more the noise it makes than anything that upsets the car. Corner off grip is phenomenal and it doesn't make the car push anywhere else on course.

I'm a fan...