Detroit Truetrac

[Gonzo1970]

In August 2017, I installed a TrueTrac into my 8.8 axle. Since that time, it has turned both rear tires every time I hit the throttle, even with one tire on gravel and the other on dry pavement. At the same time, when not under hard acceleration the differential is completely smooth and quiet. Off the throttle, it sounds and behaves just like an open differential; get on the gas and it instantly behaves like a spool.

I love it, and I could not recommend a limited slip more highly than this.

Do you think it would be the same with a 7.5"

I dont plan on pushing more than 350hp 350tq anytime in the near future (if ever). Im just worried about it being quiet and functional.

There are the Auburn Style Kits on Ebay (Carrier, Ring/Pinion, Rebuild Kit, Bearings) for about as much as a TruTrac.


I'm on the fence..

Its either spending a lot more on the 7.5 getting a TrueTrac, OR one of those kits for the 7.5 behind the 305 for now, and if the 305 ever goes t*ts up and I go with the 6.6L 400 Poncho Plan, switch rear ends to something more stout..

-Gonz

 

[Supercharged111]

At the same time, how could different grades of oil make a true locker more or less noisy?

 

[Supercharged111]

Do you think it would be the same with a 7.5"

I dont plan on pushing more than 350hp 350tq anytime in the near future (if ever). Im just worried about it being quiet and functional.

There are the Auburn Style Kits on Ebay (Carrier, Ring/Pinion, Rebuild Kit, Bearings) for about as much as a TruTrac.


I'm on the fence..

Its either spending a lot more on the 7.5 getting a TrueTrac, OR one of those kits for the 7.5 behind the 305 for now, and if the 305 ever goes t*ts up and I go with the 6.6L 400 Poncho Plan, switch rear ends to something more stout..

-Gonz

After having a POS Auburn in my Camaro and dealing with it sucking, I will NEVER run one again. They don't have clutches, they're not serviceable. They're basically an open diff with a spring pack that gets mashed in between the side gears. That's your preload, the torque the the thing spinning pushes the side gears into the case to prevent slippage. That's it. It's a stupid design and it doesn't work.

 

[500/600]

Clutches on one side of a 9"? I aspire to one day ditch the peg leg in my 9", what is it about the inherent design of the 9" that makes diffs suck for it?

The design of the carrier is such that it has room for clutches on one side only. Typically they are fiber type clutch material which isn’t so durable, but nevertheless they have half of the amount of clutches as a typical GM or Mopar or Dana posi.

 

[Gonzo1970]

After having a POS Auburn in my Camaro and dealing with it sucking, I will NEVER run one again. They don't have clutches, they're not serviceable. They're basically an open diff with a spring pack that gets mashed in between the side gears. That's your preload, the torque the the thing spinning pushes the side gears into the case to prevent slippage. That's it. It's a stupid design and it doesn't work.

Thanks!

Maybe it would be smartest to just bite the bullet and put something stout under her now.. I mean just because its Only a 305 in front of something that could withstand 500hp/500tq wouldn't bother it.. I may hear it laugh and go "that all you got up there?" but... 😀

-Gonz

 

[500/600]

After having a POS Auburn in my Camaro and dealing with it sucking, I will NEVER run one again. They don't have clutches, they're not serviceable. They're basically an open diff with a spring pack that gets mashed in between the side gears. That's your preload, the torque the the thing spinning pushes the side gears into the case to prevent slippage. That's it. It's a stupid design and it doesn't work.

i agree 100%. In the attempt to make something different the created a ridiculous abomination.

 

[Supercharged111]

The design of the carrier is such that it has room for clutches on one side only. Typically they are fiber type clutch material which isn’t so durable, but nevertheless they have half of the amount of clutches as a typical GM or Mopar or Dana posi.

Is it a packaging thing? Sounds like it applies to the aftermarket as well. There is an off the shelf option from Variloc, it's a salisbury style diff and only $750. Typicaly, these diffs are $1,000+. Think OS Giken/Kaaz.

Variloc Differentials: Availability

Championship Salisbury type, limited slip differentials for formula and stock cars.

www.icpcitation.com

 

[500/600]

Is it a packaging thing? Sounds like it applies to the aftermarket as well. There is an off the shelf option from Variloc, it's a salisbury style diff and only $750. Typicaly, these diffs are $1,000+. Think OS Giken/Kaaz.

Variloc Differentials: Availability

Championship Salisbury type, limited slip differentials for formula and stock cars.

www.icpcitation.com

Yep. Notice that all 9" carrier bodies taper in quick as they move away from the ring gear seat. That is the ONLY way that they will fit a stock type of housing due to the 9" having a rearward pinion support bearing. You cannot have clutches on both sides of a 9". The TruTrac is better although still due to the shape of the 9" tapered carrier the outer worm gears can't be as long as the would be in other makes of differentials, even a 8.8".

I have an OSGiken in the rear of my Magnum SRT8 since it has the Mercedes Benz W215 differential from the factory. It is a tremendous unit. All billet with 28 clutches, compared to typical GM and others having 12-16, and 9" Traction Lock having only 6 or so. I paid $900 for it in 2011 when they were $2000 new. It hasn't given me a second of issue.

 

[Gonzo1970]

Is it a packaging thing? Sounds like it applies to the aftermarket as well. There is an off the shelf option from Variloc, it's a salisbury style diff and only $750. Typicaly, these diffs are $1,000+. Think OS Giken/Kaaz.

Variloc Differentials: Availability

Championship Salisbury type, limited slip differentials for formula and stock cars.

www.icpcitation.com

The Ebay kit is $500 with 3.73 Ring/Pinion, Install/Rebuild kit, and Carrier which is why it was on the table to begin with... Well, that and 40 sold with 100% positive feedback, but thats easily manipulated anymore...

https://rover.ebay.com/rover/1/711-...0001&campid=5335822911&icep_item=391715702465

-Gonz

 

[500/600]

The picture below is a Detroit Locker. The large REM polished 85# spring in the foreground was removed by me and the barely visible orange 58# spring in the small hole in the differential in the background was put in by me. The lighter the spring the easier the Detroit Locker releases. They still pop and crack when they release, just not quite as loud with a lighter spring. I have disassembled and reassembled several and they do in fact look like the 'exploded' diagram in an earlier post. Although not a 'full spool' these are the most bullet proof 'limited slip' made, not even a close second. Most people don't need them and most can't tolerate to violence required to unlock them during normal driving.

Oh, as a side note, helical gear can and do whine. It is typically a backlash issue. If you notice in the 'exploded' diagram of the TruTrac in an earlier post, there is a lack of any kind of bearing that would support any of those gears. So they are constantly forced out against the case in every direction. Brilliant design, but lots of them whine. Especially after many miles once the case has worn. Really they are similar to an Auburn in that respect. Planetary gears in automatic transmissions whine when backlash isn't controlled. I have 'quieted down' several TH400s by tighten up the planetaries with shims. Straight cut gears are worse, but helical gears still whine. Show me a BW or Muncie that didn't. The straighter the cut, the stronger and louder the gear. The more angle, the weaker and quieter...………..typically.

Back to the original subject, a TruTrac is a good differential. My exhaust is probably just too quiet. 😛