Road course differential advice

[customstreetmachines]

I need a little advice. I am building a pro-touring 67 camaro for road coarse flogging. LS2/T56 w/ ford 9". I have run GM posi's on road coarses before, but never as heavily as I intend to shred this car. I have a Detroit locker in My Chevelle and it works great at the dragstrip, but seems like it might kick that back end around on corners because of the mechanical type locking, But my Chevelle is set up to go straight, so it may be a bad example for me. I need a good differential that can handle 500+ ft lbs and I plan on flogging the pee out of it. What are your thoughts Locker, Auburn cones, Air locker ????

[Scott Parkhurst]

I like the Eaton/Detroit Tru-Trac. No clutches to wear, and it offers partial engagement around corners (rather than the 'on/off' action of a Locker). It's all helical gears, so it's a solid piece with no parts that'll wear out (like a clutch will).

I haven't beat the snot out of mine (yet) but the research I did led me to it.

~SP~

[parsonsj]

I'm a big fan of Lockers. Mine works great on the street, the autoX, and on big tracks.

jp

[andrewb70]

I like the Eaton/Detroit Tru-Trac. No clutches to wear, and it offers partial engagement around corners (rather than the 'on/off' action of a Locker). It's all helical gears, so it's a solid piece with no parts that'll wear out (like a clutch will).

I haven't beat the snot out of mine (yet) but the research I did led me to it.

~SP~

Scott,

Is that the same diff that is used by Ford in the 03-04 Cobra Mustangs?

Andrew

[chicane67]

Lockers take a little finesse' to drive. Auburn sucks. ARB wont live in an impact loading enviornment...

If it were me... I bust out a Platinum Track (definate, first choice) or a Black Gold from DPI.

Or a true Torsen Gleason.... but no one wants to spend $1200.00 on a differential.

But what do I know ??

[Damn True]

Do you have any kind of metrics on the surviability of the above on the street? I mean are they a maint. intensive unit?

[chicane67]

No more maintence than that of an EATON True-Trac. And in my opinion... much less. The machining tolerances and finished components are much cleaner than an out of the box True Trac.

I know of several Black Golds that have been street driven behind 700-800hp big block cars for 20 years... and a decade or two of abuse in professional motorsports (Nascar, SCCA... etc) that would seem more like a few hundred thousand miles of street use.

The only real difference between the two is that the Platinum Track is bias pre-load tunable. Meaning... that you can add or take out bias pre-loading when the center section is out of the housing. It would be likened to a breakaway adjustment in tuning a limited slip clutch unit.

Im all over the Platinum Track. Next to a true TG... its the cats @ss for road course, AX and land speed stuff.

[Damn True]

Yeah, you had me all ate-up for that TG....until I saw how much they cost. Are the Platinums and/or Black Golds a bit more wallet friendly?

[chicane67]

The BG units are $675 for a no pre load unit... and $775 for a 1/2, 3/4 or full tight pre load unit. The "Street Rod" unit is $875.

The PT units are $750ish

[funcars]

I have a black gold that I use on the street and on the track. It works great and makes a difference on a road race track. I have a full tight version. DPI is a good outfit and can rebuild it if it ever needs it and they even provide instructions for doing it yourself. I sent them the third member a while back and they put in new ring and pinion in it in two days since I had a BG in it already.

[molyorange 77]

TrueTrac's are pretty darn durable. I had one installed over a year ago and I have Pounded on it.

[customstreetmachines]

I have heard good things about the True Trac's. The DPI diff's seem a little pricey, although they are probably well worth the money. I haven't even bought a housing yet, I am still researching. I am looking to keep it under $2k for a complete 9", not including brakes. I'd like to see some others chime in on the True trac and other diffs you guys are running.

[matthimself456]

My vote goes to the TruTrac style torsen differential. Research how they work a little. Its like pure mechanical magic.

[chicane67]

True Trac's are a good unit... but, in my opinion... they need to be diassembled, case de-burred and the pinion gears to be heat treated, cryo-ed, REM'ed (or Micronite) and then reset the mechanical lash a little tighter (they need a little pre-load).

The True Trac will take lots of abuse... as long as you dont go to the local drag strip and impact load it to death. If you go to a couple other sites... you too will see the numerous posts of people blowing True Tracs up. The biggest culprit in 99% of the related failures are from inexperienced differential builders installing the wrong differential into the wrong application... and inexperience drivers listening to the susposed 'experts' and taking what they hear as the gospel. Well... stupid is as stupid does.

As I stated before... a True Trac is a great differential... as long as you dont impact load it to death. Or if you do go to the strip... just pray that you dont hook up too hard, one too many times.

FYI... the Torsen Gleason, the Black Gold/Platinum Track and True Trac work mechanically the same. The Torsen Gleason and the Black Gold/Platinum Track are by far the strongest (or NASCAR, IMSA, SCCA wouldnt use them) and more expensive differentials. The Torsen Gleason runs about $1200 and the BG/PT run $675-750... and the True Trac (untuned) runs $375.

Let me put it another way... and simplify it... you get what you pay for in terms of strength. $675 once is cheaper than $375 twice or until you learn that you should have done it right the first time around.

Even Tom specifically states not to use it in a drag race application: http://www.tomsdifferentials.com/catalog.asp?pg=72

I also like the Detroit Locker. But... as I said earlier... it takes a little finess to drive and I wouldnt want to drive it on any thing other than dry pavement. Hell... as for that subject... I dont even like to run some of my tuned limited slips on anything other than dry pavement.

And since you stated this:

I have run GM posi's on road coarses before, but never as heavily as I intend to shred this car.

And this:

I need a good differential that can handle 500+ ft lbs and I plan on flogging the pee out of it.

You pretty much have ruled out about all other differentials... other than that of a Torsen Gleason or either of the Black Gold or Platinum Track units.

[customstreetmachines]

Well, I definately don't want to blow it out and do it twice. Spending the money to do it right is not out of the question, but I try to start with a budget (which almost never works). Tell me the characteristics that require "finesse" with the locker. My only experience with them is in cars set up to go straight. So, turning corners on the street I can feel it unlocking and locking. Otherwise it seems almost indestructable with dragstrip launches with 450 ft lbs, 3.26 1st gear a 3.90 rear gear. Is the black gold as strong as the detroit locker? Can it handle a couple of hard launches? I like the all around car aspect of pro-touring, but I am really leaning on the road coarse with this build.

[Steve1968LS2]

I'm going ot Currie next week to do a story on building a third member for the road track.

Suggestions? We will go over the differences in yokes, carriers, cone vs clutch, etc.

I was planning on building a nice 4.10 unit for Penny.. Detroit TruTrak and all the goodies.

What do you guys wanna see?

[chicane67]

You will only feel a locker 're-set' when you come out of a turn, as you progress back into a straight line. Then... BANG. It re-sets... and sometimes it can induce a lane change weather you intended to or not, from the re-set. Trail braking is going to be another learning curve for your road course duty.

Light moisture or really hot pavement will also easily induce oversteer. But if the dove tails are loaded (under accleration or deccleration) it can induce understeer if the chassis hooks up.

The DPI units are rated at 750hp... so I think it will do just fine at your power level and I think it will take impact loading much better than the True Trac in comparison. The finished components of the DPI units are far better pieces from a machining stand point.

[chicane67]

I'm going to Currie next week to do a story on building a third member for the road track.

Suggestions? We will go over the differences in yokes, carriers, cone vs clutch, etc.

I was planning on building a nice 4.10 unit for Penny.. Detroit TruTrak and all the goodies.

What do you guys wanna see?

I told you where you should have gone for this stuff... but say HEY to Ray and Chuck for me anyway.

I would concentrait any story explaination on bearing pre-load and how to do it and get it right... and on gear pattern and what it takes to do it and get it right. Get plenty of pictures of the gear pattern stuff. Pinion support assembly will be part of the bearing pre-load stuff... but its assembly is pretty important stuff.

You need a 3.062" Mark Williams thru bolt case... a DPI Platinum Trac... a Williams tapered pinion support... and some EDM lightened Visteon 4.10's. Oh wait... they dont have that kinda stuff. oops...

Seriously though. you... need a CE-4028A alloy 3.062" case, a CE-4048C alloy big bearing pinion support, a CE-5021 DPI Platinum Track or an Eaton True Trac... and... I would pony up the $150 extra for a lightened gear set, if... if... they will do that ratio. Especially if they have some USGear 4.10's in stock. And... a CE-4044B billet 1350 yoke.

Or purchase all of the MW stuff and Ill teach you to do your own differentials for free. 'Give a man a fish and he has a meal. Teach a man to fish and he eats for life'.

[Steve1968LS2]

I told you where you should have gone for this stuff... but say HEY to Ray and Chuck for me anyway.

I go where I'm told to go ;)

But I will do my best...

[Steve1968LS2]

Seriously though. you... need a CE-4028A alloy 3.062" case, a CE-4048C alloy big bearing pinion support, a CE-5021 DPI Platinum Track or an Eaton True Trac... and... I would pony up the $150 extra for a lightened gear set, if... if... they will do that ratio. Especially if they have some USGear 4.10's in stock. And... a CE-4044B billet 1350 yoke.

Gotcha.. I can pretty much choose anything from the Currie catalog.. as long as my 31 spline axles work I'm golden.

Is that case iron or aluminum? I've heard the alum cases aren't great for longevity. I don't think Currie offers the DPE Platinum deal so it will be a Eaton Ture Trac. Gotcha on the rest.