Guys, I have an 83/4 with a TruTrac that Im not happy with due to the noise it makes whilst coasting and cruising nor the way the rear wheels wobble like a loose front wheel bearing.
Im looking for suggestions to a viable alternative that will give me simialr performance.
Car is a E Body, 408/727 (solid roller cam, W2 closed chamber heads, FAST EFI, 11.5:1 CR and so on, makes around 600 at the flywheel), its mostly a street driven beast with the occasional run down the strip or round a circuit. I dont want to go spool and Im thinking a cone or clutch type LSD may or maynot work with the HP, a Locker would be probably ok but is noisy round corners, any suggestions???
I love the way the TruTrac works as such and that its maintenance free and so on, just hate the noise, people that ride with me the first time look at me like the back end of the car is about to fall out!!!

Sounds like it is not set up properly or has something wrong with it?

I have a trutrac and it is excellent with no issues... (not in an 8.75" but same idea)

The clutch type is a good alternative - I run one which is quiet and effective. That said I think the Truetrack a great differential and also wonder if something is wrong with yours.

I have a new replacement still in the box that is worse than the one I had in the car, the problem is the side gear inside of the center can move in its housing, you grab the rear wheel at 3/9, wobble it like you would to check a front wheel bearing and, well not good
[img]http://i3.photobucket.com/albums/y84/crash520/th_IMG_0121.mp4[/img]

eaton claim they are within spec!!! I'm working with Cass on this, he is a great guy and is still arguing the fact with them

eaton claim they are within spec!!! I'm working with Cass on this, he is a great guy and is still arguing the fact with them

I have a trutrac in my 8 3/4 ebody and I don't have any of your problems. Good luck I hope Eaton makes it right.

I've watched your video. If you have that much wobble at the wheel, it has to be almost 3 times that at the end of the axle in the center section. That's just nuts !!!

Stanton, granted there is some tire flex from me pulling and pushing, here is a vid of the side gear when I pulled the centre out. It has also started marking the spline of the axles about half way along the spline giving me cause for concern as for leading to a weakening of the axle, as for the noise, under load it makes no noise, on coast or through a parking lot, it sounds like a jam can full of oil with a half doz lug nuts being rolled along, and no amount of speaker volume hides it!!!!
[img]http://i3.photobucket.com/albums/y84/crash520/th_IMG_0137.mp4[/img]

What do you have for axle bearings? Green non adjustable or tapered? If tapered do you have the spacer in the center between the axles?
Ron

From the movement you have, I'm assuming you don't have conrad bearings (Green bearings), but have the stock tapered roller bearings.

I don't see the differential thrust block in your video. And, that side gear movement is normal. When under torque loads, the elements in the TruTrac 'find their own center' and the pinion gear loads keep the side gear centered.

Dr. Diff's site tells you that you need to install the thrust block when using stock adjustable bearings.
http://www.doctordiff.com/8-3-4-eaton-truetrac-differential.html

The thrust block should have been packed with your TruTrac. It looks like this:


Once you get the thrust block in, you'll be good to go. If you didn't get it, call Eaton. They have pretty good customer service, and they'll get you one.

Bob

After watching the video, I don't see that as a differential issue at all. I see wheel bearing issues. I'd defer to Cass here, though.

using factory tapered bearings, yes the thrust block is installed, yes Cass is all over this and agree's there is a problem, the only way to reduce the 'rattle' is to tighten up the bearing end float to less than the 0.008" recomended however axle bearing failure is likely due to no end float, yes again under load it finds its centre as stated, it does not make a noise under load, the issue is on coast and around parking lots,,, its freaking loud. wheel bearings are brand new.

Hey, I know your problem.....change to a Dana 60 and be done with it. Less headache and you would be on the track already...Tim

Thanks Tim, if they were more plentiful out here I would, shipping alone on a 60 would be close to the cost of one from Cass!!Then lets not talk about the exchange rate, the South Pacific Peso is not doing that great lately

I run a True Trac in my Imperial. Zero noise. That car is so quiet that I'd hear any noise the diff is making.

I hope they can get you straightened out.

mine is doing the same thing, I had green bearings at 1st, then the tapered,it is a problem with the side gears.

My friend had a TruTrac in a 12 bolt. Love the differential action for cornering exits but also complained of noise. The driveshaft could be rotated 45 deg w the wheels locked.

He renamed it True Slack and returned to clutch style.

Yeah, I have to say I love the way it works through corners and burnouts, I love everything about it,,,,,,exept the damn noise, all they need to do is sort out the side gear float and they would be awesome. I dont want to go to a clutch, Ive had those before, a spool is just a PITA as is somewhat a locker on the street,

I JUST WANT A GOOD TRUTRAC Eaton sent me a warranty replacement but as indicated its equal to if not worse in side gear slop.

There is two people above that call it a wheel bearing issue. Your wheel is flopping around and you think the center section should hold it in place? No, that is a wheel bearing issue, and you just can't have it set right if its tapered bearings. With the wheel flopping around like that, there actually would be very little movement in the center section, not an exaggerated movement. AND, there is nothing in the center section to hold the axle in, that is done at the wheel bearing. Good luck with this.

LOL It is not a wheel bearing problem, there is NO support at the spline end of the axle with this type of carrier, the side gear will move around & lets the axle move.

Use the thrust block supplied with the unit. Use tapered roller bearings, adjust them properly with .08" of clearance and all will be good. As for the original question as to what is a good alternative differential you could get the cone type and it would perform well on the street.

You are correct, there is nothing holding the axle in the center section, that wheel movement you see is the axle pivoting at the wheel bearing, the end float in that clip is set at 0.004" with a DTI, the bearing is tight in the housing, I am holding the wheel at 3 and 9, pushing with one hand pulling with the other, (just like you do on the front wheels to check for loose bearings).I can tighten the adjuster on the wheel bearing to no end float and still wobble the wheel. Futher to this, I swapped centers back to the factory open center (single spinner)used the same axles, same bearings, same set up only now Im using 0.008" axle end float, (ONLY THING I HAVE CHANGED IS THE DIFF CENTER, WHICH THE SIDE GEARS HAVE NO MOVEMENT GO STICK YOUR FINGER IN ONE IF YOU HAVE ONE LAYING AROUND) guess what,,,,,,,, noise is gone so those suggesting its the wheel bearing, think again.

What exactly is Eaton telling you is in spec ??? And they diagnose this over the phone ??? Can you slip an axle in the 3rd member{out of the car} and see exactly what's loose and how it can be corrected ??? Sounds like there's a quality control issue that needs addressed the trouble is getting the company to admit it..

Screamin, Cass has been talking to Eaton on this, he has multiple video's showing the side movement and agree's there is a problem, he spoke to them at SEMA and all they are saying is, its in spec, regarding the side gear movement, Cass is still arguing this with Eaton, when I first raised it with Cass, about 12-18 months after I purchased it, and about 2000Miles on it, I had been chasing the rattle from new, thinking it was exhaust, tailshaft, on and on you name it, then one day I just grabbed the wheel and wobbled it to find out it was as indicated, I knew the axle spine fitted well, figured I best just pull the third member for now and woek on the noise, now, at that point I reached out to Cass, I didnt buy it directly from him, a mate did, anyway Cass is an awesome guy as well all know, Eaton sent out a new replacement at no charge, again I praise them for this service as technically it was out of warranty, both Cass and Eaton went above and beyond, something rare in my country. Yes I can poke an axle into the bare Trutrac center and it will move side to side,,, lots. When compared to mopar single spinners or cone/clutch, their side gears have no movement. Im at a lose for now, I will pull one of them apart to see if there is a reason why they are like that, maybe they need to be that loose for whatever reason, the other thing is I have a 0 offset on my wheels maybe if I had more wheel out (less backspace) thus loading the axle more it would make no noise, who knows,

100%... I got my 9" center (with trutrac) and axles from Cass.

(For the 9" diff in my Torana )


Sure is a shame though with all the issues on your's..

After overnight comms with Cass, looks like I will be trying to find a Dana housing out here as a donor to build. He has confirmed that there is no side gear movement on Dana or Strange build TruTrac's, probably the same with 9", so it seems only the 8.75" have an issue.

Since that axle gear meshes with the two spyder gears, there has to be some way this gear is "controlled" by design. On stock set ups the axle gear fits into a precision recess. This has to be similar to the unit you have, except parts or something is missing. Without this control the spyder gears would have incorrect mesh/lash.

I can't imagine someone would design that gear to flop around like that as the mesh with the spyder gears and the thrusting apart of these gears is what applies the force to lock the carrier up either with clutches or cone or whatever.

If you take it apart please let us know what you find. Best of luck to you.

I know SportF, seems crazy to me, thats why I'm at a loss with this, I'll pull one of them down and have a look and let you all know, right now I'm looking for a Dana or 9" PITA having to cut them down and mod them when the 8.75 was a nice drop in afair. But, thats what you get when you play with cars right??

Why are you still hung up on using a TruTrac? You have a good 8-3/4 with the exception of the diff unit, why not keep everything and go with a new/different diff unit? It would be a lot less hassle and expense than finding and building a Dana or 9" !!

Stanton, good question! Pretty much what I asked in my first post, I guess my options are, Detroit locker, cone style, clutch pack style and spool, are there any others to throw in the mix? When I track it, it will have slicks and I'm pushing for around 500 RWHP, we should hit 600 flywheel easily. 727 and not a transbrake.

I'll offer that my experience with the Detroit locker has been just fine. Been running one in my 8.75 for 3 years now. People say they are noisy; I rarely hear a thing. People say they clunk in & out... I occasionally feel it "shift" or "unlock" when slowing while going around a corner, but as long as you know what it is... no big deal. Durability wise: its been bombproof. The only issue I have with it is that as you get on and off the gas, it will want to push the car left or right as it unlocks and locks. This is no big deal, until you chop the throttle a couple of times at the top end of the drag strip at 115 mph. Then, it will get your attention. As I look to do more racing over the next few years, I will likely be going to a spool partly because of that issue. If it weren't for the racing thing, I'd be happy as a could be with my locker.

As someone whos logged at least 100000 miles in detroit equippped trucks, I love em.

Spendy but bulletproof and always there since there's not really anything to wear out like clutches.

Thanks guys, thats what I'm leaning towards right now, unless I can find a Dana 60 out here from a F250 or similar, we dont have Dodge vans or light trucks so they are thin on the planet here.

If you have that much power, and slicks, you should cross ANY type of CONE type off your list or you'll be back in it again , CONE types are GARBAGE by design .

I agree as I have been running a Detroit Locker in my 8-3/4 about 6 years. But I have never had any problems of it making my car go to one side or the other. After I go through the traps I just lift the throttle and it slows down straight as an arrow even when braking or downshifting.