propaintball96

I have a 4th gen rear end in my iroc. The Posi is going bad and I know you cant replace the clutches in these...

Is there ANYTHING I can do to fix/replace the posi in this rear end?

Thanks!

big gear head

Take the Auburn out and toss it in the scrap metal pile. Then get a new Eaton Posi, Eaton Truetrac, Yukon Dura Grip or a '98 to '02 4th gen Torsen to replace it.

Be sure to measure the backlash before you remove anything. Then you will know what to set the backlash to when you install the replacement differential.

propaintball96

Now is this a direct bolt in? Can you give me a little more information on these. I am totally clueless when it comes to types of posi ect....

Thanks!

big gear head

The Auburn is a cone type differential. The way this one is made you can't shim it or machine it to make it work again. It's just scrap metal when it wears out.

The Eaton Posi and the Yukon Dura Grip have clutch plates in them. If they wear out you can put new clutches in them and they are as good as new again.

The Eaton Truetrac and the Zexel Torsen are gear type differentials. They use resistance in the gears to apply power to both axles. They don't wear much and work pretty well.

These are almost a direct bolt in. You still have to shim them for bearing preload and backlash.

propaintball96

Which would you recommend? the Eaton or the Yukon?

Seems like Eaton has a bigger name...money is not an object though I want quality and NOT MADE IN CHINA!!

propaintball96

Also,

What kinds of things do I need to know before buying one of these? I see they have different splines...Im assuming these are how many splines the axles have? Like I said...havent done much work on differentials...

Thanks!

Ron U.S.M.C.

Give Tom a call and explain what you have and what you want to do. He is extremely knowledgeable and has some of the best prices on quality parts.=

http://www.tomsdifferentials.com/

I have the Eaton posi and has worked well for over 6 years now.

With the Eaton posi as well as some others will need an experienced shop to set them up. Perfect time to get whatever gear ratio you want.

I paid a shop called "The Rear End Shop" to swap in 28 spline axles, 28 Spline Eaton Posi, and 3.42 gear ratio. $ 300.00 to do the hole thing. That's a great price.

mmadden55

I would recomend a Helical gear diff over a clutch type anyday. They work better for one. A clutch type only transfers some torque , better than open but just some better.

The Helical gear LSD works the opposite of an open rear, whichever wheel is turning slower gets the torque, ensuring if you got traction on either wheel you got traction. WHEN you have traction on both you get an even 50 50 split which you never get with a clutch type.

The Trutrac and the Torsen found in 98 and up 4th gen v8 cars are bolt ins.

big gear head

I like the Eaton Posi for most street/strip use. The Truetrac or Torsen work great for auto cross and road racing. The Yukon Dura Grip is a copy of the Eaton Posi, but it uses a different clutch material. All parts interchange between the Eaton Posi and the Dura Grip.

If you want to get serious about drag racing then you need a locker. The Detroit Locker will work much better for burnouts and will not slip. It's a little jerky and noisy on the street. Clutch type differentials have a little trouble with the water burnouts.

propaintball96

Who offers a helical gear differential? Big gear, what is your opinion on these? My application is going to be mostly for street and a little bit of track. Thanks for all your input guys

3rdgenmaro

iTrader: (9)

The torsen and truetrac are helical gear differentials.

propaintball96

Are these going to be too harsh for normal driving? Is there any downside to a helical gear?

3rdgenmaro

iTrader: (9)

No. Wont even be noticeable. Downsides, Im not sure.

big gear head

The Torsen and Treutrac are very smooth. The only down side that I know of is that some people have complained about them not locking up when doing water brunouts. I had one guy say that his didn't lock up on the starting line. I think most people don't have any problems out of them.

You can find used 4th gen Torsen differentials on ebay. Randy's Ring & Pinion and Tom's Differentials have the Truetrac. You will want to get new Timken bearings and a super shim set with it so that you can install it and set the backlash and bearing preload. Randy's and Toms have the super shim sets. Don't use Ratech shims.

propaintball96

Something like this?

http://www.ebay.com/itm/98-02-Camaro-7-5-3-42-Differential-Ring-Pinion-POSI-10-bolt-28-spline-Torsen-/310991048707?pt=Motors_Car_Truck_Parts_Accessories&hash=item486882d003&vxp=mtr
This is actually in Orlando which is where I live so that would be great. With 82,000 miles on this, is it almost ready to blow? I really don't mind paying extra money for a stronger, better differential.

propaintball96

Also, am I going to need a press to install this with new bearings?

big gear head

Looks like the whole bearing journal is broke off of it. If it is then this is only good for parts.

Yes, you will need to use a press to get the bearings on.

propaintball96

I think I'll just go with a new one...Is shimming it pretty tough? I'm very mechanically inclined but I don't want to be taking it back out if its that tedious...I'll just have a shop do it and warranty it.

What do you think?

Thanks!

big gear head

http://www.nastyz28.com/forum/showthread.php?t=19773
Read this.

Ron U.S.M.C.

The Helical gear differential is a great unit but I would like to straighten out a few facts about the Eaton Clutch Style posi. Unit.

First here’s what Eaton says =

The Eaton Posi limited-slip differential prevents wheel slip before it can get started. To do that, carbon disc clutch packs, preloaded by a central spring assembly, are located behind each differential side gear. When torque input increases the clamping load on the clutch packs increases. That causes the chatter-free clutch packs to grab and transfer power to the other wheel.

The clutch packs are on eather side of the difarential applying pressure to both as torque is applied.

There is no "one wheel than lock".

Both tires are held at the same preloaded pressure of 400lbs. Bough tires continually spin at the same rate un less turning. that's all the time with bough wheels.

I don't know if the helical style is continuously in posi mode or are you driving around with one wheel until you need it.

big gear head

The Eaton Posi is the limited slip differential that was installed in the '60s and early '70s Chevy muscle cars with the 12 bolt rear end. That's not saying that all of the 12 bolt rear ends had a Posi in them, but any that did have a Posi had the Eaton Posi. That is where the term Posi came from. It's short for Positraction, which is a Eaton trade mark name along with Posi. The old Eaton Posi held up very well in those old Chevys and I know of several of them that are still running around today with the original clutches still in them.

Ron U.S.M.C.

Yes, I've noticed the term Posi has become universal for most L.S.D.

I've even become guilty of that.

propaintball96

Big gear...I trust you because you obviously know what the hell youre talking about haha

Im going to be on the street mostly and I love pinning it around corning and doing donuts. Should I go with the Eaton clutch packs or should I go with the helical drive. Just make it easy for me haha

Thank you for the link also!

propaintball96

"To check the backlash you must wrap something around the yoke and housing to hold the pinion perfectly still. If it moves ANY you will get an inaccurate reading."

What do you usually use to hold the yoke still? I cant really picture what I would use to hold it still against the housing?

big gear head

I have to admit that the only experience I have with the Truetrac is in the front of 4X4s. I only know what other people have told me about them. I do have a lot of experience with the Eaton Posi. I know that too much abuse will glaze the carbon fiber clutch discs and cause them to slip easier. Donuts and stuff like that is really hard on a differential. I don't know if the Truetrac would hold up better or not. I really don't think you can go wrong with either one.

I've got an old belt that I wrap around the yoke and the snout of the housing and pull it real tight. I clamp it with Vice Grips to hold it still.

khulsebus

iTrader: (2)

I want to meet your guy. I would have a hard time doing anything besides a 9 inch for that price. Setting up a rear rates up there right next to rebuilding an automatic for jobs that I despise the most.

propaintball96

Hmm...not exactly the answer I wanted... TELL ME WHAT TO DO BGH!! haha just kidding... Well I'm thinking about going with the Eaton just because you know it is a good diff and itll do the job.

big gear head

One good thing about the Eaton Posi is that if you do screw it up you can rebuild it. There are even some options with springs and clutch material if you want to get inside it and do some tuning.

Ron U.S.M.C.

Heres a link to the shop = http://www.rearendshop.com/

I bought all of my parts from him and he charged me $300.00 for the install and came with a 3 year warrantee on parts and labor.

Dan the owner has been working on differentials for over 20 years and the guy that did mine was not far behind.


Heres a link to the 10 Bolt build = https://www.thirdgen.org/forums/tran...de-photos.html

propaintball96

That is a great price but unfortunately I live in florida and Shipping would be ridiculous...

Thanks for the link!

khulsebus

iTrader: (2)

I was being a little sarcastic, I'm down in Louisiana now. IF I were ever to be in your neck of the woods, and I had a rear that needed work that I didn't care to do myself, I'd give your guy a call. In reality, I'm going to pick up a crate rear once I get established in my new location, and in the mean time baby the 10 bolt before it explodes.

Like I said earlier though, that is a great price to do a rear. I have the time and experience, but it's a job that I hate doing.

Ron U.S.M.C.

I'm pretty sure he got me on some of the parts. .

The only thing I did not buy from him was the cover.

That shop was crazy busy. They had 4 bays going with mainly what looked like Fleet trucks.

They knock them out pretty quick.

Dan the owner listened to what I was doing with the car. A DD and no track and no slicks.

He's the one that suggested the Eaton Posi.

He even said if I could break it with what I was running now he would replace it.

He gave me a 3 year warranty on parts and labor.

How could I pass that up.

I don't do doughnuts but I will launch off the line or spin and slide around a turn until it hooks and it will shove you back into the seat with the belt locking.And if you don't respect what power that "little" 5.0 has, it will put you into the wall.

Formula 305

I installed a torsen LSD in my Formula about a month ago and I love it. Its so smooth you don't even know its working, since its a gear type LSD you don't need any additives, and there is nothing to wear out. I bought mine used off ebay with my 3.42 gears already installed on the carrier all for about $250 shipped. I would defiantly recommend going this route, its a quality unit and extremely cost effective, considering a new LSD will set you back no less than $400.