Wavetrac LSD Installed on a (Previously) Welded Ring Gear!

[Mr. 5]

Let's face it...
if you have a production date of March of 2007 to Present, you have a welded ring gear and you can't install an LSD. You have to spend about $3,700 AND have to send back your own diff. Right?
Wrong!
Autotech (Wavetrac) has come up with a solution to separate ring gears from the OEM carrier and tap the ring gear so it can be used with the Wavetrac LSD for about 700 bucks. So, for just under 2k, you can have a limited slip differential installed on your previously welded ring gear!

I gave a complete 3rd member to Autotech a while back hoping they could separate my ring gear from the carrier. Not only were they able to work with my ring gear, but they were able to come up with a solution and a process for all of those who have welded ring gears.
I have a manual transmission which has the 3.08 rear end. Up until now, those with welded ring gears who have done the LSD upgrade have had to change their rear end to the auto ratio (3.46). Some have chosen the 3.46 because it winds up quicker, but for those who wanted to keep the 3.08, they were out of luck because it is almost impossible to find a bolted 3.08. Now, it doesn’t matter.

Now I know that it’s all about personal preference with what ratio is used, but I really wanted to stick with the 3.08. IMO, since our cars have so much torque that gets hit at lower RPMs, then I think that it’s better to have taller gears in the back to take advantage of the torque band.

The Separation

The first picture is the OEM carrier with the ring gear attached.



Here is a close up of how BMW welds the ring gears to the carrier.



I’m not exactly sure what method was used to cut the ring gear off the carrier, but here is a picture of the ring gear that was just separated.



The surface was then smoothed out and tapped for the attachment to the Wavetrac unit.



Here is what the end result looks like.











The Traction
I knew the entire time that an LSD is the best modification that one can do to a RWD car, but it really hurts when someone makes a quote of around $3700, especially when you can get other mods for much less. But, it’s common knowledge that although you have more and more power, if you can’t put the power to the ground, it’s wasted.

The moment I got into my car after the Wavetrac was installed, my car felt much tighter and planted. Even when driving in a straight line, the car just felt much more controlled.
The times that you really notice the difference though is when rounding corners. Some of you guys have seen my video of when I rounded turn 4 at Laguna Seca and completely lost it doing a 540 into the gravel. I know that it most likely had to do with driver error, but I’ll guarantee that if I had this Wavetrac installed, I would have most likely saved it before my spin.
This is a slomo of my wipeout at Laguna Seca:

Differentials

Open Differentials

An open differential does a great job of transferring the power from the drivetrain to the wheels. The problem with an open differential is that the torque always takes the path of least resistance so if one wheel starts to slip, the torque will continue to drive the slipping wheel.

Clutch LSDs

These LSDs respond to driveshaft torque, so the more torque that is input by the driveshaft, the more the clutches grab giving more of the wheels equal amount of power.
The problem with this type of LSD is that it locks the rear end when enough torque is applied, which creates a recipe for disaster for those who aren’t used to drifting.

Torque Biasing LSDs

Torque biasing LSDs takes the torque and divides it between the 2 wheels and increases the “bias ratio”. The bias ratio is the amount of torque that one wheel gets over the other. For example, some torque biasing diffs have a 2.5:1 bias ratio compared to the 1:1 in the open diff. With this example, if one wheels starts to slip, the gears in the LSD will multiply the torque that is going to the slipping wheel by 2.5 and transfer it to the wheel that has grip. The problem with this type of LSD is that if there is little to no load on one of the wheels, then this means that there is little to no torque that will be multiplied and transferred over to the other wheel. So, no matter how high the bias ratio is, if there is no load on one of the wheels, the Torque biasing ratio behaves like an open diff.

Wavetrac

The Wavetrac differential is a torque biasing differential but has a device inside the diff to react when there is little to no load on one of the wheels. This device creates a load inside the unit to be multiplied against even when there is no load on one of the wheels.

Here is a quick video to show how well it transfers the torque to the wheel that needs it.

Installation

Thankfully, I had a shop near me do the install. Unitrax is a company that strictly deals with drivelines and they’ve been doing it for 25 years. They worked with installing the ring gear, setting up the backlash, and replacing the seals. I’ve never seen so many differentials in one place in all my life. http://www.gounitrax.com/

Here are a couple pictures that I took while I was at Unitrax.
You can see the stand of differentials here:



Here’s a rack of some Viper Differentials that they just completed:





What else can I say, the Wavetrac is incredible!
I'm really excited that somebody finally came up with an affordable way of working with our welded ring gears.

Videos will come shortly!

[zamm3k]

soooooooo exactly how much was this? and where can we contact autotech

[akak1997]

Hi, Congrats on the LSD, I bet you're enjoying it.
I'm also interested in the Wavetrac LSD, I've read up on all the reviews I could find (mostly VW and some BMWs) everyone seems to love it.
However, like you've mentioned, the >$3K price for the mod is a bit much. I'm so glad that you've found a way to do it for less.

The thing is, if I want to upgrade my gear to Auto's ratio, does that mean I've no choice but to buy the entire auto rear diff + housing for a LSD upgrade? We can't just buy a auto gear or it doesn't fit the manual housing? I don't quite understand how this works.

Thanks

[WhiteOne]

THANK YOU Mr5!

[Mr. 5]

Originally Posted by zamm3k

soooooooo exactly how much was this? and where can we contact autotech

Here you go:
http://www.autotech.com/

http://www.wavetrac.net/

[Mr. 5]

Originally Posted by akak1997

The thing is, if I want to upgrade my gear to Auto's ratio, does that mean I've no choice but to buy the entire auto rear diff + housing for a LSD upgrade? We can't just buy a auto gear or it doesn't fit the manual housing? I don't quite understand how this works.

Thanks

You can contact them to see if they have other 3.46 gears.
Maybe they would be able to do a swap for you.

[HondaGoneRogue]

Hotness.

[wu2x]

Finally a cheaper solution to our welded differential problem! Thanks Mr. 5!!

[bimmerboy]

I think a video of you powersliding will have many of us sold in no time.. I'm already considering it, as you are right, what's the use of adding extra power to this already powerful car when you can't put it down to the road effectively..

[akak1997]

Could you kinda explain the logistics on how you do this mod?
When you took out your diff and send it to AutoTech, you can't drive the car any more, so when AutoTech send you back the ring gear, and the WaveTrac LSD, how do you get your car to the installation shop?
Or you've the installation shop took out the diff before you send it to AutoTech and left your car there while you wait? How much down time are we talking about?

Sorry if this is a dumb question, I never did a LSD mod before

Thanks

[Mega Man]

How much and what kind of a difference do you feel?

My previous car had LSD, but I was more daring with that car. I haven't really pushed this car to probably tell what an LSD would do for me or not.

[1erich]

That´s fantastic news! How is this dif on the daily grind? Is it silent?

[Mr. 5]

Originally Posted by akak1997

Could you kinda explain the logistics on how you do this mod?
When you took out your diff and send it to AutoTech, you can't drive the car any more, so when AutoTech send you back the ring gear, and the WaveTrac LSD, how do you get your car to the installation shop?
Or you've the installation shop took out the diff before you send it to AutoTech and left your car there while you wait? How much down time are we talking about?

Sorry if this is a dumb question, I never did a LSD mod before

Thanks

Not a dumb question at all.
I actually purchased another diff from a member that already made the upgrade so i still have my old diff sitting in the garage.
With my case, I gave the diff to Autotech that did all of the machining and then I had them send the machined ring gear to Unitrax for the diff instalation.
That was my case.

If you don't have an extra diff, I would estimate that the turn around time would be about a week, but contact Autotech to get more acurate info.

[Mr. 5]

Originally Posted by 1erich

That´s fantastic news! How is this dif on the daily grind? Is it silent?

It's absolutely perfect and as quiet as the OEM diff.
The only thing that's different is that i have traction now!

[BlackjackMulligan]

quiet and awesome!!

[akak1997]

Originally Posted by Mega Man

How much and what kind of a difference do you feel?

My previous car had LSD, but I was more daring with that car. I haven't really pushed this car to probably tell what an LSD would do for me or not.

Even with stock power, and 255 rear RE01 tires, I loose traction easily. Any imperfection on the road/freeway the stability control will kick in. With a LSD, you can say bye-bye to that stupid blinking light every time you went over a expansion joint on the freeway while you're on throttle.
Also, you could Actually apply some throttle around corners even for DD w/o the light blinking again.
I think even if I don't track my car at all, I'll still go for a LSD upgrade. Any car with that kinda hp/tq needs a LSD.

[akak1997]

Originally Posted by Mr. 5

Not a dumb question at all.
I actually purchased another diff from a member that already made the upgrade so i still have my old diff sitting in the garage.
With my case, I gave the diff to Autotech that did all of the machining and then I had them send the machined ring gear to Unitrax for the diff instalation.
That was my case.

If you don't have an extra diff, I would estimate that the turn around time would be about a week, but contact Autotech to get more acurate info.

Thanks for the reply.
I read from another thread that said with the diff welded, it cannot be removed from the housing, did you manage to get it out before AutoTech cut it?
So, you've your old diff sitting in your garage... looking to sell it? I'm in SoCal

[mpukas]

Originally Posted by Mr. 5

The Wavetrac differential is a torque biasing differential but has a device inside the diff to react when there is little to no load on one of the wheels. This device creates a load inside the unit to be multiplied against even when there is no load on one of the wheels.

How does this LSD differ from the Quaife LSD? Pros-cons of one over the other?

[akak1997]

Originally Posted by mpukas

How does this LSD differ from the Quaife LSD? Pros-cons of one over the other?

Basically the Wavetrac is design to fix a short coming in a Quaife LSD, where when you've no load on one wheel you have no power going to both wheels.
Before wavetrac, the only way to get around that is to get a clutch type diff, which is stupid expensive, noisy, harsh, and require extra maintenance (changing clutch plates).

So, imho, WaveTrac is better than Quaife. However, Quaife has been around forever, and they're pretty much the standard of torque bias type LSD. Where the Wavetrac is new. Also, WaveTrac does have a clutch plate inside, so eventually, you might have to replace it, but according to WaveTrac, it should last long enough to not be a problem.

[jeremyc74]

This is pretty cool, but I'm concerned about the fact that they're machining a gear with an established wear pattern and then reinstalling it. I'm just not sure how well that's going to hold up over the long run.

Don't get me wrong though, I love the idea, and for the cost savings the risks may very well be outweighed.

[Citizen Z]

Originally Posted by jeremyc74

This is pretty cool, but I'm concerned about the fact that they're machining a gear with an established wear pattern and then reinstalling it. I'm just not sure how well that's going to hold up over the long run.

Don't get me wrong though, I love the idea, and for the cost savings the risks may very well be outweighed.

A machine shop doesn't stay in business for 25 years doing shoddy workmanship. A decent machine shop can mill parts to within 1/1000 of an inch or better. Thats way beyond the tolerances the parts were originally manufactured to.

[BrokenVert]

So does WaveTrac make an LSD for us bolted diff owners? In my case it would just be a plug and play right?