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Discussion Starter #1 (Edited)
Hi everybody,

I thought I start a thread for all those who are interested in rear LSD for the TTRS/RS3.
As some will already know, the biggest problem is: there is none to buy…
There was also a thread here about a Wavetrac LSD for the Haldex IV. Unfortunately, the project was terminated prematurely, as it turned out that the differentials of the Haldex IV equipped cars (TTRS / RS3, S3, Golf R, ...) are different and therefore it´s probably not economical for them to offer one.
At least that's how I understood it…
Nevertheless, I wanted to have one for my TTRS.
Since I've dealt a bit with AWD systems, I´m convinced that a rear LSD is necessary for a sporty AWD system…
Even if I have to say after all mods (all in my signature); there is hardly anything to criticize about the handling of the TT.
Only in situations when accelerating out of corners, the rear could help a bit more for my taste.
And there, a rear LSD should bring a noticeable improvement.

Unfortunately, as mentioned above, no one offers an LSD for the newer Haldex generations. But you can get one for the earlier (slip-depended) generations…
So after talking to some people who know a bit about differentials, we decided to take a closer look ourselves at the differences between the Haldex generations.
The plan was to modificate an LSD from the older generation, that than fits into the rear unit of the TTRS.

We organized used rear units from a Golf R32 and a TTRS.


We dismantled both and measured them exactly to create CAD Models.

The differentials are quite different on the outside as you can see here:


R32 vs. TTRS
But the good news is that the internals are the same.

We created CAD models, and after a bit of tinkering on them, we were pretty sure that the R32 diff can be converted for the TTRS rear unit. (Some new parts are required)


So we ordered a Wavetrac for the R32.


Machining the "Wavetrac" parts:



TTRS Wavetrac with new bearings and ready for install

All parts were laser welded to minimize warpage


So after driving it about 300miles now, I can say it’s absolutely worth it.
No vibration or any disturbing noises…it does exactly what I expected from a rear LSD.
The car rotates very easy and controllable under power now.
I first tried it with the OEM Haldex controller, which also works well, but I recommend installing an aftermarket controller. Under power there is no big difference, but when lifting the pedal just a bit, the OEM controller immediately disconnects the rear and the benefit of the LSD is gone...

Finally a short video just to get an idea of how it behaves (dry pavement with Michelin PSS):

 

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That's an impressive bit of work, and out of reach for the majority of us, unfortunately. Job well done.
 

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Discussion Starter #4
That's an impressive bit of work, and out of reach for the majority of us, unfortunately. Job well done.
Thank you, it was just the right project for the cold season...
But yes, unfortunately you're right ... it's not really plug & play...but also no rocket science.
Organize a used rear drive unit and some experienced toolmaker/shop and i think its not a big problem for them (with the now existing drawings) to do the job.
Disassembling the rear unit and rescue the differential is pretty easy, I would say anyone who has ever had a wrench in his hands can do this.
 

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Nice engineering and fabrication. Now we need to find a way to reproduce this in small batches for the few of us that would be interested.
 

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Discussion Starter #6
Nice engineering and fabrication. Now we need to find a way to reproduce this in small batches for the few of us that would be interested.

Thank you, Sir :peace:
Yes, that should be the goal ...I would like to see more TTs with a rear LSD!
If someone has an idea how to do that, I can deliver some drawings.
But since I'm not a professional, of course, everything at your own risk ...:cool:
 

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Fantastic work, and looks like fantastic results! Are you willing to share the CAD models and/or a more detailed list of machining operations? I have an 0AY Haldex from a Tiguan that I'd like to crack open and compare to the 0BY TTRS/RS3 unit.

Sent from my BLN-L24 using Tapatalk
 

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Discussion Starter #8 (Edited)
Fantastic work, and looks like fantastic results! Are you willing to share the CAD models and/or a more detailed list of machining operations? I have an 0AY Haldex from a Tiguan that I'd like to crack open and compare to the 0BY TTRS/RS3 unit.

Sent from my BLN-L24 using Tapatalk
Check your inbox...
 

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Discussion Starter #10
Bravo! That’s all I can say!!!


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Thanks!
Now that I drove a few more miles over the weekend, I have to say that it´s really incredible how the LSD improves the feeling of the car also in permitted speed ranges. The LSD is after the install of the CS coilovers the most noticeable mod I've done so far... can´t wait to test it on a track...:D

By the way; yesterday I got the info that the dealer (from whom I got the other differentials) got a crashed Golf R with a probably broken Haldex unit. If I can get it cheap, we could measure that too, and we would also know the differences to the Golf R diff...
 

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Discussion Starter #13 (Edited)
I heard that the case has to be reduced in a certain area to run the wavetrac?


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Yes, the height of the oil barrier inside the housing needs to be reduced. I machined it down, but you can also trim it with a dremel or something.
Do not machine it flat, the barrier is to ensure the oil flow. As with the original, I left about 3mm space to the wavetrac.
You can see it here:
 

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Wow. Ding ding ding. We have a winner
I am impressed.
Let's fire all the so called professionals and hire all the scilled amateurs...
Why was this not possible with the initial project is beyond me. I lost a lot of money on it. It was me who initially sent a complete Gen. 4 Haldex diff to China or Japan... Can't remember anymore...

If this is possible with the rear gen.5 Haldex on the latest 7 R I am Inn...

Congrats with the first place. You are my hero...

Sent fra min SM-G955F via Tapatalk
 

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Amazing work and even better is the transparency in your process!

This is definitely something I'd be interested in having done for my my car.
 

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Discussion Starter #16
Wow. Ding ding ding. We have a winner
I am impressed.
Let's fire all the so called professionals and hire all the scilled amateurs...
Why was this not possible with the initial project is beyond me. I lost a lot of money on it. It was me who initially sent a complete Gen. 4 Haldex diff to China or Japan... Can't remember anymore...

If this is possible with the rear gen.5 Haldex on the latest 7 R I am Inn...

Congrats with the first place. You are my hero...

Sent fra min SM-G955F via Tapatalk
Thank you, what an honor...;)

I followed this thread back then...so it was you who sent his diff to M-factory...a pity how this all went...
I am pretty sure that the Haldex V unit uses the same diff as its predecessor.
 

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Thank you, what an honor...;)

I followed this thread back then...so it was you who sent his diff to M-factory...a pity how this all went...
I am pretty sure that the Haldex V unit uses the same diff as its predecessor.
Yes it was pity it all ended bad...
If we could source a gen.5 unit from my 7R. Would you be interested in open it and do the measurements and if possible make the first unit for me? I do the payment needed!

Sent fra min SM-G955F via Tapatalk
 

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Discussion Starter #18 (Edited)
Hey,

rescuing and measuring the Diff would not be a big problem i think, but I have some concerns building new ones for someone else:

- There is a lot of money involved.
- As I’m no professional, I can give any guarantee neither on the labor nor on the parts – who´s to blame if something goes wrong?
- It’s very likely that Wavetrac will deny any warranty of the modified LSD.
- It is also unclear how Wavetrac behaves if you want a repair or have it serviced.
- And then there is the labor time and the access to the machine park to do this…

It’s all doable, but in my opinion the best, safest and easiest way would be to find someone in his area who's willing to do the job. Maybe there are shops in different areas that can do this…
This should be the first approach.
 

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To understand correctly.
Do we need a gen.2 Haldex unit for parts to make it work with the Gen.4 Haldex?

Sent fra min SM-G955F via Tapatalk
 
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