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Old 04-01-2017, 02:28 PM   #1
rumatt
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E46 LSD options

I'm trying to pick an LSD for my car. I'm leaning toward the MFactory helical, but I'm just not excited about it. I like the idea of quiet and low-maintenance, but am wondering how often I'm going to end up spinning one wheel anyway (I did get a stiffer rear bar...) If I could find a quiet clutch type I could be convinced to jump to that instead.

Nick, didn't you have a diffsonline diff? Was it noisy? Did you like it?

Options thus far:

MFactory helical / torsen: MFactory highly recommends for a street driven car. They downplay the odds of spinning one wheel and say you'll love it.

MFactory 1.0 or 1.5 way: MFactory says they're noisy and not recommended for street

Wavetrac: A helical that supposedly prevents wheel spin during lift. Sounds ideal in theory... but JV heard bad things about them

diffsonline: Their site tells me very little

OS Gilken: double the price and require more frequent oil changes.

Last edited by rumatt; 04-01-2017 at 02:46 PM.
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Old 04-01-2017, 02:43 PM   #2
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I just noticed that diffsonline sells clutch-type as well as helical and wavetrac. I emailed him to ask his opinion on all of them.


EDIT: Got this reply right away from dan. Not particularly informative (?)
Quote:
Matt,

Wavetrac is the only street one that has a locking mechanism to prevent free wheeling when one tire has zero action. I have 10 more coming Monday so getting that done next week would not be an issue.

Other great option would be my 3 clutch setup. This is modified BMW carrier we machine in house to work in the e46 case. This means it drives as a BMW should.

Either carrier is a great solution. The Wavetrac is appealing to many as it requires less fluid changes.

Ratio wise a 3.38 works great for a street driven 5 or 6 speed 330. If Auto I would do a 3.64.

Hope that helps and looking forward to working with you.

Last edited by rumatt; 04-01-2017 at 02:59 PM.
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Old 04-01-2017, 03:13 PM   #3
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Quote:
Originally Posted by rumatt View Post
Wavetrac: A helical that supposedly prevents wheel spin during lift. Sounds ideal in theory... but JV heard bad things about them

I don't see any difference from a traditional helical in the second half of this video

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Old 04-01-2017, 03:31 PM   #4
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I have two diffsonline units. One of them I bought used, and it slightly whines (it may have had the input flange swapped, which can cause pinion whine if it's done wrong). The one I bought new is in the race car and it's been great.

We just installed a (used) wavetrac unit in Mike's E90, but haven't driven it yet. It does spin both wheels in the same direction on the lift, but I can't speak to how it behaves in reality.

OS Giken has been incredibly unreliable in E46 applications. Failure after failure after failure is what I hear. I would not consider it.

The upshot of helical is that it gives you a basically completely clean steering response. Clutched diffs will be a lot more likely to impact steering in some way. Helical diffs also basically don't wear out, which has some virtues.

Personally, I really like the way that the 30/90 diffsonline units drive. On a street car, this is less of a factor though. I wouldn't have done the E36 diff if it hadn't been fairly cheap.
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Old 04-01-2017, 03:41 PM   #5
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Quote:
Originally Posted by Nick M3 View Post
We just installed a (used) wavetrac unit in Mike's E90, but haven't driven it yet. It does spin both wheels in the same direction on the lift, but I can't speak to how it behaves in reality.
I asked Dan about the Wavetrac (sent him that video) and he replied this:
Quote:
The Wavetrac does actually work. If that was an open diff you would barely move. The coupling inside makes sure some power is transferred to the other wheel. Out of all the helical carriers it is the best and I have a lot of friends who run them in their street cars that go skiing every weekend regardless of the roads up here.
Of course I wasn't comparing it to an open diff, but another helical


He doesn't allow anyone else to install his diff internals.
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Old 04-01-2017, 03:49 PM   #6
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Where​ is the option to just do whatever JV says?

I had a helical in the front of a Jeep for years, never even knew it was there. That said, I can't imagine noise would ever be an issue for you on any diff. It's not like this is some quiet new luxury car.
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Old 04-01-2017, 03:59 PM   #7
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Where​ is the option to just do whatever JV says?
He told me I had to pick.
Quote:
That said, I can't imagine noise would ever be an issue for you on any diff. It's not like this is some quiet new luxury car.
When the guy who sells them tells me I don't want it because it's noisy.... that seems relevant.
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Old 04-01-2017, 04:16 PM   #8
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Well, I'd do a clutch type and live with the noise. If you want quiet and maintenance free, get a helical.
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Old 04-01-2017, 04:51 PM   #9
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OS Giken is discontinued. They had to spec an undersized unit for the E46 because the case is so narrow. That ended up being a bad idea.

Jim Blanton (Performance Gearing) and Dan ( Diffsonline) will sell LSDs but only Jim will let you do the install and setup. I have dealt with Jim a lot and he is very quick and reliable. I've bought parts from Dan (crush sleeves and a set of gears way back) and he's fine too.

Here is the deal. I would not put a helical in my car for the street. I thought the wavetrac would be a "best of both worlds" thing but what I'm hearing is they aren't great. They end up acting like an open diff in about the same conditions as a helical.

The clutch type diffs should never make pinion or gear noise. That is purely setup error. Going down the road straight or around turns at speed you will never hear it. Clutch type diffs will make noise in tight parking lot maneuvers at low speeds. First, you'll hear the inside tire skidding as the clutch plates are trying to equalize the speed of the rear tires. Second, you may sometimes hear the clutches clunk a bit. Both of these noises can be minimized but not eliminated if you want the LSD to actually work.

Clutch noise gets worse the more static preload the diff has. I had Jim build my diff with 90lb-ft of preload and I run Redline shockproof oil with no additive... super thick gear oil. The MFactory diffs will have much less preload than that. I'll also put some friction modifier in the fluid to reduce the clutch noise and we'll run Redline 75/90 standard fluid which is thinner.

I'm happy to put a Blanton diff in there, but it's double the price of the MFactory unit and I don't think you'd be any more happy with it than the MFactory. The MFactory set up as a 1.0-way diff should be similar to Nick's 30/90 ramp diff. A 30 degree ramp on acceleration and a 90 degree ramp (it's probably like 85 degrees in reality) means it'll lock up very hard on acceleration and be almost entirely open on decel, which is great for a street car or autocross car.
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Old 04-01-2017, 06:06 PM   #10
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Yup, I've had clutch diff's in many cars, no reason not to go that route imo.
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