AAM 01E high bias center diff.. $275.00 shipped!

[Scotty@Advanced]

We've been installing high bias diffs in our gearboxes for a little over 2 years now and want to offer this product to the 'Zine as a standalone offering. For those not familiar with what a high bias center diff does is it widens the torque proportioning ratio from front to rear, allowing the vehicle (under conditions) to behave more like a rear wheel drive car. What we do to these isn't merely "Shim Slapping" but rather an entire differential overhaul.

The internal gears are cryo treated for the utmost in strength, and shim selections are carefully chosen to eliminate any possible gear stack movement which can cause clunking under tight turns. If the needle bearings require replacement they are replaced.

This is followed by a 1 year warranty on the entire diff, not just the parts we replace. This isn't on our website yet so contact me if you want to take advantage of this. We do have cores (and a $300 core charge) or to avoid the core charge, you can send me your diff. If there is accelerated wear on the gears your core may not be acceptable, if you have any questions contact me.

[Slave IV]

Nice! Noted for when the time comes.

[nefkntym]

Is the B6 01E diff the same?

[Rated S]

Great price, especially with the shipping!
Thank you again Scotty for supplying another great product.

[Turbo Nerd]

I know you guys can do this for the 01A, same price?

[Scotty@Advanced]

Is the B6 01E diff the same?

Yup! we can mod all 01E diffs, from 1992 to 2005.

I know you guys can do this for the 01A, same price?

Yes we might need to have shims made so it would take a bit, but we don't have any 01A cores to process.

[ThirdStrike]

wow nice. you guys overhaul plus shim it while others shim it for almost $200 more.

[*Blue-Angel*]

Yeah I got this done by Advanced Automation when I had my custom gearbox made. I can say it defiantly works as I can punch the gas and the rear tires spin and the car oversteers around turns less effortlessly than stock. I can only imagine it will help at the strip as well when I make it soon as it should help the rear tires hook. Well worth the money especially if your getting the gearbox overhauled at the same time.

[Tarmac]

Wish this were on offer when I purchased my Diff from JHM…this set-up sound much more superior. The entire differential is overhauled & internal gears are cryo treated, very nice!! At this point I haven’t had time to install my new diff & if I do, hope I don’t get that clunking sound under tight turns.

[S4James]

time to update your 4:1 diff upgrade option for rebuilt transmissions scotty.

[Turbo Nerd]

Yup! we can mod all 01E diffs, from 1992 to 2005.



Yes we might need to have shims made so it would take a bit, but we don't have any 01A cores to process.

That's fine I'm about to pull my motor for my build, so down time isn't a biggie to ship it to you. I'll PM you when I'm ready if you want to do it.

[nthusiastt]

Sweet I'm down, Scotty do you have a walkthrough on how to remove the diff?

[Scotty@Advanced]

time to update your 4:1 diff upgrade option for rebuilt transmissions scotty.

We offer an additional discount if purchased with a trans.

[Scotty@Advanced]

Sweet I'm down, Scotty do you have a walkthrough on how to remove the diff?

You bet, it's pretty simple.

Drain transmission, remove rear heat shield around prop shaft (2 T45 torx bolts). Remove prop shaft from trans (6 6mm allen bolts) . Remove rear output flange (5 T45 Torx bolts), and it should pop off, if it doesn't give it a soft whack with a hammer. pull out output shaft and flange taking great care to keep the orientation of the shims. Remove coil spring from torsen if it doesn't come out with the flange. The large bearing you are looking at is the main torsen bearing. The torsen should slide out, and if it doesn't get 2 screwdrivers and gently pry out the diff.

Assembly is opposite of installation, except the last step.. Enjoy the rear power slides you can now do with more rearward bias. Who said you can't drift with all wheel drive!

[hellrot98m3]

awesome, i will be getting this soon along with a rebuilt trans.

[URHank]

Nice Scott. Is the 016 torsen compatible for the upgrade? Also, is 4:1 the limit?

Nice Price.

[Scotty@Advanced]

Nice Scott. Is the 016 torsen compatible for the upgrade? Also, is 4:1 the limit?

Nice Price.

I'm not familiar with the 016, I'd have to have one to dissy and see what it's made of. IIRC high bias is generally around 4-5:1, any more and the helix angle on the torsen gears will have to be changed to modify the bias with an even higher ratio.

[sparkyvw]

How about a welded one for some rwd action?

[ThirdStrike]

You bet, it's pretty simple.

Drain transmission, remove rear heat shield around prop shaft (2 T45 torx bolts). Remove prop shaft from trans (6 6mm allen bolts) . Remove rear output flange (5 T45 Torx bolts), and it should pop off, if it doesn't give it a soft whack with a hammer. pull out output shaft and flange taking great care to keep the orientation of the shims. Remove coil spring from torsen if it doesn't come out with the flange. The large bearing you are looking at is the main torsen bearing. The torsen should slide out, and if it doesn't get 2 screwdrivers and gently pry out the diff.

Assembly is opposite of installation, except the last step.. Enjoy the rear power slides you can now do with more rearward bias. Who said you can't drift with all wheel drive!

Took me about 1 hour total from pulling it out to putting the new diff back in. such an easy job

[Scotty@Advanced]

How about a welded one for some rwd action?

I've got some damaged diff candidates for that! But isn't AWD > RWD?

[sparkyvw]

I've got some damaged diff candidates for that! But isn't AWD > RWD?

Yes but im bored i need some fun lol

[Jurjen]

I will definitely be getting one of these

[sparky17]

Scotty, is there an additional discount with the purchase of a transmission rebuild kit?

[Scotty@Advanced]

Scotty, is there an additional discount with the purchase of a transmission rebuild kit?

Possibly I have not given it any thought. You will save a bit on shipping.

[BITRBO]

Wish this were on offer when I purchased my Diff from JHM…this set-up sound much more superior. The entire differential is overhauled & internal gears are cryo treated, very nice!! At this point I haven’t had time to install my new diff & if I do, hope I don’t get that clunking sound under tight turns.

Same here... Scotty, despite your "entire overhaul" approach, will your modified diff still produce any of the inherit skipping or "growling" under low-speed, tight u-turns? I thought this was the case for any modded 4:1, even the more expensive STaSIS units...

[Scotty@Advanced]

Same here... Scotty, despite your "entire overhaul" approach, will your modified diff still produce any of the inherit skipping or "growling" under low-speed, tight u-turns? I thought this was the case for any modded 4:1, even the more expensive STaSIS units...

Clunking or growling is typically caused by excessive clearance between the gears or the shim stack, not the mod itself. I've had no reports of noise from the units I have in the field.

[Angular]

Stricly from a functional point of view, is there any reason one would not want to do this mod? Just wondering if there are any downsides.

[julex]

Stricly from a functional point of view, is there any reason one would not want to do this mod? Just wondering if there are any downsides.

Well, on high torque cars you will more likely break rear diff/bracket/axles since more power will be directed there by default.

[The_Auto_Tech]

Stricly from a functional point of view, is there any reason one would not want to do this mod? Just wondering if there are any downsides.

That was also my thinking. I was curious if it would make the car behave in a bad way in snow with possibly too much rear wheel bias?

[flyingfish2626]

Stricly from a functional point of view, is there any reason one would not want to do this mod? Just wondering if there are any downsides.

Driving in the snow is not going to be very good. This is the only reason I didnt install this when my transmission was just out.

[jutny]

Driving in the snow is not going to be very good. This is the only reason I didnt install this when my transmission was just out.

I'm gonna go ahead and say that's totally dependent on what you're used to driving. I'm also gonna say its just simply not true.

An understeering pig like the B5S4 needs as much as it can get when it comes to RWD bias, especially in low traction conditions since it has a tendency to not want to rotate. That said, if you've only driven FWD/AWD cars all your life (or never driven a RWD car HARD) a 4:1'd S4 will be significantly not "very good" because you don't know how to drive it properly.

All I've ever wanted out of MY S4 is for it to rotate a little more willingly, and the 4:1 does that. For me, its an issue of safety even over the fun factor... I grew up driving RWD ('70 Chevelle, Volvo 240 and 940 Turbo, Town Cars, 1st gen Rx7's...) through many harsh NE winters and never had trouble as long as I had appropriate tires. Countersteering is totally 2nd nature, and its for that reason that an understeering car is inherently "unsafe" for me, where it is the "safest" for most people that drive.

mind you, i'm not judging the driving skills of anyone here, just assessing the difference in perspective based on your vehicle history.

[Angular]

I don't pretend to completely understand how the torque biasing effect works, especially when all wheels have equal traction (compared to when they do not). This diagram is interesting, though.



And this white paper.

http://zhome.com/ZCMnL/tech/Torsen/Torsen.htm

[Angular]

Driving in the snow is not going to be very good. This is the only reason I didnt install this when my transmission was just out.

I guess the question here is whether or not all wheels receive equal torque when they have equal traction.

[speeding-g60]

so for a drag only setup, this or a welded diff?

[mushasho]

I've got this same tranny in my UrS6... same deal can be granted to us, right?

Sent from my T-Mobile G2 using Tapatalk

[Scotty@Advanced]

I've got this same tranny in my UrS6... same deal can be granted to us, right?

Sent from my T-Mobile G2 using Tapatalk

Yup!

[BITRBO]

Clunking or growling is typically caused by excessive clearance between the gears or the shim stack, not the mod itself. I've had no reports of noise from the units I have in the field.

SO upset I didn't know about your unit a few months back...

[s4-chicago]

might be interested in this, just out of curiosity will 1/4 and 1/8 times be affected much?

[Scotty@Advanced]

might be interested in this, just out of curiosity will 1/4 and 1/8 times be affected much?

Not unless your spinning front tires.

[onemoremile]

I guess the question here is whether or not all wheels receive equal torque when they have equal traction.

So under equal traction or normal cruising the tires have equal torque. Under any conditions that the stock diff would split torque, it does so in the same way but can now send more of it to either end. I've had it for a couple years and it works great in the snow. You don't notice it unless you are trying to and then it becomes a huge amount of fun.