[EFI Logics]

Just recently we completed installing the below items into the EFI 135i:

• Wavetrac ATB limited slip differential
  -OEM BMW gear fluid
  -2 Brand new BMW differential output seals (1 per axel shaft)
• Ferodo DS2500 brake pads
• Motul RBF 600 brake fluid

First up we did the brakes. They came out quickly and easily. The rotors still have life in them so I decided to only swap the pads and fluid. Naturally, I choose the Ferodo DS2500s after having used them in different platforms I knew this pad would be a good choice for balanced street and HPDE/AutoX driving. We made sure to bevel down the edges of the brake pad for smooth initial engagement. This helps to eliminate the noise upon first use. The OEM fluid definitely had to go after having been in the car for some time in favor of the Motul RBF 600 fluid. Its boiling point is resilient enough to withstand high temperatures and provide good feel for the pads, which it does very well.

After the brakes were taken care it was time for the differential. Using the uniquely sized wrench (I believe 52mm), we removed the rear end from the car and sent the differential to Autotech Driveline in Florida. **********s supplied the differential through their installation kit and partnered with Autotech in which they separate the ring gear using CNC machinery. The gear is then machined, tapped and threaded to match up with the Wavetrac differential. The differential is fastened to the new OEM gear using 10 ARP ring gear bolts. After completing the job the differential was then sent back to us for reinstallation back into the car. The only thing to note is the differential needs 2 new seals (BMW Part # 33 10 7 505 605 for my 08 manual 135i) in order to be reinstalled back into the car. I used OEM BMW fluid (filled in Castrol containers from BMW) because that is what was recommended by Wavetrac. You are not limited to only BMW fluid though.

Driving Results:

I choose this setup to be able to withstand HPDE aggressive braking and increase rear end track in all situations. It made a massive improvement in all situations requiring rear end grip such as off the line pulls, launches and powering out of low-speed corners! Simply put, the Wavetrac differential is the best improvement I have made. No doubt… It is absolutely awesome. Drifting is so much easier now in comparison to the factory open differential. Beforehand I felt I had to use the weight of the car aggressively to be able to get a slide going. In my mind, that’s a slide and not a drift in which you can use the power to get the rear end to rotate. I admit though that due to the increased rear end grip and control gained from the differential the rear end now feels softer. That’s why I picked up the Powerflex rear subframe inserts in advance, but those have yet to go in.

These pads are definitely up for some abuse. They are super smooth, they engage nicely and I feel you can control the pad pressure really nicely. If you let off the brakes just a bit after approaching a turn hard, the pad will release easily. They dust about the same levels as stock. You can’t really expect less from a pad that will withstand higher temperatures, more aggressive use, provide better feel and remain quiet. However, they do make an slightly audible click when go you from forward to reverse, or at a hill, because they tap within the caliper. They do not fit as flawlessly as factory but it is so quiet and hardly noticeable that it doesn’t bother me the slightest bit.

Thank you Elliott at **********s for you working with me to get this completed!

Next Up:

Install some last minute bits and hit up Pocono and NJMP!

Here are some pictures:



















NOTE: I didn't do Eibach springs as well. They were just in the shot.

-Josh

[turugara]

When's your next njmp day?

[TurboBimmer]

Nice writeup! Are the DS2500 pads quiet in daily driving?

[EFI Logics]

Originally Posted by turugara

When's your next njmp day?

I'll be out there September 10th with SCDA. Are you running NJMP as well?

Originally Posted by Autobahn335i

Nice writeup! Are the DS2500 pads quiet in daily driving?

Thank you! Yeah, totally. Since we beveled the rough edges down before putting them in they literally didn't make a single squeak, even on first application. I expect a little noise, probably more in the winter time when it's cold outside, but they really aren't obnoxious at all. In my opinion, they're the best dual purpose pad you can buy for a mid-weight sports car that sees light track duty. The only downside is they're a tad expensive when you look at them in relation to competitive pads. Totally worth it though...

-Josh

[nitehawk]

Is the OEM gear oil 75w90 or 75w140?

The OEM stuff is pricey! I spoke with Wavetrac today and they mentioned Motul Gear 300 75W90 and Gear Competition 75W140 are good alternatives to OEM.

[BMW Junge für Leben]

i installed my wavetrac a couple months ago and it is by far away the best mod i've done to my car, couldn't agree more with you! from everyday driving to pushing it on the track the wavetrac has improved my car no other mod has yet!

[CJ421]

Nice pics and writeup. I can't agree more that an LSD is the #1 performance enhancer for these cars, bar none. It's disappointing we don't have an LSD from the factory; LSDs weren't always restricted to the M cars.

I'd go for the solid subframe bushings to be honest. I had the M3 bushings and they're still not all that hard. Far better than stock however. The subframe is held on very poorly in the stock 135i/335i (it's not even a full bushing, hence you can fit in those inserts).

Did you put on aftermarket toe arms yet? Those will eliminate the rear's tendency to steer the car under acceleration.

[EFI Logics]

Originally Posted by nitehawk

Is the OEM gear oil 75w90 or 75w140?

The OEM stuff is pricey! I spoke with Wavetrac today and they mentioned Motul Gear 300 75W90 and Gear Competition 75W140 are good alternatives to OEM.

I can't say I know off the top of my head, but I can find out. It is pricey fluid, for sure. A friend at a local dealer gave me a good price though. Motul makes some top qualities fluids and their gear oil would work just fine as well.

Originally Posted by CJ421

Nice pics and writeup. I can't agree more that an LSD is the #1 performance enhancer for these cars, bar none. It's disappointing we don't have an LSD from the factory; LSDs weren't always restricted to the M cars.

I'd go for the solid subframe bushings to be honest. I had the M3 bushings and they're still not all that hard. Far better than stock however. The subframe is held on very poorly in the stock 135i/335i (it's not even a full bushing, hence you can fit in those inserts).

Did you put on aftermarket toe arms yet? Those will eliminate the rear's tendency to steer the car under acceleration.

Thanks my friend! Yeah, way back when the non-M cars were were fortunate. You've got a really nice setup on your car!

Yes, the M3 replacements would make an even better improvement but we will not be doing it for my car. They are still an OEM bushing so they will always deflect a bit as they were intended for road use. If you want something that will give you precision feedback you can always go with something more aggressive, but I would not recommend it for a car that sees street duty. Having a little feedback through deflecting suspension bushings, as opposed to them being extremely solid and firm, isn't necessarily a bad thing for feedback and control. Even running up on a bumper on a road course in a car that's solid as a rock can upset the grip. You ever see a time attack car hop?

I am still utilizing the factory toe arms as well. Those would make for a nice improvement in the rear end without a doubt...

-Josh

[CJ421]

Thanks Josh - appreciated.

I have the Rogue Engineering toe arms and they do the job, but you've likely seen this thread regarding longevity issues with the spherical bearings ...
http://www.e90post.com/forums/showthread.php?t=658930
I like the Megan Racing ones, they are solid. Definitely gonna get those when mine wear out.

I'm interested to hear how the Powerflex inserts work out for you. I've heard mixed things (mostly skewed by the fact you don't have to drop the whole subframe to install). The M3 GTS and I think the new M5 both utilize solid subframe bushings. And the solid bushings ... yeah, it's still debated whether the solid bushings can work in the long term in our cars without averse effects on the body. I think the E9X was actually designed to have some play/deflection back there. I'd put my concerns to rest if I saw the E9X M3 and the M3 GTS with the subframes removed to see if there's any additional reinforcement where the subframe connects to the body. It seems to me though that BMW has had a lot of trouble figuring out the rear subframe - the E9X doesn't have as bad of subframe-related issues as the E46, but it still does. Anyways I'll stop ranting. Here's threads on the topic if you're interested:
http://www.m3post.com/forums/showthread.php?p=7234453
http://www.m3post.com/forums/showthread.php?t=696371

P.S. I have Redline Synthetic 75W140 in my Quaife differential. Works great.

[EFI Logics]

Originally Posted by CJ421

Thanks Josh - appreciated.

I have the Rogue Engineering toe arms and they do the job, but you've likely seen this thread regarding longevity issues with the spherical bearings ...
http://www.e90post.com/forums/showthread.php?t=658930
I like the Megan Racing ones, they are solid. Definitely gonna get those when mine wear out.

I'm interested to hear how the Powerflex inserts work out for you. I've heard mixed things (mostly skewed by the fact you don't have to drop the whole subframe to install). The M3 GTS and I think the new M5 both utilize solid subframe bushings. And the solid bushings ... yeah, it's still debated whether the solid bushings can work in the long term in our cars without averse effects on the body. I think the E9X was actually designed to have some play/deflection back there. I'd put my concerns to rest if I saw the E9X M3 and the M3 GTS with the subframes removed to see if there's any additional reinforcement where the subframe connects to the body. It seems to me though that BMW has had a lot of trouble figuring out the rear subframe - the E9X doesn't have as bad of subframe-related issues as the E46, but it still does. Anyways I'll stop ranting. Here's threads on the topic if you're interested:
http://www.m3post.com/forums/showthread.php?p=7234453
http://www.m3post.com/forums/showthread.php?t=696371

P.S. I have Redline Synthetic 75W140 in my Quaife differential. Works great.

Yeah, spherical bearings are always prone to longevity issues... They just don't have the durability and need to be rebuilt after awhile.

Good points on all accounts.

-Josh