DEFIV Rear Differential Brace REVIEW

[NikB316]

Intro
I contacted Rick @ Defiv many weeks ago regarding the rear diff brace he made for the e92 M3 after reading the review posted and watching the wheel hop video. Even though I don't launch my car a whole lot, I was very intrigued by the review mentioning how it took care of a great deal of the DCT sloppiness. I knew this product would be even more so beneficial with the upgraded AA Gen 2 Stage 3 kit I was putting on. Rick was awesome to deal with and gave answered any questions I had very promptly with great detail. He had everything built in less time than originally estimated and was extremely patient and understanding with my schedule being moved around a bunch.

Install
I dropped the car off on a Tuesday night at Rick's garage in PA. Talked to him for quite a bit and he is VERY knowledgeable with all types of high HP cars. He is very passionate about what he does and quite the enthusiast. I also asked Rick to let me know how he felt overall about the car as I always like getting opinions from people who know what to look for. Rick was more than accommodating to this and any other requests I had. Rick started texting me the next day with updates and pictures throughout the install. Again, awesome service! I picked up the car on Thursday night as promised. The car was freshly hand washed using quality products and my tire pressure was properly adjusted. I didn't ask for either but do I have to mention again how good the service was?

Impressions
When I picked up the car I had Rick take me for a spin to see his opinions on everything. Even from a passenger's point of view, the rear of the car felt very solid (like a brace was put on...hmm...). Had some fun with the DSC off and no wheel hop where the car would usually be all over the place! NICE!I have driven the car for about 10 days now and will try to summarize my impressions. The rear of the car used to feel like it would bounce around a bit and now it feels totally planted. This has given me a big increase in confidence while driving. As mentioned above, you literally feel like a brace is holding the rear tightly.A HUGE added bonus to this is that the DCT transmission is running flawlessly now! I have driven many e92 M3s, owned NA & FI ones and all of the DCTs had some hiccups - from a bit of lag when downshifting every now and then to just some other odd behaviors. I have tried to get my car to repeat the small hiccups I used to experience and haven't been able to. I have probably put a good 500+ miles on the car since pickup and WOW. The car just feels so much stronger!

Conclusion
In my opinion, this is the best ~$1k (including labor) I've spent on the car, period. This is MUST HAVE for any M3 especially you DCT guys! I cannot speak for you 6speed guys but even if there is no added benefit to the transmission, it is still a big improvement on the car. Especially without having to spend thousands. I know it always helps to be able to test out a product before buying so if anyone is seriously interested they are more than welcome to go for a spin in my car.

Rick, you have done an excellent job with this product and your service. A+.

[j2m]

That's pretty cool
Do you have any pics of the brace before it was installed?
Is it welded or bolted on?

[e92zero]

wonder if this will take care of the broken diff bolt problems that some are having.

[jjw2331]

Did you notice any NVH?

[JDM3]

Sounds like a great mod for those with wheel hop. I've NEVER experienced wheel hop and I've put my car through its paces. 600whp and a couple hundred launches at the quarter mile. Personally, I wouldn't waste 1k on this....

[M3takesNYC]

But vary based on each car. My DCt has always been flawlessly smooth, no lag and precise. Never have experienced wheel hop. Not sure this mod is for everyone.

However perhaps I would question if this is a bandaid to the underlying problem of why you are having that much wheel hop to begin with? Perhaps there is something inherently wrong or not right in your suspension setup inthe first place that this brace is masking because the vast majority of us don't struggl with your symptoms

[NikB316]

J2M,
I don't have any but I can see if Rick does.

jjw2331,
No vibration or harsh at all. Rick did let me know before installing that I might experience some noise. If there is a noise it's not something really noticeable given my exhaust (not too wild) and supercharger.

M3TakesNYC,
I would love to see how it helps more stockish M3s. My buddy who doesn't have any serious performance mods may be getting it put on. Most of the FI guys I have talked to encounter some wheel hop. Thinking back to the 08 M3 I leased for 3 years without performance mods, I didn't have as much wheel hop but the DCT didn't feel as crisp as it does. I also had a Carrera with PDK which is smoother and didn't have any of the imperfections that were on the SMG (e60 M5) or DCT. I always keep that in mind for reference.

[FogCityM3]

Wonder if solid differential bolts would get you 90% of the way there

[italyix]

Originally Posted by mhabs

Wonder if solid differential bolts would get you 90% of the way there

Definitely cheaper than doing the brace. Having both subframe bushings and diff bushings, my car feels solid. There is zero slop, although my route was more expensive than the OP brace.

A great alternative to whomever does not want solid bushings with added NVH. Nice piece OP!

[1MOREMOD]

im not sure how people havent had wheel hop. go out in the rain take of traction control and stand on it in a straight line. the ass end dances around and feels like the differential is gonna fall out.

[NikB316]

Exactly. It's definitely more pronounced with all the power now but still...

Originally Posted by 1MOREMOD

im not sure how people havent had wheel hop. go out in the rain take of traction control and stand on it in a straight line. the ass end dances around and feels like the differential is gonna fall out.

[NikB316]

There's a bunch of information here along with the original introduction to the product:
http://www.***********.com/showthrea...-final-testing

[NikB316]

Not sure why it isn't showing up above but here's a bit more info on explaining "What it does..." from Rick. He has worked on some very high power cars and have had a similar brace for the 335 for quite some time I believe.

"Well, my initial driving impression of a s/c E9X M3 left me noticing a large deficit of proper power transfer to the rear tires and excessive chatter/hop from launch on the right surfaces, most notably a certain amount of instability/odd behavior during tire spin. There wasn't a sense of which way the car was going to go during aggressive wheelspin and high rpm DCT upshifts felt very "twitchy",if not a little dangerous. Further inspection revealed that the front two bushings matched the same poor design as the N54 cars and were damaged to a greater extent. Most importantly it shares the same terrible 3 point mounting strategy, which is the birthplace of wheel hop,albeit the upper rear bushing seemed to be stiffer than the N54's mount. Another thing that struck me as horrifically insufficient for higher output S65's was the actual LSD unit's design itself, the short/long axle shaft/axle cup spline design and the fact that the passenger side rear wheel can only receive a portion of the power at best leaves me in a position to highly recommend doing an OS giken conversion if boosting your S65 or building a stroker/etc. The factory unit is set to fail under extreme loads, not to mention power transfer is undesirable. Regardless of what lsd unit one runs power and the fact that the differential unit can twist/bang around once shock is applied will lead to only one thing; breakage will occur despite the stronger components utilized in the M cars. The theory and design of this variant are exactly the same as the N54 design, although the differences in diff covers,subframe design,etc led the actual solution looking quite different...but it's job is exactly the same. As a sidenote, I have been using OS giken with Supras for many years, so I can do the OS diff installs if need be as well as the supporting modifications/machining required to do so. OS converts the diff assembly to a stronger and much more stable equal length spline shaft/clutch type lsd unit that mirrors units they have been very successful with in preceding years. It's my first choice in clutch type lsd's. highly recommended in boosted/high output apps. Favorable results/added stability were gained running an oem lsd, much more than I expected. It really tightened up the back end of the car, I'm going to let LM get a full impression of the differences in the car because of his seat time preceding the changes eclipses the short test drive I had beforehand.I'll wait on his input before releasing officially, only because i want to ensure perfection."

[NikB316]

Nice man! Not too many people out there yet with these similar mods but man they really make a big difference. I'm sure when someone actually takes a car properly setup for a ride they will see...even handling wise the car feels better no doubt. Doesn't feel like the rear is bouncy.

Originally Posted by italyix

Definitely cheaper than doing the brace. Having both subframe bushings and diff bushings, my car feels solid. There is zero slop, although my route was more expensive than the OP brace.

A great alternative to whomever does not want solid bushings with added NVH. Nice piece OP!

[Vic311]

Very interesting, so this takes swapping the rubber diff mounts for solid mounts a step further by introducing a subframe to diff brace, essentially unitizing AND bracing the diff and the subframe. This upgrade seems very worthwhile if you launch consistently.

A good DIY on it with more pics..if anyone is interested

http://www.e90post.com/forums/showthread.php?t=806041

[NikB316]

Great link. I know Rick is a bit more well known in the 335 community and the M3 brace is really new. I'm one of the first few with it on.

Some more info copy and pasted for you guys...


"Well, the //M specific diff brace/lockdown process of design is done for the most part, the test vehicle is back in the hands of it's owner and will be available once more comprehensive feedback/video is acquired from said owner. That being said, I had to re-design this one from scratch, it shares similarities with the N54 cars only in regards to the two front diff bushings, everything else is drastically different. A jig has been made for replication and during the process I realized that there are several ways to offer this as far as materials used in duplication, naturally cost increases will apply to which material I use, so I figured it would be best to get feedback from the community in regards to the matter. The initial prototype was made from 4130 chromoly steel, which was selected mostly because there's mountains of it around the shop, the only drawback is the manufacturing of each unit is time consuming, probably double what the second version takes to make, which utilizes 4130 plate steel, cut to a template. equally as strong, but about 12-15lbs heavier. Each piece that is made from 4130 will require powdercoating, which bumps the price a bit again. obviously the full tubular design is more attractive and much lighter,but the use of that would drive final cost near $800-900+,whereas the plate version would be a bit more affordable...and as an added dimension in expensive materials, I could use titanium as well but now were talking well over $1k...but I could make them if desired, those would be made to order obviously. I believe I have enough spare Ti laying around to make one at this point. So, thoughts/feelings/questions regarding the final incarnation of this would be greatly appreciated. here's a teaser of the tubular one in the jig.mounts to car via supplied polyurethane bushings on either end."

Originally Posted by Vic311

Very interesting, so this takes swapping the rubber diff mounts for solid mounts a step further by introducing a subframe to diff brace, essentially unitizing AND bracing the diff and the subframe. This upgrade seems very worthwhile if you launch consistently.

A good DIY on it with more pics..if anyone is interested

http://www.e90post.com/forums/showthread.php?t=806041

[AlteredBe4st]

Originally Posted by 1MOREMOD

im not sure how people havent had wheel hop. go out in the rain take of traction control and stand on it in a straight line. the ass end dances around and feels like the differential is gonna fall out.

I second that statement. 1k on a brace, I'm not impressed.

[1MOREMOD]

Originally Posted by ajcxnejx

I've NEVER experienced wheel hop and I've put my car through its paces

follow my instructions and you will.

[NikB316]

Originally Posted by Purple Derple

Sorry is this part a diff brace or a tie bar? Hard to see from the photo. Seems to me like this won't do anything to prevent wheel hop but may help save your diff in the event it does happen. May help in keeping the pinion angle from winding up, but again i dont know where the feelings of stability and "planted" are coming from. Thanks for quoting the marketing material from the prospective vendor btw that's really objective stuff.

Definitely helps with wheel hop. I have witnessed it first hand with my car as well as other owners on both 335s and M3. Here's a video of another user with an ESS Supercharged M3...

I can't tell if the last sentence is sarcastic?

Lenzm3edan,
I would recommend driving a car with the brace on before coming to conclusions. I have had a ton of mods and $1k (Including installation) is very fair for what this product does.

[mkPOTO]

very interesting, would of loved to see numbers before and after at a track or something

[VCP]

The differential and its torque twist witch is cause by the rubber mounts it hangs on is a big cause of wheel hop the differential will twist more then you think. Most times wheel hop happens is launching the car and the tires are grabbing for traction. Each little slip of traction the torque twisted differential will unload and the rubber bushing will spring the differential back to a neutral position. The regain of traction will load the differential twisting it down again starting a pendulum affect that will make the suspension load and unload wheel hop happens. There is many other causes for wheel hop but on IRS rear ends this is the main one. The differential brace he is reviewing will help keep the diff from loading and unloading helping with wheel hop.

I do believe it happens on the m3 in varying degrees many times the driver will not feel it. Other times BAM BAM BAM BAM. HP levels, tires, age and state of rubber bushings all play into wheel hop. Take a stock hp m3 with some big sticky rear tires and do some good launches probably get some mean hop like being on a sticky drag strip starting line. I say stock hp m3 for the reason of not having the compete power of over whelming the tires. The feeling of the car becoming more planted and stable could be from lsd differential being able to work more efficient in a turn due to it not waiting for the bushing to react to on and off throttle inputs. Just my two cents....

Originally Posted by Purple Derple

Sorry is this part a diff brace or a tie bar? Hard to see from the photo. Seems to me like this won't do anything to prevent wheel hop but may help save your diff in the event it does happen. May help in keeping the pinion angle from winding up, but again i dont know where the feelings of stability and "planted" are coming from. Thanks for quoting the marketing material from the prospective vendor btw that's really objective stuff.

[swamp2]

A few comments.

• If the product can/does eliminate wheel hop it could be a great product. I have had wheel hop on multiple occasions and it does feel like the rear end of the car is falling apart.
• Pics are terrible and the link to the non M system doesn't help as the systems appear very different.
• I do not at all buy these overly optimistic (imaginary) reports of all sort of benefits and improvements in feel, more solid, less bounce (sure less wheel hop, maybe).
• There shouldn't really be any more benefits for a DCT over the 6MT.
• It simply can not improve any flaws/shortcommings you have found with the DCT. This is in your head OP, sorry.
• Quotes from the designer of the system need some serious improvement. It sounds like bable/techno babble without really getting to any sort of engineering/technical explanation of the product and what it is actually doing. Too bad VCMperformance had to fill in for the vendor with a reasonable good/simple explanation of what this product actually does.