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03-13-2013, 12:57 AM | #23 |
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I am definitely interested in this if it will fix the diff bolt breaking problem. But I would really prefer not to increase the NVH on this car. What's at the 2 ends of the brace where it attach to the subframe? Are the rubber or poly or hard bushings?
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03-13-2013, 02:06 AM | #24 | |
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There website is very light on info, but it is the same chassis so the link for the non-m is essentially what it looks like for the M3 just different specs. I am not sure I buy into the no NVH part as they are replacing the 3 oem rubber diff mounts for solid ones and using a 4th brace all of which will transmit diff noise. For full result it's probably best to go with just the solid diff mounts and solid subframe bushings..but that is the more costly route |
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03-13-2013, 08:18 AM | #25 | |
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Imaginary reports? Sounds like you've taken my car for a spin.
The only people who have driven my car since the brace have commented on how the back feels more solid. Or maybe it's a placebo effect on all of us? Including a couple of people that have probably driven 100+ M3s combined... I'm not the only one to report it helping out the DCT slopiness. There are some people who have driven my car before and should be driving it later this week I'm better weather. I'm sure they can chime in. The DCT shifts hard, sends a pulse down the driveshaft to the diff, without brace the sloppiness if the diff mounting absorbs and delays the energy to the wheels by moment alone. The brace allows for the energy to transfer more directly. The potential vendor may be opening up an account here. I was simply copy and pasting from a forum - not quite meant to be any official statement. I am in no way affiliated with the vendor. Did not receive any discount on the product (even though I tried!), etc. Might want to try something before you knock it. As I said, if anyone wants to drive my car to get a feel all I ask is that you meet me at my convenience. Quote:
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03-13-2013, 08:20 AM | #26 |
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The E36M3 is known for breaking diff mounts and there are several braces available that help. I run one, have over 500 rwhp and over 500 lbs rwtq, and have never broken the diff bolt even on drag radials. I also use harder poly diff bushings and those alone might do the trick. I'd like to see a set for the E90M3 as an option short of solid and short of a brace.
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03-13-2013, 08:28 AM | #27 | |
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Rick did warn me of the possibility of some diff noise. The other customer experienced some noise when decelerating I think at 60+ not nothing really bad. Keep in mind he has a very loud exhaust system. After listening again there may be a faint noise but I really can't tell between my exhaust and supercharger. Rick didn't find anything when testing out the diff on my car but if I'm around his area I told him to take my car for a spin to check up on.
There is definitely no added vibration or anything else, at least on my car. The other option you mentioned is really interesting and would love to see the outcome. The more products available for the community the better! Hopefully Rick will get a chance to chime in and answer everyone's questions. I just made him aware of this thread. This is my written review so I will answer anything as best as possible. Keep in mind my technical knowledge is pretty slim but having driven 50k+ miles on a relatively stock DCT NA M3 and my DCT FI M3 I am pretty familiar with these cars. Quote:
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03-13-2013, 08:35 AM | #28 | |
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Yeah I was just talking to the shop that handles my engine work and have done a lot more high power E36 builds. They have a brace fabricated and seems to definitely help out. Would love to see if using harder poly diff bushings would help. I'm sure we will see more of these types of fixes as the FI M3 market is rapidly growing with all of the preowned M3s available.
Btw nice numbers - esp that torque. Hopefully it's only a matter of time before a nice turbo kit is out for us e92 m3s. Quote:
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03-13-2013, 11:51 AM | #29 | |
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Some praise and skepticism along with a request for a better written description of the product and better pictures is not knocking it. No need to get defensive over your choice to have this mod.
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03-13-2013, 12:26 PM | #30 | ||
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As far as NVH, this kit is replacing the 3 factory bushings and it's adding another mounting point that might be solidly mounted to the sub frame. If that is the case, NVH will definitely increase. Will this help a DCT more than a manual? No. In fact it should help a manual a lot more. Ever seen how harsh a 6MT power shift is? Sadly, there is no technical specifications on this product and going by how something "feels" is not the best method of testing the efficacy of this bracing kit. No pictures, no drawings... these things would help. I am with swamp2 on this. |
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03-13-2013, 12:45 PM | #31 |
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^I can see the lock down for the 335i/135i adding to NVH as it replaces the factory rubber bushings with the solid ones and even the 4 link is a solid connection. However, the brace for the M3 is different so I am hoping it won't add to NVH. Given the long bar as the leverage for the diff, the bushings at the end of the bar where it attaches to the subframe might not need to be that hard parhaps? I guess we will see when more detail comes in.
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03-13-2013, 01:28 PM | #32 | |
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You shouldn't take a reply as being "defensive" - isn't this a discussion board? Purple, I understand what you are saying but keep in mind that I am no manufacturer nor did the manufacturer make any claims other than what the actual product is and that it can help with wheel hop. DEFIV didn't mention once to me that the car may feel more planted and stable as it does. Didn't even realize it was a mod that I would be feeling while driving the car throughout and not just launching. I only came to realize this when I picked up the car. The other benefits I am feeling are my own views which are shared by others who have had a chance to experience the product. DEFIV has done work on some very high HP cars and is a small independent shop. Am I skeptical of manufacturer claims? Sure. There is plenty of BS - and not only from the smaller guys. I bought this based on learning about it from the manufacturer and speaking in depth about it to someone who has had it on their car before mine who's judgement I trust. I guess the placebo effect has been hitting everyone who has tried it out! This is just my own personal review. For specific questions you are best contacting Rick at like.defivfab@gmail.com. Hopefully he will be on here sometime to answer your guys questions and have an informative discussion on what I feel is a very beneficial product.
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03-13-2013, 02:14 PM | #33 |
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Ok, I'm here to answer a multitude of questions in regards to what this is, why it works and whatever else you'd like to throw my way. We'll start with the factory differential mounting strategy-for whatever reasons, bmw opted to utilize a 3 point mounting system on this car.Any understanding of torsional loading will quickly unveil the faults of the design, perhaps it isn't as apparent on factory or lightly modified cars,but when a supercharger or added displacement,etc falls into the mix, the weakness of this design becomes apparent-especially with the dsc off. I was approached by a local s/c M3 owner preceding the OP's install do devise an M variant after the success of the N54 version. Balancing between effectiveness and low nvh was not immediate, I ended up having to utilize the solid forward diff mounts (same as an N54 car) which are billet aluminum. Originally,the brace was solid mount to the subframe, but excessive nvh became apparent, so the design was altered. Two brands of polyurethane were used before deciding to have a softer formulation made via Energy suspension, which is now in use. The way it works is rather simple, it essentially mounts to the differential via 4 of the cover screws and then affixes to the subframe via a custom insert nut and sleeve system in the drain holes located just inside of the rear subframe to body mounts. It does it's job by restricting the differential from rotational movement under load. Wheel hop is created by a reactive effect of a multitude of areas. the first being the tires as the fight for grip-all this rotational loading is applied back to the differential-which is receiving steady power in via the propeller shaft. The resulted reaction is a push-pull effect which is where the 3-point system shows it's weakness. The passenger side will then bounce up and down creating a tramping effect, which transfers back to the wheels and the suspension will amplify this motion via the springs. that's how wheel hop works, and why it's prevalent to some with higher output and more aggresive driving styles. It's interesting to note that these effects can be tamed slightly via stiffer suspensions/ coil-overs on some cars, alignment plays a role-but none of those solutions solve the core of the issue, they're simply band-aid approaches. If you drive your car in a way that hop doesn't present itself then obviously this product isn't for you, I'm not here to argue why every M3 needs one, because they don't. Those of you who do experience these issues are whom the product was intended for,plain and simple. Results so far have been very positive, I understand we live in a suspicious and proof thirsty world(I'm probably worse in regards to skepticism than most of you, so I can understand)
As far as shift feel goes, the same benefits apply to DCT or MT6 cars. Restriction of unwanted movement results in tighter upshifts and stability regardless of transmission type. As far as track testing is concerned, It's winter here in PA so that's currently impossible although proper before/after documentation will come in the spring.If there's any specific data anyone would like to see, feel free to ask. The brace shown in the OP's pic is one of 3 variants, it is the "plate" style. Next in line is the 4130 chromoly tubular version, which is lighter obviously. I'm currently working on a limited run of Titanium braces which will be a numbered production run. These are all currently made to order, I will post pictures of the other versions as they are made, which will be within the next week or so. Any other questions you may have, feel free to ask me via post/PM. I will inquire into vendor fees before discussing sales here. Thanks Rick@Defiv Fabrication. |
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03-13-2013, 05:41 PM | #34 | |
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The best thing you guys can do is drive a car that has it and compare for yourselves.
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03-13-2013, 06:59 PM | #35 |
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I guess I could see how this could help. The gear changes in S6 going all out in 1st and 2nd are downright thunderous! I would have to think that takes a toll on the differential! Man those 1st to 2nd gear shifts in S6 at WOT is just absolutely satanicly abusive. Reminds me how much I love it!!
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03-14-2013, 12:05 PM | #36 | |
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Power applied to diff-causing pinion climb-this is correct. The oem rubber bushes allow for up and down movement,so as power is applied the nose of the differential climbs. This vertical movement is normal in any rwd arrangement, the problems start to arise because of the single mounting point in the rear-since the right side is unsupported,the combination of the nose of the diff rising coupled with the rotational energy applied allows for excessive movement there.this allows for movement, but the cause of hop itself only begins here, it's a reactive effect. It's reciprocation. The energy is transferred through the differential to the axles. On the M3 the axle tubes are the floating style, the move side to side within the confines of their CV joints so binding isn't necessarily an issue,an suspension geometry is unaffected by any lateral movement of half shafts...it is however affected via weight transfer. This is where the reciprocation comes into play-even though the spring's ability to be,well,a spring- is suppressed via the shock it's extreme loading that allows it to fall slightly out of the shocks dampening control for a moment. Two very strong physical forces are at work here, forward movement and a downward thrust via weight transfer. As the tires fight for grip, an adverse reaction of spring energy is trying to push back up on the car, which every rwd car does by nature of design. This is where the return strain on the axles is sent back to the differential. So now that the right side of the diff being unsupported and the rubber front bushes show their weakness. "Every action has an equal and opposite reaction",perfect classic phrase for the situation...this adverse reaction will thrust the diff in the other direction, yet the applied load via the engine is still pushing the other way. This push-pull effect amplifies itself rather quickly into the infamous "bang!bang!bang!" relatively quickly as more traction and power are applied. A system is only as good as it's weakest point.The RR being the only unsupported point of the diff, coupled with 3 other "soft" points ability to move make it the obvious place for the reaction to begin... As far as the M suspension arm/link design goes, that doesn't really demand upgrading until you really start demanding more from the car in a road course situation,toe changes aren't really an issue here. I'm assuming the root of that question is based on why the cars pitch side to side aggressively as well, and i'll answer that as well. The unsupported RR causes a more aggressive adverse reaction on that side causing an imbalance in power applied to both tires. There's some other interesting factors involved here: the half-shafts are different lengths, the right side being the longest. Taking the M lsd apart unveils a host of other concerns, It's unlike any other clutch type lsd I've ever seen, I find myself asking "why the hell did they do this" rather often. It's a rather bizarre arrangement,both axle cup lengths are drastically different, the right side has all the clutches, the left side is essentially the same as an open diff, for it's driven via spider gears only and has very little support due to it's short spline shaft. I have seen a failure of bearings on a car that has seen track time. If you look at any other clutch style lsd like the OS Giken,etc,etc-the "proper" way to use a successful lsd in a performance application involves equal length input shafts,clutches on both sides of a center spider gear assembly. It's worth saying that side to side unpredictability has been tamed drastically by providing proper support to the oem diff unit, but I reccommend an OS lsd to anyone seeking the ultimate setup. They are pricey and require modification/machining for this platform, but are worth every dime if your serious about pushing your M on any track. Hopefully that covers your questions and then some |
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03-14-2013, 01:18 PM | #37 |
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^^^
.Let the logic flow through you.
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03-14-2013, 01:38 PM | #38 |
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I didn't buy this product because of hype or claims coming out of the sky.
Rick speaks the truth!
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03-14-2013, 01:43 PM | #39 |
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03-14-2013, 04:57 PM | #41 | |
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http://www.m3post.com/forums/showpos...3&postcount=16 "MDM is not the best method for the track. It still applies brakes when your tires slip resulting in power loss. For the best results....EDC soft and DSC off. Best times are obtained using DR's, heat them properly in the water box and use launch control at 5500. Using LC with street tires is a waste of time and adds to more transmission stress since you will get a burnout and tire hop." I haven't been on the strip yet myself and have wondered the best way of launching...another reason I went with this item. Granted I won't be using DR my first time it may help quite a bit with my street tires. Has your DR setup and technique allowed you to totally avoid wheel hop but it used to be present with street tires? That's an awesome 1/4 mile time so I'm sure I can learn a couple things from you...
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03-14-2013, 07:36 PM | #43 |
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Do you guys this that the brace puts too much stress on the differential ?
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03-14-2013, 08:17 PM | #44 |
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So you and m33 have never had any wheel hop at the drag strip just asking you guys seem to go a lot and I find it hard that you never get a bit of hop.
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