E92 M3 Track / Racecar Project

[rTrackM3]

After a couple weeks of prep work I finally have some updates to share. We removed several pounds of miscellaneous metal throughout the interior. There is a collection waiting to be weighed... I will report back with the results. The trunk was completely cut out and replaced (not officially installed in pics) with 1/8 inch carbon fiber.

Within the next week (at least that is the plan) the cage should be finished and the wiring will be thinned out. Then.... PAINT!

[rTrackM3]

Main Hoop

[rTrackM3]

Trunk

[Redd]

Won't cutting out the trunk floor affect rigidity?

[slicer]

Thanks for sharing your build!

Did you happen to weigh the OE plastic trunk floor panel?

[admranger]

Originally Posted by Redd

Won't cutting out the trunk floor affect rigidity?

If the carbon fiber floor is designed and bonded to the chassis correctly, it'll be stronger (and much lighter) is my guess.

[rTrackM3]

Originally Posted by Redd

Won't cutting out the trunk floor affect rigidity?

Looking at how big of a hole is there.... good and valid question. Removing the trunk in that capacity is not uncommon. If you leave that bar in the middle alone (which we did) it shouldn't comprise the integrity of the tub.

The rear part of it was a large plastic floor panel that was held by several nuts. It was not one construct and it was there to primarily house the heavy tire pump.

The front part (above diff/subframe) was metal, but a very thin gauge. In fact, it might have only weighed 3-5lbs? However, if you take 3lbs in ten different locations... It all adds up and we are desperate to get this car light.

In addition, we are going to tie in the cage to rear strut tower / rear subframe (some would argue this isn't necessary in the E9X chassis) so overall it will be more rigid.

Originally Posted by admranger

If the carbon fiber floor is designed and bonded to the chassis correctly, it'll be stronger (and much lighter) is my guess.

I have seen some people use standard nut and bolt hardware. We were strongly considering using an industrial 3M adhesive tape. There is probably minimal value to making the chassis stronger with this carbon delete setup. More for weight savings and style points.

Not sure what the best solution is to fix the carbon to the chassis if anyone has ideas?

[rTrackM3]

Originally Posted by slicer

Thanks for sharing your build!

Did you happen to weigh the OE plastic trunk floor panel?

Happy to share this, Slicer. Trying to enjoy the journey my friend.

I will weigh it this week with pictures and post it here. After holding it last week... Maybe 5-7 lbs? Pretty heavy. We'll see how close I am. HAHA

[slicer]

Originally Posted by ryanosiecki

Happy to share this, Slicer. Trying to enjoy the journey my friend.

I will weigh it this week with pictures and post it here. After holding it last week... Maybe 5-7 lbs? Pretty heavy. We'll see how close I am. HAHA

Sweet - thanks!

[roastbeef]

i would imagine that crossbar in the rear is responsible for most of the rear rigidity. i've always enjoyed this build (and others) http://the-perfect-exposure.blogspot...ld-thread.html
that connect the rear subframe into the roll cage for maximum rigidity.

[admranger]

Use structural epoxy to adhere the CF panel to the steel. Clean and prime the steel. If it was aluminum I’d us BR-127 primer. Not sure for steel.

[rTrackM3]

Originally Posted by admranger

Use structural epoxy to adhere the CF panel to the steel. Clean and prime the steel. If it was aluminum I’d us BR-127 primer. Not sure for steel.

Awesome! Thank you for the information. It will be one of the last steps after the interior is completely painted.

Potential products.... https://www.3m.com/3M/en_US/bonding-...osite-bonding/

[maicol76]

Originally Posted by ryanosiecki

Need a little wind here!!!!!

cool~!!
How did you remove sound deadening material?

[OG Shark]

Originally Posted by ryanosiecki

Awesome! Thank you for the information. It will be one of the last steps after the interior is completely painted.

Potential products.... https://www.3m.com/3M/en_US/bonding-...osite-bonding/

Here’s all you need



Awesome build! Looking forward to seeing it’s progress.

[rTrackM3]

Originally Posted by OG Shark

Here’s all you need



Awesome build! Looking forward to seeing it’s progress.

LMAO!!!! . Love the picture!

[rTrackM3]

Originally Posted by maicol76

cool~!!
How did you remove sound deadening material?

I tried the dry ice technique twice and both times it did not work. Was not cheap either. Don’t know the market cost, but locally I found someone for $1 per pound. Picked up about 25lbs to start.

https://m.youtube.com/watch?v=Eesr-AcQzNw

After trying the dry ice I went to the ole heat gun and scraper. It might not matter so much since it’s a racecar and will be prepped/painted, but it is pretty easy to scratch the surface with scraper. This process took me about 30-45 min to remove all of it.

[ThunderMoose]

Originally Posted by ryanosiecki

I tried the dry ice technique twice and both times it did not work. Was not cheap either. Don’t know the market cost, but locally I found someone for $1 per pound. Picked up about 25lbs to start.

https://m.youtube.com/watch?v=Eesr-AcQzNw

After trying the dry ice I went to the ole heat gun and scraper. It might not matter so much since it’s a racecar and will be prepped/painted, but it is pretty easy to scratch the surface with scraper. This process took me about 30-45 min to remove all of it.

That's what I did followed by xylene.

[tsk94]

Originally Posted by ryanosiecki

I tried the dry ice technique twice and both times it did not work. Was not cheap either. Don’t know the market cost, but locally I found someone for $1 per pound. Picked up about 25lbs to start.

https://m.youtube.com/watch?v=Eesr-AcQzNw

After trying the dry ice I went to the ole heat gun and scraper. It might not matter so much since it’s a racecar and will be prepped/painted, but it is pretty easy to scratch the surface with scraper. This process took me about 30-45 min to remove all of it.

Heat gun and scrapper worked great when I did my car. Since I was going to spray the interior I wasn't worried out scratches but it wasn't too bad at all.

Nice build, keep the updates coming!

[rTrackM3]

Originally Posted by tsk94

Heat gun and scrapper worked great when I did my car. Since I was going to spray the interior I wasn't worried out scratches but it wasn't too bad at all.

Nice build, keep the updates coming!

Agreed.

Also, for those who are wondering... When I weighed the sound deadening it came in at 13lbs.

Thank you! Should have some photos / updates later this week!

[MPower7]

Originally Posted by dogbone

My car now with the carbon doors (70 lbs loss from fully gutted doors) and carbon headlight blanks (15 lbs loss---NOT 40 LIKE BIMMERWORLD CLAIMS!!!!) should be hovering right at 3100lbs no fuel no driver. Every scale is different. But I think it's possible that we're a couple pounds under 3100lbs.

As far as studs, I'm not blaming defective product. And if you know anything about my build thread, I have been on a quest for knowledge over the last 8 years. That learning didn't blindly ignore the topic of studs. In fact quite the opposite. As I kept breaking studs, I kept doing more research, trying different brands of studs, trying different types of steel, trying to use careful technique on installation, trying not to abuse them with an impact gun when they're hot (I don't do long wheel to wheel races), replacing them right at 12 months, trying forged wheels versus flow formed, calling high end race shops to see if they had any advice. Believe me, I have not just played the victim on this topic. I found no 100% reliable solution while on 12mm studs.

Strom Motorsports is a very high end race car builder. He puts like $200k into every car he builds. I spoke to him one day and he said that they built two identical E92 M3 race cars with 12mm studs. One never broke studs. The other broke them regularly. He was resigned to the idea that they just need to replace them every 6 months.

I believe that this platform---for whatever reason---puts odd stresses on the studs on the front wheels. And once you have enough power and grip, the problem starts to surface. My friend has an E90 M3 setup very similar to me---supercharged, JRZ, AP Racing, full aero, etc. He never broke a stud. Then he moved up to Pirelli DH 305 square. Almost immediately, he broke a stud at Chuckwalla. Chuckwalla has a banked bowl turn that puts enormous stress on the front of the car. I broke two studs there that same weekend. And our broken studs were on the same corner of the car. I mean, c'mon.......this my fault?

I'm sorry, but anyone who simply tells you that studs are only taking a simple clamping force and aren't dealing with any other kind of load, and that everyone breaking studs is doing something wrong, are not looking at the whole picture. Something else is coming into play.

I used the Rogue Engineering jig kit to drill out E9X M3 front hubs to 14mm. That's been doing really well so far for almost a year. (I didn't drill the rears to 14mm because I'm concerned the rear flanges don't have enough margin to be drilled out, so the rears are 12mm.) I don't like having to change the torque value on my CDI torque wrench for front and rear, so ultimately, I will figure something out that has the same settings all the way around the car. I love the press in stud idea, but on the E9x M3, it's looking like the rear press in studs can't be swapped out while the hub is on the car if you have a parking brake (which I do). So, you may have to remove the rear hub flange to replace the press in studs which is a huuuuuuge pain in the ass. I haven't sorted it out my final ideal solution yet.

I've had Apex 12mm studs on my car for 10 months. No track days yet due to some unforeseen circumstances. Would you still replace after 12 months of street driving?

When a stud breaks, what happens? Can you hear it immediately go?

[dogbone]

Originally Posted by MPower7

I've had Apex 12mm studs on my car for 10 months. No track days yet due to some unforeseen circumstances. Would you still replace after 12 months of street driving?

When a stud breaks, what happens? Can you hear it immediately go?

If you have any doubts about your studs, then swap them out. No one can give you 100% bulletproof advice there. It's not expensive when you consider the overall costs of tracking.

As far as studs breaking, you don't hear them break, and if it's only 1 or 2 studs, you don't feel it either. You only find it when you either check your studs or swap wheels and find a loose stud. The worst I've had is two studs breaking at the same time (which has occurred on three occasions). I didn't hear or feel anything. I only found it later in the paddock when switching wheels.

Most of the studs I've broken have remained on the car after they've broken, so they're a bit sneaky if you are just looking at them. Only a couple have completely disappeared off the car while on track, and even in those cases I didn't hear or see them come off. I had the unpleasant experience of looking at my wheel and seeing a hole where the stud used to be.......

Studs can break in a couple different ways.

-The most common breakage I've had---around 20 of them---is the stud breaks inside the hub threads. This is difficult and frustrating to recover from because you have to be able to turn the remaining stud fragment out of the hub. But this is difficult because it's loctited in. In my experience, I have to use a Dremel to grind a slot into the stud without ruining the threads of the hub. The 12.9 steel Bimmerworld race studs are harder than the regular 10.9 steel studs and make this process even more difficult. Once I have created a slot in the stud, I can usually get enough leverage with a screwdriver to turn the remnant of the stud out of the hub. You also gotta use a propane torch to heat up the Loctite to help break that bond. It's frustrating. I also completely disassemble the brake setup so that I have full access to the hub.

The last time I broke a stud, the remnant inside the hub froze in there and there was nothing we could do to get it out. Several of us tried. I had all the tools and was not getting anywhere. The fragment turned a little bit and then completely froze in place. So frustrating. I carry spare hubs and ended up replacing the whole hub. Replacing the whole hub is only 4 bolts. In my opinion, it's far easier to replace the whole hub than it is to sit there wrestling a broken stud fragment. But you gotta have a spare hub waiting around......

-The less common break that I've only had a couple times is the stud breaking about 3/4" outside the hub leaving a stump. It's much easier to recover from this break if you have a decent stud puller since there's a stump to grab onto and turn out.

My opinion: If you actively track an E9x M3 with high grip tries, at least the front hubs should be moved up to 14mm studs. The rear seems less critical. I've only broken one rear stud in 8 years. These days, there are now several options for doing this:

-Drilling out the front hubs to 14mm using the Rogue Engineering jig kit which is the route I went last year. It's been a fine solution for almost 12 months. I suggest not doing the drilling work yourself. (I didn't.) Just send the hubs to a metal machine shop and let them do it. If you go this route, tap the threads to a pitch of 1.25. (Rogue gives you the option for a couple different thread pitches when you buy the jig kit.) (I am hesitant to drill out the rears because, in my non-engineering opinion, the hub flanges don't look wide enough to support drilling the holes wider. Rogue says you can do it, but it looks too close to the edge in my non-engineering opinion.)

-Future Classic makes a four corner 14mm threaded stud solution using F80 M3 hubs.

-Core4 Motorsports has just finished a prototype 14mm MSI press-in stud solution for all 4 corners. The fronts are drilled-out E9x M3 hubs and the rears are F80 M3 hubs. After much thought, I have decided to give this solution a shot. It feels like the most hardcore and beefiest solution. Core4 is shipping the prototype set to me right now. I should get the hubs on Monday. Press-in studs have an advantage over threaded studs in that they don't rely on threads inside the hub to provide the tension to hold the wheel system together. They are held in place by a large flange on the backside of the hub. This alleviates the stress in my most problematic place---inside the hub threads. Plus, since there are no threads to reduce the core thickness of the stud inside the hub, the stud has a larger diameter of solid non-threaded metal in that critical spot. So, a 14mm press-in stud is a big jump in shank thickness inside the hub versus a 12mm threaded stud (and also an increase in shank thickness over a 14mm threaded stud) and there's no thread tension inside the hub. It's a win on all accounts from what I can tell.


Last thought: If you only go to 14mm in the front and leave 12mm in the rear as I have done for the last year, you are presented with a situation that is not ideal----you have to set your torque wrench to different torque values for the fronts and rears. I really do not like doing that. The front 14mm are at 105 ft lbs. And the rear 12mm are at 90 ft lbs. During a busy track day with lots of distractions, switching between those two settings is a potential source of making a mistake. Not the kind of mistake you want to make......So, I look forward to the day when I can once again set my torque wrench to one value and just leave it there.

[gills]

Originally Posted by MPower7

I've had Apex 12mm studs on my car for 10 months. No track days yet due to some unforeseen circumstances. Would you still replace after 12 months of street driving?

When a stud breaks, what happens? Can you hear it immediately go?

Dogbone did a great job of explaining. For a street car (at least with press-in studs), you simply should never need to worry about them. You will have to service your wheel bearings before the studs. And the argument can made for track cars as well.


I’ll add more to it when I have a longer moment, but in the meantime I’ve compiled a picture & video gallery of broken stud incidents that you can see in the link below. Sometimes you can feel it happening where it sounds and feels like a very bad wheel bearing. Sometimes it happens instantly without warning. The videos in the gallery show both scenarios.


https://www.core4motorsports.com/gallery-of-broken-bmw-wheel-studs