GRM is totally to blame for this- SPEC E46 content

So, A while back I was running one of my cars at a Sebring track day. I had made an agreement with my wife to hold off wheel to wheel racing until the kids got older. I try to keep a car in the stable that is built to a rule set so I can compare the times I run with what the faster rats are doing at the same track.

I horse traded my interest in a Spec Miata that I had built for a couple friends. I ended up with an FB RX7 built to EP rules that I had been in charge of keeping on the track. Once the previous owner tried a Miata is was all over for the EP car. Frankly, I think the EP car scared him.

I have a bit of history with RX7's, Jim Susko and I developed the system he sold under the G Force Engineering badge. We owned two identical cars together before I moved to Florida in '96. They were the test beds for what became the standard for the chassis.

Back to the story. So, Happy Hour at a Chin event and this:

Became this:

Because of this:

The hub came apart at probably the best spot on track; the middle of turn 16. I slid across the wide grass and hit the wall pretty hard. The wheel rolled into the shot a couple seconds after I stopped.

I was thinking about what to do with the car, it will be fixed, but not right now. I was looking for a platform I could get the kid started with auto-x and some track days and a Miata was my first choice. Wife said, "Its too small"

Then I see this side bar story here talking about Spec E46. Interesting... I already have a love/hate relationship with BMW's and a lot of the special tools for them! Perfect.

I start looking for a car and find one advertised as a 330ci that needs work for $1200. I drive to Naples to look at it and it is actually a 328ci. I tell the guy its just a shell for me and offer him $500. He takes it and I drive the car into the trailer.

The car is pretty clean, it was painted years ago. About the only thing I'll use is the shell and the diff for the 3.46 ratio.

The engine turned out to be in great shape and it will go on the shelf in case my son grenades the M52B28tu in his E39 Touring. I sold the cats for $400 on the bay so you are looking at a free car in my book.

Was wondering what sort of progress you had made.  I need to get over to the shop and see whats what. 

I remember that grm did an issue on the e46 series. Can't wait to see where this goes.

I found a 330 donor that had been wrecked pretty bad. A near head-on collision on a state route ripped the left rear suspension off and sent it into the woods. Police and the wrecker driver couldn't find the wheel/brake and half of each control arm.

As a parts car it gave me an engine, transmission and driveshaft. Brakes on 3 of 4 corners and right side trailing arm. All for $600.

I cut it up and put the front clip and right quarter on the racks.

Gutting and other misc stuff. Used a combination of dry ice and then propane torch to get areas the ice didn't.

I looked into the methods people are using to fill the sunroof hole and went my own direction. There are a few fiberglass panels and even carbon fiber ones available. I finally have a project to use "That tool I always wanted."

I built an English wheel frame a few years ago and finally got around to ordering the wheelie parts a while back. I caught Hoosier Profiles as they were slowing down/retiring and got a 4x9 upper wheel and a set of 3x3 anvils.

Prepping the roof hole and fitting my first custom part off the wheeling machine.

I had about a 5/8" in lip to attach it to. 3M panel bond is the way to go so there is no problem with welding heat.

Starting the initial cage design. I checked out a few different kits that are offered up to see what people are doing. I've been building cages off and on for about 30 years so I already had some ideas. I ripped off a few things I liked and added a few things I didn't see.

With the rough outline in place a got serious about clearing everything out of the interior.

Huge progress in a short amount of time!

Engine cleaned up and most of the unneeded stuff removed. I still need to take the EGR valve off and make a block off plate. I ceramic coated the manifolds. Usually they get a partial cure before installation and then exhaust heat finishes the job around 700F. I happen to have a wife that does ceramics so we have a few kilns at the shop.  700F in a kiln is available in about 20 minutes and an hour later they are fully cured.

I also made my own solid engine and transmission mounts.

Speaking of firing things. The E46 has a huge hole in the fire wall when you remove the climate control box. There are aluminum panels available, but knowing what temp aluminum turns into a puddle, I decided to make one out steel. I've never been in a car that is on fire but I want all the fire making stuff sealed away from me as much as possible.

I threw the car on the scales to see how I'm doing with adding lightness. Its looking pretty good, I put a stock seat in it to keep things close to honest before the cage weight is added. The stock seat weighed in at 58lbs and working after weigh in I found another 20 or so pounds of stuff and removed it. It still has door glass and uncut doors at this point.

It has to be 2850lbs with driver and I'm about 190. The car has about 5 gals of fuel in it.

I like to paint as much of the interior as I can before installing the monkey puzzle of tubes. I cut the back window out after trying to remove the dark tint without success. I have one from the parts car that is clear and it also helped with the painting.

I resprayed the clear on the sunroof section after I saw how bad it turned out. its tough to spray up with a gravity feed gun.

The cage will come together quickly now. I paint the tubes with epoxy primer before the final assembly. If I don't manage to get paint all the way around at least the epoxy is waterproof and durable enough to live without top coat. I use Southern Polyurethane primers and clears and they even mention the epoxy primers don't need topcoat on chassis or suspension parts.

I love these easy strip discs for cleaning everything off the ends of the tubes. I found them on the big river site, they last a long time if you work "off the edge", it will shave itself a bit if you catch an edge though.

You can see how well it cleans without digging into the material.

I love that the main part of the cage structure lives on 4 plinth boxes. The only metal thick enough to make me feel good about a mounting point is the inner rockers. The floor and the metal in the step up for the rear seat are just a hair thicker than foil.

I started construction of the cage with the tubes going to the floor knowing they wouldn't end up being attached there. It held things in place to start welding but as soon as the main section was complete they were trimmed down close to their final length. This let me finish the welds around the tops of tubes and also paint the greenhouse section of the cage.

I'm going to take advantage of the shell being white originally and keep the firewall and under-dash area white. If I ever need to root around under there the extra light reflecting will be nice. I'll pick a line above the pedals to tape off and the floor will be the charcoal grey.

The last two mounting points, done. I'm pretty happy I can still climb in and out of a trunk and weld standing on my head.

My real world got in the way for a week and I had to work. Back to playing now.

I have been interested in the use of different side impact defense measures since I saw a cool pod on a SuperTouring car that had been brought over from the UK for the N. American series. I was told it was a honeycomb material inside a carbon fiber covering. It was about 2' long and 8" tall and was attached to the door X bars on the cage. I liked the fact there wasn't an extra foot of tubing in each door bar to let a car intrude toward the driver if the tubing collapsed.

I was trying to find out how to recreate something like that without an autoclave and found the latest stuff used by Nascar called Impaxx foam. It sounded perfect for what I wanted to do and its a proven product. It comes in 4" thick panels which works for me because the E46 door is 4.5" deep. A 24"x30" piece is about $200 by the time you add shipping.

It cuts nicely and you can sand it with a DA. It doesn't like high speed sanding or a flapper wheel on a 4.5 grinder, too much heat generated and it melts to a blue goo. I ended up removing large sections by dragging a circular saw sideways to make a rounded groove.

I removed the stock diagonal door bar that bolts in but left the top bar right below the window. I knew the foam wasn't going to be up that high and it can still do something for me with out weighing too much.

The final fit had to happen in two pieces to get the coverage I wanted. The inside surface of the foam is about where the stock door panel  would be.

The foam supplier told me what Nascar uses as a backer,it's called Tegris. It's a thermoplastic composite that spreads the load and stops intrusion of stabby things that might hit the driver. The supplier said if you aren't as worried about intrusion as Nascar is, some .090 aluminum would be a minimum to back it up with.  I found out the best set up is an aluminum-Tegris-aluminum sandwich. If I can get some Tegris to play with I may change the inside skin later.

I need to pick up some poster board to make a pattern for the aluminum skin. I have the basic design in my head. Its going to hook into the slot that holds a trim piece on the top of the door and be riveted around the inside of the door.

Wow super cool stuff!

I only had a couple hours this weekend but I managed to get something done.

The idea of using the slot that normally holds the window trim had one problem. The slot has a slight curve so I had to make a separate piece to hook into it. I hit it a few times with the shrinker/stretcher tool and it dropped right in.

I cut the aluminum and got the rough shape to fit with a couple bends.

The two bends kept me from having a "sharp" corner and it helped clear a couple weird shapes at the ends of the door. I still have to spend some time on the final fit and finish.

I'm going to go with panel bond to hold the skin to the "hook" and attach the skin to the door like it is a piece of a monocoque chassis with rivets every couple inches.

Suspension ingredients showed up today! I had to dig through and put hands on stuff for, you know, personal reasons.

I need to make some brackets to attach the shocks and struts to the shock dyno to see what the clicks do.

nice!  

what brand caster/camber plates are those?  they look nice and not annodized some obnoxious color

In reply to fouckhest :

Ground Control. Bimmerworld chose them for the camber plates and adjustable rear spring perches for the Spec E46 kit they sell.

jgrewe said:

In reply to fouckhest :

Ground Control. Bimmerworld chose them for the camber plates and adjustable rear spring perches for the Spec E46 kit they sell.

Oh nice, I had a set of there uppers on my mk4 vw r32, they make nice products.

For a person who doesn't know much about bmw's what makes a 330CI desirable? 

In reply to Somebeach (Forum Supporter) :

In this case the E46 330 is the only car in the class. You can also use the sedan version with success, I think I read that you have to work a little harder to get it down to the minimum weight.

The chassis has some issues when put on track but the rules allow for known fixes to be applied.

I had a good few days in the shop because of the rain we've been getting. I got the cage welded on to the plinths and installed some of the tubes I had already fit and painted. I have to finish the X in the rear support area but I need to be in the right mood for that.

I got the main pieces of the door bars done. A design to absorb a load over a large area is different than the kits available. I was able to take the bars out to the aluminum skin and keep them there for about 2'. The bars are about 10" apart when they are parallel. That gives me 240 sq.in. to take the hit behind the Impaxx foam. The bottom of the stock door bar inside the door is about even with the top bar.

I just have the bars wedged in there right now. I'm trying to decide how to fill the space between them. I'm allowed to add a support in the middle of the door bars that goes to the rocker. I'm leaning toward building off of the bars that will come down from the A pillar and meet back up above the plinth. A series of triangles will only add about three more pounds of tubing over a single bar.

I'm going to do the foam on the passenger side too. My son will have an instructor for a while, might as well do what I can for passenger side safety.

Those bars still need a little bit of work on the fit. They will be about 1/4" off the aluminum but I don't have it yet.

jgrewe said:

In reply to Somebeach (Forum Supporter) :

In this case the E46 330 is the only car in the class. You can also use the sedan version with success, I think I read that you have to work a little harder to get it down to the minimum weight.

The chassis has some issues when put on track but the rules allow for known fixes to be applied.

FWIW, I believe you can use the E46 323/325/328 chassis if you swap in the 3.0L drivetrain from the 330.

Thanks for putting all the detail into this thread, the workmanship is top notch!

I'd be curious to see what those shocks do on your dyno if you are willing to share, more just for curiosities sake as I don't have an E46.

I was wondering about that foam and what good it serves if it gets hit - figured it would just get pushed into the passenger compartment.  But making a wall of sorts that the foam can compress against makes sense.  
 

id mount that onto my bumpers under the bumper covers too