[gstas25]

Hello!

2006 BMW 325XI. How would you guys fix this? Just needs to work. Bolts look like they'll need to be hammered out. It appears the flange steady (part #18307541458) broke off. See pictures. The car is only loud once the car becomes hot. Looking for ideas. Amazon has a ton of flange repair kits etc. Meineke recommends welding in new metal pipes in place of these, seems like the more tough and expensive route. Thanks.

[TheeGovernor]

Originally Posted by gstas25

Hello!

2006 BMW 325XI. How would you guys fix this? Just needs to work. Bolts look like they'll need to be hammered out. It appears the flange steady (part #18307541458) broke off. See pictures. The car is only loud once the car becomes hot. Looking for ideas. Amazon has a ton of flange repair kits etc. Meineke recommends welding in new metal pipes in place of these, seems like the more tough and expensive route. Thanks.

Drill out and remove old studs. Get new gaskets and use new coated hardware. Look up n54 threads for nut and bolt info.

[Efthreeoh]

I've done this exact repair. It's not easy. The exhaust flange is very hard stainless steel. I have a lift, air tools, and machine shop experience (meaning I have proper training on how to drill holes in metal).

The common way to approach this type of exhaust repair is to remove the cat-back section of the exhaust so you have room to work on the cat side flanges where the studs are. Cut the studs flat, then use an air hammer to drive the old studs out. I've done that on several cars in the past.

Well on my E90 no dice. The studs became fused to the flange due to daily heat cycles of the exhaust. So the next step was to drill the old studs out. I cut the studs using an pneumatic cutoff tool; using a hacksaw will take a very long time and numerous blades. Like I said the exhaust steel is very hard stainless, so you need even harder drills (drill bits) to get any bite into the steel. Common everyday drill bits will not work and will dull in about 2 minutes. I have high-speed industrial grade drills. The biggest hole I could drill in the space where the studs are in the flange was 3/8ths (10MM). The problem with drilling the holes is getting the center punch on center of the stud to dimple the metal so the drill doesn't "walk" off center. I hit the center mark pretty dead on but in the end the holes were not perfectly centered.

So I got the holes to 3/8ths and pretty close on center; I couldn't get any larger hole drilled in the flange. I used SAE Grade 8 bolts 3/8 x 1.5 inches long with Grade 8 lock washers and nuts. Using common Grade 5 bolts will eventually break. I mentioned earlier that I have a lift and a bunch of special tools only to explain that it is not an easy task. I doubt you could get this accomplished with the car on 4 jack stands and you lying on your back because you need a good amount of pressure on the drill to get it to bite into the steel. I was comfortably standing on my feet with the car at the perfect height.

My advice is to have a mom and pop custom exhaust shop do the repair for you. You do not need to weld in any new metal. Just drill the studs out and use bolts.

[gstas25]

Thank you very much for taking the time to help me out. I'll see if I can find a shop willing to drill out the old bolts. They do look very difficult to get to, I can't imagine how they/I would be able to fit a drill in that space. How did you get to it? Looking at that bolt closest to the car. :/

[gstas25]

Also, though this was a pretty cool tool. However don't know if this would fit on one of those nuts/bolts being so closely tucked next to the exhaust pipe. Pretty cool though!

[Efthreeoh]

Originally Posted by gstas25

Thank you very much for taking the time to help me out. I'll see if I can find a shop willing to drill out the old bolts. They do look very difficult to get to, I can't imagine how they/I would be able to fit a drill in that space. How did you get to it? Looking at that bolt closest to the car. :/

The xi version may have more chassis framing. Once the rear exhaust is removed, there is enough room.

[TheeGovernor]

Originally Posted by Efthreeoh

I've done this exact repair. It's not easy. The exhaust flange is very hard stainless steel. I have a lift, air tools, and machine shop experience (meaning I have proper training on how to drill holes in metal).

Sorry Efthreeoh, but when you say stuff like "machine shop experience" and then say stuff like "And remember the smaller the diameter the slower speed you need to drill" in other threads I have to call you out. Correct me if I am wrong. http://www.mytgtools.com/re3.php

[Efthreeoh]

Originally Posted by TheeGovernor

Sorry Efthreeoh, but when you say stuff like "machine shop experience" and then say stuff like "And remember the smaller the diameter the slower speed you need to drill" in other threads I have to call you out. Correct me if I am wrong. http://www.mytgtools.com/re3.php

I do remember writing that in a thread a while back. I forget the context however. I can understand your confusion based on the table posted, which is a good guide and shows that RPM of the twist drill needs to be slower as the material hardness increases. I was most likely referring to the speed of the feed rate of the drill into the material rather than strictly just the RPM of the drill. As the table indicates, the art of drilling a hole is dependent upon several factors. The idea of production machining is to use the correct drill RPM, and feed rate of the drill into the material so as to gain the maximum life out of the tool. The ideal cutting speed (RPM and feed rate) is when the material "chip" comes off the twist drill as a long spiral piece. All that said, drilling a hole in hard metal using a hand drill motor vs. a drill press (or machining center) are very different things. Using a hand drill motor is difficult to get the correct RPM at the drill face while attaining the proper feed rate. Usually a person dulls the drill quickly or breaks the drill or chips the drill cutting face (which I did with one of my drills trying to drill the studs out of my exhaust flanges). In this thread I am trying to explain to the OP that DIYing this repair is not as simple as chucking in a drill bit (to use the layman's term for a twist drill) from a $12 drill bit combo pack from Lowes into a Kobalt drill/driver from Lowes and drilling out the flanges in 5 minutes.

As far as background, in my mid 20's I earned a living early in my career as an equipment planning engineer for an major aerospace manufacturer and I have a degree in industrial engineering.

[Glene]

Originally Posted by gstas25

Hello!

2006 BMW 325XI. How would you guys fix this? Just needs to work. Bolts look like they'll need to be hammered out. It appears the flange steady (part #18307541458) broke off. See pictures. The car is only loud once the car becomes hot. Looking for ideas. Amazon has a ton of flange repair kits etc. Meineke recommends welding in new metal pipes in place of these, seems like the more tough and expensive route. Thanks.

What does the flange sturdy for? Is it sandwiched between the flanges or on the outside of the flange?