Aftermarket Downpipe Rubbing

[NCGermerican]

Hey Folks - I wanted to call out an issue that was recently solved, that I had been dealing with for about 2 years.

Basically, I had a nasty grinding noise from the front driver's side of the car, but only when turning to the right or going in reverse. I changed everything I could think of - rebuilt the brake calipers, new rotors, new [Hawk Ceramic] pads, replaced both wheel bearings (even though they were fine).

NOTHING solved the issue. I was very close to ordering a rebuilt steering rack, as that seemed to be the last thing that could possibly be making the sound and feel I was experiencing.

So, I took my car for an alignment to a well known, Euro repair facility that has specialized in Porsche alignment setups for many years. I told them about the noise and feel and they were able to easily replicate it.

Well, they found the issue. Basically, my Fabspeed exhaust (the "downpipe" portion) was rubbing against the frame of the car - along the pinch weld where the castor block mounts.

I CANNOT believe I never saw this, even after installing/removing/reinstalling/removing the exhaust many times over my ownership.

So here is my question/dilemma. I also have a Fabspeed downpipe (that connects to the turbo). The factory downpipe has a support bracket that bolts to the block, preventing the downstream exhaust piping from making contact with the body. There seems to be 0 aftermarket downpipe options that have this bracket attached.

The shop also cautioned me as this would put extra strain on the bolts that mount the turbo to the motor mount arm. Oh and they also called out that by running the Tial wastegate, and no longer having the wastegate brace to the torque tube, I'm putting more stress on the header studs, which could lead to a leak down the road.

Anyone else have any experience with this type of situation?

I swear. I may just put this car back to stock....

[Dave W.]

I also bent the flat sheetmetal piece on the castor block mount to make room for a larger downpipe. I read about this mod a long time ago. It's common. I don't have a bracket on the downpipe and haven't had any problems. But I did replace all turbo mounting hardware with new 12.9 grade bolts when I put it on.

When I installed an aftermarket wastegate, I also noticed that the wastegate had very little support. There are plenty of reports of the header and crossover (Under?) pipe cracking with normal use. An aftermarket wastegate without the bracket would make matters worse. So I made a simple bracket out of flat steel, approx 1/8" thick and 3/4" wide. It bolts between the torque tube flange bolts and one of the wastegate mounting bolts. Since it's thin enough it was easy to bend and twist it into shape. It doesn't need to carry much weight, the main purpose is to triangulate the wastegate so it doesn't shake from vibration and road impacts. It's been on there for 15 years and going strong.

[Tom]

My 3" downpipe rubbed through the heat-shield. Spoiler alert, they don't really fit without some extra effort, despite what those selling them say...

viewtopic.php?t=157&hilit=heat+shield#p904

I often worried about my Tial just hanging there off the crossover and dump tube pipes. For the longest time I had intended to make some kind of support but never got around to it, and the longer I ran it without the support, the less I worried about it. If I had to guess, I'd say it's been on there 20 years or more...

[NCGermerican]

I also bent the flat sheetmetal piece on the castor block mount to make room for a larger downpipe. I read about this mod a long time ago. It's common. I don't have a bracket on the downpipe and haven't had any problems. But I did replace all turbo mounting hardware with new 12.9 grade bolts when I put it on.

When I installed an aftermarket wastegate, I also noticed that the wastegate had very little support. There are plenty of reports of the header and crossover (Under?) pipe cracking with normal use. An aftermarket wastegate without the bracket would make matters worse. So I made a simple bracket out of flat steel, approx 1/8" thick and 3/4" wide. It bolts between the torque tube flange bolts and one of the wastegate mounting bolts. Since it's thin enough it was easy to bend and twist it into shape. It doesn't need to carry much weight, the main purpose is to triangulate the wastegate so it doesn't shake from vibration and road impacts. It's been on there for 15 years and going strong.

This is very helpful - thank you! The shop that performed the alignment and found the source of the issue was able to grind away a little bit of that metal from the castor block mounting point. They sprayed some paint to help avoid corrosion. However, while the noise is gone, I still feel just a TINY bit of vibration at the same points (backing up and turning to the right), so it might still be making contact, just not as severe. I'm either going to grind off more or try to bend it out of the way. The proper way to do it will be to remove that downpipe section of the exhaust, which is annoying.

I may also try to fab up a brace for the WG like you described. I have a spare piece of flat aluminum stock that might work and if not, I could pick something up at Lowe's.

[NCGermerican]

My 3" downpipe rubbed through the heat-shield. Spoiler alert, they don't really fit without some extra effort, despite what those selling them say...

viewtopic.php?t=157&hilit=heat+shield#p904

I often worried about my Tial just hanging there off the crossover and dump tube pipes. For the longest time I had intended to make some kind of support but never got around to it, and the longer I ran it without the support, the less I worried about it. If I had to guess, I'd say it's been on there 20 years or more...

Thanks Tom! I read through the thread you linked....just curious - have you ever thought about modifying that heat shield to make it "2-piece". Meaning a bottom section (that bolts to the block) and a top section that could be removed without removing the turbo? Imagine being able to service/remove the AOS without needing to remove the turbo!

[Tom]

My 3" downpipe rubbed through the heat-shield. Spoiler alert, they don't really fit without some extra effort, despite what those selling them say...

viewtopic.php?t=157&hilit=heat+shield#p904

I often worried about my Tial just hanging there off the crossover and dump tube pipes. For the longest time I had intended to make some kind of support but never got around to it, and the longer I ran it without the support, the less I worried about it. If I had to guess, I'd say it's been on there 20 years or more...

This discussion got me thinking about my exhaust hangers.The SFR cat-back pipe has hanger tabs that were welded on in the wrong direction. Earlier attempts to use standard exhaust donuts kept failing, so my exhaust has been held on by being bolted to the motor up front, and the one factory hanger at the very rear. I thought about removing the muffler and fixing the hanger tabs, but came up with a lazier solution by modifying the hanger to reach the hanger tabs. It seemed to work, and even eliminated a little exhaust vibration rattle I'd get on cold start up. Long overdue!

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[NCGermerican]

Funny you say that. The hangers on the Fabspeed were "sort of" in the right space at the more forward location. I had to drill a new hole in my hanger to compensate for one side being off.