Size for stock exhaust?

[V8ctor]

Hey fellow Gx’ers!

I’ve run into a pickle with my 06 gx470. Whilst replacing the exhaust, I realized that the exhaust flange on the cat side rusted out along with the bolts and broke off the pipe itself.

I’ve got a new catback exhaust going on, with new bolts, but I’m confused on how to best tackle this issue. Based off YouTube videos, I suppose I can buy a new split flange, tighten it with bolts, and then attach it to the new exhaust with my new bolt/springs.

Do I need anything else? A gasket?
Also is the stock front cat pipe 2 or 2.5? I’d like to buy the correct size flange once.

 

[V8ctor]

Here’s a picture for reference.

*p.s. the truck is on jackstands, the floor Jack is just extra*

 

[Rednexus]

I would suggest taking the GX to a muffler shop and having them re-weld the flange to the Y-pipe, or weld on a new flange It will provide the best repair overall. That area receives a lot of bending/movement between the Y pipe and the cataback exhaust system, so a less-robust repair may fail again. Then bolt your new exhaust to the repaired Y-pipe and flange.

 

[V8ctor]

I would suggest taking the GX to a muffler shop and having them re-weld the flange to the Y-pipe, or weld on a new flange It will provide the best repair overall. That area receives a lot of bending/movement between the Y pipe and the cataback exhaust system, so a less-robust repair may fail again. Then bolt your new exhaust to the repaired Y-pipe and flange.

Ahhh thank you very much.

All good and true points. Since I removed the stock exhaust already, I’ll just attach the new one to the hangars and drive to the shop. Thanks!!

 

[V8ctor]

I would suggest taking the GX to a muffler shop and having them re-weld the flange to the Y-pipe, or weld on a new flange It will provide the best repair overall. That area receives a lot of bending/movement between the Y pipe and the cataback exhaust system, so a less-robust repair may fail again. Then bolt your new exhaust to the repaired Y-pipe and flange.

Sadly, I’m back here again asking for your help. I went to several muffler shops but they don’t have that size flange in stock. They recommended hacking it and making me a custom exhaust. I don’t know how I feel about that because if something fails in the future, I can’t just bolt on a new part.. everything must be made to adapt.

Anyways, one of the shops told me to bring them the new flange, and they would take care of the rest.

Does anyone know the diameter of the y pipe where it connects to the catback exhaust? I know my catback is 2.5”, and it’s slightly larger than the y pipe. I’m guessing 2” or 2.25”. I can’t find it online.

 

[Rednexus]

Would installing a new Y pipe be emissions-legal in your area? If so this might be an option:

89230 Doug Thorley Y pipe, 2005-2009, 4Runner, GX470 with 4.7L V8 - Underdog Racing Development

This Y pipe from Doug Thorley replaces the stock Y pipe with an easy bolt in installation. Bolts to the rear of the front cats and to the stock or aftermarket cat-back exhaust. The Y pipe is made from 409 grade stainless steel.

urdusa.com

You should be able to get the O.D. of the hole through the flange by measuring the I.D. of the donut gasket. It also looks like you have enough of a nub still remaining of the pipe that you could also measure that (and confirm it based on the donut gasket size). You'd then need to find a flange with a hole equal to that OD, and hopefully a bolt spacing similar to the OEM flange and your catback exhaust.

 

[GrizzlyClint]

When I got my mid-mounted muffler replaced it was 2.25” piping. Not sure if that helps but there you go.

 

[V8ctor]

Unfortunately I live in NYC and they’re strict with emissions. My local shop doesn’t do visuals, but it MIGHT throw a code, and that’s no bueno. It does look very nice though! I used to have a Jeep srt with catless pipes; it’s not worth the hassle.

I spoke with magnaflow and they offer a direct fit catalytic converter #93657. The inlet is 2” and the outlet is 2.375” OD.

I checked bearriverconverters on eBay, spoke with a sales rep, & got a flange repair kit 2.375” which should slide over. I’ll clamp it on, and if it fits, I’ll take it to a muffler shop so they can weld it properly.

I’ll keep you all updated when it arrives. There may be someone reading this in the future faced with the same issue.

 

[V8ctor]

When I got my mid-mounted muffler replaced it was 2.25” piping. Not sure if that helps but there you go.

Thank you! I think you’re right..

Previous owner frankensteined the hell outta the stock exhaust with crappy welds & different pipes so I can’t prove it, but based on what I’ve seen online, the catback is 2.25”

 

[Jstawgn]

The actual pipe size is 60 mm. Not many place would have metric pipe flange. Maybe got to find it online somewhere.

 

[V8ctor]

Alrighty!!

I successfully installed the new exhaust flange yesterday! The nub on the cat pipe was really rusty, but it was still solid so I was able to clamp the new flange.
It IS 60mm like Jstawgn said, but the 2.375” fit just fine. I used the included bolts. As for the catback, I should’ve named it earlier..
It’s the MBRP catback for 5th gen 4Runners.. but don’t let that fool you! It does FIT, but with the new clamp extension, I had to cut a part off the connecting 2.5” pipe. It looks GREAT! Thanks!!

 

[V8ctor]

 

[V8ctor]

And now I’m gonna hijack my own thread.

I initially stated my GX had no rust in my intro to this forum. Clearly that’s not the case, because it does have surface rust (northeast salt). Well it’s worlds better than my old rotting 4Runner. As such, I spent a couple hours wire wheeling the frame, rear crossmember, behind the spare, and the rear diff. Got most of it off pretty easily. Since I was running outta daylight I opted to forgo the front for another day and figured it was time to reward myself by removing the running boards.

OH BOY WAS I IN FOR IT!!

The passenger side came off with a little elbow grease. The driver side is a different story. One of the 12mm bolts (behind driver front wheel) is spinning, but won’t come out. There’s a nut on the other side that’s stuck to the bolt as well and they’re both spinning. I know this because I discovered a hole next to it! I took off a chunk but I’ll have to cut the metal board hangar thingy off to get the rest of it.

What do you suggest I do about the rot? It’s not on the frame. It’s not the floorboard either. I’ll take photos tomorrow after work.