Functional offroad exhaust mods

winkosmosis · Sep 5, 2009

My stock big round cat prevented me from installing a DPG belly skid plate, so I had a muffler shop replace it with a much slimmer Catco cat.

I also had a 6" flex coupling put in to isolate the header and head from hits to the exhaust system.
I don't like the idea of a rock hitting the muffler or tailpipe and a long rigid exhaust system multiplying that force many times once it reaches the header and possibly damaging seals. I've heard of headers cracking too, so I think it's a worthwhile mod.

fyrfytr1717 · Sep 6, 2009

Looks good. Out of curiosity, was there no room to mount the flex coupling in the "down" portion of the pipe? I'm planning on doing this soon and that's where I was hoping to put it.

Begster · Sep 6, 2009

I have to ask, is that duct tape on your driver side lower control arm?

winkosmosis · Sep 6, 2009

fyrfytr1717 said:
Looks good. Out of curiosity, was there no room to mount the flex coupling in the "down" portion of the pipe? I'm planning on doing this soon and that's where I was hoping to put it.

I think they'd have to remove the pipe to do that because there's not much space up there. I went with the next best spot, but as it is if something hits the lowest part there is no flex

winkosmosis · Sep 6, 2009

Begster said:
I have to ask, is that duct tape on your driver side lower control arm?

Yeah I put a piece of mouse pad in there to prevent cutting the tire when it was rubbing on the LCA. I put some washers in the steering stops but I left it because it still rubs occasionally.

magimerlin · Sep 6, 2009

I do... I choose to use a little smaller flex piece though

xjclassic2000 · Sep 6, 2009

winkosmosis said:
Yeah I put a piece of mouse pad in there to prevent cutting the tire when it was rubbing on the LCA. I put some washers in the steering stops but I left it because it still rubs occasionally.

WJ lower control arms would solve that if you are stock height. They are the same length as stock, stronger and are shaped to allow full lock without rubbing. The only thing you need to do is modify the bushings. There are a few write ups on it.

winkosmosis · Sep 6, 2009

xjclassic2000 said:
WJ lower control arms would solve that if you are stock height. They are the same length as stock, stronger and are shaped to allow full lock without rubbing. The only thing you need to do is modify the bushings. There are a few write ups on it.

Can they clear 31x10.5 tires with no washers in the steering stops?

Rod Knee · Sep 6, 2009

xjclassic2000 said:
WJ lower control arms would solve that if you are stock height. They are the same length as stock, stronger and are shaped to allow full lock without rubbing. The only thing you need to do is modify the bushings. There are a few write ups on it.

I have 31 inch tires on a 2 inch boost and did the WJ LCA swap. It turned out to be a very good mod. I have no washer steering stops giving me stock turning radius. I just ground the bushings down with an angle grinder...they came out fine.

xjclassic2000 · Sep 6, 2009

I'm not 100% sure. Heres a pic. Top is stock bottom is WJ

winkosmosis · Sep 6, 2009

I found that pic and it didn't look like a big enough bend but I guess Rod Knee cleared that up. Sounds like a good mod. The turning radius loss with the washers is more than you would think

3fifty · Sep 7, 2009

I hate the WJ LCA mod. My spring perches hit when I droop. They creased both arms all the way across. Im hoping to get some adjustables before they crack on me.

Rod Knee · Sep 7, 2009

3fifty said:
I hate the WJ LCA mod. My spring perches hit when I droop. They creased both arms all the way across. Im hoping to get some adjustables before they crack on me.

Hmmm...you know what they say. Every jeep is different. Neither of the write ups on the WJ LCA mod that I've read mentions the problem you have.

ehall · Sep 7, 2009

magimerlin said:
I do... I choose to use a little smaller flex piece though

that's what my setup looks like, a small piece in between the down pipe and the cat converter

3fifty · Sep 7, 2009

Rod Knee said:
Hmmm...you know what they say. Every jeep is different. Neither of the write ups on the WJ LCA mod that I've read mentions the problem you have.

I know. I wouldnt have done it if they had.

I can take pics to show you the damage if you like. I trimmed the perches and they still hit when flexed. Before chopping them they would hit on large potholes and bumps.

jeeperjohn · Sep 7, 2009

I did this also. It has helped prevent cracked headers for quite some time now. I also made a skid for the cat out of 1/4" plate because I trashed a brand new cat once.

Rod Knee · Sep 7, 2009

3fifty said:
I know. I wouldnt have done it if they had. I can take pics to show you the damage if you like. I trimmed the perches and they still hit when flexed. Before chopping them they would hit on large potholes and bumps.

Gad zooks...I just checked my LCA's and one of them is indeed creased below the rearward lip of the spring perch. Not enough to be a big worry, but something to monitor for sure. I don't know that I'd trim the lip over concern about weakening the perch.

3fifty · Sep 7, 2009

I didnt trim much. Just the lip. Maybe an 1/8th inch to raise it. I figured any little bit would help. I trimmed as much as I could without going into the thick stuff.

Ill get some pics this week. Mine are pretty bad.

tharlanjr · Sep 7, 2009

I hate those flex pipes. The PO of my camry put one on after the header and it split in half.

Now my car sounds REALLY bad.

I was told that those aren't meant to be permanent...

but idk

Rod Knee · Sep 7, 2009

Rod Knee said:
Gad zooks...I just checked my LCA's and one of them is indeed creased below the rearward lip of the spring perch. Not enough to be a big worry, but something to monitor for sure. I don't know that I'd trim the lip over concern about weakening the perch.

I'm going to reverse my remark on the creasing of the LCA. My conclusion above seems to have been based on little more than a rough/rusty spot in the powder coat coincidently beneath the lip of the spring perch. I now am sure that I'm a not having a problem with the perch contacting the WJ LCA, but for anyone researching, I can see how this could be a problem with rigs capable of greater droop than my modest "budget" boost allows, especially without proper bumpstop adjustment.

Functional offroad exhaust mods

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