downpipe with a flex pipe?

Does anyone know of a company that makes a replacement downpipe with a flex pipe built in already? It doesn't have to be a fancy high performance one just need the flex pipe. I would just have my local shop weld one in but they want like$150-$175 to do it and thats keeping the stock pipe. Plus I have to drop my jeep off to have it done just kind of a PIA situation. Also if I could get rid of that stock pipe with the dent in it I figure thats a small upgrade.

Also the reason I want the flex pipe in it is because I have cracked 6 headers now and I am getting tired of replacing them. Don't worry I havent bought 6 becuase I cracked the stock on and then bought a Banks header and they have the no crack gaurantee so 4 Wheel Parts just keeps giving me a new one everytime. But I heard that the headers crack alot due to the rigid nature of the exhaust setup putting stress on the header causing it to crack.

Check your motor mounts and your trans mount.

To answer your question directly: no, never heard of such a beast but have thought of the same thing myself. Find a cheaper exhaust shop: I got mine bent up for ~30 bucks.

I checked the mounts and they are all good one of the motor mounts is fairly new just a couple of years and the other is original but still in great shape. Trans mount also looks good from what I can tell the rubber isn't dry rotted and is not torn.

Unfortunately we only have one exhaust shop here in Statesboro, Ga. and the next town is a bit of a drive away. We had a Mineke but they were ungodly expensive and ended up going out of business.

I know that mine is cracking due to stress from the engine torquing because I knew when I towed my boat last, which is way too much for my Jeep to tow, that my header would crack from the engine having to work so hard and sure enough it did. So I replaced it and now it has cracked again. It has gotten to a point now where under normal driving they wont last more than about 6-8 months before I can hear the exhaust tick again.

I also should add that my exhaust is extra rigid since I have a dual exhaust set up but I don't want to get rid of it because it is cool and I paid good money to have it put in.

Yikes. That's fairly expensive, if you were any closer I'd tell you to show up with a six pack and I'd find a way to fix it. Installed a new flexpipe in my aunt's rav4 back in May, total material costs 20 bucks.

Sounds like your motor is moving around too much. Your mounts may look good, but in fact are probably letting it flop.

I kept cracking the mount where the crossover pipe comes back over the crossmember. The trans mount looked fine, wasn't cracked, and didn't show any signs of damage. Once I replaced it (and put in 2 M.O.R.E. bomb proof mounts,) I haven't cracked that mount, or the header either.

I agree with everyone that something other than the rigidity of the exhaust system is causing the cracks. I'll also add that adding a flexpipe may prevent it from cracking the manifold but flexpipes suck and will fall apart. Flexpipes are the first thing to go on any exhaust system.

cmelo said:

I agree with everyone that something other than the rigidity of the exhaust system is causing the cracks. I'll also add that adding a flexpipe may prevent it from cracking the manifold but flexpipes suck and will fall apart. Flexpipes are the first thing to go on any exhaust system.

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I've had a flexible section I got from an RX7 exhaust system at a junkyard on my junk for several years now and it's still in great shape.

Ben824 said:

I checked the mounts and they are all good one of the motor mounts is fairly new just a couple of years and the other is original but still in great shape. Trans mount also looks good from what I can tell the rubber isn't dry rotted and is not torn.

Unfortunately we only have one exhaust shop here in Statesboro, Ga. and the next town is a bit of a drive away. We had a Mineke but they were ungodly expensive and ended up going out of business.

I know that mine is cracking due to stress from the engine torquing because I knew when I towed my boat last, which is way too much for my Jeep to tow, that my header would crack from the engine having to work so hard and sure enough it did. So I replaced it and now it has cracked again. It has gotten to a point now where under normal driving they wont last more than about 6-8 months before I can hear the exhaust tick again.

I also should add that my exhaust is extra rigid since I have a dual exhaust set up but I don't want to get rid of it because it is cool and I paid good money to have it put in.

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1) Engine mounts are an "all or nothing" deal - betcha can't eat just one! When one fails, replace all three. Full Stop.

2) I'm sure their price for welding in the flex join is mostly labour. Got something else you can drive? Take in the downpipe and a flex join, and just ask for a cut-and-weld. Probably be twenty bucks. Last time I needed a few things welded, I just set it all up myself then took them by the shop, said I'd like to have them welded and I'd be back in a few hours. Cost me five bucks.

True dual, or mock dual? I'd like to know more about how you set that up, if only for my own curiousity...

If you decide to replace your stock dented downpipe while you're at it, you'll need to consider things like lift, travel, tracking (trackbar), etc.

It might end up taking you a bit of trial & error wheeling to know when you've got the clearance just right...... trust me...... :farmer:

5-90 said:

1) Engine mounts are an "all or nothing" deal - betcha can't eat just one! When one fails, replace all three. Full Stop.

2) I'm sure their price for welding in the flex join is mostly labour. Got something else you can drive? Take in the downpipe and a flex join, and just ask for a cut-and-weld. Probably be twenty bucks. Last time I needed a few things welded, I just set it all up myself then took them by the shop, said I'd like to have them welded and I'd be back in a few hours. Cost me five bucks.

True dual, or mock dual? I'd like to know more about how you set that up, if only for my own curiousity...

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The exhaust is not a true dual in the sense of 2 pipes coming from the header back but its not fake where one pipe is just there for looks and there is no exhaust actually coming out of it. I have a flowmaster 50 series muffler with a single inlet and dual outlets. I did the dual exhaust because I like symmetry and I hate the look of one exhaust tip. If you would like to see pictures too just let me know and I will take a few and post them.

As far as the mounts go I try changing out the trans mount and see if that helps but the drivers side motor mount is fairly new and in great shape last time I looked at it. The passenger side looks to be in great shape as well so I think I will just leave it alone.

I actually had some Rustys poly and rubber mounts and they both transmitted soooo many engine vibs through the Jeep that it made every tick and rattle in my Jeep come out even when idling so combine that with my ADD and sitting in traffic was hell and about drove me insane. I liked the performance the mounts and I felt like even power got to the wheels just a bit quicker with those mounts (no I am not saying I think I gained horswepower from motor mounts). Anyways I tried tuning the Jeep up every way I could think of thinking it was just a rough idle and it got better but was never fully cured until I put the factory mounts back in with the driver side one being brand new and the passenger side being original but still in great shape. And I bought the new one from the dealer because the ones they had at Autozone looked like cheap junk. This is all why I want to go the route of a flex pipe. If I have to replace a rusted one every 4 years I can handle that compared to dealing with engine vibs and replacing cracked headers every 4-6 months.

I am not sure how a replacement stock style downpipe would affect my trac bar since they are not close at all really. I have a lift so the original intention of the dent in the pipe won't matter. And I dont have some crazy susupension setup its just a RE 3.5" lift. I figure as long as I keep it like the stock design it shouldn't cause a problem with any future long arm setup that I might go with.

Unfortunately this is my only car and the pipe is welded at the cat since I have a replacement high flow cat.

Some cheap flex pipes: http://performance-curve.com/flexpipes.aspx

Ben824 said:

I am not sure how a replacement stock style downpipe would affect my trac bar since they are not close at all really. I have a lift so the original intention of the dent in the pipe won't matter. And I dont have some crazy susupension setup its just a RE 3.5" lift. I figure as long as I keep it like the stock design it shouldn't cause a problem with any future long arm setup that I might go with...

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Your track-bar determines where your front axle/wheels track in relation to your vehicle.

If you lift your vehicle more than about 3" without making some type of adjustment, your
front axle/wheels start to track too far toward the driver's side. The dent in the stock
downpipe is intentional in order to clear the front driveline under suspension compression.

OK, question for those with the flex section, where do you insert it? At the cross-over or in the straight section in front of the cross member or in the down-pipe? Do you butt weld the section in or use connectors?

Thanks.

Crawler said:

Your track-bar determines where your front axle/wheels track in relation to your vehicle.

If you lift your vehicle more than about 3" without making some type of adjustment, your
front axle/wheels start to track too far toward the driver's side. The dent in the stock
downpipe is intentional in order to clear the front driveline under suspension compression.

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I'm 90% sure my trackbar is adjusted properly and I still hit it with a 5.5" lift and long arms/heim steering/RE Extreme trackbar. I imagine it's just under crazy flex.

~Scott

sjkimmel99 said:

OK, question for those with the flex section, where do you insert it? At the cross-over or in the straight section in front of the cross member or in the down-pipe? Do you butt weld the section in or use connectors?

Thanks.

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"Somewhere in the downpipe" will be sufficient - between the header collector flange and the four-bolt flange at the front of the catalytic converter.

The problem is that the exhaust setup is terribly rigid in the forward section, and that's why header cracks are almost invariably accompanied by engine mount failure. The mounts fail and allow relative motion, then the header weldments fail (the HAZ in the weldment fails first.)

@Ben24 - poly is "harder" than the 'rubber' used in OEM engine mounts, and will therefore transmit more vibration. This is normal. Besides - if you want bad, I've seen where some drag racers machine their mounts out of a high-fatigue aluminum alloy or mild steel! When you're dealing with something that might run for fifteen minutes in between overhauls, you can get away with quite a lot...

5-90 said:

"Somewhere in the downpipe" will be sufficient - between the header collector flange and the four-bolt flange at the front of the catalytic converter.

The problem is that the exhaust setup is terribly rigid in the forward section, and that's why header cracks are almost invariably accompanied by engine mount failure. The mounts fail and allow relative motion, then the header weldments fail (the HAZ in the weldment fails first.)

@Ben24 - poly is "harder" than the 'rubber' used in OEM engine mounts, and will therefore transmit more vibration. This is normal. Besides - if you want bad, I've seen where some drag racers machine their mounts out of a high-fatigue aluminum alloy or mild steel! When you're dealing with something that might run for fifteen minutes in between overhauls, you can get away with quite a lot...

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I am aware that polyurethane is harder than rubber and I had heard that it may transmit more vibs into the chassis. It was just much more than I expected and more than I was comfortable dealing with on a daily driver in stop and go Atlanta traffic which if any know Atlanta is more stop than go. Thats why I then tried the Rustys rubber bushing engine mounts and again still more vibs than I cared for which I assumed was due to the fact that with their bushings there was almost half the amount of rubber material in their bushings than compared to the factory mounts. I plan to look over all the mounts again since it has been a few months since I last closely examined them but since not all Jeeps are created equal I think my issue is in the exhaust system itself since I have to really push down on the header to force the downpipe to move down enough to allow the header to fit over the studs in the head for the header.

Ben824 said:

I am aware that polyurethane is harder than rubber and I had heard that it may transmit more vibs into the chassis. It was just much more than I expected and more than I was comfortable dealing with on a daily driver in stop and go Atlanta traffic which if any know Atlanta is more stop than go. Thats why I then tried the Rustys rubber bushing engine mounts and again still more vibs than I cared for which I assumed was due to the fact that with their bushings there was almost half the amount of rubber material in their bushings than compared to the factory mounts. I plan to look over all the mounts again since it has been a few months since I last closely examined them but since not all Jeeps are created equal I think my issue is in the exhaust system itself since I have to really push down on the header to force the downpipe to move down enough to allow the header to fit over the studs in the head for the header.

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Just wanted to make sure - not a lot of people know about poly v. elastomer, so they're surprised when the ride suddenly gets harsher (poly suspension bushings have the same effect.)

And yep, I'm familiar with ATL traffic!

The core of the problem is that the exhaust setup is too rigid - the only available flexion where it's really needed is the small elastomer block at the crossmember, that has the "smile" cut into it for the tongue on the cat flange. More is needed - ergo, the flex joint addition. While I'd say fully 80-85% of manifold weldment failures are preceded by engine mount failure (enough to fully establish a causal relationship,) not all cases have the mount failure as a factor - so vibrations can play a part (even with good mounts.)

Again, adding a flex join should see to that little headache neatly. And, you can add it anywhere in the downpipe - the key is that now there is some flexibility in the forward end of the exhaust system undercar.

Weld or clamp, your choice.

Ben, I believe that Meineke is open again, just so you know.

RenegadeStang said:

Ben, I believe that Meineke is open again, just so you know.

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Is it? I really never go down that way so I guess I'll have to go over there and see what they would charge.