ColoradoJeepXJ

Ok, here's the problem:

When I’m bouncing around off road, my front driveshaft keeps hitting the exhaust pipe. When I bought the Jeep, the exhaust pipe had a couple of small dents but after taking it off road a few time, I put several more dents in it. I thought the pipe might be bent, so I put a new one on. It still hits and after my last run, the driveshaft actually popped a hole in the pipe.

I have a 4.0L with a HP D-30. The axle is centered, motor mounts are good, exhaust manifold looks good and the exhaust mounting point just before the cat looks good.

Does anyone else have this problem and how can I fix it.

Joshman503

I have never seen this before. Are you running bumpstops up front? Thats the only thing i can think of. Hopefully you figure it out. Exhuast leaks and fumes are never fun.

Is the exhuast stock? is the hanger still connected to it?

ColoradoJeepXJ

I have extended bump stops and do not want to add anymore to it or I’ll end up with less travel than stock. Currently the exhaust system is stock and hung correctly.

I just did a search on “that other site” and found pages of people with the same problem and a bunch of ideas, but no real solution other than a custom down pipe. Since I apparently need to replace the current down pipe, I guess I’ll go custom. That should cost some coin.

whowey

I had and have the same problem... I just think Jeep engineers never really expected the amount of travel we expect out of the d-shaft...

BlueXJ

I know you said you checked the mounts but that is what was broken on mine when I first got it and the front DS would hit it. Check those mounts again.

Kyle

X2 there should be no contact at all with those two parts. Im thinking something is wrong with your mounts.

ktmracer419

never seen that before

i dont understand how it hits with a 5" lift and extended bumpstops, especially that badly.

everything i could think of being the culprit you already covered

muddeprived

My solution to this problem would be to go to an exhaust shop, show em the problem and have them re-route the exhaust. It shouldn't cost much. They can just cut out what's in the way and add new piping in a different location, higher or whatever they feel won't hit. I've seen a couple exhaust tweaks using flat exhaust which isn't round but oval and wider and it enables the same amount of flow. Or just adjust your bumpstops. Flex it out on a hill till it's just about to hit, measure the distance of bumpstop space and add that much more. Hockey pucks would be useful here.

Bouncy

A few more detailed pics might help.

I am wondering if your exhaust manifold is bent away from the motor. I haven't ever hit my pipe and I have had the full range of lifts on my XJ. 2", 3.5" 4.5" 6" 7" and now 8" long arm.

That pipe should be hugging the motor and roll under the tranny pretty tight.

One thing mentioned about not wanting alot of bump stop...Why not. Bump stop is your friend. Stopping the tire from going UP ensures your putting weight on the tire to climb. You want as much Down travel as possible so your drive tire can meet the trail.

Many people think UP travel is best. Its the down travel to the ground that gets the vehicle's tire on the dirt/rock and moves the jeep. Keep that in mind and also with added bumpstop, your body does lift more to get your bumper over your obsticle.

ColoradoJeepXJ

My current bump stop allows about 4” of travel at the perch. That’s enough to allow me to stuff the tires without hitting anything.

I rechecked the motor mounts and both ends of the down pipe. Everything is tight. The exhaust manifold is tight and looks like it is in good shape. The one thing that I don’t think is correct is that the exhaust manifold holds the down pipe a good 2-1/2” off the motor. I guess I’ll have the new pipe bent to move it closer to the motor. From the dents and holes in the pipe, it looks like I only need to move it over about 1” to get it out of the way.

BlueXJ

Yeah mine is much closer to the motor almost touches it. You will be fine when you get that fixed/replaced.

Bouncy

Two things.

1. APN sells a really good CHEAP aftermarket header. Mine was $120 shipped to my door. Fixes the cracking manifold issue, gives you the correct angle to hug the motor, adds performance, and oh yeah...ITS CHEAPER than borla or anyone else for that matter.

2. Around me, I can get the local exhaust shop to bend me up pipe dirt cheap. A few pipes I have had done for $20, I think I remember getting TWO down pipes for my XJ for $75. I needed one to get me by for a month till I could get the other one ceramic coated. And no my spare wont fix your jeep. I had a 3" flange put on the header and ran 3" pipe for flow.

ColoradoJeepXJ

I don’t think I want to do headers yet. Things start to snowball when I get into it and it’s too early in the season to have that kind of down time. If I pull the exhaust manifold, I’ll want to pull the head and redo the valves. Then I’ll want to replace the rings because of a blow-by problem. Then, since I’ve got it apart, I’ll want to stroke it.

For now I’ll just go with a modified down pipe.

Thanks for the help.

.

Bouncy

Boy do I know that story.

Was an axle swap, lead to new suspension, then long arm, then skids, then bumpers, then stroker and new trans for 23 spline...then 231 sye.

What rolled in as a simple 8.25 swap with new disc brakes and new booster, rolled out as the above build. I just wanted a lincoln locked 8.25 I tell ya :P I ended up with a D60 full detroit with discs and a D44HP front ???? But I love it

ColoradoJeepXJ

Just went shopping at the local pick & pull and found a down pipe that looks to be bent exactly the way I need it. I had to spend $5 on it. As I was pulling the pipe off, there sitting beside me glistening in the sun was the right front axle I needed to replace the one I busted Sunday. It looks like someone just wanted the wheel bearing and left the shaft sitting there for me to find.

Some days it all works. I think I’ll buy a lotto ticket.