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New Walker Downpipe vibrating on crossmember.

M

mrtosh

NAXJA Forum User
Location
Woodbury, MN
I just finished up installing an APN manifold(header), NAPA downpipe(Walker#55277), Magnaflow cat, and Dynomax Catback. Install went off w/out a hitch, except for trying to get to the number 1 bolt to torque it down. It is physically impossible from the top or the bottom to get a socket on it. Was eventually able to get it tight w/a 14mm gear wrench. The exhaust sounds a bit deeper than stock and has a little more throttle response. Only down side(no pun intended) is the new downpipe rest right on the crossmember, soo it rattles when you hit a bump, start it, and shut it down. There really is no way to move the pipe to make it not hit, but was thinking of heating it up and denting it... Maybe notching the crossmember? Anybody else have this issue? Anybody find a fix?
 
sounds like your motor mounts are bad...and maybe your tranny mount too...
 
JNickel101 said:
sounds like your motor mounts are bad...and maybe your tranny mount too...
Click to expand...
I don't know about that... If they were bad when I really rev it it would rattle or wedge against the crossmember causing vibes(which has happened before on a previous jeep)... It only rattles on start up and shut down. The pipe sits maybe a 1/8" above the crossmember and no matter how I moved it it would sit like that. I've heard of other guys having the same problem just don't know what they did to fix it.
 
was your stock exhaust manifold cracked?

you could just go look at your mounts to see if they're bad - stock ones suck anyway - instead of theorizing.
 
My stock downpipe rattles on my Rusty's 1 inch drop crossmember. I replaced the motor mounts and it still rattles. I am planning to change the tranny mount next.
 
JNickel101 said:
was your stock exhaust manifold cracked?

you could just go look at your mounts to see if they're bad - stock ones suck anyway - instead of theorizing.
Click to expand...
I checked the motor mounts when I did the APN, they were fine. The stock header was cracked. The pipe sits right on the crossmember..... No matter how you turn it at the header connection.. I fail to see how the mounts would make a difference if it's sitting on the crossmember(or a hair above) in the first place? Even w/solid motor mounts it would hit the crossmember.
 
I heated and flattened the down pipe where it crosses the cross member, my last down pipe replacement was also more than a little off.
If I had it to do it again, I'd try loosening the the flange at the exhaust manifold and the clamp at the CAT then put a piece of wood between the down pipe and the cross member (taking some of the stress off of the hanger), then re tighten. Pretty sure you can get some clearance at the cross member this way. In other words push up on the last 90 degree bend before the cross member, with the exhaust flange and the clamp at the CAT loosened. Getting the exhaust pipe to spin/twist a little at the CAT may be unlikely if it has already been tightened with a clamp and dimpled. I might also try heating and bending the exhaust hanger at the tranny mount.
A coupe of spot welds at the CAT to exhaust pipe joint along with the clamp, also helps keep this spot from relaxing and sagging.
 
trans mount
 
mrtosh said:
I checked the motor mounts when I did the APN, they were fine. The stock header was cracked. The pipe sits right on the crossmember..... No matter how you turn it at the header connection.. I fail to see how the mounts would make a difference if it's sitting on the crossmember(or a hair above) in the first place? Even w/solid motor mounts it would hit the crossmember.
Click to expand...

If your motor and/or trans mounts are bad, your engine/tranny will be sitting lower and therefore, your pipe will sit lower and hit the crossmember.

Also, bad motor mounts will cause your exhaust manifold to crack. Again.
 
Not to sound like a broken record but if the mounts were bad wouldn't the old downpipe rattle as well?



JNickel101 said:
If your motor and/or trans mounts are bad, your engine/tranny will be sitting lower and therefore, your pipe will sit lower and hit the crossmember.

Also, bad motor mounts will cause your exhaust manifold to crack. Again.
Click to expand...
 
I installed one and never had an issue with that. I would think that the stocker would have had the problem as well but who knows. I had poly trany and motor mounts on mine so it raised everything up a bit, even more than a new rubber trany mount would.

It might just be the way your set up is. Maybe you can add an extention peice to pull the down pipe towards the front of the jeep more (where it's supposed to be).

Other than that, I'd fix it the same way you fix everything else on a jeep, with a hammer.
 
The hanger on my downpipe was bent, and the pipe would hit the crossmember when I went over potholes and such. Exhaust shop hit it with the torch and tweaked the hanger- took about 10 minutes, problem solved. HTH.
 
I thought I'd resurrect this one from the grave since I'm having the same problem w/ the same parts. I am installing:

1A Stainless Steel Exhaust Manifold (http://www.1aauto.com/1A/ExhaustManifolds/Jeep/Cherokee/1AEEM00146/250322/1999)
Walker 55277 Downpipe
Magnaflow 23226 Direct Fit Cat
Dynomax 17340 Cat-Back

I just installed my engine after a complete rebuild. I installed new OEM motor mounts and transmission mount when I put it back in. The downpipe connected perfectly to the exhaust manifold and the metal "bar" that goes through the mount above the cross member went right through. The problem I saw right off was that the downpipe was within 1/8" from the rear of the cross member. When I put the cat on, the weight was enough to have the downpipe make contact with the crossmember. BUT, the cat was angled up a bit. So, when I put the muffler on for a test fit, it was smashed up against the aluminum heat shield. I need to have the downpipe come over the crossmember w/o hitting and be angled downward. What's the problem here? I've read about people using this combination on multiple XJs w/o issue. For me - it will NOT work. Thoughts?
 
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