My HF Cats keep cracking. They have been replaced under warranty many times and I even had an engine damper installed to prevent this. Any alternatives? Have any of you had this problem and how did you solve it? Im thinking of just getting test pipes but I dont know if I will have the same issue. The crack happens at the weld where the cat is welded to the pipe closest to the engine. I figure if test pipes are only welded at the flanges, then I should be good, right? Any help is greatly appreciated, need to resolve this week.

 

I could've sworn I read a thread a while ago about how Nismo exhaust causes crawford cats to crack...

guess it is still a problem...

 

that's true, the nismo causes cracking in the crawfords. Try not to bottom out your Z...

 

yea, it's the catback causing it. poorly designed y-pipes = cats crack very quickly

 

I havent bottomed out at all though and there are other guys with the same exhaust who havent had a problem, although there are plenty that have. I heard that it is any exhaust that is not true dual. Will I have this problem with UT-R resonated test pipes?

 

+1 on the nismo causing hfc's to crack

 

yes; poor desing = anything will crack; if your cats are cracking i don't see any reason why test pipes wouldn't.

 

Is there a soloution to this problem?

 

If you don't have the original cat brace on them, having it fabed up so that was helping to support the cats could help.

Also, does the Nismo Y-Pipe have flex pipe sections?

 

I have gone through 3 versions of these cats. V1 had a hanger welded to it. They said this is the problem and redesigned with out it. v2 no hanger but still some little plate over the weld and now this is the problem. V3 no hanger no plate held up for longer but eventually cracked again and always in the same spot. Personally I just think it is a crap weld. I mean look at the weld on a Crawford cat some time, its like a piece of spagetti its so thin. But the last version did have a thicker weld and I do need to get it on a lift to confirm but I have gone through enough of these since Thanksgiving to know a cracked cat when I hear one.

If by flex on the Y pipe you mean that braided section, then the answer is YES. Not everybody with a NISMO exhaust has had this problem as far as I know. I know of atleast one guy with Nismo and Crawfords and his are fine.

 

This might not be good news but: I've had both cats welded due to the same problem. I almost look at it as a necessary evil. I don't want to change my exhaust, nor do I want to go with different cats. Many things can go wrong when you mod a car and this happens to be the result when you combine these products. Both times I went to this hole in the wall type place which charged me $20 to get them welded. I've looked for other alternatives short of changing my setup and I haven't found any.

 

from what i've seen, having the original cat brace, more often than not, makes FAR more problems than it solves in terms of cracking. Hence why kinetix and crawford no longer make them w/ the brace.

 

i still say it's the nismo; i really like the sound of it but the fair majority of comments on it + hfcs/test pipes are 'wtf! why are mine cracked!!! ' Granted, not everybody, but the majority. Rather curious though how some manage to avoid the fate (although maybe only temporarily?)

 

has anyone had a test pipe crack or is it just the cats?

It never cracks at the flange, only at the weld to the Cat itself. So I think a non resonated one piece pipe should hold up fine but I want a resonator and that involves welds in the problematic area. This is my dilema.

Wednsday I go back to the shop and I need to figure out what to replace these cats with. OEM is not an option(Smog only) so it looks like test pipes are the logical way to go and they carry UT-R and Top Speed so I figure one of those should be good, they dont sell garbage. So then the question is: Resonated or nonresonated?

Will either choice be an improvement in sound and performance, over HF cats?

 

I've had my Nismo exhaust & Crawford cats for over a year now w/ no cracking (keeping fingers crossed).

- ****, maybe I shouldn't have said that w/ my 666 post!

 

TOO LATE! In fact, I wouldn't doubt it if they both cracked at the exact same time you posted.

 

I better go home & check them now.

 

I'm not trying to bash you but, Nissan put that brace there for a reason. True the Nissan cats are way bigger but, a brace which offers more support should not contribute to cracking. The brace itself is mounted to the tranny with rubber spacers allowing for some movement. I know I’m not an engineer and I can’t say for sure if the brace on Crawfords or Kinetix helps or make things worse, I’m just trying to help.

Thanks,
Gary


Maybe your right and it's not the brace.

 

lol....hope i don't get any bad mojo from attaching my name..but..


i have had the same problem and when it cracks you can really hear the leak. i had a shop reweld the support and cat and had him do the other side as it was beginning to crack as well. i believe its just the way it is because i have fuji ti, crawford cats, and fuji y...they just don't fit right or something.

you would have to relieve that pressure somehow and that would take some modification of the exhaust

for now, i will live with it...really no choice

 

Are you guys with the cracked cat problem's noticing any road rash on your exhausts when you inspect them?