Several months ago I replaced one of the crawford cats (the right side) on my coupe. It cracked. Fortunately, Doug was willing to send me a new cat for free (best customer service ever). Recently, I just notice that now the cat on the left side got a crack too, to make things worst, the right side that just got replaced several months ago got a small crack again.
The local muffler shop weld both cats today. However, the guy told me that it might crack again due to the design of the system and the bracket.
The cracks on the cats are always at the same spot, which is near the bracket.
Does this ever happen to anyone? at first I thought it was normal to have a crack at the first time, but since this already happened twice in a short time period, it made me worried.
The only exhaust mods i have is crawford cats, Gruppe-s Y-pipe and Fujitsubo exhaust. Is it possible that crawford cats are not compatible with the Gruppe-s Y-pipe and Fuji exhaust?
Someone please help me, why do my cats cracked twice in a very short time period?

 

It's the bracket. Have your muffler guy remove it.

 

do you mean that yellow color brackets that are attached to teh transmission? yeah. I just got that removed.
Should I replace both cats with a set of new cats or does welding the cracks will do the job just fine?

 

If the crack is where the cat and the pipe meet up, just weld it.

If there is a crack in the body of the cat, that is a manufacturing defect from the cat maker.

 

No, the crack on my cats are on the joint between the body of the cat and the little brackets on the cat. Is that crack can be fixed by just welding it?

 

Does your Y pipe have the flexible portion like the stock one?

 

yes it does have the flexible part, it's a Gruppe-s y-pipe.

 

Agreed, this is what my mechanic did after welding my cracked bracket.

 

biscotti, i think we are exactly on the same boat. I was just wondering if it's OK to just weld the crack. Do I need to replace the cats with the new one?
By the way, after removing the bracket, I do feel more vibration from under the car. Is this normal?

 

I think its ok to just weld the crack, its stainless steel so you need to weld it with the right stuff. This is according to my mechanic friend, who has done all of my modifications, so I trust him. Removing the bracket seems to have increased some of the vibration, usually when the engine is cold, but at least the rattling is gone, this was driving me crazy. For now, I'm just going to wait and see, worse case scenario is to return my cats to OEM. I hope you kept your stock cats.

 

biscotti, I feel the vibration under heavy torque.. expecially at 2500-2700 RPM. I feel vibration from underneath the car. Do you feel that too?

 

Yeah, some vibration is definitely there, but I can live with it for now. Once everything warms up it is less noticeable though.

 

hmm.. I dont feel any vibration when the engine is cold. I only feel it when I drive at 2500-2700 RPM. especially on second and third gear.
By the way, when you rev the engine, do you hear raspy hissing sound as the RPM drops?