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Both cats failed last year, 1st time. On the right side the cat has a bracket with 2 bolts. I can barely see the left bolt and cannot get to it. I've tried swivel socket, numerous wrenches etc. If anyone can help out I would be truly grateful. 1993 c4. If I own a c4 I have to be mechanical.
Thanks all!!
I would take it to a shop go ahead and soak them with some good penetrating oil since your under there. I do all my own work but sometimes best to leave it to a pro.
Which bolt are you having issues with, the bolt that holds the cat to the brace, or the bolt that holds the brace to the transmission? I just replaced my left side cat, and that was an adventure. The car is still up on ramps, so I'll crawl under tomorrow and see what I have to work with. Also, is your car auto or manual?
From a L98 owner I am curious about this Thread. Why are the LT1 cats/pipes different lengths? I’ve seen many aftermarket exhausts for LT1’s and know they are different than mine.
From a L98 owner I am curious about this Thread. Why are the LT1 cats/pipes different lengths? I’ve seen many aftermarket exhausts for LT1’s and know they are different than mine.
Wondered that myself. Driver's side bolts up to the exhaust while the passenger side slides into the exhaust.
The left cat was easy after spraying the 3 header nuts and the 3 cat bolts with WD for a day. The right side header nuts soaked a day and came right off. The bracket to cat left one of the two is what I can't get to. It's barely visible and I don't see the bolts attaching the bracket to the auto trans. I did get a swivel socket on it but it was a cheap import and broke. A socket and swivel is too long and wont turn due to the angle. I've got a Snap on 15 mm swivel coming. Hope it works. Can't take a picture of what I barely see.
Failed to mention..the flowmaster cats are much smaller than the oem, same shape and length. Probably be able to get that bolt back in if I ever get it out. Of course the FSM just says remove 2 bolts.
Crawled under my car and took a look. Lo and behold, the right side brace is not there. But I don't see where access to either bolt is difficult. I wouldn't think there is that much difference between my 95 M6 and your automatic. I will post up a pic of what I have.
Brace is gone, but can see where the bolt goes in.
I think that is the same bolt that I dealt with when removing my Cats to install my ARH headers/Cats, it is up by the bellhousing with no way to get any tool up there.
The bolt seems to be accessed by removing the transmission! I cut the bracket instead.
This probably does not help the OP much but the ARH Cats did not use that mounting point which is why I cut the bracket.
I think that is the same bolt that I dealt with when removing my Cats to install my ARH headers/Cats, it is up by the bellhousing with no way to get any tool up there.
The bolt seems to be accessed by removing the transmission! I cut the bracket instead.
This probably does not help the OP much but the ARH Cats did not use that mounting point which is why I cut the bracket.
For some reason, GM put one brace to transmission bolt in a spot that requires either tilting the transmission or drilling an access hole in the floor pan to remove. The OP indicated this was the bracket to cat bolt. If he can get that out, there will be no need to remove the bracket.
Yes indeed that is the hole for the bolt but in that picture you have a world of room more than me. I cannot even see the bolt from the angle you used and I don't fancy removing the trans or cutting a hole in the floor. How in the world did you cut that bracket with the cat attached. Still crossing fingers the new swivel will do the trick
I found the driver's side brace cut off on my car. From the cut, it appears they used a torch. I assume they were able to get the old cat out, and since the aftermarket replacement didn't require the brace, just cut it off. (Since it is also nearly impossible to remove.).
In your case, can you get a sawzall, or something like that in there? On a more radical side, if you want to save the brace, is there any way you can use a sawzall to cut off the cat inlet just downstream of the brace?
Thanks College Station and hope all is well there. They must have cut that brace after removal. I didn't even see it till I took the cat off. There is just no room to get at the right bracket unless I cut the cat in half which I might try if the swivel socket doesn't work. I'll report back this weekend. Thanks for all the input!
I'm not happy to report the new swivel socket did not do the trick. It's a full size socket, the broken import was a shallow socket. I can get on the bolt but not turn due to the angle and no clearance. So now it's either try to cut the cat off or cut a hole in the floor. Thanks for all the input!!
I just went through this this week putting my Melrose headers on. I did the right side first and thought that was bad. I spent 2 hours on the right upper bolt before I said Oh hell I'm just going to BUBBA it. I used my battery powered sawsall to cut the bracket since the headers don't use the bracket. I don't feel good about it but it worked. Once I decided to go that route it only took 10 minutes. If you decide to follow my poor example just be careful of the ground strap right there.
Good luck,
Dave
need help replacing cats, PLEASE
