'94 AT Precat Removal

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Nov 7, 2016 | 03:17 PM

Andrewsvette

Thread Starter

Intermediate

Joined: Jun 2013

Posts: 38

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From: Dallas Texas

'94 AT Precat Removal

Hi all,
I tried doing some digging around before posting but couldnt find exactly what I was looking for. I am dropping the exhaust off of my 1994 AT to do some fiberglass repair on the passenger floor board and have everything busted loose from tips to exhaust manifold bolts. The only thing I cant get to are the brackets that are on what I am assuming are the precats on each side. Does anyone have any tips or tricks to get to these bolts and bust them loose? It is all i lack to have the entire exhaust dropped from the car besides the exhaust manifolds. Any help is appreciated.

Andrew

Nov 27, 2016 | 09:56 PM

Andrewsvette

Thread Starter

Intermediate

Joined: Jun 2013

Posts: 38

Likes: 0

From: Dallas Texas

Bump, any help is appreciated looking to pick this project back up this week!

Last edited by Andrewsvette; Nov 27, 2016 at 09:56 PM.

Nov 28, 2016 | 02:06 AM

wikdwizard

Pro

Joined: Jun 2009

Posts: 697

Likes: 30

From: Kansas City, Kansas

The PS is relatively easy from the bottom. The DS has one bolt that is easier to get from the top with the manifold removed if I recall correctly. It's not a fun one to get to. The other option if more clearance is needed is to remove the C-member/driveshaft and lower the rear of the engine/trans, but that comes with it's own bag full of cautions and obstacles.

Last edited by wikdwizard; Nov 28, 2016 at 02:13 AM.

Nov 28, 2016 | 01:11 PM

c4cruiser

Team Owner

Joined: Dec 1999

Posts: 34,873

Likes: 487

From: Lacey WA RVN 68-69

NCM Sinkhole Donor

Try soaking them with something like PB Blaster and let it sit overnight. Might take a second application, but they should come off.

No "precats" on the LT-powered C4's. Those are the only cats on the car. The large can behind the trans is a resonator.

Nov 29, 2016 | 12:16 PM

mrodoc

Instructor

Joined: Feb 2015

Posts: 234

Likes: 20

From: Stuart Florida

I did this about a year ago. If I understand your question, those brackets are a !**%!! to remove. They are bolted to the Tranny Bell housing. I had to drop the c-beam and driveshaft and let the tranny tip down and the rear of the engine tip bacbackward towards the firewall. I let the engine tip until the oil pressure sending unit was almost touching the firewall. Then I used a 22" evtension and a 6" extension coming in from the rear top of the tranny, and I got them loose. I tried to avoid this, but skinned too many knuckles and just wasted time.

Nov 29, 2016 | 01:02 PM

ddahlgren

Melting Slicks

Joined: Dec 2008

Posts: 2,772

Likes: 64

From: Mystic CT

Unless a show car get a sawzall cut them in a handy place. if you insist on putting the pre-cats back on use a piece of strap and a couple bolts to connect the cut parts.

Nov 29, 2016 | 10:48 PM

Silver96ce

Drifting

Joined: Mar 2012

Posts: 1,492

Likes: 61

From: New Jersey

Quote:

Originally Posted by Andrewsvette

I assume that that the '94 LT1 exhaust is the same as the '96 except for the extra O2 sensor post cat on the drivers side. You don't have to remove the catalytic converters with the exhaust system. On the drivers side there are two nuts and a bolt holding the rear of the cat to the exhaust. Be aware that they often snap so soak them good for a couple of days. On the passenger side, the exhaust slides over the pipe exiting the passenger cat. Again, this can become stuck so soak it well. If you want to remove the passenger side cat with the exhaust, I found it easier to remove the bolts holding the cat to the bracket. I used a metric half moon gearwrench (14mm? - not sure since it's been a couple of years) on the bolts holding the cat to the bracket then a nut and bolt to attach the other end of the gearwrench to the box end of a combo wrench for leverage (and access) to break them loose.

As another said these are the only cats on the car.