Installing a Heffner Cat Back exhaust and need to know the recommended fastners to use. Should they be SS or high temp. fine or corse thread?
Thanks in advance.
DJ
Thanks in advance.
DJ
Recommended Fastners Heffner To Cats
- Thread starter DanielJ
- Start date
- Feb 22, 2006
- 367
Hello,
We use grade 8 fasteners. The bolts are 3/8 - 16 x 1 1/2. Also grade 8 nuts and lockwashers. If this is a new system purchased from us there should have been fasteners in the box. If not, let me know and I'll send some right over.
We use grade 8 fasteners. The bolts are 3/8 - 16 x 1 1/2. Also grade 8 nuts and lockwashers. If this is a new system purchased from us there should have been fasteners in the box. If not, let me know and I'll send some right over.
Thanks for your response. Purchased the unit used. Thanks too for offering to send the bolts out, but will purchase local.
Regards,
DJ
Regards,
DJ
Heffner customer service sucks.... it took almost a damn hour to get that answer. Sheesh!
Happy with the one hour response!
Followed your guidelines to removal of exhaust. Had my good friend and fellow FGT owner help me out. Both "first timers" on OE FGT Exhaust removal but we both have lots of experience working on cars. We had a great time doing the work and were rewarded with an exceptional exhaust note on start up. I'll post some pictures and comments on the removal process where we were having some minor issues. We were no where near what some report a 3 hour removal/install process.
Now on to all fluid replacement.
Best,
DJ
Last edited:
BlackICE
GT Owner
Accufab also uses the same fastners. I am probably going to switch them out for metric sized bolts. Everything else is metric on the car so why not. If you carry a tool kit with you then don't need to worry about having the wrong size socket or wrench to do the job, or have to carry SAE sizes too.
dpdive
GT Owner
Come on Daniel lets see the pics. I hope you like the sound of the Heffner as much as I did.
As an FYI stainless bolts on an exhaust system is a very bad idea. They might look good but they will never come off once they have gone through several heat cycles.
I did black Jet Hot over Shawn Fischer's shorty headers, cats & GT Guy cat back. Then Fischer's inconel heat shields over the entire exhaust. Hopefully no more melted wires, clips, bumper cover, etc. and even more HP.
As an FYI stainless bolts on an exhaust system is a very bad idea. They might look good but they will never come off once they have gone through several heat cycles.
I did black Jet Hot over Shawn Fischer's shorty headers, cats & GT Guy cat back. Then Fischer's inconel heat shields over the entire exhaust. Hopefully no more melted wires, clips, bumper cover, etc. and even more HP.
First, let me say this was a fun and worthwhile adventure. I think that doing the work alone and without a lift is certainly more difficult. Clam shell “On-Or-Off” will be a personal preference, however, with the unit on, be sure to use protective tape where you think contact areas are and where you think it is not necessary, then you will be ready.
With the OE muffler in place, I saw no access or a way of removing the top vent shield (just below the license plate area) torx screws to the sides are clearly evident and then from the back I could only see the pop rivets that attaches the screen to a bracket. So, this part remained in place during the removal process of the oe muffler. Note, if the license plate is removed, the two screws that attach the screen to the said bracket would now be accessible for total removal. However, not a big deal at this point.
With all attachment points removed and associated muffler brackets, no matter how we tried to rotate/push/pull/wiggle/cuss at this muffler, we encountered resistance from the right exhaust tube hitting the back of the transmission and be infull contact with the clam shell (remember that tape?) Finally, we delivered that hummer with one guy in the engine compartment and the other pushing on the tail pipes. Our baby was well over 50lbs (or whatever the weight is) and out of the car.
Thank goodness, installation is not what you read in most any car manual, “Reverse Of Removal Process” as the Heffner pipe was a snap to install. Loosen up the cats, get the brackets back in, put in the bolts, align up the exhaust pipes as best as possible, install the screen (large hole “Challenge Grills”) install the bumper and then tighten it all up. Finally, install the lower grill. Remove all that blue tape. Reinstall the belly pans unless it is time for new blood, clutch/brake fluid and anti-freeze, which is currently being completed on the car.
So, to remove Clam Shell or not, it may be a good idea if you want less worry-grunt-groan-worry will something get screwed up, but the shell flexes enough and with proper protection, should not be a big deal, just plan on contact with the unit and the muffler.
OE exhaust:
Heffner installed:
View from the top. See the little Philips head screws just under the license plate screws? Also, I’m missing one of the vent nuts/washers on clam shell:
Bolted into place:
Side view:
All in save for belly pans:
Appropriate use of OE muffler:
I’ll see if the video of pre/post installation can be posted a bit later on.
Thanks.
DJ.
With the OE muffler in place, I saw no access or a way of removing the top vent shield (just below the license plate area) torx screws to the sides are clearly evident and then from the back I could only see the pop rivets that attaches the screen to a bracket. So, this part remained in place during the removal process of the oe muffler. Note, if the license plate is removed, the two screws that attach the screen to the said bracket would now be accessible for total removal. However, not a big deal at this point.
With all attachment points removed and associated muffler brackets, no matter how we tried to rotate/push/pull/wiggle/cuss at this muffler, we encountered resistance from the right exhaust tube hitting the back of the transmission and be infull contact with the clam shell (remember that tape?) Finally, we delivered that hummer with one guy in the engine compartment and the other pushing on the tail pipes. Our baby was well over 50lbs (or whatever the weight is) and out of the car.
Thank goodness, installation is not what you read in most any car manual, “Reverse Of Removal Process” as the Heffner pipe was a snap to install. Loosen up the cats, get the brackets back in, put in the bolts, align up the exhaust pipes as best as possible, install the screen (large hole “Challenge Grills”) install the bumper and then tighten it all up. Finally, install the lower grill. Remove all that blue tape. Reinstall the belly pans unless it is time for new blood, clutch/brake fluid and anti-freeze, which is currently being completed on the car.
So, to remove Clam Shell or not, it may be a good idea if you want less worry-grunt-groan-worry will something get screwed up, but the shell flexes enough and with proper protection, should not be a big deal, just plan on contact with the unit and the muffler.
OE exhaust:
Heffner installed:
View from the top. See the little Philips head screws just under the license plate screws? Also, I’m missing one of the vent nuts/washers on clam shell:
Bolted into place:
Side view:
All in save for belly pans:
Appropriate use of OE muffler:
I’ll see if the video of pre/post installation can be posted a bit later on.
Thanks.
DJ.
For others that may one day follow in Daniel's footsteps.....
If you remove that upper black screen, you can get the OEM exhaust up and out much, much easier. As Daniel noted, there is a T27 torx screw on either side of the panel holding it to the frame horns. And then there are two Phillips head screws just to the outside edge of the license plate opening. (The pic below shows one of the two screws.) With the OEM muffler in place, use a 90-degree Phillips head screwdriver to remove these two screws. Thankfully, they are very short. The screen can then be removed which allows the OEM exhaust a LOT more room to be rotated and lifted out. With an aftermarket muffler in place, the screws can be put back in with a normal screwdriver.
If you remove that upper black screen, you can get the OEM exhaust up and out much, much easier. As Daniel noted, there is a T27 torx screw on either side of the panel holding it to the frame horns. And then there are two Phillips head screws just to the outside edge of the license plate opening. (The pic below shows one of the two screws.) With the OEM muffler in place, use a 90-degree Phillips head screwdriver to remove these two screws. Thankfully, they are very short. The screen can then be removed which allows the OEM exhaust a LOT more room to be rotated and lifted out. With an aftermarket muffler in place, the screws can be put back in with a normal screwdriver.
OE Configuration:
View My Video
Heffner:
View My Video
Smoke out of exhaust at initial start up is due to the oil prime sequence after oil change.
DJ
View My Video
Heffner:
View My Video
Smoke out of exhaust at initial start up is due to the oil prime sequence after oil change.
DJ
