Exhaust removal

[lotusolly]

Hi all,

Started this afternoon to try and remove my backbox. I expected it to be a tricky job as it appears to have been untouched for 16 years but wondered if anybody who has succesfully achived this could offer any time saving tips?

Managed to remove the cat heatshields ok to expose the back box flanges and as expected the nuts and bolts now resemble a rusted blob and there was no chance that they were coming off with a spanner or socket!!

Ground off one side of the bolts and expected to be able to tap the remaining bolt out of the flange but it wasn't going to be that easy and it was still solid! Ground off the other side and tried tapping through again but still not shiffting, even with a parrallel punch and large copper mallet!! Have these just rusted solid and going to need a plain drill out or did Honda thread one of the flanges?

Anybody got any tips for getting to the top bolt on each of the flanges?

I have got new headers to go on so the other end of the cat is going to need to come apart but I wasn't intending doing the header change just yet although they can be bolted back in if it is easier to remove them to get the backbox off now?

The old backbox is still in full working order and I would like to save it to be able to refit it to the car if I should decide to sell it so don't really want to damage it in the removal process.

Many thanks

Olly

[greenberet]

Jeffrey Albertine (Jeff A on NSX Prime) wrote an article titled "DIY Headers & Exhaust" for NSX Driver (the NSX Club of America's magazine) that may be useful: http://www.tuckerbud.com/Track/Headers/DIYHeaders.doc

In case you don’t have it, the Service Manual has good diagrams showing what kinds of fasteners are used where. You can download it here: http://www.nsxprime.com/wiki/Service_manuals. In the 1991 Manual, page 11-127 shows how the catalytic converters are mounted.

If you soak the nuts with a 50/50 mix of acetone and automatic transmission fluid several times you may be able to remove them without shearing off the carriage bolts in the process.

If the nuts still won't come off, twist them hard enough to shear off the bolts. The carriage bolts are pressed into the catalytic converters so grinding off the heads on the cat side won’t help much. Once you have the nuts off the muffler side of the flange, you should be able to lever the cat and the muffler apart. Then, on the other end of the catalytic converters, remove the nuts holding the cats to the exhaust pipes and remove the cats. Take them to your local Honda dealer to have the remaining stubs of the carriage bolts removed. I wouldn’t try to remove the remnants of the carriage bolts with a hammer because the shocks could damage the ceramic cores of the catalytic converters. Better to let the Honda dealer use a press, heat, cold, etc. for the job. Then buy new nuts, bolts, and gaskets and you should be good to go.

Good luck!

[lotusolly]

Thanks for the links, that makes things a bit clearer. The fact that the cat bolts are pressed in explains why they are not coming out very easily!!!!

Still got to try and find a way of getting to the top bolts in the flange without destroying anything other than the bolts though!!!!!!!

Many thanks,

Olly

[anflecher]

I had to pull in the SLK exhaust time, I just cut the rubber, and ordered the installation of the new. They are a big pain. I tried to go with my buddies shop, he had to use a large crow bar to pry loose.