Exhaust hardware type...

[Omahaug]

Does anyone know what types of exhaust hardware are generally acceptable?

I know on some systems they use locking flange nuts. I don't know what warrants that. For example my Honda uses locking flange nuts, but it also uses spring bolts and has no flex joint, where as the car I am replacing this exhaust on does use a flex joint and no spring bolts. I'm assuming the spring bolts are replacements for flex joints since the engine will still torque the exhaust to some degree so there has to be movement somewhere.

I bought some stainless steel bolts that I plan to use with zinc-plated flange nuts I bought. The nuts are not locking and I didn't buy any lock washers either. I'm hoping to avoid galling and couldn't find stainless steel locking nuts to match anyway. Down the line the zinc-plated nuts will probably rust away before the stainless steel. I'm planning to copper anti-seize the whole setup.

Do the zinc and stainless steel work with each other galvanically?
Am I likely to experience problems by not having used locking nuts or washers?
Should I have bought flange bolts to match the flange nuts?

 

[OilSwag]

Well I only have experience in non salty conditions. I'm not in a snowy region and I'm not by the beach. So in a full exhaust I can use aluminized pipe for exhaust instead of stainless and not have issue like someone in New York or wherever. For an almost fool proof leak proof connection V band is the king in my opinion unless the whole exhaust is welded. I am not afan of flex joints at all. Until I bought my really used G35 did I ever have a car with flex joints. I had full exhaust on Mustangs and LT1 cars and a few 350s and various other cars without any issues. I do think a flex joints can help but it's going to be the weakest link in the exhaust. If your car is low to the ground and scrapes I can see the flex busting. I'm sure any hardware can last enough, obviously stainless is the way to go but not a must. I think a good diy exhaust coating is enough for hardware and weld seams. I live in Tennessee so don't have the salt issues but haven't had to cut anything off or torch anything either.

 

[andyd]

regular muffler clamps are grade 2 hardware. I use grade 2 5/16 coarse hardware on the flange connections between the cat and the resonator instead of OEM BMW stuff of a higher grade and way more 'spensive. Doesnt make any difference, they both rust solid. The OEM Boysen exhaust isn't life time mostly because my '88s were survivors long past the average age. I much rather deal with frozen grade 2 [censored] if I have to shear it or cut it. Exhaust hardware is one time use. I've sheared and then had to drill out a few stainless bolts. Its real slow work because fast speeds will burn an HSS bit. Even grade 8 is overkill except for studs. I use brass or copper nuts on exhaust manifold flanges down pipes. If you wanna put your money to good use, buy brass or copper nuts, not stainless.

 

[JHZR2]

The only exhaust I've had to work on was my Mercedes and it has copper hardware.

 

[wrcsixeight]

deleted.

 

[Olas]

Steel bolts and copper nuts will not stick to each other and will be relatively easy to undo.

That said, if the exhaust fits properly youll only fit and forget - stick it together with whatever fixings you have and in 5-8-10 years when it's time for a new exhaust just cut the old one off.

Also, flexi joints are only a band-aid for bad engine/gearbox mounts. Get decent mounts and ere is no requirement for a flexi.