Special Exhaust Bolts? - Toyota Nation Forum : Toyota Car and Truck Forums

91boz · 07-14-2010, 12:57 PM

The bolts that fasten the cat converter to the Y pipe are pretty rusty. I am going to be replacing the y pipe assy. and they might need to be cut off. I would like to know if these bolts and nuts are different from the ones I can get at Home depot?

Nervous · 07-14-2010, 02:12 PM

Home depot sells crappy bolts, stay away from them. Bolts have grades. Home depot usually sells bolts grade 2 - 3. Bolts used in the car, for holding crank pulley, engine subframe, etc have grades 8 - 10. You may see the grade number on bolt's head. Than grade higher then it is better quality.
Go to ACE Hardware store, they sell a lot of metric high quality bolts and nuts.
And for exhaust I would use stainless steel bolts/nuts.

bigbird · 07-14-2010, 03:46 PM

id stay away from ANY hardware store. automotive grade bolts (especially exhaust) are designed to withstand rapid heating and cooling as well as rust pervention. hardware store bolts and such are graded differently then thoes used on automobiles. this is an instance where it may be better to get the part from your stealership, that way you know it's gonna fit right too.

ive used bolts from ACE, HD, Lowes...they may fit, but will rust quickly...the ones that dont rust, wont fit properly.

***Gothmog3VZ*** · 07-14-2010, 04:14 PM

^ +1

Get galvanized, stainless steel, or aluminium bolts & nuts, you don't want em rusting to shit within 6 months

91boz · 07-14-2010, 05:52 PM

OK thanks! I think I'll go check the dealer or to my nearest Napa and get them there.

jon1000 · 07-15-2010, 09:36 PM

A solid rule to follow when replacing ANY fasteners on a car is to replace them with the same grade or property class that you take off. Property classes (PCs) are used when speaking about metric fasteners, not grades. Higher grades or PCs are not better. They represent the raw material, heat treatment and hardness of the bolts as well as tensile strength. Harder is not always better. It also means more brittle. Some fasteners are intentionally designed to yield. Some of the harder screws are not annealed the same way and do not hold up well to heat. They lose their holding power after being subjected to heat.

Never, ever use an aluminum fastener in contact with 410 stainless steel. The reasons are a bit complicated, but you can look up "Galvanic series of metals" if you are interested.

Fasteners on vehicles are chosen for a reason. Many are for safety concerns. It may not seem that an exhaust component could be that critical, but you may feel differently if you are traveling behind someone and a part of their car hits your windshield.

Fastener Engineer for twelve years.

RichieRichJP · 07-15-2010, 11:57 PM

Quote:

Originally Posted by bigbird

id stay away from ANY hardware store.
ive used bolts from ACE, HD, Lowes...they may fit, but will rust quickly...the ones that dont rust, wont fit properly.

I don't know. The ones at lowe's are 8.8 and they are SS. As long as you know what size and pitch then you shouldn't have a fitment issue. I've replaced the whole underbody of my MR2 with Lowe's SS bolts and they've sat on there for a year no problem.

bigbird · 07-16-2010, 03:55 AM

^ good luck with that

. it's only been a year, but it is florida, which is encuraging.

91boz · 07-29-2010, 11:49 AM

Replaced the cat bolts and nuts with stainless ones from the local hardware store. Local Napa parts guy told me there is no difference as long as the grade is equal or better.

71Corolla · 07-29-2010, 11:57 AM

Will stainless bolts actually hold up? It seems logical that they will, but in practice do they? The heat on an exhaust system is tremendous, it damages just about any kind of material over time.

djb2 · 07-29-2010, 12:37 PM

Quote:

Originally Posted by 71Corolla

Will stainless bolts actually hold up? It seems logical that they will, but in practice do they? The heat on an exhaust system is tremendous, it damages just about any kind of material over time.

It depends on the type of SS (stainless/stain-resistant steel).

Some SS will cause accelerated corrosion on nearby non-SS parts. The most appropriate alloys to minimize corrosion are usually weak and require up-sized fasteners.

This, plus the added cost of SS, are why exhaust systems are often assembled with copper-coated carbon steel fasteners.

If this is a one-off (you are only buying a few fasteners for your own car), you'll be paying more for the packaging than the metal and are unlikely to be able to find out the alloy or plating. It's best to just buy SS.