Alternative to Exhaust Donuts on the 308?

Felpro makes exhaust gaskets that fit. You should be able to get them at any muffler shop (as has been said a few post back), but if they look at you like you have 3 heads you could have them start looking through their p/n's for that specific manufacturer.

 

When I swapped out my cats for a set of hollowed-out cats (not true testpipes), I replaced all of the hardware with new, Grade 8 bolts, nuts, and washers from the local hardware store. No backfiring on deceleration, and no apparent leaks....

Aaron

 

I ordered all SS bolts, washers & nuts from McMaster-Carr for my 308. There were 2 or 3 positions in the exhaust that I couldn't get the generic parts to fit because of tight bends, so I reused original hardware. For replacement springs I used some die return springs from McMaster-Carr. They're really a great place to get generic stuff for the Ferrari from, such as all-stainless hose clamps. www.mcmaster.com
You can find some part numbers for 308 exhaust donuts in the 308 parts cross-reference thread in the classic section.

 

speaking of harware the infomous 'ring nuts' are bearing nuts and can be purchased thru mcmaster carr. here's alcoa's spec, https://www.alcoa.com/fairchild_fasteners/catalog/pdf/3668_Simmonds_Bearing_Nuts.pdf

 

Don,
Would you mind posting the McMaster P/Ns?

I've been having some problems with my both manifolds developoing cracks in the combiner section just behind the donut flanges. While part of it seems to be that the metal is getting thin, I don't remember all the donut joints having spring on them. If so, then will want to order new hardware.

- Verell

 

Just a heads up on using stainless for exhaust nuts and bolts. They have a problem with gauling under exposure to heat. That is why you saw the bolt kit for the 288 in a post a ways back in this thread, steel and not stainless. I think you are better off using a hardened steel with anti-seize compound. I have used the coil spring and a lock washer and things seem to stay tight. I do go back in occasionally and check for tightness. Regards, Vern

 

i'm looking at the setup there and something doesn't seem right. if you sleeve the bolt and run the spring with the washers, exactly how can you compress the spring? it looks as though the ID of the washer is smaller than the OD of the sleeve. the washers are belville washers and when compressed act like a spring exerting force to keep the clamp force constant. if you where to alternate the washers hat/cup/cup/hat/hat etc. you'd have a spring with a specific rate amount but i digress.
using the spring loaded hardware at the cats or test pipes isn't needed as the exhaust as already turned 108* from the flexing rotation of the motor. they are needed where the headers collect to the muffler as thats where the motor rocks. if you want to you can use 4 belville washers, 2 at each end of the bolt with the cups facing each other for the cats/test pipe connection.

i have been sifting thru the mc master carr site and so far have located most of the same hardware for a fraction of the cost. the issue of galling with stainless is when you run stainless with stainless. although stainless would be great for corrosion resistant needs it's to brittle for this application and i'd suggest against it. if you want stainless go with 300, but be warned a 300 bolt is $10 for a M8x50mm. black oxide is a good choice or cad plated. i'll post up the part numbers as soon as i have them.

 

alright here we go.
$31. US for everything and then some
McMaster-Carr
91287A162 Bolt M8x70mm $10.18 for 10
9657K24 Spring $9.69 for 6
93795A230 lock nut $4.48 for 50
91477A151 SS belville washer $2.32 for 10

please note i did this from memory, the bolt may be to long but this is a good picture of cost.

 

Please explain further....I'm not familiar with the term "gauling."

Aa

 

cold welding of parts, they chemicly weld to each other. quick and dirty answer.

 

Oh sh*t....I better check mine this weekend, then!

 

That should be spelled "galling" (if you want to search for more info).

 

Crap I did spell that wrong didn't I, sorry about that. Anyway it can be guite a problem even if you use anti seize compound.

 

My metallurgy friends indicate that it's not the heat that galls the stainless it is, rather, movement. It's the heat cycling that causes the movement no doubt, as minimal at this movement may be, but likely stainless is not a good choice here as you say.

 

Vern, Scott and Cliff pointed to an item that may cause problems. Stainell hardware has a tendancy to gall, or having the metal "smear" and transfer itself to the other part. Typically a nut and bolt will tend to bond and lock if this occurs. Heat worsens this problem, only because it dries out any form of lubrication that may have been between the two. I believe this is due to the nickle content. To lessen the chances a bit of lube will help to keep the surfaces from bonding by creatinng a barrier. In a heat application I use a good antisieze, preferably copper. This compound ic actually fine copper dust in a liquid, so it acts much like the copper coating used in OEM. The liquid can get destroyed by heat, but the copper is still there.
On the SS topic: Take care in any application useing air tools ti tighten or loosen SS fasteners, as that can lead to galling. New fsteners need a touch of any oil WD-40 for example. Failure to add this can lead to galling upon tightening, and they will need to be cut off to change.
BYW: oil does not seem to hurt nylon locking, so not to worry.

 

smg2,
Tnx for the McMaster info.

 

In some other applications we use stainless studs with brass nuts. The nuts typically need to be replaced every time they are removed, but no galling and no loosening under use. Not sure how well that would work here...

Bill

 

Then there are us ancient luddites that keep a 20 year old can of NAPA powdered lead based anti-sieze around for exh. fittings. Copper is about as close as you can get thesedays tho.
;^)