Replacing OSla 15 muffler bolts

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BigCountry
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Joined: Fri Sep 14, 2001 12:14 am

Replacing OSla 15 muffler bolts

Post by BigCountry »

I know I've heard guys talk about drilling out and tapping their la's mufflers to accept 4/40 socket head bolts but I was just curious as to what length bolt those of you that have done that are using. I'm getting tired of fighting with the OE muffler bolts. Thanks [:D]

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The Snake
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Post by The Snake »

Looks like a 1" screw. Carefull, I did break a tap in one of my mufflers. I should have used more oil. It works great and makes engine changes so much faster and they don't come loose like the stock screws.

Victor (the Snake) Shamulus
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Pat_Willcox
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Post by Pat_Willcox »

Best to use a 3/32' drill first in the bolt holes and then use 4/40 tap with "Sear's cutting oil." 1" hex head screw.
sgilkey
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Post by sgilkey »

Please note that aluminum galls very easily when being tapped, and with these tiny taps, it's easy to break one off! Because of the special attributes of aluminum, there is a special tapping fluid/lube for it (vs. steel), I use "Tap Magic" for aluminum and it works well. Be sure to back the tap up frequently to break out the chips.

Since I switched to McMaster Carr stainless steel, phillips-head machine screws for my muffler bolts, I have had no problems with metric-sized bolts of stock size, saves the hassle of re-tapping. The McMaster bolts are far superior to the very soft stockers.

Scott Gilkey
BigCountry
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Post by BigCountry »

Hey Scott,

As an alternative or for those that prefer that option do you have a McMasterCarr part number? While they have everything under the sun sometimes digging through their site even with the search function can be rather daunting.

I've did a couple mufflers the other nite and everything worked great. I bought a nice little drill bit/tapp set at Lowe's awhile back for just this sort of thing and it has the bit matched up with the tap so there's no guess work..Thanks for the suggestions guys


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sgilkey
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Post by sgilkey »

McMaster Carr p/n 92000A112
18-8 Stainless, phillips (not JIS) drive
2.5mm x 25mm
5.88 per box of 100

Scott Gilkey
Dawg
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Post by Dawg »

I have been tapping the holes to 4-40 and using 1 1/4" hex bolts and have yet to have any problems at all. I use WD-40 as a lube when tapping. I do not drill out the hole first. I am careful not to force anything.
Tim Treneff
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Post by Tim Treneff »

Micro Fasteners stocks 2.5 x 25 metric socket heads.
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