9/16 x 18 tap?

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pghfj40

pghfj40

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I'm installing a reverse switch in my SM420 tranny... which requires drilling & tapping for the sender...

Anyone have a 9/16 x 18 tap they'd be willing to lend?

I can't find one; tried @ Sears, True Value, Ace, Napa, Fastenal, Lowes.

Thanks! -Ed
 
Last edited:
Try farnam and Phile ( Spelling?) in bellvernon they have a very big selection of big taps.

Sorry I could not help.
 
Find a tap yet?
 
got one in my hand as I type this!

Give me a call if you want it it will be at my house at approx 5:15 PM
 
Sorta...

A coworker brought "a" tap in today--not convinced it's the right one, but will hafta wait till i get home to check.

Got a couple leads if not: a local hardware store (Eastwood, in Penn Hills) will order one for me but it'll take a week.

My inspection garage guy offered to lend me his (but then didn't have the right size, so called his tool guys... waiting to hear back).

Also i found one @ J&J Tool Supply up in Lower Burell (sp?) for only $7.32 for HSS ... I'll head up there if the other options don't work out (otherwise i'd prefer not to spend more on gas just ta get it than the tool itself!).
 
Here's some other info that I didn't know:

There are 3 types of straight thread taps.

Starting - these have a long tapered end ( probably 5 to 6 threads tapered ) to get the threads started. This is a must have when taping a hole freehand

Plug - these have just the very first two threads tapered. These are used with a machine or to clean a existing thread.

Bottoming - these have no tapered end and are needed when you want to run a bolt to the bottom of a hole rather than bind the threads.

There is also a thread size tolerance but for most apps it isn't a issue.

MSC tool

Enco ( a division of MSC )

KBC tool all sell stuff like this
 
Done!

Thanks for use of the tap, PJ!! :cheers:

I chose to drill/tap at the angle for better tranny hump clearance when using the connector shown in the last pic; straight-on/vertical would've worked too, and would've been simpler (if i were smrter and just used simple right-angle insulated fastons).

OH! NOTE--for anyone else doing this--note that the shifter rod that actuates the switch is NOT solid and has a void that will leave your switch un-actuated while in reverse if you drill in the wrong spot... The pix don't show this, look closely for yourself or cram your finger in there & you'll feel what i'm talking about.

For the record
- 9/16"x18tpi worked great
- the 1/2" drill worked fine (vs. 33/64 recommended)-- the cast metal is very soft.
- i used teflon tape to help seal since the (hand-ground) seating area is imperfect
- reverse switch: Napa P/N NS6578 (two terminal acts as normally open SPST)
- standard GM 90-degree T-connector w/ series-56 faston (has locking tine for retention in connector)



Some pix for posterity...

DSCN1530.jpg


DSCN1529.jpg


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DSCN1551.jpg
 
Very clean install!!!

Me likey! :)
 
And... since this is also part of my wiring project (though i'm finding there's a LOT of mechanical/fab setup for "wiring" since i'm customizing everything)... here's a teaser of my center console & switch box i'm working on...

DSCN1499.jpg


Includes
- winch enable
- winch in/out
- compressor enable
- ("hopefully near" future) front ARB
- ("hopefully near" future) rear ARB
- keyed ignition
- start button (runs on "accessory" so can move a lil w/out starting)
- keyed fuel pump on/off and front/rear pickup selector solenoid (not shown)
- lighted 12V power socket
 
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