I was at the local parts shack and the tap they brought out when I asked for the 7/8-18 RH thread tap is marked "Spark Plug Tap".

I checked it against the 7/8-18 threads on the TRE I have and they "appeared" to match... Everything looked correct. But the "Spark Plug Tap" has me wondering is this gonna work is the pitch different or this this just a dumb way of keeping it separte from the 7/8-14 fine thread taps?

The price was right so I figured something had to be wrong :confused:

Spark Plug Threads as listed in the Machinery's Handbook are Metric. M14 and M18 are the two most comon sizes. This the the S.A.E. standerd. M18 is the largest and the English equivelant is .709 inches.

7/8-18 is not 'Spark Plug Tap'. Dunno why it is labeled that. Who is the manufacturer of the tap?



Eric

I don't remember the manufactorer but it was for sure a 7/8-18 tap I measured it with a decent caliper 2X. Counted threads - layed the tap into the threads on the TRE and spun it around to see how they fit together and everything.
I just don't know why it was also called a Spark Plug Tap.

I did a search before I posted here and found this info - but it still didn't answer my question:


The tap looked just like this:
Snap-ON 7/8-18 Spark Plug Tap (http://buy.snapon.com/catalog/search.asp?partno=T2818)

7/8-18 "Spark Plug Tap" also made this chart....

http://www.korit.com/tapndrill.htm

ok, I checked your link. I have no idea why it is called that. Maybe some one else has a clue. It's not S.A.E. though.

:confused: :(


Eric

p.s. The pitch for 7/8-18 is .055555 , For M18x1.5 the english equiv. is .05901. But the 7/8 is too large by .165 Dia.

Originally posted by uglyscout
7/8-18 "Spark Plug Tap" also made this chart....

http://www.korit.com/tapndrill.htm


Hmmmmm. Ok, maybe it is for an application other than Automotive?

All the metric ones on that chart are in my handbook. The 7/8's is not :confused:



Eric

If they are as cheap as that snap on one, buy it, test it out on a piece of tube, thread a TRE in there, and let us know. For that price i will fo sho buy one. I just spent 25 bucks on 7/8-18 threaded inserts to make a tie rod.

Ian-

I just disovered that the reamers you need for the chevy TRE's are referred to as "Steering Ball Joint Reamer". Makes searching for them 100% easier. Looks like they go for about $100.

For the Record, the snap-on reamer doesn't work for shit. It's just a finishing reamer. Sure it gets the job done, but it's not fun.

I'd like to find a good cheap source for the left hand 7/8 - 18 tap.

Originally posted by KrustyKruiser
If they are as cheap as that snap on one, buy it, test it out on a piece of tube, thread a TRE in there, and let us know. For that price i will fo sho buy one. I just spent 25 bucks on 7/8-18 threaded inserts to make a tie rod.

Ian-

The Tap I found was $19.00 at my local store - they even had them in stock.. I think I am going to buy it test it out and if it doesn't work - take it back :D There was a little gaurantte on the back of the package!

I'll let you know if it works.

Now for left handed..... :confused:

Just do the search thing here and your guess is as good as mine.

Originally posted by Nobody
I just disovered that the reamers you need for the chevy TRE's are referred to as "Steering Ball Joint Reamer". Makes searching for them 100% easier. Looks like they go for about $100.

For the Record, the snap-on reamer doesn't work for shit. It's just a finishing reamer. Sure it gets the job done, but it's not fun.

I'd like to find a good cheap source for the left hand 7/8 - 18 tap.

I bought one @ Goodson $60 p/n TR-216-2
http://www.goodson.com/scripts/mshop/

I actually used it for the first time last night. Cuts great. Did the 2 knuckles, TRE and the pitman arm with no problem and still feels just as sharp. Chucked it up in my drill, went slow and steady and worked like a champ

Originally posted by uglyscout

Now for left handed..... :confused:

Just do the search thing here and your guess is as good as mine.

Ohhh sure, I've found them. $80+...... Hardly seems reasonable when the RH tap is only $20. One can say that there is no demand, but we all know that's not true!

Bump!

I got a few people together that want to go in on a Left hand 7/8-18 tap. Anyone have a good source?

I might be interetsed if the price is right! Put me on your list for now.

As for the "Spark Plug" tap I found for cheap - I bought it and it is for sure 100% the right tap. It is marked 7/8 - 18 tpi UNF, it is the RH thread tap. It is sold under the 'Century' name at my auto parts place. And they had them in stock - $17.00 or so.

So when the parts guy looks at you like your on crack when you ask for a 7/8 -18 tap ask him to look it up under the sparkplug tap section :)

Originally posted by uglyscout
It is sold under the 'Century' name at my auto parts place.

Are your specifically trying to hide who your "auto parts place" is? ;)

I ran into the same problem trying to find taps to thread tie rods for my Land Rover-11/16 X 16 (I believe) Ended up having to order through Cutting Tools, inc. Both of them (LH and RH) cost me just shy of $50.00. While I was recovering from the shock of having paid $50 for two pieces of shiny metal, I promptly broke a tie rod end and needed the tap to deepen the threads so I could drive while waiting for a new tie rod. Of course, the one I broke WAS the left-hand thread side!

if you can't find them cheaper, I can try my local Cutting Tools inc. shop and see what their price is.

Paul

Originally posted by DRM


Are your specifically trying to hide who your "auto parts place" is? ;)

Nope :D I just figured that something labeled a "Century" tool at my local Auto Value, is probably something else on the West coast at Napa. Until I moved to MN I had never heard of Auto Value - now I can't go 10 miles without seeing one.

I Did not use LH thread on my current tie rod, i just got 2 RH inserts, and 2 RH tre's. If it needs adjusting ill takeone end off and spin it. The benifit to this is, one spare fits all, and no need to look for the more rare LH thread stuff.
So the RH will work for those that sacrifice quick adjustabilty.

Note- This rig has full hydro and is on a trailer.

Ian-

Two Right don't make a wrong. RH threads all around :D

That's my plan as well. Unless I come up with a LH tap for dirt cheap in the next week, I plan to build mine with all RH threads and be done with it. For as much bashing and abuse my truck sees, being able to adjust the toe to within 1/16 is going to be good enough - and what's pulling the tie rod to make an adjustment when you accustomed to pulling an entire axle??

I got my LH tap at a machine tool sales shop in downtown Sacramento, 12th st, can't remember the name of the place though.
It was forty dollars and took a few days to get in.
The cost is due to the quality. Other than us four by builders, there is not that much demand for LH stuff. LH taps are going to be more of an industrial tool, and the quality has to much better for production repeatability.
Just like bearings for high quality machine tools. A bearign may look like just any old bearing you can pick up at NAPA, but do to its finish and tolerances, could cost hundreds, even thousands of dollars. This is reqired for repeatability in production.

Originally posted by uglyscout
I might be interetsed if the price is right! Put me on your list for now.



I wasn't talking about a group buy(forbidden), just a couple friends that are willing to go in on One tap. Sorry :(

However, if I can pick up one of these $40 - $50 LH taps that's becoming affordable.

Thanks for the leads....I'm going to look into Cutting Tools, inc!

Originally posted by PTSchram
Ended up having to order through Cutting Tools, inc. Both of them (LH and RH) cost me just shy of $50.00. Paul

Don't suppose you have a part number? ....phone number?

Originally posted by Alpo23
Spark Plug Threads as listed in the Machinery's Handbook are Metric. M14 and M18 are the two most comon sizes. This the the S.A.E. standerd. M18 is the largest and the English equivelant is .709 inches.

7/8-18 is not 'Spark Plug Tap'. Dunno why it is labeled that. Who is the manufacturer of the tap?


This was the spark plug size for early production cars. Early teens to the early 1930's.