1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Flywheel nut thread

Thread Tools
 
Search this Thread
 
Old 07-21-11, 06:58 PM
  #1  
RAWR

Thread Starter
iTrader: (3)
 
OneRotor's Avatar
 
Join Date: Apr 2004
Location: 90024
Posts: 3,860
Likes: 0
Received 2 Likes on 2 Posts
Flywheel nut thread

So I am still trying to get a working motor in my FB. I picked up a 12a from an ex-racer who told me that his nephew rebuilt the motor from the best parts of 6 motors that they disassembled. He said that the chrome on the housings is good, the irons are good, the rotors and e-shaft are good. I went to install my freshly resurfaced flywheel, and realized that the threads are a bit boogered on the e-shaft where you thread on the flywheel nut. I was wondering if anyone knew off the top of their head what the thread was, so I could source a die and clean up the threads before attempting to install the flywheel.

Thanks

-Jim
Old 07-22-11, 12:12 AM
  #2  
Lapping = Fapping

iTrader: (13)
 
Jeff20B's Avatar
 
Join Date: Aug 2001
Location: Near Seattle
Posts: 15,725
Received 70 Likes on 64 Posts
I use a small triangle file to clean boogered e-shaft threads if I ever encounter any.

I just checked. Pitch is 1.5mm. Same as exhaust studs. It looks a lot finer than that, but only because it's so big! Anyway that is why the threads are easy to clean up with a small triangle file. So save yourself the trouble.
Old 07-22-11, 05:13 AM
  #3  
Have RX-7, will restore


iTrader: (91)
 
mazdaverx713b's Avatar
 
Join Date: Oct 2003
Location: Ohio
Posts: 21,713
Received 1,053 Likes on 892 Posts
you can also use a thread file. they are usually produced with several thread sizes cast into the body. mine has eight different sizes and its produced by snap on.
Old 07-22-11, 11:25 AM
  #4  
Moderator

iTrader: (3)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,841
Received 2,605 Likes on 1,848 Posts
rule #1 is always put the nut back on! threads can't get screwed up that way
Old 07-23-11, 09:55 AM
  #5  
RAWR

Thread Starter
iTrader: (3)
 
OneRotor's Avatar
 
Join Date: Apr 2004
Location: 90024
Posts: 3,860
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Jeff20B
I use a small triangle file to clean boogered e-shaft threads if I ever encounter any.

I just checked. Pitch is 1.5mm. Same as exhaust studs. It looks a lot finer than that, but only because it's so big! Anyway that is why the threads are easy to clean up with a small triangle file. So save yourself the trouble.
Any idea what diameter it is? I know that the nut is ~42mm across the flats, so it's what, 30 or so mm in diameter? 30x1.5?
Old 07-23-11, 11:53 AM
  #6  
Lapping = Fapping

iTrader: (13)
 
Jeff20B's Avatar
 
Join Date: Aug 2001
Location: Near Seattle
Posts: 15,725
Received 70 Likes on 64 Posts
42 isn't the answer to everything. Have you ever actually measured the nut?

I can't measure the shaft dia for you now. I already threw a flywheel on it and dropped it in yesterday. lol
Old 07-24-11, 01:06 PM
  #7  
RAWR

Thread Starter
iTrader: (3)
 
OneRotor's Avatar
 
Join Date: Apr 2004
Location: 90024
Posts: 3,860
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Jeff20B
42 isn't the answer to everything. Have you ever actually measured the nut?

I can't measure the shaft dia for you now. I already threw a flywheel on it and dropped it in yesterday. lol
The outside of the threads measure 35.8mm, so I'm assuming that it's a 35x1.5.

I'm going to go to Granger tomorrow and pick up a 1.5 turn/mm thread file and give that a shot. If they don't have it, I'll order it from McMaster Carr.
Old 07-24-11, 02:56 PM
  #8  
Lapping = Fapping

iTrader: (13)
 
Jeff20B's Avatar
 
Join Date: Aug 2001
Location: Near Seattle
Posts: 15,725
Received 70 Likes on 64 Posts
1.5 is a common size. VWs use it for bellhousing bolts. I'm sure you'll fine one. Maybe I should get one.
Old 07-24-11, 04:32 PM
  #9  
RAWR

Thread Starter
iTrader: (3)
 
OneRotor's Avatar
 
Join Date: Apr 2004
Location: 90024
Posts: 3,860
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Jeff20B
1.5 is a common size. VWs use it for bellhousing bolts. I'm sure you'll fine one. Maybe I should get one.
McMaster Carr has the files listed with a set of small, metric dies for ~34.00 + Shipping. I'm going to bomb over to Granger tomorrow before they close and see if I can get one of theirs (with just the 1.5turn/mm cut profile) for ~16.00
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
sinclair7seven
General Rotary Tech Support
11
09-11-15 10:15 AM
DerpyToast
2nd Generation Specific (1986-1992)
13
09-07-15 12:20 AM
Enzo1944
New Member RX-7 Technical
2
09-06-15 08:57 AM



Quick Reply: Flywheel nut thread



All times are GMT -5. The time now is 01:22 AM.