Bolt Tap Sizes

Cape Codder

Cape Codder

Well-known member
Where can I find a chart for tap sizes of each bolt on the Model A and more important the pitch for each of these? Also how would I know I've got the correct pitch tap? Is it marked on the taps?
thanks for your time.
Joe Grobleski
Cape Codder
 
Taps and dies are marked as to size etc. there was a listing of some bolts in the Restorer Mar/Apr 2000. alot are S.A.E.,U.S.F., NF etc. I'm sure there are other lists available.
 
You need to get the correct class of fit:

Classes of fit

The way in which male and female fit together, including play and friction, is classified (categorized) in thread standards. Achieving a certain class of fit requires the ability to work within tolerance ranges for dimension (size) and surface finish. Defining and achieving classes of fit are important for interchangeability. Classes include 1, 2, 3 (loose to tight); A (external) and B (internal); and various systems such as H and D limits.


Ford made many of the threads to a tighter tolerance. A quick example are the rods that go from the radiator to the firewall. I made the mistake of taping these and found the nuts to be VERY loose. Many of the nuts and bolts on the A will pull a small amount of metal out and they get much looser.



Anymore I hand clean the threads of nuts with a pick and wire brush the bolts.


OH- some nuts are super hard and can ruin taps.
 
Kevin in NJ said:
Ford made many of the threads to a tighter tolerance. A quick example are the rods that go from the radiator to the firewall. I made the mistake of taping these and found the nuts to be VERY loose. Many of the nuts and bolts on the A will pull a small amount of metal out and they get much looser.


.
Click to expand...

A very common mistake. Most sets out there will make for loose fit.
 
I find the hardware thread sizes and class fit near the back in the PARTS PRICE LIST. I have a few different time periods of this booklet and pick the time closest to what I need to know about. You can buy a reprint Jan.1, 1928 Parts Price list, and a reprint July 1, 1931 reprint, but I don't know of any others currently being reprinted. I also bought a nice reprint of the October 1, 1929 Parts Price List from Grtchen Minners about 8 years ago, but don't know if any more are available.
 
Please save yourself a heap of headaches, bite the bullet on the price and purchase a thread chaser kit. They are way different from a tap and die set. They will clean threads without removing metal and will save you a lot of misery. Mine is a Craftsman 40 piece Rethreading Kit. Had it so long I can't remember what I paid for it but it was well worth it. Saved many a thread on my Tudor!
Paul
 
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