I wondered why the threads on these bolts were so boogered up. Then I looked in the holes and saw the fine threads. It seems the chap who assembled this car wasn't paying close attention. Fortunately the threads in the holes are OK.
If at first you don't succeed, get a bigger wrench.
Is that a crack on the left side of the yoke?
I'm surprised the female threads took the punishment. Must be Grade 2 replacement bolts. Any markings on the heads?
Inside threads are always much stronger than outside threads. At least that's what I once read in, 'The Nuts and Bolts of Nuts and Bolts."
I'm thinking of the same thing with dear, old departed dad. When doing the rear axle seals job. Passenger side axle nut was loose by 1.5 turns with a cotter pin and modern Hyatt bearing. Just finished drivers side axle nut on tight, orig.Ford Hyatt in very good shape and no cotter pin. I guess God does look out for dad, drunks and children.
George n L.A.
That statement is not supported by engineering facts. Given two identical materials, thread shear will occur on both inside and outside threads at the same time. Material strength governs the strength of the threads. It doesn't make any difference if the threads are inside or outside. The weaker material will always strip (shear) first.
Besides, Steve's rectal folliculitis problem makes this thread worthless. Sorry I even posted to it.
Steve..just curious,...will you cotter pin the other u-bolt nuts?
Steve - And here I thought my problem was "unique"! When I pulled my seized-up engine out of the '27 depot hack for Steve Tomaso to rebuild, I also found a front cross member that was in absolutely horrible shape! In fact, I showed it to Steve up at Steve's "T" Works, and he said he'd never seen a worse front cross member. But what your post reminded me of was that I found EXACTLY the same situation with those two bolts as in your photo. Mine were also a coarse thread, and my first thought was that the fine threads in the casting were probably all screwed up, but nope! Those fine threads were perfect and the proper cap screws went in just fine! Whew! It was bad enough putting in the new front cross member; didn't need MORE trouble! Those castings must be made out of some pretty good stuff, huh Steve?
Yep, and lucky for us. I suppose that's why there are so many of these cars left.
Fine thread... Course thread... Close enough!
Ken, I cited an engineering book when stating inside threads are stronger than outside threads. What's your reference?
I am installing an engine in a car for a friend, where he found those bolts to be 3/8" EPOXIED into the yoke. Threads in yoke (which were perfect) have been chased and proper 7/16 bolts have been installed. Every model t owner thinks they're a mechanic, and some of them actually are.
Jim, no, not a crack. Just a little ding.
Chrome vanadium steel versus chocolate plow bolts. Dont forget to get that paint off the inside; thats a frame to motor ground.
Boils need lancing... troop
I wonder why the upper front bearing support cap is not painted the same as the lower half. Doesn't look like it's from the same car.
Yep, same car. I just haven't painted the top half yet.
I would recommend removing the paint from the mating surface where the engine pan"nose" contacts the yoke. This will help the electrical system(starter) make good contact through the pan and back to the frame.
This is a 1915. I am the starter.
Female threads have a longer root path and thus more thread shear area than male threads. For one turn the root path of female thread is approximately Pi x OD thread. Root path of male thread is approximately PI x ID of the thread.
Jeff on my 1919 runabout one side is coarse thread and the other is fine.
Somewhere down the line it was retapped to a coarse thread.
When I restored it years ago I didnt have another one to replace it so I left it as is.
You cant tell tell the difference until you unscrew the bolt!
Excellent point indeed. Except it doesn't apply to the shear area of threads in contact with one another. The surface area of the threads in this zone will be the same. The root is simply for clearance.
I looked at a bunch of later style front mounts. All are tapped with coarse threads. This is no excuse for cross threading your mount but it may explain where he found the bolts to do so.
somewhat off topic but in follow up of the discussion regarding engine ground. I put a grounding strap from the engine pan to the frame on both my cars so I don't have to worry about grounding.