It seems we've ended up with several different sizes for reproduction ring gear screw threads and the replacement brass screws; the original #14-24 thread, 1/4-24 and 1/4-28. Then there's some oil paddle kits which I understand use 6mm screws.
I'm installing oil paddles on my flywheel and metric stuff is much easier to get, so I'm thinking of also using 6mm screws.
Question is, it seems to me I could use high tensile 6mm screws and 'force' them into the ring gear holes (i.e using the screws themselves as a tap), with the mismatch of thread preventing them coming undone.
Has anyone done this? Or should I do it the proper way and re tap? Also thought of using slightly longer screws and running down a nyloc nut on the transmission side of the flywheel to keep the screws in place. Would there be any disadvantage in that?
I used the 6 mm screws with the oil slingers and they worked fine. The threads are so close that they screwed in with just slight resistance. I also used lock-tite on the advise of a friend. I had to pull the engine out after about 3K miles and they were still perfectly tight.
6mm screws will go in about 10mm before binding. They work good on the bendix cover, too.
Recent experience by a good friend of mine found the bolts provided with the oil splashers are not compatible with original ring gears. The "specially machined" bolts provided by the vendor tighten up after about 2 turns and will break off if you try to force them. When he called the vendor, they asked if he had a new or old ring gear and when he said it was old they replied "yea, we've heard that before". The original and replacement brass screws fit the ring gear just fine.
If buying oil splashers, ask the vendor if they are providing bolts and if they will fit an original ring gear.
Texas T Parts provides a 1/4x28 tap to re-do the screw holes and provides the proper bolts when you purchase theirs.
Really? The splashers I referred to came from them and there was no mention of a tap or potential of a problem in either their catalog or the instructions that come with the kit. Unfortunately, the bolts won't work as delivered in an old ring gear. The splashers look fine but the bolts were a disappointment. With a proper tap they would likely be just fine. It would be good of them to point this out in their catalog and offer the tap (at an appropriate cost) for those cases where it would be needed.
You don't need to be afraid to put metric screws in a T.
The original is #14 x 24 TPI, threads per inch.
6mm is closer to #14 that 1/4" is.
1mm thread pitch is 25.4 TPI, certainly closer than either 1/4-20 or 1/4-28.
How do you think the 24 TPI threads in a flywheel will look after they've been run through with a 1/4-28 tap?
You'll save agony by a trip to Ace for 6x1mm screws that will penetrate 6-10 mm. They're automatically self-locking.
You've described my situation exactly. One of the reasons I chose this oil slinger kit was I was led to believe no retapping was required and the 1/4"x24 screws had been specially made to fit the original thread. Aside from that, the paddles themselves look very well made and a heavy duty part.
After telling my tale of woe to supplier, I was advised that the screws supplied were for the replacement ring gears and were "a tight fit in some original ring gears". Tight they were; one snapped before it was all the way in. That's when I realised something wasn't right and carefully removed the few I had got all the way in. A cheap tap good enough to last doing the 16 holes should have been supplied with the kit if they are not going to provide the correct screws. In fairness to the supplier, I was told future literature for this product would mention the issue. I'm not looking to blame anyone but just hope the feedback assists with product improvement.
If only the #14-24 thread had been used to make the repro parts to start with! The taps/dies must exist because I understand another supplier sells the brass magnet screws which really are the right thread.
Exactly right, I'm not trying to slam the vendor either. The splashers look fine, the bolts which are the correct 24 TPI are just too tight in an original ring gear.
THe brass replacement screws will go in with fingers or very light pressure so I belive it is a problem with the bolts being ever so slightly oversized.
Ralph may have the best bolt answer with the metric bolts but I've not tried them.
You can buy 14-24 taps at most machine tool suppliers in the USA. Try Google.
Ron the Coilman
Over the years the repop flywheels did have a batch of 1/4-28. I have one. Imagine a fellow unwittingly using the 1/4-24 brass magnet screws in one of these. Then again, maybe it would be self locking. But with brass?
Ralph's suggestion of 6mm screws in the original holes is spot on (do not tap them!).
I tried 30mm long screws which went in nicely; not too loose and not too tight...rather like going into a nyloc nut. There's enough protruding on the other side if you wish to peen them, but I don't think that's necessary.
Alas, it wasn't going to be as simple as that...it appears the holes where I tried to put the 1/4-24 screws in have had their threads damaged so the 6mm screws don't grip properly.
Third attempt of what should have been a really simple exercise will be to now go and get yet another set of 6mm screws; this time 40mm long and fit nyloc nuts to the other side.
I may just have this sorted out by the weekend!
All assembled at last with the 6mm screws. The nyloc nut idea was no go...the nuts get in the way of the bendix. Glad I checked that now and not waited until it's all back together and I step on the starter switch.
No only will nuts on the ring gear side of the flywheel interfere with the bendix and the pan, nylocks are a bad idea in hot engine oil- the locking insert looses it's locking ability at temperatures such as those in an engine.
The whole problem with the ring gear threads started 4-5 years ago when a supplier let a batch
of incorrectly tapped ring gears get out, and then fixed the problem by making magnet clamp screws with he wrong thread to match their incorrectly made gears.
FWIW--Three or four years ago I was told by the Company, they had just researched it for another customer, where I buy my fasteners the nylock system was ok up to 375 degrees F, after that you are on your own.