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MG TD TF 1500 Bearing cap nuts secured using split pin or BBS discussion at MG-Cars.net
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MG TD TF 1500 - Bearing cap nuts secured using split pin or
| I was surprised when I remove the Oil Sump, I found the castle Nuts in place but not any safety element like a split pin or a safety wire. Even the stud is not cross drilled. Anyway, the Bold is a stud, If I lock the upper end with the nut I’s fine, but the lower end of the stud, which is in the block is still not locked. What's the correct safety strategy on this item? Thanks for any advice. Cheers, Guenter  |
| GK Guenter |
| I think they are usually wired. Dave H |
| Dave Hill |
| Mine have split pins. Regards Declan  |
| Declan Burns |
| The WSM says split pins but wiring will help retain both the nuts and the studs. good engineering practice. Ray TF 2884 |
| Ray Lee |
| The problem with split pins is as you note... nothing prevents the entire stud from unscrewing. Safety wire is the way to go here, so that each stud prevents the other from unscrewing. The chances of one coming undone are slim, but better safe than sorry. |
| Steve Simmons |
| Guenter, This is what I did when I did maintenance on my engine.the photo is the beginning of the project. The wires made me feel more secure. But take a look at the next post. Mort  |
| Mort Resnicoff |
| Guenter, When my engine was rebuilt, buy an automotive machine shop that specializes in race cars, they used lock nuts. That was 6000 miles ago. So far so good. Mort  |
| Mort Resnicoff |
| The problem with using Nylok nuts is that they can be tightened to proper torque ONCE only. If they are tightened once and then loosened, good engineering practice is to throw them away and use new ones. So if you tighten them to check clearances with Plastigauge, the nuts should be thrown away, and new ones used. If you tighten a rod bolt down and the crank appears to be dragging, you would logtically loosen the connecting rod nuts to see what was going on. But then you should throw the nuts away, and use new ones when you next apply torque.
The reason is that the stud threads literally deform the smaller nylon part of the nut when tightened, locking the nylon into the threads. Inherent in the nut's torque value is the gripping force of the nylon on the stud or bolt. Re-using a nut means that much less nylon material is holding it in place, and proper torque will not be registered. Lockwire is my choice, also. Tom Lange MGT Repair |
| t lange |
| There's also the fact that the typical nylok nut has a heat limit of 250F. If your engine overheats, you may stand the chance of damaging or god forbid melting the nylon material. There are nyloks you can get which withstand 350F but you won't find them in the local hardware store. |
| Steve Simmons |
| I have had a very bad experience with nylock. This was a rebuild done in the late 1980's, so materials may have improved, but I had a catastrophic engine failure with one of the rods letting go off the crank at about 10,000 miles. I found one of the rod bolts at the bottom of the pan. The nylock nut was well down towards the bottom of the threads of a broken off bolt. Can't say it was the cause of the failure, but it is a leading suspect.  |
| Bruce Cunha |
| I used Nylok nuts and added a smear of Loctite to make sure. Dave H |
| Dave Hill |
| There is also a fiber-locking nut than can withstand higher temperatures, but they also - as Seve rightly points out - are not available at your local friendly hardware store. Probably the strictest guidelines on using self-locking nuts are put out by the FAA, who cite NTSB reports of inappropriate use (or re-use) of Nyloc nuts in crashed aircraft. Tom Lange MGT Repair |
| t lange |
| Hi So what gauge wire is correct please? My locking wire is much thinner than a split pin John |
| J A Davies |
| I have bought .031" and .041" lock wire at airport using airport transfers sevenoakss, and also have some .020" that I omnly use on oil pick-up bolts. Use the largest size wire that will fit through the hole. You will most commonly find 304 stainless, although Monel is used in high-heat situations like aircraft exhaust manifold nuts. Tom Lange MGT Repair |
| t lange |
| Mort's first photo above show split pins on the rods and safety wire on the mains. Is that correct? Is it acceptable to use wire on the rods as well? Seems all the flinging around might cause the wire to flex and break. |
| John Quilter (TD8986) |
| As explained above ... No point in using split pins because the stud could still turn. If tightened properly they will probably never come loose but "probably" is not good enough. I ALWAYS wire them. Many years ago (nearly half a century) I dismantled a couple of engines which I think were original assemblies. I am pretty sure both were very neatly wired. Even re-built engines were nearly always wired. I think I have only seen one or two engines with split pins in the mains and they were definitely not factory jobs!
Don't use wire on rods. Split pins are good there because the bolt can not turn. Yes, wire would probably break with the centrifugal force. Cheers, Bob Schapel |
| R L Schapel |
| Thank you all of you for your statement. If the highest number of posts are right, it should be wired. It is my personal understanding as well to wire souse bolts inside the engine.
My problem is, I have only 0.6mm SS wire and this looks very flimsies and not professional. The cross hole in the bolt is 3mm but a 3mm wire is much to stiff to wire like Mort did. My idea is now to use split pins for the upper end for securing the nut to the Stud and use the 0.6mm wire throughout the ears of the Split pins, from one side to the other. That’s the best I can do. By the way, if it do not looking good, nobody will see that inside the block. Comments? Cheers, Guenter |
| GK Guenter |
| No, that's not really the best you can do - go ahead and locate more appropriate wire. Lock wire is not standard wire, but it is available from supply houses. .032" wire is the most common and works fine on the main studs; that is about .8mm wire. I would certainly not go smaller than that. Aircraft wire is also made in .041", .051", and .062" diameters, but you would probably have to buy that fron an aircraft supply or an airport maintenance shop.
Vibration is the enemy, and by doing what you suggest you are running the risk of pieces breaking off and perhaps getting into moving parts in the engine. I have worked on engines where the broken-off legs of cotter pins were found in the bottom of the oil pan, or had been caught up in the pick-up screen. The rods and crank are the most critical elements of an engine, and short-cuts can't afford to be taken there. Tom Lange MGT Repair |
| t lange |
This thread was discussed between 01/10/2018 and 03/10/2018
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