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Old 06-18-2020, 02:56 AM
oldskewel oldskewel is offline
Join Date: Nov 2014
Location: SF Bay Area
Posts: 1,100
oldskewel is on a distinguished road
I did the TimeSerts using their $100 kit, but not the $400 BMW kit.

Some notes I took back when I did it:
Head bolts are M10-1.5

inserts cost about $2 each

kit costs about $100+, including: a tap for the insert's outer threads; drill bit; a counterboring tool to make a little groove for the "top ring" (below) to seat in; an insertion tool / forming (vs. cutting) tap to install the insert into the tapped hole; a few inserts and a plastic box. All of the above seem to be very high quality. Machine shop quality vs. hardware store.

Inserts are made of mild steel which appears to be black oxide coated. So they have a slightly rough surface finish.

- The kit contents might be completely standard parts, not requiring the special kit, so maybe you could skimp on cheaper taps and make do without the counterbore and special insertion tool. Details on this below.

- e.g., a M10-1.5 insert will have outer threads of M12-1.5. Same exact pitch (1.5 mm here), since that's what the "time" is in timesert - that the threads are synchronized. An M12-1.5 tap is a standard size that can easily be bought as a standalone piece. So for example if you just need to put one insert in an easy application, you could just buy the $2 insert, a <$10 tap at the hardware store (if you did not already have it), and would be good to go.

- There are two main features of the insert - top ring and bottom threads

- Top ring. purpose is to stop the insert from threading in any further. There is a wider ring around the outer edge at the top of the insert. The kit comes with a special counterboring tool to make it so the fully inserted insert will be flush with the surface of the material. A less precise substitute for the special tool would be a slightly bigger drill bit to countersink a little. That's what I ended up doing on the M54, since the threaded holes were countersunk already by about 6 mm - so the counterbore tool in the kit was no use, and I used an oversized drill bit to go in about 8 mm.

- Bottom threads. This is the more critical aspect.

- The bottom 2 or 3 threads are normal on the outside (e.g., M12-1.5), but on the inside (e.g., M10-1.5) surface of the insert, they are not triangular, but rather rounded. The concept is that when the insertion tool/forming tap bottoms out the insert (when the top ring bottoms out against the counterbored surface), the insertion tool will then drive and forge / form / tap (as if tapping threads, but by forming rather than cutting) through these bottom threads, except that rather than cutting away the extra material, they cold-form it into sharp triangular threads, and also deform the outer surface of the insert, pressing it into the block, making the insert permanently pressed into the block, so it will not unscrew.

- So the tap forming tool looks like an extremely sharp and perfect screw, with a roughly squared end to it. I think the squared aspect is to focus the pressure on the 4 corners rather than having to cold form and press the entire circumference at once.

- That's all the theory, and I think it's all good. But actual practice has some issues.

- First one, is that the instructions are not clear on how much to insert the insertion tool into the insert before inserting the insert into the block. Presented as if it does not matter. My findings are that it does matter, and best is to insert the insertion tool into the insert right up until the bottom threads are engaged, then insert the insert into the hole, then when it bottoms out at the top ring, the insertion tool will cold form the bottom threads, seating the insert. I put thread locker on the outside of the insert / inside of the hole as well to keep the insert locked in place. Main problem I found with that approach (and even worse when not pre-installing the insertion tool/tap into the insert) was that the insert would stop inserting before it bottomed out, and then the cold-forming would occur, locking it in place too early. And too late to fix.

- Solution, which worked great, was to:

- use an existing regular bolt as the first insertion tool. It should be smooth fitting within the insert since it will be removed, leaving the insert behind, before the insert is locked in place. Put some oil on it for easy removal, thread locker in the block hole and outside of the insert. insert bolt into insert, right up to the bottom threads.

- then insert the bolt+insert all the way until the top ring seats. Ideally, this will happen without the bolt starting to go past the bottom threads.

- remove the bolt. Hopefully the insert stays where it is, with more friction on the outside of the insert, vs. the oiled inner surface.

- then insert the oiled insertion tool/tap, all the way through past the bottom threads, cold forming them and embedding the outside of those threads into the block threads.

- unscrew the insertion tool/tap, and done.

- the youtube 50skid did not buy the kit. He thought the insertion tool / tap could be completely substituted for with a regular bolt. He got it done, but I think if he actually had an insertion tool/tap, he'd have understood the utility of it.

- I can guess that the kit wants to make itself look specialized and needed, so they don't mention using a bolt as stage 1. Also, like everything else in making things, people are obsessed with speed and efficiency, and timesert probably wanted to reduce the number of steps. But it's pretty clear to me that other than adding a step, there is no downside to using a smooth bolt first, and then the cutting insertion tool/tap to finish the insertion.
2001 X5 3.0i, 190k miles, AT, owned since 2014

Last edited by oldskewel; 06-18-2020 at 03:04 AM.
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