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Do you remember what size and specs were the 3 bolts holding the mounting bracket for the heavy side o the SDU motor? everything I have at home seems to get stuck after few turns.

Proton wrote: ↑Mon May 29, 2023 10:33 am Do you remember what size and specs were the 3 bolts holding the mounting bracket for the heavy side o the SDU motor? everything I have at home seems to get stuck after few turns.

Nope, sorry, I don't think i ever had any reason to remove it.

I know nothing about Tesla parts but a lot of automotive threads are metric fine rather than the more standard course thread. A fine thread bolt will start in a course thread hole but only go in a turn or so. I'd guess something like M10x1.25mm for a motor mount (a M10 course thread would be 1.5mm pitch).

Proton wrote: ↑Mon May 29, 2023 10:33 am Do you remember what size and specs were the 3 bolts holding the mounting bracket for the heavy side o the SDU motor? everything I have at home seems to get stuck after few turns.

Standard M8 if you mean the rear SDU's 'ear'.

Since it's alloy sometimes cleaning the threads helps with the correct taper offcourse.

Before you do make sure we talk about the same holes.
(same engine rev. etc.).

@catphish I apologize posting here. Probably I should have posted in a new thread.

It looks like M7? I tried with 12 mm Wrench and it seems to go in. I just did not want to strip the threads.

Referring to an external thread chart, here's a list of various M8 thread pitches and diameters for M8 bolts:
It appears that the bolt you are measuring has a minor dia. of 7.5mm, which corresponds to a M8 x 0.5 bolt thread (extra fine). Around here, that's an uncommon pitch.

The most common M8 pitch I encounter (~80%) are M8 x 1.25 (coarse), and maybe 15-20% are the next finer pitch, M8 x 1.0 .

The rest are not common around here at all, though they're available. Of course, Tesla uses all kinds of unconventional things, but I'd start with horses, not zebras

A thread pitch gauge is an invaluable and inexpensive tool. While I use mine maybe 3x/year, when you need one, it saves a lot of time. The one pictured below runs USD$10 via Amazon:
Better quality ones run about twice that, but you can generally make do with a cheap set. My set are small enough to fit in an M8 tapped hole.

HTH

I'm pretty sure i didn't buy new bolts for it and that i could fix my mount to it. So if it's any other thing then standard then i'm baffled.

The chart and measurement don't match because the minimum diameter is the one of the drill to make the thread.
So the plain shaft so to speak. That's why a finer thread gives a thicker bolt (less thread height).

What's measured on the photo is the external diameter on the threads...
M8 bolts in cars are often socket 12. Normal M8 bolts are socket 13.

EV_Builder wrote: ↑Mon May 29, 2023 8:22 pm The chart and measurement don't match because the minimum diameter is the one of the drill to make the thread.
So the plain shaft so to speak.

The minor diameter is what is measured at the root of the thread, what you're describing is what is shown on a "tap chart".

EV_Builder wrote: ↑Mon May 29, 2023 8:22 pm What's measured on the photo is the external diameter on the threads...

That can't be, because there is no 7.5 mm "OD". Proton must be using the blades at the end of the caliper to measure the minor diameter of the bolt.

The minor diameter plus a bit of tolerance is the tap char / drill size.
What remains is thread height x2.

I disagree. With a caliper you can't reach that deep in the thread. The thread is a spiral. Also I'm 90% sure I used standard bolts. Plus M8 means it's 8mm outside . The chart gives the tolerances for all measurements. So M8 should be between 7.9 and 7.7 outside.
By jumping between the flanges you easyly go out by 0.2mm.

If that bolt is the correct one measure 10 threads with the caliper and we know the pitch.

Are you Proton?

Proton measured 7.5mm "somewhere". If you've measured a bolt, you would know that the blade portion of standard calipers will measure to the bottom of the threads: by turning them slightly from perpendicular to the bolt's axis. This is actually the way this measurement is supposed to be accomplished. Take a look at how Proton has the calipers oriented to the bolt:
Proton is measuring at the root of the threads ("minor diameter"), and has observed 7.5mm .

From the chart I screenshotted, the only place that can be measured on an M8 bolt that is close to 7.5mm is the minor dia. of an M8 x 0.5 -- a fairly rare bolt. Proton's bolt doesn't fit the hole, so that matches the observed reality.

I had said that it's much more likely that the bolt needed is M8 x 1.25 . Quoting myself:

asavage wrote: ↑Mon May 29, 2023 5:01 pm The most common M8 pitch I encounter (~80%) are M8 x 1.25 (coarse), and maybe 15-20% are the next finer pitch, M8 x 1.0 .

---

Honestly, I can't follow the rest of what you posted. We agree that it's likely to be M8 x 1.25 . What you are on about otherwise, I'm going to dispense with as some communication fubar that's not worth chasing.

I've split these posts off, please respect that projects threads are not meant for long-wound general discussion

Pretty sure it's a standard M8 coarse bolt - (I replaced mine)

Just checked, it's a normal m8x1.25. Maybe your threads are damaged?

Not sure. I know the pitch is x1.25. The bolts were used on the Nissan motor before I took if off the car. It uses the 12 mm wrench.

Japanese manufacturers like 12mm. You won't find any 13mm head M8 bolts on a Honda motorcycle for example (at least the older ones).

For now I just placed the motor in with the same type of screws but a lot shorter just to be able to finish the motor mounts. after you screw them in they work a lot easier which make me think that I was possibly using the right screws but the inside night have been dirty? I still do not feel good that I do not have 100% info on what they are supposed to be. I just do not want to damage the internal threads.

I happen to own a lot of thread insert kits (Heli-Coil, TIme-Sert, PowerCoil) as I've done a lot of thread repair over the decades, and in a situation like this, where you fear that running a tap down a hole to clean it out might cause damage, having a thread repair kit handy is a nice Plan B. You can always repair the hole(s).

Thread repair inserts have the advantage, in aluminum holes at least, of providing a stronger clamp junction than just bolting into the base metal. I like them a lot. I've probably installed several hundred, over the years, mostly repairing holes that other people have damaged. I used to do a lot of remedial repairs after someone else gave up.

cloudy wrote: ↑Wed May 31, 2023 1:54 pm Just checked, it's a normal m8x1.25. Maybe your threads are damaged?

Thank U. Memory served me right.

I was sure the measurement/chart wheren't realistic.

@proton :
If you remove the bolt and you see it's like touched i advise to retaper with the male standard M8 tap. Alloy thread oxidizes easyly leaving tighter tolerances and giving the feeling that the bolt isn't correct.