Help with bolts

[Lachaga26]

Hello everyone I’m currently doing a clutch replacement on my sons Datsun 620 75 but he seemed to use a impact gun on the bolts  connecting the flywheel. After tapping and re threading the holes I realized I need new bolts but I can’t seem to find them anywhere and I already checked junk yards but nothing. Can I use these bolts from the 240 260 280 Datsun’s for my 620 here’s a link https://zcardepot.com/products/flywheel-bolt-set-oem-240z-260z-280z-510

I only say this because it look vary similar to my bolts but i don’t know please help 

also the boat size for my suns Datsun are 1/2 20 fine x1

[datzenmike]

Yes.

[Stoffregen Motorsports]

Some bolts are longer than others. Make sure they don't bottom out in the threads. Possibly this is what happened to cause them to get boogered up in the first place.

 

 

[datzenmike]

When I was much younger, I had an L20B out for the winter. Threw it together and later that summer the flywheel bolts all sheared off. Probably because the threads were rusty and it tightened up before actually clamping the flywheel down. Hard lesson.

 

All L series flywheel bolts should be the same 12315 - U6000/A8600/21001 

 

Automatic flex plate bolts may be different when not used with the 3N71B so stick with manual flywheel like you link, and should be OK.

[Lachaga26]

What about the pressure plate bolts would I be able replace those with 240 bolts from arp

[Lachaga26]

Also thank you vary much mike your like the god of knowledge that comes down to Datsun’s also thank you stoff 

[yenpit]

3 hours ago, Lachaga26 said:

What about the pressure plate bolts would I be able replace those with 240 bolts from arp

 

Pretty sure the AUTO flexplate bolts are shorter than the MANUAL flywheel bolts.  I have plenty of each USED if you still need.  PM if interested!

 

The pressure plate bolts I would suggest Grade 8 if you buy new at the hardware store.

[iceman510]

10 hours ago, Lachaga26 said:

also the bolt size for my suns Datsun are 1/2 20 fine x1

 

For a 1975 620 they should be metric, not SAE, 12mm x 1.25mm thread (maybe 1.0 but unlikely.  I would have to physically check one again).

 

19 minutes ago, yenpit said:

The pressure plate bolts I would suggest Grade 8 if you buy new at the hardware store.

 

The pressure plate bolts should be 8 x 1.25mm, so not graded by SAE values like grade 5 or 8.  Get metric 10.9 grade.

 

 

[datzenmike]

I found the same part numbers for auto flex plate but only the 3N71B ones. The 510 Borg Warner were different. But hey, go with standard transmission bolts and you can't go wrong. Yes I think I've seen two different sizes also.

[Stoffregen Motorsports]

5 hours ago, datzenmike said:

All L series flywheel bolts should be the same 12315 - U6000/A8600/21001

They're not.

[datzenmike]

Agree, I'm sure I have had different lengths too

[banzai510(hainz)]

flywheel bolts

https://www.partsgeek.com/catalog/1977/nissan/620/clutch/flywheel_bolt.html

[datzenmike]

23 hours ago, Stoffregen Motorsports said:

They're not.

 

L16 man and auto bolts are same number. This is true for the 521/510 and the early 620 L16 (maybe L18) L20B are different for the manual but auto bolts same as the earlier L16 man and auto. This probably indicates that the L20B flywheel is thicker at the mounting bolt location than the 5 bolt flywheels is my guess. I assumed that 5 and 6 bolt flywheels were, other than mounting bolts, essentially the same. 

[Stoffregen Motorsports]

Which is probably what happened to cause the bolts to get stuck in the first place. Someone probably used bolts that were too long. Or they didn't understand the whole thread interface concept thing.

[datzenmike]

Mine were rusty as hell. I looked at them and, shrug. This was when I didn't care.