M/T Flywheel Bolts VS A/T Flywheel Bolts

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01-25-2006, 09:17 AM

s0ber

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M/T Flywheel Bolts VS A/T Flywheel Bolts

Anyone know whats the difference? I know there the same exact thread, of course, but is it a length difference or what the hell?

01-25-2006, 09:26 AM

Jeff92se

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Different lenghts. MT versions are longer I think. Do NOT interchange them!

01-25-2006, 09:29 AM

s0ber

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I have a few MT ones here, they look tiny.... :\

01-25-2006, 09:37 AM

s0ber

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Is it possible to use A/T bolts on the M/T?

01-25-2006, 09:55 AM

cardana24

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they are diffrent sizes for sure. I had to take an auto flywheel off before I put the manual flywheel on my motor. I would not want to take the chance of the auto bolts running too deep...thats just me. But I am positive they are different lengenths.

01-25-2006, 02:19 PM

abci30

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the part number for the M/T flywheel has changed. When i got mine for a swap the bolts that came with it were the exact same size as the auto ones. I'm thinking they did this so they would not have to carry 2 sets of flywheel bolts. So depending on which flywheel you have you the a/t and m/t bolts may be the same. IIRC the auto ones are shorter than the M/T ones

01-25-2006, 02:23 PM

Kevlo911

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My manual swap SHOULD be comming soon, but my flywheel might be mounted on a different crank

01-25-2006, 02:59 PM

s0ber

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Quote:

Originally Posted by Kevlo911

My manual swap SHOULD be comming soon, but my flywheel might be mounted on a different crank

3.5? I30??

01-25-2006, 06:35 PM

Germr497SE

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Auto Flywheel ?

i think auto cars dont have a (flywheel) they have tq converter... may be Im

wrong duh.....

01-25-2006, 06:41 PM

#10

s0ber

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They have a flexplate, basically a flywheel without the friction rotor thing on it.. and 4 bolts to bolt onto the torque conv...

01-26-2006, 08:18 AM

#11

s0ber

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Well I have finally got some M/T bolts and took a pic of both...

The length doesnt look like that much of a big deal..

01-26-2006, 08:58 AM

#12

juani

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I think I used AT flywheel bolts to bolt on manual flywheel when I did the swap. I have to check the left over bolts from swap in my garage, but till today(more than 8 months) it runs fine.

jeff92se: any reason why I shouldn't use AT flywheel bolts? Can it become lose?

01-26-2006, 09:04 AM

#13

Stephen Max

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The engineering rule of thumb (actually there is a scientific reason behind it) is that as long as you can get three threads fully engaged, you will be able to develop full tightening torque in the bolt. The AT bolts are long enough based on this criterion.

01-26-2006, 09:13 AM

#14

Jeff92se

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Stephan. I thought it was more like 8 threads? Sober. Put one of those auto bolts though the flywheel and see how many threads stick though the other side Then decide if you want that little # of threads holding a 22lb steel mass turning 6,000 rpm right under your right side nad

01-26-2006, 09:16 AM

#15

Kevlo911

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Better safe than sorry....

01-26-2006, 09:27 AM

#16

s0ber

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Quote:

Originally Posted by Jeff92se

lol thats pretty convincing.. me =

01-26-2006, 09:37 AM

#17

Stephen Max

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Quote:

Originally Posted by Jeff92se

J.E. Shigley, Mechanical Engineering Design, Third Edition, page 252:

"It is interesting to know that three full threads are all that are required to develop the full bolt strength."

The flywheel spin loads act normal to the bolt axis, so no spin loads are imparted to the bolts. Bending moments are avoided by the hole clearance so that the expanding flywheel does not react against the bolts.

01-26-2006, 09:40 AM

#18

Jeff92se

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I just think there's a specific reason why Nissan designed at least 6-10 thread engagement for each bolt. Although the spinning might not create any signifcant loads, I'm sure the clutch and said parts add side loads and also vibrational loads from being bolted to the flywheel

Quote:

Originally Posted by Stephen Max

01-26-2006, 11:47 AM

#19

Stephen Max

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Quote:

Originally Posted by Jeff92se

Yeah, I don't think anyone would design a threaded connection with only a three thread engagement, but you could if you wanted to. The strength and stiffness of a bolted connection isn't due to the bolts only, but in large part to the rigidity of a preloaded assembly. The preload is determined by the number of bolts and the bolt torque, and the torque in a bolt can be fully developed with only three threads.

01-26-2006, 11:47 AM

#20

Stephen Max

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Quote:

Originally Posted by Jeff92se

01-26-2006, 11:50 AM

#21

streetzlegend

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this swap is never gonna happen!!!! diaf

01-26-2006, 11:53 AM

#22

s0ber

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Quote:

Originally Posted by streetzlegend

this swap is never gonna happen!!!! diaf

01-26-2006, 11:57 AM

#23

s0ber

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Alright I took some more pictures, here's the thread lengths on the A/T bolt... with and without the flywheel spacer thing w/e it is..

There is clearly more than 3 threads here..

01-26-2006, 12:08 PM

#24

Jeff92se

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w/ the 5-sp flywheel?

01-26-2006, 12:12 PM

#25

s0ber

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yeah thats a 5spd flywheel

do any of you happen to know what the "flywheel reenforcement plate" thing there is for?

EDIT: According to FAST its there for the A/T flexplate, but I dont see it for the M/T?? Is it needed?
You can see it in the 1st pic above..

01-26-2006, 02:57 PM

#26

abci30

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i don't think my early post was clear. they changed the part number and design of the m/t flywheel recently. You will need to use that plate and you can use the A/T bolts since they are now the same. If you use the M/T(12315-77A00) bolts with the newer design flywheel with the plate you will not be able to tighten down the flywheel to the crank because the bolts are longer. IIRC Old flywheel part number is (123102y910) has thicker center and does not have that plate. New flywheel part number (123102y911) has to be used with the plate and the same bolts as the A/T flex plate. Sorry i don't know the part number but if you call the dealer and ask they will have it.