Motor swap gone wrong? Flywheel not fitting AT crank
 

Greetings all,

In the midst of a motor swap and cannot get the flywheel onto my new motor's crank. The donor motor is a 2003 VQ35DE non-revup from an AT replacing my 2003 VQ35DE non-revup from my 6MT. I'm attempting to install a 17lb chromoly flywheel, stage 1 clutch and pressure plate from conceptZ. Try as I might neither flywheel, old or new, will go onto the new motor's crank. The AT flywheel easily slides on, though. The motor is a jdm if that has any relevance. I've searched the FSM but still left without my answer.
The importer said it'd hook up no prob, he also convinced me to cut the pilot bearing out of the crank which was nerve wracking and exhausting.

I thought I could simply bolt my 6MT with a new flywheel, clutch and pressure plate and drop her in but that doesn't seem to be the case?

Help is appreciated, I promise I know how to use search, if no i'll bear the flames

The pilot bearing has a special puller, I bet that was a chore to cut off.

What exactly do you mean the flywheel won't fit? Take some pictures and upload them so we can see what you're talking about. Is the bolt pattern different or something? Do you not have the alignment dowel lined up properly? Did you try to reinstall a new pilot bushing before installing the flywheel?

Check the block stamping and serial number, it's right behind the passenger side heads, I suspect it's NOT a VQ35DE. Might be a VQ25DE or VQ40DE or something else.

Thanks for the reply. The block is 414920B VQ35. Neither will slide down to where I can even thread bolts, which eliminates the possibility of conceptZ selling me the wrong product (?) use of a rubber mallet doesn't help either. I couldn't get an action shot as I'm home alone but it seems to just ride the edge of the crank as if too small an opening.
https://cimg2.ibsrv.net/gimg/g35driv...3db85fd0ce.jpg
17lb chromoly next to stock DMF I've been able to line up the bolt pattern and the pin visually, but that's as far as I can get. I'm almost ready to bore out the middle of the chromoly, probably not.
https://cimg4.ibsrv.net/gimg/g35driv...f1599bfd70.jpg
414920B VQ35
https://cimg8.ibsrv.net/gimg/g35driv...4d53ca4e54.jpg
pilot bearing being cut away and chiseled out, can see where i caught her once
https://cimg1.ibsrv.net/gimg/g35driv...e01d9f4df8.jpg
upper left is flywheel that came with this motor it is the only one of the three I can get down to be able to thread bolts

VQ35 isn't a correct part number, there will be TWO letters after it because there are multiple VQ35 blocks, it definitely looks like a DE flex plate though, the HR one is quite different.

At this point I would call CZ and ask them if they've run into this issue before. I know there were a couple of Nismo variants of the DE motor and as far as I was aware they all used the same crank but there's a slim possibility that you ended up with a motor out of a specialty built engine, it might even be an aftermarket crank from a built engine. You would need to inspect the casting marks and such to try to find any identifiers.

It's not uncommon to run into JDM vs. USDM differences in stuff but I've never seen this particular issue before.

so you got the AT pilot bushing out? and it still wont fit? I agree, never seen this happen before. May be worth opening up the bottom end, pull the oilpans and take a look inside. You may have a surprise or two inside. JDM engines can sometimes be like finding easter eggs.. back in the day on SR20s and 2jzgtes we used to find all sorts of goodies.. hk$ turbo kits etc.. maybe your engine is built up.

when you were removing the AT pilot bushing did you strike the crank rear snout? could be mushroomed out a bit. did you measure the holes distance? how about the diameter of that crank snout on the AT engine? any pics of the old engine you can post? does the new flywheel fit on it? is there a dow hole on the new flywheel? so many questions I know..

Did you ever figure this out? It's my understanding that the AT and MT cranks are not the same - but it would be nice to have some real confirmation!

They are the same, they have different pilot bushings though. You MUST remove/install the correct pilot bushing.

I mean you're supposed to change out pilot bushings when you replace the clutch/transmission anyways so this should be obvious, some people like to cut corners though. It's a $5 part.

Thanks.
Sounds like I overpaid for my replacement engine because I spent considerable time finding an MT engine while there were several AT ones for much cheaper. Live and learn, should have come here asking questions first!

Not necessarily, there are two types of VQ35DE (well 3 if you count the transverse mounted ones in FWD Altima/Maxima but I'm not talking about that platform). One has intake-only cam timing and 2 cam phase sensors and was used in everything with the automatic transmission and 2003-2004 6MT cars. This engine is extremely common and much lower in price.

2005-2007 coupes with 6MT and 2005-2006 sedans with 6MT used the other kind of VQ35DE called the "rev-up" engine which has intake and exhaust cam timing and 4 total cam phase sensors. The rev-up motor is significantly more rare and expensive.

The long block is the same in either variety with the exception of the oil pump, the rev-up has an oil pump designed for the extra 500rpm that it's built for.

Regardless of the type of VQ35DE all 6MT uses the same pilot bushing, all 5AT uses the other style of pilot bushing. I spliced together someone else's photos and added a caption that shows how to easily tell whether you have the rev-up or not.

https://cimg1.ibsrv.net/gimg/g35driv...017fcffdbc.jpg

Figured an update was in order:

After removing the strange AT pilot bearing/bushing the flywheel concept Z sold me was the culprit. I am glad I didn't go to hammer crazy with the flywheel as am sure they wouldn't have returned it. Went over to my pals at Z1 and got their lightweight flywheel which was able to slide on the first time without much more than a few moderate taps of my rubber mallet! Was so relieved to see that I didn't warp something and am able to use this motor in my 6MT!! included a few pics from the build. Motor was successfully started on 01/07/20!

https://cimg4.ibsrv.net/gimg/g35driv...52a1c14e8e.jpg

https://cimg2.ibsrv.net/gimg/g35driv...1c0db26583.jpg
https://cimg0.ibsrv.net/gimg/g35driv...987c5cf90b.jpg
https://cimg9.ibsrv.net/gimg/g35driv...942a53e1ba.jpg
https://cimg8.ibsrv.net/gimg/g35driv...ffd8c0f86b.jpg
https://cimg7.ibsrv.net/gimg/g35driv...fcb67cb100.jpg
https://cimg6.ibsrv.net/gimg/g35driv...71d6aa3601.jpg

Thank you to all the replies, just to confirm this was a VQ35DE out of a JDM AT dropped into the waiting arms of my '03 6MT sedan. Since these pics i have welded the diff and installed gk tech rear dual caliper brackets and the 5mm knuckle spacer. Next up Coilovers!!

So CZP ended up sending you the wrong flywheel or a defective flywheel?

After almost getting into it with one of their techs over the phone, he also could not comprehend how in the world it did not fit, I simply insisted on the refund on the hopes some one in inventory and/or shipping sent the wrong product. It didn't seem damaged and everything looked good but clearly something on the inner diameter was off. The new one weighs 19lbs but it was for the same year make model but for some reason it fit perfectly.

Not dogging on CZP they have done me great and Z1 are no angels when it comes to order misprocessing, this one was a miss for them.