I purchased my M35 (Base) in mid 2006. I have to replace the belts and idlers and the Z1 site says there's a difference in early and late 2006 VQ35DE engine applications. I understand the later setup eliminated one idler, using a spacer of some sort.

Q1) can you tell which kit is needed by the VIN ?
or
Q2) Can I order the later one and make the change, if needed on the car?

thx

Not familiar with the Z1 website.
I have a very early build 2006 M35x. When I go online to source parts that have been changed during production, they always give you an inception date for the part change, usually identified by something like "before/after 9/2005" as an example. You can find the build date on the door sill manufacture tag.
The belts did not change (from my recollection), but the idler pulley part # did, as I recall. I do not think they changed the idler pulley setup, still 2 idler pulleys, but I believe the A/C belt idler pulley part # was changed.

Go to an INFINITI OEM parts website (there are a few to choose from) & look for the parts you want. When you source parts info from an OEM Infiniti parts supplier they will note running changes in the parts description. These changes are noted by before/after build dates, as I described above. If you need an example of an OEM supplier website, let me know.

Not being familiar with Z1, I am surprised they note a difference in the pulley, but fail to elaborate the onset date of the part change. I see a few parts suppliers will often ask you for a VIN # to verify the parts you are ordering are correct.

Again, I have a very early 2006 production date, (06/2005) and I often run into parts changes that occured along the production cycle. Never been a problem, as the parts catalogs used by the OEM suppliers list the before/after production dates when required. I did change the A/C idler on mine a few years back. In my case, I bought the idler, as well as the bearing for the idler. I never used the bearing, as the new idler came with the bearing installed.

Thanks for your reply. My car is an early manufacture also. I have checked under hood and there are 2 idlers, 2 belts. In so, have been searching for OEM parts and have found a site called Amayama dot com featuring old OEM parts. Quite comprehensive with parts pages online to ID items. Issue is, they are in Japan and shipping costs are not cheap. I'll be ordering at least the Idlers from them..

Not sure where you are located, I am assuming you are not in USA, making your parts source more economically desirable than purchasing from USA or Canada. These OEM parts are not obsolete. I am sure you did your homework, good luck!
One further note, I have found in replacing parts over the years that changes noted for later builds worked fine on my early build. Brake parts & wheel bearings are two I have not have issues with. Keep in mind, YMMV!

Why not just remove the idler and get the belt for the newer production date from now on? It isnt needed and just takes up a couple HP from the engine. In fact the belt actually works better without the unneeded pulley since more of the belt wraps around the crank
https://www.z1motorsports.com/fan-ac-an ... -5640.html


Since you will already be down there and the belt removed, consider upgrading to lightweight crank and alternator pulleys as well to gain a few HP.

Enigma, you just solved an Enigma!
My 06 M35x has a build date of 7/2005. The Z site you linked states pre-august 2005 build (for the 3 idler set up).
The OP posted that he had 2 idlers, which would indicate the new setup. One on left lower, the other on right lower, as depicted on the Z site diagram you linked. The third idler that has been eliminated is on the upper accessory belt, passenger side, again as depicted in the website linked. I am unaware of any M35DE engines with a 3 idler set up, at least I have not seen or heard of anyone reporting such to this day! Production for the M35 started in 02/2005 in Japan, as the Fuga. Not sure when the North American M35/M45 series production started.
Good Info!

I purchased OEM belts from InfinitiPartsDeals. Also picked up a couple "replacement" idlers from NSK on Ebay, however after the R&R exercise, found that the OEM idler pulleys have double bearings and the replacements didn't. The OEM bearings were still tight and dry at 120K