Author: Jack

After you’ve acquired the basic components to convert your Z31 to turbocharged, there are still a few parts crucial to completing your conversion successfully. Nissan re-used a large number of components between both early and late model years and turbo / non turbo cars, but one component that had significant differences was the crankshaft pulley, seen here in the exploded FSM diagram:

The crankshaft pulley, also sometimes called the harmonic damper or harmonic balancer, is the pulley driving all 3 of the Z31’s accessory belts, as shown here in the FSM for turbo and NA:

The above diagram shows the main difference between the engine layout of the NA and turbo cars, with the alternator on the lower driver’s side of the engine on the NA cars, and on the lower passenger side for the turbo cars due to the turbocharger system occupying the driver’s side area of the engine bay. On 1984-1986 300ZXs, the NA cars used V belts for all 3 belts, while the 85-86 turbo cars used a micro-ribbed V belt for the alternator / water pump pulley. The pulleys and belts are otherwise exactly the same between NA and turbo, meaning swapping to the 84-86 crankshaft pulley will mean that you can purchase OEM style 300ZX turbo belts for maintenance, and that your belt system will be functionally identical to the OEM turbo cars.

As usual, the issue here is locating these crank pulleys. They are not common, with no examples on eBay as of the writing of this post for turbo 84-86 cars. Many for sale are damaged, with cracking or chipping on the edges that may result in vibration or stress on the crankshaft. I found a few in fair shape, but I decided I didn’t want to risk my engine’s health if I could find a better way. A few hours of searching and reading later, I came across a few old forum posts discussing CSPs and replacements, as well as aftermarket options. This site has information similar to the forum posts I saw:

“There are a few crank pulleys (harmonic balancers) available for the VG30E.

Unorthodox Racing (NLA)
Ross Performance

Weight:
Unorthodox Racing – 1.70 lbs?
Ross Performance – 10lbs .8oz
Stock (86 NA) – 6lbs 1.2oz

The Unorthodox pulley and Ross pulley have micro V for the alternator and water pump, while the A/C and power steering are V-belt.

The Unorthodox pully is solid aluminum while the Ross is carbon steel with a rubber dampener.

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Ross Performance Nissan VG30 Z31 Metal Jacket Harmonic Damper

High carbon steel hub / pulley units
High carbon steel damping ring, fully bonded using an anti-vibration, anti-tear natural rubber
Damping weight optimized for much higher RPM and power level over an OEM unit
Aerospace grade anodized aluminium power steering pulley
OEM diameter water pump/alternator and A/C pulley to maintain optimal belt wrap
Under driven power steering pulley to protect power steering pump at high RPM*
Lightweight anodized aluminium timing disk
Laser etched 360° timing marks
Designed for use with our universal dry sump drive adaptor and 19T HTD pulley**
Steel components corrosion protected with a hot phosphate coating process and a high quality matte black paint finish
Uses grade 10.9 or better hardware
Complies with SFI spec 18.1

*power steering pulley is not underdriven
**a dry sump drive is not available for the vg30e

In order to utilize the Ross balancer you need a micro v-belt and micro-v pulleys.

On the left is the micro-v alternator pulley, on the right is the micro-v water pump pulley.

There is a lengthy wait time to acquire a Ross Harmonic balancer as each one is made to order. The overall quality and finish of the piece is immaculate. The fitment is perfect, the crank snout of the A/B series VG30E is 25mm, they machined it exactly and it slipped right onto the crank of my engine with no play in fitment and no fighting it.”

The Ross Performance Parts VG30ET harmonic damper is made in Australia, and comes with a glowing endorsement from multiple Z31 owners who have purchased it. It starts at $644 AUD, or about $450 USD before taxes and shipping. When they were available, new OEM Z31 harmonic balancers went for $300+, but as they are NLA for the most part the Ross harmonic balancer looks to be the best option available. I’ll continue to research Z31 CSPs for turbo conversions to see if I can locate any other manufacturers or high quality examples.

After venturing more than 300 miles round trip to Mt. Carmel, PA for my 120K mile service, the Z ran smoother and stronger than ever before. With the confidence that my timing belt wouldn’t suddenly become interested in martyrdom, I drove around for a few days locally enjoying the nice weather. I still have my KONI struts set to the softest ride setting as I continue to break in my Shiro springs, and the car feels balanced with much less rear end dipping under heavier acceleration. Even with daily driver tires, the Z grips the road much more tightly and consistently.

All this to say, 3 days after my perilous journey to Xenon, I noticed a “clunking” noise coming from the front suspension during tighter turning and bumps. After restoring my entire front suspension (writeup / info to come, once this repair and rear sway bar end-link replacement are complete), the culprit appears to be the only two components not replaced – strut mounts and/or strut bearings, both of which were re-used after being cleaned up during restoration. I set about getting my hands on a new set of strut mounts to replace the original ones and complete my suspension refresh.

Strut mounts, from what I’ve learned, are a wearable component with a set lifespan. Over time the strut mounts can crack and deform, and at this age even well cared for Z31s will need strut mount replacements if they are seeing real world road usage. So, first try: Nissan OEM part websites, like this, or this, or this, etc. They all have confusingly similar names, to the point I forgot which one I ordered my clutch master rebuilt kit and slave cylinder from (lol). None of them have the strut mount, which isn’t surprising.

Next, reputable 3rd party parts sites, like RockAuto. The preferred brand of replacement suspension parts where available for the Z31 is KYB, but the KYB strut mounts are out of stock on RockAuto, as well as pretty much everywhere else on Earth (more on that in a bit). Here are the current options for strut mount replacements on RockAuto as of 1/2023:

Same thing at The Z Store. We know these parts existed at one time, they are currently unavailable, sucks to suck. There are always eBay options, but I’m a bit sketched out about buying parts from random Ebay vendors and hoping they fit, or are even for the right car. As a last resort fine, but I’d like the most possible assurance that I won’t need to do this repair twice.

In the mean time, I went out and bought a set of used OEM strut mounts from a 300ZX used parts site, either 300ZXpartsforyou (wonderful guy, located on west coast USA) or Vintage Z Parts. The set I got is in fair shape, but ideally I wanted new components to ensure the best operation and longest lifespan of the suspension. I kept searching for either the KYB strut mounts, or some other alternative, but found nothing. Finally, impulsiveness and past-tense FOMO got the best of me, and I found a site that claimed they had the KYB strut mounts in stock for a fair price, so I pulled the trigger and ordered two.

Again, relief was short lived. I got an email about 2 hours after my order:

We are currently back ordered on this until end of next month. Please let us know if this is okay. Thanks.

sales@propartdepot.com

Fuck.

Well, wheels are already in motion. I decided to throw good money after forever-on-backorder money and ordered a pair of the MEVOTECH strut mounts from RockAuto. As usual, they arrived on schedule, exactly as described, boxes and hardware intact. I will be comparing the OEM mounts I have in the garage with these new strut mounts to see if there are any noticeable changes to dimensions or fitment. The MEVOTECH strut mounts did come with strut bearings as well, but I previously purchased KYB strut bearings as well, so I will compare those as well to see if they are interchangeable.

So I have my parts, and the replacement shouldn’t be too bad, outside needing to break out my Harbor Freight spring compressor one more time after all the use it got doing my suspension overhaul. Minus that, we already broke all the fasteners loose and replaced most of the components, so the only concerns I have are removing and replacing the strut assembly without hurting the ball joint boots and other delicate pieces. I’ll add a part 2 once the repair has been done, as a write up for replacing the strut mounts and any hurdles along the way.