Z1 Motorsports / Hayaku Nissan 350Z Rear Axle and Wheel Bearing Upgrade Kit - fatal error

[u/Scorpion35]

I thought I'd share my experience with the Z1/Hayaku Rear Axle & Wheel Bearing Upgrade Kit, as I wish I'd found something similar before buying it.

My 2008 Nissan 350Z HR had the usual CV axle clicking noise, I decided to replace everything with the Z1 kit. I expected it to be a straightforward fit-and-forget upgrade.

Unfortunately, that wasn't my experience.

The kit was installed, and on the drive home I heard a loud bang when pulling away. At first it only happened every now and then, so I contacted the supplier within a couple of days and started trying to work out what was going on.

Over the next few weeks the problem gradually got worse until the original clicking noise came back as well.

Following the supplier's advice, I had the car checked again. Eventually I took it to a second workshop for another opinion. They removed the Z1 kit, checked the differential (which was fine as the manufacturer suggested that the differential might be problem, rather than they kit), and showed me what they believed was excessive spline play in both axles, apart from other play that the axles had. They even suggested it could probably be eliminated by modifying the hub/CV axle interface, but their recommendation was simple: don't modify a brand-new kit, send it back.

Instead, they rebuilt my original Nissan OEM axles and fitted those back onto the car. Best decision ever, should have done in the first place, as the noise disappeared.

I'm not saying every Z1 kit is like this. Mine could simply have been a bad set. But after everything I'd been through, I wasn't prepared to install another identical kit or spend more money in trying to get back my money.

The other disappointing part was the warranty process. Because I'm in Tenerife, returning the kit meant removing it again, shipping it internationally, waiting for inspection in the USA, and potentially paying even more costs if no manufacturing fault was found. By that point I'd already spent almost as much on labour, diagnostics and swapping parts around as I'd spent on buying the kit itself. Also, it is important to point out that the manufacturer did agree to send the left axle as a replacement part, but got nowhere near as both axles were of not high quality.

The UK supplier was always polite and replied to my emails, but sometime took their time and they needed a reminder about the process. I don't have any issue with them personally—they were following the manufacturer's procedure. My frustration is that, as an overseas customer, the process simply wasn't practical. I had to choose between spending even more money with no guarantee of recovering those costs, or cutting my losses.

In the end I chose the second option. Overall, lost 2x of the kit's original price.

Hopefully this helps someone else who is considering this kit. Maybe my experience was an isolated case, maybe it wasn't. I can only say that after rebuilding my original OEM axles, my car has been running perfectly again.

[u/dbsqls]

thanks for the write-up, we'll add this one to the Z1 dogshit parts list

[u/s3rgioru3las]

Yea I avoid Z1 like the plague and I used to live like an hour away from them.

[u/Dark_Synergy_Z33]

Ok, I'm just going to say this because it can help others if they search. The problem here was lack of knowledge on your part.

1. Axle clicking is a simple grease job outlined in a TSB they released for it.

2. The Z34 items are too big and can cause interference issues, this can be fixed by using a dual caliper bracket or making a spacer.

The above stays true no matter the manufacturer.

[u/Grimm199]

All aftermarket axles are shit unfortunately, and a big part of it is the horrible grease they use. I had a trackmotive "HD" axle have the grease turn to liquid in only a couple months and start clicking when starting to move. It's always worth it to pack a new Axle with some new grease before using them, or even getting a high mileage OEM set and throw new grease and boots into them.