I have been thinking about upgrading the OEM wheel studs for some time, it’s a potential failure point that’s always in the back of my mind on track. In addition, I have noticed with most aftermarket wheels running more aggressive offset etc the wheel itself is thicker and therefore the thread engagement of the wheel nut is reduced.
On the stock wheels I have around 10 turns of thread engagement and with my Konig’s and TE37’s I have just over 7. It is recommended for a M12x1.5 thread to be around 8 turns for a safe and secure fitment.
As I mentioned previously, with a 3mm spacer that I will add to the TE37’s to give a touch more clearance to the front Brembo’s, this leaves me with far less thread engagement than ideal.
I have been looking into stud options and the ARP 100-7726 is marketed for GM car but accordingly to Andy Hollis (Grass Roots Motorsport and HPDE Forum) they work well in the ND hubs. They are the only extended stud option that you can fit without removing the hubs which is a bonus. They have an extra 5mm available thread length which will be ideal and give me the correct engagement with a stronger stud than OEM. The downside to this is cost, these “GM” studs only come in packs of 5 and around £42 a set!
It also seems another common failure point for the ND (and all MX5’s really) are the hubs themselves, most likely due to high cycle fatigue and thin wall thickness that is used by Mazda. This seems to be a much larger issue in the US, which is most likely due to the wider wheel and tyres then tend to fit increasing load on the hub/bearing. Until recently there has been no solution to this other than replacing the OEM hubs as a preventative maintenance item. 949 racing has now brought out a new thicker walled hub and stronger bearing (see link below) which looks like a fit and forget solution which is great.
As my car is only run on track 2-3 times a year with lighter wheels and far less aggressive tyres, with a decent helping of mechanical sympathy, I am unsure if these are entirely necessary for my use case, but it would certainly provide peace of mind. A hub/wheel coming off on track is not a nice though. Interested to see what people’s opinions are?
Removing the hubs is very easy, you just remove the whole brake calliper with the pads left in. That is just 2 bolts per corner. I used a wedge to keep the pads secure in the calipers.
Yeah appreciate the front hub removal is straightforward (unless the seating area is corroded) but easier not to have to do it. The rears are also more involved and requires more interesting leverage angles to remove the hub bolts without disconnecting the link arms and impacting alignment etc.
I have a set of ARP100-7719 studs, these are the correct ones for the 5, but you do need to remove the hubs. I would recommend removing the hubs anyway, it seems that many of the failures are created by bad mechanics putting excessive force through the hub surface. I have gone a different route with my set up and no longer need the studs.
I have fitted the ARP 7726 studs and they went in just fine. I used a ball joint press to remove and install worked a treat. Appreciate the advise, I think most damage must come from people hammering them out or using wide tyres with more rotating mass.
I didn’t want a stud quite as long as the 7719 so the 7726 is perfect as looks OEM and won’t collect additional dirt on the end of the thread.
Two things that I have failed to mention and feel slightly guilty about not doing sooner are some very nice parts available from @AdamR28 at CleaR Motorsport. I imagine some of you will be familiar with these already, but I wanted to mention them as they really do make an improvement to how enjoyable the car is to drive.
The first is the sound tube Adam has developed which essentially replaces the heavily sound dampened OEM tube with a less restrictive item that comes with different foam inserts so you can tune the intake sound to your taste. Even with aftermarket induction kits/filters these cars sound rather poor in my opinion when it comes to induction sound. This kit makes a real difference, and you can hear a nice level of intake noise at higher rpm and together with my exhaust mods the sound is perfect. Very simple to fit and even make yourself but to be fair by the time you have sourced all the parts you may as well buy Adams kit which is very well priced.
The second is a throttle pedal plate extension which comes with a set of spacers and all the hardware so you can adjust it to your own preferences. I had the Verus pedal plate fitted previously, and it didn’t offer enough overhang towards the brake for easy heel and toe and sat slightly too high. The CleaR motorsport one is bang on and makes blipping the throttle so much more natural. Very impressed.
Adam also has other parts available (braces etc.) so feel free to take a look on the Car Cottage Ebay site.
Completely agree . I have ones of these fitted as well. Makes a the clutch pick up point feel so much more natural and easier to manage setting off from a stop.
Hi @Jonathan_W, unfortunately I’ve not had chance yet. The car is still up on axel stands, Ive been busy tinkering and replacing all the fluids, fitting braided lines etc.
Hopefully once everything has arrived to fit to the car I can get it on the wheels and take it out for some pictures.
The tyres are fitted to the wheels and look great. Yes that’s right I ordered them from Japan with the wheels as you can’t get that size in the UK and it worked out pretty cost effective.
. I have ones of these fitted as well. Makes a the clutch pick up point feel so much more natural and easier to manage setting off from a stop.
glad you like the bits!