BEAVIS' White Track Car

[beavis]

Speaking of good value fast cars....

[Custardtart]

Hey what’s a few $$$$$ between freinds!

[Daffy]

Hey what’s a few $$$$$ between freinds!

[SKYHI]

And then a challenger appeared

[rascal]

Bit of a shame that 1:02.78 wasn't during the Interstate Challenge......

[beavis]

Track must've been 0.5sec faster due to weather conditions

[beavis]

Took my MX-5 out to Winton Raceway last weekend for some fun.
The car is really starting to get settled, and I'm slowly seeing fewer and fewer issues.
And, as such, I'm able to focus more on just driving the thing.

It has quite a bit of pace now, so there is a fair demand on the brain to keep up and be able to focus on where to position the car.

I did have a couple of small issues, firstly I swapped to a 4-port MAC valve, which was plumbed backwards resulting in hitting boost cut, so swapped the hoses on that for an easy fix. And, I am cooking brake fluid after about 4 or so hot laps, so more time needs to be invested in brake cooling, and perhaps better fluid.

In the end the car achieved a 1:28.9 laptime, which I'm fairly confident is the fastest an MX-5 has ever been around the track.

Nonetheless, here's some in-car video.

[beavis]

Hey so I've made some changes to the car recently and I haven't had a chance to mention them here, so time for a little update.




BRAKES

Firstly, I've swapped out the front brake calipers and rotors for a new AP Racing based setup sourced from V-Sport in Sydney.

It's an interesting kit, it's chunky... really chunky, but still fits under some 15" wheels.
This AP kit runs a Commodore spec rotor that is available over the counter at almost any parts shop and while it is almost exactly the same diameter as the Wilwood at 296mm, it is critically 28mm thick. The caliper is an AP Racing CP9200, which offers increases in pad area and thickness of roughly 30% over the Wilwood Dynapro4 pad.

I believe I have good reasons for why this is the right move for my car. The larger caliper and rotor make for more thermal mass, as I really felt I was working the old Wilwoods harder than they could cope with. The pad depth is great too, so much more life to a set of pads compared to the little pads of the old Wilwoods.
It's a pricey kit, but if I want to be able to actually drive the car then it is kinda necessary.








That said, this doesn't mean this AP kit is for everyone and it doesn't mean that the Wilwood kits are no good. Do your own research and find the right solution for your application.





SUSPENSION BUSHES

The second part of todays fun is an upgrade to my suspension bushes.
The existing bushes had spent their entire life over the last 6yrs (or more) in 2 separate track cars, AND I was suffering from a failed bush in a front upper control arm, so things were due for replacement/upgrade.

I opted for the SadFab delrin bush kit (with poly+bronze sleeves in certain locations to ensure suspension doesn’t bind). I was happy to justify the slight premium cost of this over something like one of the off the shelf poly kits as this SadFab kit had all the right answers to maintain free suspension movement and avoid the binding issues of typical poly bushes.

Naturally, this is a fairly extensive job. Obviously including the removal of all the suspension arms, so it took me a good couple of days over a weekend. I am lucky in that I’ve had the suspension apart before, and I live in an area where corrosion isn’t a huge concern, so all of my cars undercarriage comes apart quite nicely.

Bush removal and installation is more or less as per any bushing replacement. Although the delrin bush needs to be reamed after install into the arm as it may deform slightly and this reaming ensures that the supplied sleeve fits perfectly with just the right amount of freedom of movement. Also, because the MX-5 has cam adjustment bolts for the lower suspension arms, this means that the bushes may not always be perfectly square, as such there are certain locations that require a poly bush (rather than 100% delrin). To alleviate the negatives of poly, the kit includes a kind of “double sleeve” (a sleeve with a bronze insert) for the poly bushes to maintain the free movement and avoid the dreaded binding issues. Installation of the poly is much the same, but without the reaming step.

If you are curious on the "proposed benefits" of this kit, I suggest a read of the Bushing Mega thread on the MiataTurbo forum, here: https://www.miataturbo.net/
In terms of performance, I took the car out on track at Winton after these bushes were installed. There was no perceivable change to the ride quality, a mildy sharper and more distinct feel to the suspension, but not a night and day change that I can detect.

I think for the price/performance of the delrin solution, it's not the kit of choice for an every day street car, and really it's targeting the track oriented/enthusiast MX-5er more than anything.

[16bit]

question re your diy coolant reroute you did from this video below...

how have you found having the water temp sensor being on the cold side of the engine? should it be on the back? i would really like to do this reroute and not have spend a few hundred dollars if i don't have to.

thanks!

https://www.youtube.com/watch?v=SqQeMYl2eeo

[beavis]

Indeed I moved the sensor to the back of the head about a year ago, which is where it should be ideally.
It's easy to do as there is a plug there that simply swaps with the front, just a matter of unbolting them and swapping.

[16bit]

ok cool! when i drop the coolant i will attempt this swap myself. i got some gal steel pipe and need to figure out what hoses to try and use, might be able to cobble something together with what I have hopefully.

thanks for getting back to me.

[beavis]

I'd hoped I would get a chance to take the Turbo NB MX-5 to Phillip Island before year end, thankfully I just got an entry into the December event with the Alfa club.
It was a slightly frustrating day with a LOT of slower traffic on track with me which made it hard to get a comfortable lap, but I ended up with a PB of 1:41.9
I discovered that the car suffers from some fuel surge under the very long left hand corners of 2 & 12, so I needed to keep the tank over half full to alleviate that.
Sadly my GPS wasn't working properly so the data and laptimer isn't perfect in the video, but the official track-supplied timer verified the time.
As usual, some light homework to do and things to tweak before the next event.

And excitingly, now the fastest an MX-5 has ever been around PI.

Video of the day:

[Alex 2550]

Congratulations Brendan,
The car is coming along very nicely, great times there.
I saw your brake temp issues and the ducts you made over at miataturbo and was wondering how long it would be before there was a caliber change.
Keep up the great work.


Sent from my iPhone using Tapatalk

[beavis]

Thanks Alex. Was your post a question?

A few images from Phillip Island 2 weeks ago thanks to a fellow MX-5er.

[MrTurkey]

Great job Beavis, good to see the car continue to develop and get faster.

Hope to catch up at a track day sometime in 2020.

Cheers, Chris