Snowmotion's NB8a

Snowmotion · Postby **Snowmotion** » Sat Mar 08, 2014 9:00 am

Yes, a leaky exhaust. Back under the car today to find the leak.

Snowmotion · Postby **Snowmotion** » Sat Mar 08, 2014 11:58 am

Found out why the mid gasket failed. MX5 don't use a conventional flat gasket but rather a round solid gasket.

hks_kansei · Postby **hks_kansei** » Sat Mar 08, 2014 12:48 pm

Mine has no gasket at the moment.

I just used a heap of exhaust sealant instead....... because I had that with me, and a gasket would mean I had to go all the way to the shops.
And I was drunk.

Snowmotion · Postby **Snowmotion** » Sat Mar 08, 2014 8:13 pm

hks_kansei wrote:Mine has no gasket at the moment.

I just used a heap of exhaust sealant instead....... because I had that with me, and a gasket would mean I had to go all the way to the shops.
And I was drunk.

I had the regular compression gasket but it did not like the track day and developed a significant leak. Local exhaust shop (Tuffy's Epping) were really helpful.

Snowmotion · Postby **Snowmotion** » Sun Mar 09, 2014 7:30 am

Fitted a new O2 sensor whilst under the car. With little service history on the car not sure when it was last replaced.
Pulling out the sparco seat for a while to keep my wife happy. I will see how I feel about this. Not sure it will stay out long.

Snowmotion · Postby **Snowmotion** » Tue Mar 11, 2014 3:15 pm

A little bit of footage from last weeks track day at Wakefield. Nothing too exciting but awesome when doing it.

MLR · Postby **MLR** » Wed Mar 12, 2014 9:27 pm

Lots like its nice and tight, try lowering the arse by 10mm to get rid of the little bit over oversteer if its annoying you, it may tighten it up a bit.

What tyres are you running? What hot temp pressures were they?

How did it feel and what plans now?

I am looking forward to getting mine out, I'm actually looking forward to playing with ride height, tyre pressures and dampening settings between sessions, for me that is 50% of the fun.

Thanks for the vid, it gives me some initial times to chase.

A mate has done a 1.11 at Wakie in a NA6 on semis, its got exhaust, intake and a tune though, I think its putting out just under 100kwatw, he is a fairly good steerer though.

Good to see someone using their car as a sports car was intended, well done.

Snowmotion · Postby **Snowmotion** » Wed Mar 12, 2014 9:56 pm

Yes, the arse could be a little lower but on the Bilstein shocks and Eibach springs I have there is no adjust-ability. I have to save for Coilovers in the future.

Running Federal 595 RS-R (195/50/15). I worked them down through the day and in the last session they were 33psi hot. Talking to another MX5 driver there running the same tires on similar car said I could go down to 31psi hot. The cold temp is around 26psi.
The car felt really balanced and very adjustable. When the arse stepped out it was easy to correct and catch. Equally through turns 3-6 it was just playing with the throttle to keep the car pointed where I wanted to go so I am pretty happy with that. The tyres look like it is a little heavy on rears as they seem to have worn a bit more than the fronts.

Plans... would like more power but determined to keep this car NA and as simple as possible.
So I need to replace the mid exhaust pipe as that is still stock and I am sure there is some flow to free up there.
I am working on 2 types of intake to reduce restrictions, 1 for the cold side, 1 for the hot side. Will see what I like after I try them out.

I could also be more ruthless and remove spare tyre and carpets before next session.

MLR · Postby **MLR** » Tue Mar 18, 2014 10:05 pm

My little Bessie is up for it first super sprint this Sunday at Wakie, I shall be chasing your 1:18 with much vigour.

Mine has a full 2.25 exhaust from stock headers back and a short intake, also running BC coils and 205/45 16 RE002 tyres, but the loose nut behind the steering wheel may remove and advantages of these mods.

Ride height is 125 front and 130 rear measured from the base of the jack points, I will be taking my C spanners to play with the heights if needed to dial in the over/under steer characteristics' if needed and play around a bit with dampening if sessions permit.

I will be removing the spare and other superfluous stuff, I need all the help I can get.

When is your next outing.

Snowmotion · Postby **Snowmotion** » Tue Mar 18, 2014 10:23 pm

I am sure you will get there.
There are some mods sorely need to get better times. New mid pipe with better flow. (next mod)
Improved intake. Have made the short ram, just need the cover.
Better suspension. In the long term plan.

No fixed plan at this stage for the next track day. Winter gets busy for me with work so not so easy to get a spare day.
Might watch for a Sydney track day but only downside is I will have no comparison to the last outing.

Good luck with the times.

Magpie · Postby **Magpie** » Wed Mar 19, 2014 6:27 am

MLR wrote:Ride height is 125 front and 130 rear measured from the base of the jack points, I will be taking my C spanners to play with the heights if needed to dial in the over/under steer characteristics' if needed and play around a bit with dampening if sessions permit.

Just remember changing ride height will impact the weight distribution of the car and may give other problems., more than likely different handling characteristics for left/right corners. When you did the ride heights was the car on a perfectly level surface and did you have the driver's and normal amount of fluids in the car?

For example with me the RR sinks 5mm, LR 0mm, RF 6mm and LF 0mm when I hop into my car.

MLR · Postby **MLR** » Wed Mar 19, 2014 5:07 pm

Magpie wrote:
MLR wrote:Ride height is 125 front and 130 rear measured from the base of the jack points, I will be taking my C spanners to play with the heights if needed to dial in the over/under steer characteristics' if needed and play around a bit with dampening if sessions permit.

Just remember changing ride height will impact the weight distribution of the car and may give other problems., more than likely different handling characteristics for left/right corners. When you did the ride heights was the car on a perfectly level surface and did you have the driver's and normal amount of fluids in the car?

For example with me the RR sinks 5mm, LR 0mm, RF 6mm and LF 0mm when I hop into my car.

Ride height was measured with 1/2 tank of fuel and me sitting in the car on a level slab, I'm looking for the ride height changes to impact the weight distribution, if its over steering I will lower the arse a bit or lower the front to dial out under steer.

From some local testing it seems that its a bit tail happy, If I can I will have it set up with only the slightest amount of understeer, I feel I am happier when its set up like that.

I also was sitting in the car when it was aligned to keep it a level playing field.

I believe raising or lowering by 10mm or so will not impact to heavily on the alignment settings.

The car has not been corner weighted and most likely never will, all I will do is some basic adjustments to try and get it to a state that I like and can deal with.

It wont be perfect but it should end up being good enough for me.

Black_Penguin · Postby **Black_Penguin** » Wed Mar 19, 2014 6:32 pm

Under/Oversteer is best tuned out with damper adjustments, sway bars or tyre pressures. You will change the camber by raising or lowering the car. By changing ride height you can change the roll centres and so the roll axis but unless you know the exact roll centre heights and know how ride height affects the roll centre heights its a fruitless enterprise.

Magpie · Postby **Magpie** » Wed Mar 19, 2014 7:12 pm

Black_Penguin wrote:Under/Oversteer is best tuned out with damper adjustments, sway bars or tyre pressures.

10mm is a very large change especially if you have 10mm rake. Using my car again as an example subtracting 3mm from LR and adding 2mm to RF adds 8kg to LR and subtracts 8 kg from RF. Plus the RR gains 2.5 kg and the LF gains 9kg but no change in height. What I'm trying to say is it is not as simple as you think and changes can have strange results (not strange when you understand it). If you have 10mm of rake WITH the driver in the car it will have a tendency to oversteer.

From 949
The Miata seems to work best with about .25" positive rake (rear higher) measured at the pinch welds without driver in car and about 1/4 tank. It seems the the roll center axis doesn't like to be too far out of sync with the roll centers. In general, you can lower the rake to increase rear grip and improve transitional stability up to the point that the rear suspension begins to bottom. Lower the front to increase front grip and turn in response, again, until it begins to bottom the suspension excessively. In general, once we have an alignment we like, the only tuning we do at the track is to raise and lower the rear to fine tune. Lower to add rear grip, raise to reduce it. Too low and the suspension will bottom so that's your limiter.

0.25" = 6mm rake and this is WITHOUT the driver in the car. Again as indicated that when the driver hops in the car will squat and the rake should almost disappear. Whilst they do make adjustments at the track to ride height they should know how many turns raise/lower the car and then make corresponding changes to other corners to keep the corner balance at the desired settings. Unless they want to deliberately change the left/right corner handling.

Have a read of this article http://grassrootsmotorsports.com/articles/understanding-corner-weights/