SDT Track Day with Training - 11 July

[Magpie]

Afternoon session no rain! However the miss in the car developed again, this is getting painful. Swapped out plugs, CAS, COP's and made no difference. I suspect that it is a heat relate issue or an earth issue. It only happens after a period of pushing the car.

Thanks to all the people who pointed out that my rears are now locking up way before the fronts, this is the next issue to fix. The car was very squirmy under very heavy braking as the rears were loosing grip (locking). Tweaked the front rebound a bit and reduced some of the squirm but it was a handful.

The American was fastest in the hill climb in the morning and another MX5 third fastest in the afternoon (against the 86's).

Managed a 1:18.51 will post some video with Chris in the car giving me advice on lines etc. Previous session at Morgan Park 1:23.70. I will post the video of my overtaking of G By the way Grant thanks for waving me past.

[The American]

Such a lot of fun! The drive home in the rain with almost completely slick semi-slicks was interesting at times! A few car niggles (fuel surge at half a tank , suspect an A/c hose ruptured) but all in all a brilliant morning.

Felt sorry for the WRX driver who put his car into a tyre wall on its first ever outing!

[Magpie]

An EVO in the afternoon ripped its front lip off spinning on Turn 1. This was the only event in the afternoon.

[Red_Bullet]

looking forward to the video

[Magpie]

This was with Chris (instructor) in the car, he was also in the car that crashed.

Next time I'm at Morgan Park I'm going to try and short shift into 4th before the apex under the bridge.

[ndragun]

Nice one Mark. Came to the realisation that its been just about 10 years since I've been to Morgan Park - which is vaguely terrifying thinking about how time flies.
Love turning the car on the brakes unbalanced at turn 1. Once I get a bit of work-life balance back, I'll be out there...

Felt sorry for the WRX driver who put his car into a tyre wall on its first ever outing!

Morgan Park seems to be the place many-a-modded-WRX goes to die.

[Magpie]

Chris gave me some really good advice for turn 1. In the beginning I was turning late, however he suggested turn in early and hit the second inside curb and power out. I did not get to the second curve but turning in early worked. I have a few videos of the line Chris suggested from behind other cars and me having to slow because I would have run into them .

There is at least one more SDT at Morgan Park in 2015.

[Magpie]

This is a dump from the Racelogic files I have for Morgan Park. Red being the most recent. Changes to the car are engine (inc E85), pads and tyres (red FZ201 and blue R888's).

The trace is done by distance so not time to give a better idea of the changes on each point of the track. Speeds are higher so you would expect the acceleration to be better, there is a difference in the braking as well again this is more than likely pad differences. Cornering G seem to be similar, however the biggest change is between T4 and T6 this is a high speed corner.

I still have more time to make up around Morgan Park, looking forward to next time!

Morgan Park Difference by Eipeip, on Flickr

[gslender]

Get a brake bias adjuster installed. You won't believe the difference in braking it will make.


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[MattR]

Rather than use a brake bias adjuster to mask the initial problem, look at the overall brake balance in terms of the calipers used, the piston sizes of the calipers front and rear, and the sizing of the master cylinder.

If you are going to run what you brung and just put up with what you have, then an inline adjuster will work, but you will have an inherently out of balance solution.

If Mark goes down the track of a pedal box with separate master cylinders, (which he was considering at one stage in the build) then he can get the balance right by selecting the right size cylinders to suit the calipers used. He may also want to look at the calipers he is using and make some changes to better suit the car, now he knows the limitation of the current braking system.

The inline bias adjuster should be used to make fine adjustments to the braking system to tweak the balance, not set it up. However, as like most things, there is compromise and it becomes the go to device to try to fix what is a fundamental flaw in the balance of the braking system for use on the track.

[gslender]

Rather than use a brake bias adjuster to mask the initial problem, look at the overall brake balance in terms of the calipers used, the piston sizes of the calipers front and rear, and the sizing of the master cylinder.

Don't agree on so many levels. The oem car comes with a fixed brake bias setup for street use. There is no reason why that would be suitable for track work, especially with so many brake modifications already made.

But sure, spend more money on brake pedal boxes, different callipers and pads, rotors, and you may still not arrive at a consistent braking performance etc.... or just install the brake bias and dial in the better braking performance.

[MattR]

I think you misunderstood my post.

With all the work Mark has done with the car for track use, or if you are building a track car and changing brakes to get better braking performance, then it is better to get the brake balance and piston sizes right from the get go, rather than use an inline bias adjuster to mask what is an inherently badly balanced system. And if you then are looking at running a twin master system with pedal box, then you can use the balance adjustment as it should be, for fine tuning balance as the weight changes as you use fuel or for different event types, or as conditions change, eg for wet weather, you may want less brake on the front wheels to prevent locking up.

As I said in my post, if you are going to run what you have, then the in line adjuster will give you better balance, but you are really only masking the problem and the braking system will never be as good as it could be if properly sized for all components in the system.

If you are changing brakes you can get the overall balance close enough that you don't need to make balance adjustments to suit 95% of the time. On my old race car I used Willwood Dynalites, 4 spot brakes off the rear of a NASCAR, with volvo/Pugeot 2 spot rear brakes and a 15/16" master with the rear pressure limiting valve for the original drums removed. The master was iffy on volume, so it always had a "low" pedal but pullled up very well, the master was changed to a 1" and then the brakes were spot on, also helped by no booster as you get so much more feel through the pedal. All four wheels locked at the same time on a dry track, so for my driving style, the balance was spot on and didn't need any adjustment to the balance. For the new race car, brakes are Z32 alloy 4 spot calipers up front, R33 GTS 2 spot rears and will be using a 1" non-ABS master with no booster. Out of the box the balance should be pretty close for balance as the piston sizes all match for the braking force I need. If it does need fine tuning, then I probably will look at an in line bias adjuster, but only to provide a fine adjustment to the overall balance. If the balance is way out I will be changing calipers as required to get the balance right before I look at fine adjustments through line pressure.

[Magpie]

MattR there will be no pedal box as this is not legal in a road registered car, further it bumps me up into a class that I don't want to be in. Further, removing the booster and redesigning the whole brake system is not on the drawing board at the moment. I'm sticking with the OEM NB8B calipers (I have 2 sets of them) and master/booster.

G this hurts to publicly agree with you, but I agree with your logic (there I have said it).

The 'squirm' is under hard straight braking only, plus at the moment my heel toe technique is causing some compression lockup at the same time. Hence I have been working on braking hard, slowing down, then gearchanging/rev matching to get rid of the possibility of compression lockup. A few more clicks on the front (harder) helped a slight bit and did not change the handling in the corners. As did dropping the tyre pressures a bit.

The plan is to change to a different pad compound (Winmax 6.5's). These pads work from a lower temp and have a higher mu than the W5's, this should help a bit. Reason for the pad change and not a bias valve straight away was after discussions with Jason (Plus) and Marty (Motorsport Brakes) about the planned use of the car over the next 3 months a pad change is worth testing first. The plan is to fine tune the car, that is why all the feedback from Morgan Park is so usefull.

In the end a bias valve may be installed and this will aslo allow the rear brake sensor to be installed as well. Next test day is 28/07/15 at QR, however it will be run in the same configuration as Morgan Park with the exception of a tyre change. Have been given some suggestions to test if the miss reappears again as well.

I'm trying to do as little changes to the car setup as possible and get some seat time. The car is starting to become a handful as I'm slolwy learning to drive it faster and the little things in handling need to be attended to not changes to the baseline.

However the shell I have in the shed will have a complete brake system designed for it, even no booster MattR

[gslender]

If it does need fine tuning, then I probably will look at an in line bias adjuster, but only to provide a fine adjustment to the overall balance. If the balance is way out I will be changing calipers as required to get the balance right before I look at fine adjustments through line pressure.

I agree with that. Question is whether to install the bias first, determine how much adjustment is needed, and if only minor then job's done - if not, then yep, further major upgrades/changes are required, and using the bias to further refine. I'd only suggest that installing a bias is simple and effective and can even be left installed with no adjustment meaning you can leave it as is, or adjust away and see if you can improve.

Next test day is 28/07/15 at QR

Really? The event calendar states that McElrea Racing has the tracked booked for that Tuesday? I'm keen to go out again late July, but can't see anything on the weekend or weekday worth going to - the weekend appeals to me more than weekday (unless it is really worth going).

I've ordered a fuel pump sock and will be looking to replace/fix that and hopefully rid myself of that fuel starvation that I'm having - otherwise I need to keep more than 1/2 tank of fuel in the car at all times!

G

[The American]

here's the last clip I took of the day before the gopro ran out of electricity:

[youtube]https://youtu.be/MhTTBx7ff0Y[/youtube]

I was also having fuel surge issues anywhere less than half a tank.