TESTED the breaks yesterday

[spatz]

ok as mentioned I went for some engine mapping yesterday cause it was a sunny dry day here. While I was doing my rounds on country roads around the place I am living I was doing around 110 mph when I just saw 3 deers approaching my road at full speed. So breaking was necessary and while we approached each other with me breaking harder and harder the front wheels finally locked up but I could catch car quickly and also avoided hitting the deers by a few meters.
I always wanted to test my balance on an empty road or air field so it happens I did it yesterday.
I guess that front wheels locking up just before standing is a good sign ? So no need to change my balance bar ?

[Steve_D]

locking up at the front first is just what you are looking for.

Steve

[xr287]

Brakes!!!!

Sorry, sounds like the balance is about right though. Fronts should lock before rears and must be good tyres and/or good road surface if you were almost at a standstill before it happened.

[Gulf LS3]

xr287 said:

Brakes!!!!

Sorry, sounds like the balance is about right though. Fronts should lock before rears and must be good tyres and/or good road surface if you were almost at a standstill before it happened.

how good is your German Dude???

[xr287]

Gulf LS3 said:

how good is your German Dude???

Es ist sehr gut danke!

But I didn't realise he was German, sorry.

[spatz]

oh that was a typo probably my mind wandered off for a sec, i was not on a mini break but heavily testing my BRAKES !
Anyway approaching 3000km and still working on the ECU. Still impressed with the carb guys, that they could get this thing working
at such a wide temperature range ......with so little adjustments possible.

[harry b]

spatz said:

ok as mentioned I went for some engine mapping yesterday cause it was a sunny dry day here. While I was doing my rounds on country roads around the place I am living I was doing around 110 mph when I just saw 3 deers approaching my road at full speed. So breaking was necessary and while we approached each other with me breaking harder and harder the front wheels finally locked up but I could catch car quickly and also avoided hitting the deers by a few meters.
I always wanted to test my balance on an empty road or air field so it happens I did it yesterday.
I guess that front wheels locking up just before standing is a good sign ? So no need to change my balance bar ?

In the conditions you drove, with the temperatures in the tires at the time of braking, probably ok, but could be very well too low on the rears, since you didn't lock up the rears at all. As you said, you need to test it until the rear end starts to wobble and wants to step out. Circumstances always require different settings, so if you want to have the max breaking front and rear get an brake balance adjuster, either on the balance bar, which is illegal for road usage, or get a limiter in the rear brake line
Something like this:
http://www.isa-racing.com/index.php/cat/c278_Brems...
The ones with a lever are typical used in rally cars, there for I like them a lot. Quick adjustments without the need to turn on a knob, which you don't have time for to turn when needed fast.

[ezakimak]

harry b said:

In the conditions you drove, with the temperatures in the tires at the time of braking, probably ok, but could be very well too low on the rears, since you didn't lock up the rears at all. As you said, you need to test it until the rear end starts to wobble and wants to step out. Circumstances always require different settings, so if you want to have the max breaking front and rear get an brake balance adjuster, either on the balance bar, which is illegal for road usage, or get a limiter in the rear brake line
Something like this:
http://www.isa-racing.com/index.php/cat/c278_Brems...
The ones with a lever are typical used in rally cars, there for I like them a lot. Quick adjustments without the need to turn on a knob, which you don't have time for to turn when needed fast.

Harry,
Just trying to learn a bit more hear, what range of adjustments can you get out of these, how far does the lever move and what would be the equivalent movement on the balance bar?

Just curious.

Regards Ryan

[harry b]

Normally up to 60% reduction with the flick of the leaver. In the old days, here I go again, there was no ABS, so when changing from tarmac to gravel or mud, you just flipped the leaver and things were a bit more in balance. A balance bar could do the same if you can get the leaverage in the same amount. You should always start with different pumps for front and rear to have innitial offset in balance.
Difficult to say how much difference you would need, since weighttransfer and shocksetup comes into play here.

[spatz]

harry b said:

In the conditions you drove, with the temperatures in the tires at the time of braking, probably ok, but could be very well too low on the rears, since you didn't lock up the rears at all. As you said, you need to test it until the rear end starts to wobble and wants to step out. Circumstances always require different settings, so if you want to have the max breaking front and rear get an brake balance adjuster, either on the balance bar, which is illegal for road usage, or get a limiter in the rear brake line
Something like this:
http://www.isa-racing.com/index.php/cat/c278_Brems...
The ones with a lever are typical used in rally cars, there for I like them a lot. Quick adjustments without the need to turn on a knob, which you don't have time for to turn when needed fast.

thanks harry for the comment, have already thought about making the balance bar adjustable, with initial setting after building the car I definetely had too much on the rear, so changed it to the current state and so far looking good, will monitor more closely but since I am not racing but having fun on roads the perfect balance in all situations maybe not so important

[ultimass]

If you are setting up the brakes with the bias almost equally split in the dry(just a touch more on the front) - in the wet you will need to alter the bias more to the front other wise you will find yourself going backwards when you hit the brakes.

I learnt the hard way!!

Martin.

[spatz]

ok thanks,

will not drive in the rain though, too dangerous with this car

[xr287]

ultimass said:

in the wet you will need to alter the bias more to the front other wise you will find yourself going backwards when you hit the brakes.

Is this an ultima specific thing? Because wet weather brake bias in everything else is more bias to the rear when wet. Less grip means less braking power so less weight transfer, less weight transfer on the front means even less grip on the front when braking hard so dry weather brake bias causes you to prematurely lock the fronts in the wet.

[ultimass]

With mid or rear engined cars, if you lose traction only on the rear while breaking you get what is known as the pendulum effect - the part of the car that weighs most tries to move forward ie. the back and unless you are perfectly square and balanced, the car swaps ends especially in the wet.

Ask any older Porsche 911 owner.

[CycleSi]

l've got a brand AP Racing Bias Proportioning Valve l want to sell if you're interested?

Still boxed and unused - it would certainly allow you to play around and adjust the front to rear brake bias.

http://www.apracing.com/info/products.asp?product=...

Email me if you're interested.