IWOC Listserver Classics - TechnicalMembers have often sent in explanations on why things happen. Here are a selection of those.
Subject: [iwoc] Warped Discs
From: Simon Moxon
Date: Thu, 14 Jun 2001 09:26:25 +0100
Why do I keep warping brake discs?
I upgraded from the standard MY98 2 pot setup to a 4 pot setup from a P1 with standard P1 discs. After 5000 miles the discs became really badly warped, that bad that the juddering through the steering wheel hurt your hands. I replaced these discs along with some pads a month ago with PAGID equipment from Scoobysport, and now, only 800 miles later it seems the PAGIDs are warped as well. :-(
I do not consider myself to be someone who abuses the brakes, and in fact since moving to the 4 Pots I have never managed to make them fade, even with standard pads/discs, so what could be causing it? Could there be a fault with the caliper etc that could be causing this, or is it more likely something I am doing?
Thanks
Simon
Subject: [iwoc] Re: Warped Discs
From: "Pete Croney"
Date: Thu, 14 Jun 2001 13:06:16 +0100
Treat them very, very gently for the first 50 miles of urban driving. No high speeds, big distances to the traffic in front and very very gentle braking. After this, very gradually increase the braking pressure, so that after another 50 miles you are now doing high speed stops. Motorway type driving counts for zero miles in this, but if you do drive on the motorway in the first 50 miles, try to use the brakes as little/as gently as possible.
During the second set of 50 miles, always allow the brakes to fully cool, before doing another big stop. If you need to brake after a big stop, try and be gentle.
The longer and more gently the process is done, the longer the discs will last and the better they will perform.
The object of the exercise is the coat the discs in a uniform layer of pad resin and to heat cycle the discs, very gradually raising the temperature each time.
It is vital that you do not stop with your foot on the brake in the first 100 miles. Use the handbrake.
Once this has been completed, the discs will offer fantastic retardation and will be completely reliable.
Pete
Subject: RE: [iwoc] Brake Upgrade Survey
From: "Darren Soothill"
Date: Tue, 4 Jul 2000 03:52:00 +0100
Well I think I can answer most of your question apart from price information as I have been through most of the brake options during my Scooby owning years!!!!!
This setup was very poor considering the performance of the car and was very easy to get to fade certainly well below the performance of the car.
The harder pads helped a bit but the brakes still did not give you the confidence that you should have to be able to cope with a car with the sort of performance that this one has!
The 4 pot setup gave a lot more feel and bite to the brakes and gave a massive boost in confidence but it was still fairly easy to get the brakes to fade on the road. When we changed the pads we found that the standard pads had started to crack. These where the standard STI pads which may be a different compound to the pads on the 4 pots that come over here.
What a difference the pads made and for most people this setup would be fine for fast road use the brakes never seemed to fade even taking the car to Donnington I didn't get them to fade although at this time I was very new to track days so wasn't pushing the car as hard as I could do and I was on the original standard road tyres which meant the tyres where going off first. The biggest problem I had with these is an unpredictable brake pedal in that you didn't know how long the pedal was going to be when you came to the next corner which was not much use on the confidence front. I only ever got this to happen on the road once but the brakes where always there for you and would stop you.
What a difference the change to Brembo made after the initial bedding in period the brake where fantastic certainly no chance of getting them to fade on the road and on track it was down to how long I wanted to stay out as I was now running on Slicks which meant I could keep going and going pushing harder and harder. The only problem I had was with cracking the disks which where replaced under warranty but I decided to switch to
I couldn't believe that things could get better but they did with a noticeable setup in brake performance again this is a fantastic setup that I have never managed to get to even thing about fading even after doing considerable numbers of laps at various different circuits including Donnington, Cadwell, Brands Hatch and a number of airfield days. The pagid pads are also very hardwearing and I would certainly recommend those to people as well. I have also spent a day out with an instructor with him getting me to go faster and faster at Cadwell and not once did I worry about the brakes in that day I went though 2 tanks of fuel.
Darren
Subject: [iwoc] Buying/testing a boost gauge
From: Glen Stenhouse
Date: Wed, 14 Jul 1999 00:03:35 GMT
Hi all,
Just a thought on how to test when buying and testing a boost gauge. Since it was a topic of debate recently I figured you all may find it of use.
Take 2 syringes with you. One 2.5ml and one 20ml, and a piece of rubber hose.
Use the 20ml syringe to test if the guage is smooth, responsive, sticky, jumpy, etc....
With the 2.5ml syringe you can test the accuracy of the gauge with the use of a known mass. Balance the mass on top off the syringe plunger and check the reading.
Pressure in bar = (weight in grams/650) x 0.98
Best,
Glen
NZ with the WRX Type RA and an electronic/LCD boost gauge, ie:the PossumLink ECU
Subject: [iwoc] Fabled ecu reset.
From: Bob Rawle
Date : Tue, 4 May 1999 21:47:07 +0100
The engine management system on our cars seems very similar to the Bosch motronic system. All the same functions are monitored and the turbo boost is controlled in exactly the same way. So, lets assume that the Subara ecu is a rip off of the Bosch system. There are a set of default values in the ecu. When power is removed it reverts to using these "average" settings. As each car is different a system of "adaptive learning " is used so that the ecu optimises itself by fine tuning itself. This also allows for component tolerancing. It then stores and uses these values as long as power is maintained. The knock sensor is used to keep the timing advanced as much as possible dependant on fuel quality. If low grade fuel is used the the ecu will sense knock and retard the ignition. If this is not found to eliminate the knock then it will then reduce boost pressure. Once the condition is stabilised it then attempts to restore the advance slowly until it finds the knock point and then it backs off again. In this way the engine is always run at the highest level of power for the fuel grade and temperature conditions. It necessarily follows that disconnecting the power after filling with SUL will then force the ecu to use default settings. As the car is driven the SUL will allow much more advance to be run and the boost will not need to be reduced. That's why the car feels better after the "reset" There is absolutely no need at all to run it at boost for a period of time to teach it settings. It will always use the highest optimum boost and most advanced ignition settings that it can. Just changing to SUL will allow the ecu to start to advance ignition settings as it will not be knocking.
The mass airflow meter, temp sensors, lambda sensors, air temp sensors, etc are all used in conjunction with the knock sensor to this end. The ecu cuts the ignition when it is unable to eliminate knock by timing or boost reduction. It assumes the worst and plays safe.
Guess I've gone on a bit but I've read so many postings about the "mythical" reset that I thought I would put my point of view. I have studied the Motronic system to a high degree of detail and would welcome any comments/feedback on this anyone would care to give. I have the Bosch reference books available if needed. I've also posted this on the SIDC BBS.
Bob
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