My '86 GTI build

Re: My '86 GTI build

Postby walterclark » Sun Mar 06, 2016 5:10 pm

Rabbit Farmer wrote:Glad you won the contest..... do I get a cut?


Not won, runner-up. Got a T-shirt. Want part of it? By the way, thanks for putting me on to that contest. I am not sure what they are doing with the photos, but I wouldnt be surprised to see them somewhere at some point.
The older I get the better I was.
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Re: My '86 GTI build

Postby 3rdgendennis » Mon Mar 07, 2016 2:50 pm

walterclark wrote:Roadmaster! That is what I was going for...

Image


:lol: :lol: :lol:
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Re: My '86 GTI build

Postby walterclark » Mon May 23, 2016 6:20 pm

Ascutney was a pretty good "shakedown" for the tablet instrument cluster. The tablet worked flawlessly - which is a pretty big deal considering how rough that upper section is in my car. I made a couple small tweeks to it today. I lowered the shift point RPM color change (yellow to red) from 7000 to 6800 to give me a little more lead time that I am coming up on a shift (7100). And I added some software damping to the fuel gauge.

The changed ring and pinion puts me back to where the car was before I went with the 020 from a speed/rpm/gear standpoint and it feels much more in tune with the hill. My top speeds at the braking points after straights is back up where it was.

I was pretty disappointed with my driving this weekend. Mainly my shifting but I cant seem to shake some Deja Vu of past offs. I lost maybe 4 seconds on almost every run because of at least one missed shift from 2nd to 3rd. My second and last run Sunday would have been a pretty good one save one of those. Just past the ambulance turn I really botched it. A couple stabs at 3rd didnt go, I pulled it back jammed it forward and found 1st (and 7800 RPM according to the log), then having slowed from 52 to 27 in the process, and after 4 seconds total of fooling around since I first took it out of 2nd I found 2nd again. Of course now I am accelerating from 27 instead of from 52 toward the next braking zone. I am also giving up valuable speed into turn 5 because I cant seem to bring myself stay on the throttle thru there after my spin at Ascutney 2 in '14 which took out the suspension and both ends of the car.
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Re: My '86 GTI build

Postby KevinGale » Tue May 24, 2016 9:15 am

walterclark wrote:... I cant seem to bring myself stay on the throttle thru there after my spin at Ascutney 2 in '14 which took out the suspension and both ends of the car.


I know about that. I've lost two places on the hill that I used to be full throttle due to offs. Now that foot just refuses to go to the floor in those places. I've tried telling it that the pavement was perfect last weekend and I had new sticky rubber on the car but to no avail. :lol:
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Re: My '86 GTI build

Postby sachilles » Tue May 24, 2016 12:47 pm

If it makes either of you two feel better, I was suffering the same thing this weekend.

While I "knew" I could hold my foot flat in a couple of places, my intestinal fortitude override was in full effect. Something about not wanting to write off a car I've been only able to drive for a day or so. It all felt so strangely familiar, that I wanted to trust it.

I also could not shift to save my life. Found myself just staying in too high of gear at times.

:shrug:
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Re: My '86 GTI build

Postby KevinGale » Tue May 24, 2016 5:13 pm

sachilles wrote: Something about not wanting to write off a car ...


Exactly. In both places I know I could push the pedal to the floor but the fear of crashing again in the same place makes me lift. Bad enough to crash but to do it again in the same spot...

At least for me it's not really so much the fear of the crash itself. It is more the long and expensive slog to put the car back together. If someone would just give me a fixed car right away I bet I could make my foot stay down.
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Re: My '86 GTI build

Postby walterclark » Tue Sep 20, 2016 8:04 am

Well, now that the season is almost over I can say the move to the tablet for a dashboard has been excellent. No reliability or connection/update issues when driving and the instruments seem to stay up with things nicely despite running the communications across Bluetooth.

The Samsung Nexus 10 has proven rugged and very easy to see from the drivers seat under all conditions. It is even easy to see on the GoPro, which is maybe 30 degrees off axis...many modern displays are pretty directional to help with perceived brightness on axis and to help reduce screen washout from light sources off axis.

Previously I mentioned some of the reasons I picked this tablet over the hundreds of others available. Large, bright very high resolution screen. Fast computers to minimize display lag. Support for USB "On The Go" or Host Mode AND the correct serial profiles to permit it it act as a display for the MS3. These last 2 items eliminate maybe 90% of the tablets out there.

I have taken to booting up the tablet on race morning and leaving it on all day - just putting the display to sleep when the engine is not running. That doesnt seem to drain the Braille battery too much and the startup time for the dashboard is shortened to a few seconds since all that is needed if for the app to reconnect to the MS3 once it powers on with the ignition.

The Nexus 10 has one quirk that is a bit of an irritation, but I have learned to work around it. When charge power is first applied to the USB port with the tablet shut down, the built in battery charge controller takes about 2-3 minutes doing something with the battery (probably some tests) before it begins charging it. The tablet displays a large battery symbol with a lightning bolt during this time. When that is done the display switches to a battery symbol with relative charge level indicated and it begins charging. If I boot up the tablet before the first symbol goes out the charge circuit will not allow more than a standard USB 500ma "charge" current to flow. If I wait until the symbol goes out before booting up the charge circuit will permit up to 2a, depending on what the 5V USB power source can supply. This is important because the tablet draws over an amp during operation with the screen illuminated and over 500ma when the screen is asleep. This means if I boot the tablet immediately after applying USB power the tablet battery will discharge all day, or until it is dead.

I made that mistake at Burke. One morning I got in the car to warm it up for a few minutes an hour or so before it needed to be moved from the campsite to its staged location behind the wrecker and switched on the USB and booted it immediately. By the time I started the car to move it the tablet battery was dead and it shut down because the 500ma from the USB isnt enough to run it. Once shut down the charge circuit cycled and began charging at its 2A max rate and by the time I was ready for my first run and booted it up, the battery was mostly charged and the charge circuit was allowing enough power to run the tablet and not discharge the battery. When new the Nexus 10 battery is a 8+AH battery which should run the tablet all day the way I use it, but the battery in this one is fairly used up (maybe the equivalent of 1AH life) and high quality (meaning actually tested to be 8+AH) replacement batteries cost what I paid for the tablet. There are $40 replacements on eBay but reports are these are actually batteries that were rejected by Samsung and will likely be a lot less than the rated AH or be short lived. Replacing the battery requires a complete disassembly of the tablet which also risks reducing reliability or outright breakage. I have had both of the ones I bought partially disassembled to solder in the remote power switch wires so I know first hand what is involved. If I follow the USB power / boot up protocol I outlined in the last paragraph it is not an issue so I havent replaced it.

Having confidence in the tablet as a useful and dependable dashboard, I no longer carry my old dashboard as backup and I bought, modified and configured a second tablet as a spare. Maybe this winter I will try rooting the spare and see if I can get it to allow the battery to be charged via the USB while the same USB is direct connected to the MS3. That would eliminate the need to use the Bluetooth and probably reduce the small lag in instrument response further. Somewhere in an earlier up date I think I mentioned that these Nexus support what is called USB OTG or Host mode and the needed serial USB profiles, which is required for a tablet to connect to the MS3 and act as a dashboard. What Samsung does not allow is for that wired connection to also supply power to the tablet from a USB power source. To change that requires the tablet be "rooted" and a couple hacks to the internal code be applied to permit that. Lucky for me, and one of the reasons I picked this tablet is a few talented people have developed working hacks for this tablet to do just that.

If I have time this winter I may also streamline the wiring in the car to eliminate all the wiring unique to the old dashboard. The tablet only needs the USB cable since it (or the BT )provides all the I/O and power. All the sensor wiring now goes to the MS3, some sensors like the low and high oil pressure switches are not needed, and all the wires (maybe 20) to the old dash can be removed entirely.
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