Author Topic: Past Life  (Read 2763 times)

Offline Hyper

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Past Life
« on: May 04, 2013, 11:01:21 AM »
I spent most of 2011 in, on, or under this thing.  This was my first GT program and I guess it went well.  We won the GT championship. I pulled back in 2012 to spend more time at home after my daughter was born.  They have since pulled out of competition.  Coincidence? Maybe.  Anyway, I got to do some fun projects on this car that I'm sure you guys could appreciate.


The hauler in 2011 form..


One of the first things we tackled was brake feel.  The GT3R is very much a street car and still has many of the production car compromises.  Some of these are magnified by the transition to race car. The brakes are one.  Eliminating the power booster leaves a large empty space and reveals a weakness in the design.  The panel that the brake masters are attached to is very flimsy (.040 if memory serves)  and the brace that connects it to the firewall has 2 legs that are offset.  The drivers could feel that after the pressure peaked it would back off as this panel flexed.  This was documented in the telemetry as well.  Inspection revealed that there was a very visible upward deflection of the whole master cylinder assembly due to the weak firewall.  The imagineer envisioned a very elaborate system ( as they do ) and I was originally looking at an improved bracing between the bulkhead and firewall.   I finally came up with something much simpler...

This started as a piece of rectangular tubing.  I cut triangle out of the sides, leaving the top and bottom that was then folded back on itself and welded together.  It tied in like this..

I made the panel sandwiched between the cage and bulkhead to stiffen the bulkhead as well and then everything was powdercoated white to blend in so the lookieloos at the track wouldn't spot it so easily..

Worked very well, but in the search for tenths good is seldom enough.

I'm not saying I'm Batman. I'm just saying we've never been seen in the same room before.

Offline Hyper

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Re: Past Life
« Reply #1 on: May 04, 2013, 11:16:49 AM »
Half way through the season we decided to try pull masters.  This came about in the usual fashion.  Thursday afternoon a box of parts shows up and they say make it happen before Saturday.  Downside is the box only has half of what you need. Have fun.  To eliminate any remaining flex that may have persisted and to support the substantial force that the masters would be subject to, I dove into the deep end of the material rack for something beefy.  I tend to overbuild, but my stuff doesn't break.  I believe you make it stronger and then lighten it later.  This was just a piece of plate and some angle.  Alignment was important for the shaft movement though...



The foot of the pushrod shown here where the balance bar attaches was thankfully a part I didn't have to make.  It had a bung that I drilled the shaft for and press fit before welding.  The other end is threaded into the other section of pushrod attached to the pedal.  To do that, I turned down the head of an allen bold to press fit and weld again.  This gives adjustment in the shaft as well as the masters..


In the rush, I measured incorrectly.  I went to the center of the balance bar rather than the mounting surface.  Fortunately it meant I cut it long.  Unfortunately the now welded foot wouldn't fit into the lathe.  So I squared the chop saw as best as I could then used a vice to square it up on a disc grinder.  Better to be lucky than good sometimes.  Granted I never drove the car at full tilt, but in the time I did spend in the car, this was the best feeling set up.  But drivers and engineers get things in their head so the project continued at the end of the season..
I'm not saying I'm Batman. I'm just saying we've never been seen in the same room before.

Offline Hyper

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Re: Past Life
« Reply #2 on: May 04, 2013, 11:24:10 AM »
One of the drivers had run a car with a floor mounted, self contained pedal assembly and decided that was the ticket.  This is what we used in the DP's, but they have a nice flat floor and square tubing to mount things to.  The GT3 has the standard uni-frame tub that is anything but flat.  Experience with the DP's showed that the pedal box would need to be easily removable for cleaning and service. So we started with this..

And ended with this

I had to cut out ribs in the floor for clearance. Then I made the panel that the assembly would bolt to..


This got threaded bungs welded onto it and then the whole assembly was welded to the floor.  It's a nice set up, but it changes the seating position and when your manager won't get you the quick disconnects you need, it's very messy to install and remove and a pain to bleed.
I'm not saying I'm Batman. I'm just saying we've never been seen in the same room before.

Offline Hyper

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Re: Past Life
« Reply #3 on: May 04, 2013, 11:28:47 AM »
This was one of my favorites. Full carbon fiber dash assembly from Carbon Art.  The whole things weighs 7 pounds, bracing and all and it was weight up high...


I'm not saying I'm Batman. I'm just saying we've never been seen in the same room before.

Offline Brass_Machine

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Re: Past Life
« Reply #4 on: May 04, 2013, 02:00:45 PM »
Some nice fabbing going on there.

You have any pictures of the DP?

Eric
Science is fun.

We're all mad here. I'm mad. You're mad.

Offline Hyper

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Re: Past Life
« Reply #5 on: May 04, 2013, 04:59:37 PM »
I think they are on my old desktop in storage because most of them were downloaded from the internet.  I know I don't have nearly as much as I should.  Didn't have a camera phone then  :doh:  Here's one..

This is my buddy Dustin the first time he dared to get in the car.  This was the Action Express 9 car that won the 24 in 2010.  We hired Dustin out of the Nascar Tech school and the 24 Hour in 2009 was his first race ever.  We were fastest in practice, started on the pole, led most of the race and won.  I told him to quit racing because it will never get any better than that.  I was fortunate to have him on my car.  He was green but very easy to teach and willing to learn.  He was so ambitious to get to go over the wall for pitstops that he has lost over 100 pounds since this picture and is now the fueler. 
I'm not saying I'm Batman. I'm just saying we've never been seen in the same room before.

Offline Hyper

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Re: Past Life
« Reply #6 on: May 04, 2013, 08:35:02 PM »
This is something a little different.  At the end of 2011 we took the car to Mooresville to do a windtunnel test.  It's big money to rent the wind tunnel and you have to gather a lot of info for it to be worthwhile so everything has to be done very fast, which is normal, but it also has to be extremely accurate.  This was fairly easy on the Dp's.  Everything is accesible and changes could be made quickly and accurately.  The pushrod suspension made a lot of that possible.  Spring changes on that car were measure in seconds with no effect on the suspension settings.  Changing the springs on the GT3 was a complete pain though.  Particularly thanks to the German's insistence on soldiering on with a strut front end.  Changing springs on that car required a trip to the scale pad to recheck every measurement and adjust accordingly.  For the windtunnel that wasn't possible.  Also with a pushrod set-up, ride height was very predictable since it was accomplished without changing the spring preload.  That is not the case with a conventional coilover as preload is the height adjustment so there can be some variation through the range.  One thing we needed to do at the test was run through a range of ride heights so this is what I came up with...


This is just PVC tubing.  The main section was split lengthwise and sectioned to compress to the needed O.D. and then the 2 larger collars towards the bottom are solid and slide over the main shaft to keep it together.  To adjust height we would put the car up on the air jacks, slide the upper collar down to allow the smaller split rings to slide in and then slide back up to hold them in place.  The split rings allowed us to adjust a predetermined amount in a matter of seconds.  Kinda hokey, but it worked out great.
I'm not saying I'm Batman. I'm just saying we've never been seen in the same room before.