LSPR- Day 1

Lake Superior 2011

Pre-event Prep

Volkswagen used a flange with pinch bolts to attach the front struts to the spindles.  It's easy to assemble and allows for a decent amount of camber adjustment.  It also means that every time you hit a bump, a big bump, the assembly stands a good chance of moving.  There just isn't enough friction.

In newer cars, ones designed with the aid computers and after consumers expected things like air conditioning to be standard, the front strut assembly is more robust and uses precision machined parts to stay in alignment.

Higher end race struts have eccentrics that allow the adjustment of camber while preventing the assembly from flopping around like a wounded duck.  These work so well, I decided to turn an set of eccentric washers prior to the event and install them onto the struts.  As usual, I ran out of time, but did manage to get one on the passengers side, which, by all accounts worked great.

The tire situation for the event was mildly dire- I'd sold most of my "extra" tires earlier in the season to shuffle funds around, and had 4 newish Lassa tyres left over from 100AW.  I also had a stack of used Michelins, and had made arrangements with Chad Eixenberger to buy a couple of unused Lassas from him on Friday night after he arrived at the event.  I would love to have a stack of fresh mounted tires before each event, particularly because every time I try to scrimp on tires, something absolutely bizarre seems to happen.

On The Road

The busy boys from Newton left home early Thursday morning and rocketed up to Houghton to take part in this years event- Barney, Marc, and Andrew.  As it turns out, Houghton is about the same distance from central Iowa as it is from Ann Arbor. Who thought up this UP thing anyway?

Houghton

Scruinteering following Thursday PM registration was a non-event. I had plenty of time to go through the car and clean it up prior to the event, which always helps the process go a bit smoother.  The practice stage is  typically fairly bumpy at LSPR, and with some of the rain they'd gotten, it was looking pretty mucky.  With Andrew's early evening arrival to the event, I made the decision to not rush through the practice stage and make more work for ourselves cleaning up the car.

Friday

After a long day on the road, everyone was a bit slow to get moving Friday morning. It was misting and spitting rain while we stocked up at Wal Mart.  These trips are an excuse for our Dad to buy deli ham and Doritos.  He's also been trying for the past 35+ years to get Andrew to eat Mayo on a sandwich.

In the parking lot, we tried to apply some new stickers. Wet. That didn't work well at all.  We'd had a better opportunity the evening before, but opted instead for Pizza at the Ambassador.  In hindsight, the pizza was still the right choice.

We also were looking to air up the motley collection of tires that would accompany us through the day.  The Van had come equipped with air actuated tire chains, and we'd been using that compressor to take care of our tire needs for a few seasons.  This day would be the day the system failed, though, leaving us without air for our spare tires, and adding to our overall stress level.

Struggling with what was formerally a very easy task left us without time to change tires on the car for the first two stages- the rock strewn Moyle gravel pit.  Out of time and a bit crabby, we headed up the road to Parc Expose.

Parc Expose was soggy and left me wishing driving shoes could combine Nomex AND Gore-Tex.  The parking spot on the front lawn of the hotel guaranteed an opportunity to really get soaked.

The gravel pit stages were wet, but more notably, full of sharp rocks.  The first left turn has claimed a lot of cars, and this year, I'd space out and cut the corner too close, leaving us with a flat tire on the co-drivers side. Changing the tire in service required rotating tires from rear to front due to our only spares being a slightly different size than the Lassas that we'd had on the car.  Scrimping was becoming a real pain.

Leaving service, we'd made it about 3 blocks when we realized that the tire we'd moved from the rear to the front was also flat. WHAT?!  We changed it with our spare in the car, and made off to stage 3.

Stage 3 was normally a wide open fast stage, but today felt nearly impassable as the car struggled to slog through the muck and mud that used to be a road.  We spent most of the stage in 4th gear at full throttle trying to claw through, struggly to stay pointed in the correct direction.  The transit back to Kenton was about 20 miles after the stage and was a welcome break from being wet and changing tires.

Oh, wait, about that last bit.  I noticed that we'd somehow were getting a flat on the driver's side front.  Out of spares, we pushed for as long as we could on the transit, only to stop and wave down BIlly Mann and borrow his spare.  The Honda and VW use the same bolt pattern and size wheel - we lucked out.

Back in Kenton, we set about more tire shenangigans to prep for the upcoming Passmore stage- a LONG fast stage that we usually do pretty well with. The stage started off well enough - damp and not as outright fast as usual, but certainly driveable.  Halfway through the stage, I realized I no longer could get into 4th gear. OK?  Pressing on, the sounds from the gearbox became worse and worse, and by the time we neared the end, we'd made the decision to withdraw to prevent further damage to the gearbox.

We returned to the Kenton service and drove the car onto the trailer, strapped it down, and went back to the hotel, fairly dejected and supremely irritated.

UGH

The final damage, in 4 stages, was 3 ruined tires, a stripped 4th gear, and a ruined no longer available ring and pinion that had cost me $800.  I drank beer that night.

The Iowa crew decided to bolt the next morning, leaving me to find my own entertainment for Saturday....

A 2012 update

I'm clearly horrible about updating a blog.  Blame self absorption. Distraction.

What's happened since August?

1. We went to LSPR and had one of our more goofy events.
2. I picked up a full time contract position with Nissan.
3. We went to Sno*Drift and had a semi-typical outing for that event.

I'm going to be trapped in a hotel in the middle of nowhere this coming week, which should offer ample opportunity to catch up...

Where did you go?

Into the shop, of course.

I will be posting pictures of the A3 Golf safety cage build up, and putting together a thread about Megasquirting the Jetta.

Right now, I'm having some issue controlling the fast idle circuit and need to dig in and see if there is some test software available so I can check the output at the before it wanders too far away from the I/O on the MCU.

My pressing projects finding me wishing I had an Oxy-Acetylene set, and an Oscilloscope. Yin and Yang?

Rally Minnesota- Jetta rental

Chad Eixenberger put the Bent Mettle Racing Jetta on the podium at the recent Rally Minnesota event held May 20-21 in Park Rapids, MN.  The event was marked by very wet road sections on the stunning, long stages.

For interested parties, we are making the car available for either a standalone rental, or can put together a complete arrive and drive package.

Chad will be campaigning the Jetta again next month at the Nemadji events and then taking delivery of a newly prepped 1995 VW GTI.

Rally computer magnet mounting

The Jetta is equipped with a US made and supported Alfa Pro rally (http://rally.cc/) computer to measure time, speed, and distance.

The Alfa uses a switch to ground to trigger the pulse counter to measure distance- for cars with a VSS, it will interface directly, but on the Jetta, we used the included Hall effect probe and magnets.

The magnets were glued inside the rear left rotor, with the probe mounted off an ear from the rear stub axle fixing bolt.  This worked great until the rotor finally succombed 5 seasons of use and cracked.  In the rush to replace it, something went wrong with the magnet mounting leaving the unit unable to measure distance.

A Garmin Zumo GPS measuring speed and distance has been the extended temporary workaround for the past couple of seasons, but definitely wasn't optimized for rally use.

With the Jetta starting duty as a rental the rally computer made the list of "must fixes".

An email to Mike Friedman later, and I had a new probe and magnet kit sent out.  We are using the same basic layout for the probe, but with a removable ring mounted to the inside of the disc.

This only requires that the rotor be drilled and tapped to mount the ring.  The holes are easily layed out with a caliper, then drilled and tapped by hand from the front side.  The magnet mounting disk is reusable when the time to replace the rotors comes around again, which should prevent a repeat of the issues encountered last time.

Serviceable, durable, and done.

Small big lathe project

Over the course of the last 5 seasons, the bearing housings on the strut mounts have gotten pretty beat up.  With one cracked, it's time to make new ones.

This part starts off life as 4" diameter stock, and is stepped down to 2".  A 4" chunk of aluminum is reasonably hefty. This piece, 16" long, cost a cool $100.  With the relatively large diameter, the linear speed across the cutting tool is somewhat high, and will load up the machine if the depth is too great.

It sure does look pretty impressive sitting in the lathe, though.

For something of this size, the use of a live center while turning is a must.  The chuck jaws have been reversed, and the part is centered with a dial indicator prior to center drilling.

Then it's just a matter of whittling away- it's going to take about 65 passes. Yikes!

Followups:

No pictures of the boring steps, but eventually the housing made it's way to the mill for holes and getting squared up.

The DRO speeds up punching holes in the part, as well as the milling operations. Rather than spin in the part center with a indicator, an onsize plug for the bore was turned center drilled.  A center drill in the mill to pick up the center gets within .004" or so of center.  For this part, that's accurate enough for the remaining operations, and significantly faster.

The balance between time and cost comes down to knowing required tolerances for a piece part, as well as the assembled part.

Bending stiffness- door bars

Multiple tubes in the same plane are required to prevent side intrusion. The builder is left with several options as to tubing diameter and wall thickness. This spreadsheet compares idealized properties of the tubes to give an idea of how adding extra elements would affect weight of the assembly, or overall bending stiffness. (Stiffness largely drives energy absorption unless the tubes buckle or otherwise plastically deform)

				Number of Tubes
constant	OD (inches)	thickness	I	1	2	3		Relative mass per unit length		Stiffness to mass ratio
0.04900	1.50000	0.095	0.10376	0.1038	0.2075	0.3113		0.4191		0.2476
0.04900	1.50000	0.120	0.12456	0.1246	0.2491	0.3737		0.5200		0.2395
0.04900	1.75000	0.095	0.16937	0.1694	0.3387	0.5081		0.4937		0.3431
0.04900	1.75000	0.120	0.20482	0.2048	0.4096	0.6145		0.6142		0.3335
0.04900	2.00000	0.083	0.22964	0.2296	0.4593	0.6889		0.4996		0.4596