Camperdown College Lawn Mower Racing Team


3/8/2015

The latest progress report!

The last five or six weeks have been busy with the machine all coming together to now be a fully operational racer!

Early June we took the machine up to Bendigo for a big session with Brian- almost 12 hours non-stop! The objective was to have fully functional steering by the end of the day and Brian did not disappoint us! First port of call was to a bearing shop to purchase all of the rose joints- Brian got us a nice little school discount! Steel for the tie rods, steering assembly and dash mount was next. Then we headed to an industrial supply shop for about $100 worth of various bolts, nuts, lock nuts, grub screws and washers.

Close inspection of our pictures show a neat little steering set up that Brian has perfected over the last few builds. Strong stub axle hangers with 1” bolts for axles. These mount onto steer tubes that have machined bushes top and bottom along with grease ports. The Front cross member is dropped to keep the machine low and this has given a small amount of camber. Brian assures us that the camber is unnecessary but we needed it for looks….

Brian set up the Dom on the lathe to build the tie rods while Brad and I helped with the axle construction and fitting. We moved onto the steering joints below the handlebars and this is where the fun began. The need to have lock to lock steering without the handlebars driving into your ribs means that millimetres make a big difference. The position of the control arms and steering rods need to take into account the chain drive and exhaust. The lower steering links also need to remain free at all angles- this means that there shouldn’t be any links that end up straight or over centre to each other.

Finishing off by attaching the handlebars to the steering shaft and mounting the shaft to the dash surrounds, the steering was then functional. We had a rolling chassis! Bringing the machine home we still had a huge list of jobs to do. Machining the hubs down so the stub axle bolt didn’t protrude past the rim edge, trimming excess bolts in the short steering links, strengthening the steering tube mounts, setting the tracking, a few extra welds here and there, Loctite on everything and finishing the handlebar mounting.

Two weeks after the trip to Bendigo, Brian called in at school to check the progress. We had done most of our extensive ‘to do’ list but we were able to utilise his expertise once again to help finalise our brake design. Brad supplied a calliper of a Chinese quad bike and Brian helped design a holder. We cut this with the plasma cutter and mounted the calliper. Strength was the main focus here with extra gusseting and supports added to the final mounting position. The master cylinder was then mounted up besides the engine and the lever passed through the foot plate.

After the big injection of help and inspiration from Brian the project was really coming along. We had ran the engine and stripped the electrical down to the bare minimum. The steering was finished and the brakes were functional. The lads got to work on the chain guards- we found some ‘unused’ chopping boards up in Science and were able to make some nice guides. Lots of little jobs now, securing the keyway in the axle, circlips on the hubs, connecting the clutch and accelerator, bleeding the brakes, tightening up EVERYTHING, finalising the foot wells and mounting the seat.

Rural Welding, a local fabrication business took great care in adapting some Toro rear guards to our mower. We retained the Rancher centre section and the guys fabricated some strips to join the two together. The also bent us up a centre section cover which we cut reliefs for the steering and brakes and then attached to the main chassis with tek screws. This meant the mower was now safe and ready to try!

We couldn’t wait for Saturday to take it to our track so last session Friday we snuck down to the school oval and did a few hot laps. Thankfully the gardener was down at the junior campus and the grass stood back up over the weekend! The mower ran very well, a bit spluttery but we got to have a spin. The steering, gears and brakes all worked as we expected and we were able to blow the cobwebs out of the engine.

The next day Marty, Jo and Brian came to our race site with their mowers and marked out a really fun track. We rode our mower around until the exhaust pipe broke off at the cylinder. Another hour or so and then the carby fell off due to a perished inlet manifold. A few families
from school came out for the test and the atmosphere was amazing. So many smiles and people clapping. Everyone was blown away with Marty, Jo and Brian’s knowledge and enthusiasm. A few of the crowd members even scored a go on their machines! An A Class machine might be my next project….

The past week was a race against time to get the machine ready for Neerim Test and Tune Day. The parts were easy to get but the exhaust proved a little tricky. Curdie Car Care came to the rescue and donated all of the bits and their time to fabricate a new exhaust system for us. They also bled the brakes and had a good look over it.

Arriving at Neerim the machine was drenched from the trip up and we had lots of trouble starting it. All the VicMow guys came to the rescue helping us to strip and dry the electronics, replace two carbys and replace lost bolts from the rear end (these things really do vibrate!). Darren’s loaner carby has given us about a 30% power increase so this week’s task is to purchase our own upgrade. Our sprocket carrier stripped its bolts, so it will be modified to take complete bolts and lock nuts. Besides all this it ran well. Last step is to paint it up and put all our sponsor stickers on- ready for our sponsors day and then the Mow Down!

As the build nears completion I would like to acknowledge that this project and end result would not have been possible without the generous help from Brian and Dianne and the ongoing support from VicMow. The club members have supported our students and implemented policies to promote mower building in schools and have fostered a curiosity in motorsport. If you have read this blog and need any more information, do not hesitate to ask a VicMow member and do not hesitate to contact our school or me directly. If you are a teacher thinking about a similar project please get in touch as we can help with curriculum planning and legal requirements. See you at The Mow Down!

Ben