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Archive for April, 2012

417X – Sydney Model Autosports

April 18, 2012 Leave a comment

This is my setup for med grip asphalt. Still a work in progress but it gets around pretty well.

TRF417X Setup – Craig McPhee – SMA – 20120418

Categories: Setups

Reedy Powered

April 17, 2012 Leave a comment

I’ve been using Reedy batteries since TITC and I’ve been really impressed with their quality and performance, so when I was offered a deal with Ace Hobby Distributors to represent the brand I jumped at the opportunity. I’ll be running Reedy products at all major meets including MuchMore Masters and AARCMCC Nationals.

Reedy is a great company with a long and distinguished history, and ACE are big supporters of the Aussie racing scene. Click the images and check out their websites!

Categories: Product News

TRF diff a la McPhee

April 17, 2012 2 comments

Updated 25 Aug: I’ve slightly updated this build recently. Overall the mod has been working very well, but in modified I have had a couple of failures – one diff stripped because the backlash was too great, and another from a case stripping. You will see that rather than over-tightening the diff screws to crush the gaskets and get the backlash tight I now sand the case to check the backlash. I assemble the diff a few times as I go to ensure it’s going to work when it’s filled with oil, and I give everything a good clean before filling it up. Otherwise the mod is as it was…

Since returning to the blue team in February I’ve had some trouble with the tamiya gear diff unit II. At TITC Kiyo gave me a run down of how he builds the diff, very simply he trims the gears and adds 0.3mm shims on the long side and 0.2mm on the short side. I tried this and had my washers cone quickly, like after 2 runs. To be fair RC Addict was SUPER high grip and I was running boosted 4.5. He suggested using the small outer diameter shims but I had these collapse even quicker.

So I started looking for a solution and to date this is the best one I’ve come up with. What I like about this fix is that it’s really easy! You’ll need:

– 1 x Tamiya gear diff unit II
– 2 x 5x10x0.5mm shims (the OD probably doesn’t matter, up to 13mm fits)
– 1 x gasket (additional)
– Sandpaper

So here are all the parts, I’m rebuilding a diff which is why the stuff is used. The gears have been trimmed from the parts tree and the flashings removed, but they have not been sanded.
20120417-194258.jpg

You’ll probably find that the 0.5mm shim will fit off the bat, but it will be too tight
20120417-194305.jpg

We want a tiny amount of play in the outdrive, so we’ll need to sand the outside of the case to allow the outdrive to sit a little deeper into the diff. I’m using 800 grit here, and it doesn’t take much effort to remove the required amount.
20120417-194311.jpg

Once you have a bit of play, this side is ready. My play is approx 0.1mm.
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Now for the other side. The big side is harder to keep square as you sand, so it’s best to take it slow
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To ensure I have the correct backlash with the two gaskets and the larger shims, I now sand the big case where the gasket will sit (seen in red). I take about .2mm off the case, which equaled 33.7mm when measured from the end of the outdrive – I’ve only done this once so far so it may not be exactly right for all diffs.

Now for the double gaskets. This is required because using bigger shims we have brought the gears closer together. I use associated green slime on my gaskets, but TBH with two gaskets I haven’t had any leaks.
20120417-194530.jpg

Assemble as normal, and tighten the screws till they pinch firmly.
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Now you’re ready to go. Check the backlash – mine is very minimal, and while the mesh feels a bit tight and ‘geary’ at the moment I think this will be nice and smooth after it’s run in. If not then I have sanded the case a too much!

Edit: The shims I’m using are from http://www.smallparts.com.au, which is an Australian retailer. They are carbon spring steel so they are very strong, and they cost next to nothing when you buy a reasonable quantity.

Categories: Tips & Tricks