Frenzy Gear Ratio 8.5:1 vs 8.7:1

[James Kovach]

I am not a Head Speed Freak :P. I like flying my 50 size nitros in the 2000 RPM range. With the 8.5:1 Gear Ratio on the stock Frenzy, this puts an OS 50 running right at its optimal rpm, 17,000 RPM. So to get the engine running above this RPM so that it will fall into the optimal RPM, you need to run 2100 or better. I actaully found that 2200 was best. I did not like this at all to be honest. It is just too fast for my liking.

Well the Frenzy's drive train is basically a Raptor 50 setup. Raptor 50s also have the same gear ratio stock. But Thunder Tiger put out and "optional" gear set that puts the gear ratio to 8.7:1. This set comes with a 96T main gear and 11T pinion. So I decided to get one and see how it would work out on the Frenzy. It is a little pricey at $25, but I would rather have that 8.7 ratio. They also do not sell the 96T gear alone, so in the event of stripping the main gear in a crash, you will have to buy the complete set again. For me it is not that big of a deal. I am not crashing that much anymore <knock on wood>.

The main gear is a direct swap. Unscrew the stock Frenzy gear and install the TT 96T. For the pinion, you will need to cut about a 1/4 of an inch off the top of the pinion. It is pretty obivous when you put the two side by side what and where you need to trim the pinion down. After that, it swaps right in with no issues. Then it is just a matter of putting everything back together. I did not have to pull the engine to make the swap. I just worked it out by tearing down the starter shaft section. It was pretty simple to figure out .

So today I put 5 flights on my Frenzy with the new Gear Ratio and I am extremely happy with it. Running a Head Speed anywhere from 2000-2100 RPM does not result in the engine power dropping off when doing manuvers that have a lot of collective and pitch. Now the engine will drop down into its power band when the head gets loaded. Turned my Frenzy into a whole new beast. Even crusing around at 1800 RPM was better, with the 8.5:1 ratio it was damn near pointless as the engine would just fall off too hard.

So if you are not into running 2200 RPM, I highly recommend you give this Gear set a change. The model number for the gear set is PV0518. Some shops add a few letters to the front of it, but if you search for this you should be able to find it.

If anyone tries this, let us know what you think.

I have also seen there is an 86T main gear for the Raptor 30s. I am pretty sure you could swap it right in as well without replacing the 10T stock pinion. I did not try it as I wanted the 8.7:1 ratio. This is the ratio that my Knight 50 3D uses and I really like that ratio.

[BC]

That sounds like what I need. Im not a big stick banger and would prefer a lower hs as well. I will consider this option...thanks!

[BC]

pv0518 on its way ;)

[James Kovach]

I think you will be very happy with the results. Cutting down the pinion is really the only modification you need to do. Just stand them up on end and you will see how much to take off.

[Rudedog]

Sparx can you load som pics of the mod? i am mostly interested in the pinion. how did you cut it?

[James Kovach]

Rudedog,

I did not take any pictures as I did the replacement. After I had done it, it dawned on me that I should have documented it.

It really is a pretty straight forward swap. When you have both pinions sitting on your bench, you will see what you need to cut off the new pinion pretty easily. The top of the pinion seats into the starter shaft bearing block. The top side of the new pinion is too long and will not seat all the way into that bearing so you need to cut it down a bit. The nice thing is this is not a precision fit. You just need to cut enough off so that the bearing will full seat into the bearing. if you take off too much it is no big deal. You would have to really mess up the cut for it to not work. I am going from memory, but I am thinking you can take anywhere from 1/4 to 1/2 inch off the top of the pinion and it will work with no problems.

To cut down the pinion, I used a cut-off wheel on a dremel and then cleaned up the cut with a bench grinder. You could use a hack saw and file as well if you do not have any power tools as I stated above, it does not need to be precise. Just make sure that you bevel the edges of the cut when you are done so it will slide into the bearing.

[grnmac1]

Hey guys,
I did the same thing with the gear and pinion, I just used a dremel cut off wheel to cut off the excess. Perfect fit:thumbup: the clutch and the bell will fit as well, Also another bit of info, the tail belt from the TT Raptor 30 will fit in the V2 version. :thumbup:

[heartnspirit]

You can see one of the raptor 87 tooth main gears installed and a brief explanation here:
http://allthingsthatfly.blogspot.com/2009/04/js-models-tz-v2-frenzy.html

[James Kovach]

hehehe, thanks, I was going to post here later that my review was up for the Frenzy :)

I wish I would have documented the change with some pictures, but it is so simple, I do not see the need to tear my heli down again :P

[BC]

Dumb question but whats a good way to get the pinion off of the clutch bell.....i dont want to wreck anything ;)

[James Kovach]

BC,

I heated the area where the pinion thread into the clutch bell. Then used two pair of Channel Lock Pliers. I wrapped a rag around the pinion as well. Took some force as it was thread locked in there pretty good. I grabbed the clutch bell just below the pinion. I did not apply force to the largest part of the clutch bell as I thought that look like it might deform with too much pressure