Need Input On How This Tranny Setup Works!

[crrcboatz]

Short story, a new friend Don Shuart of Dallas, convinced me to build my 36 inch team believer using 1 motor verses twins. Ok well I decided to use a trans. along with a aveox 46x43/2 with the trans. It has a kv of 737.
Chris at FD put the combination together with a 20% reduction. I told him I wanted to run the boat either 4s2c or 5s2c.
I decided to do the math today and DANG the motor is only going to produce 11800rpms BEFORE the reduction using a 4s setup!! He told me that was fine that the reduction would allow it to turn a x457 prop, vs the direct drive of a say 1800 kv motor on 4s would be 28000 rpms and it would be on a x445or x447.

I thought the transmission increased the rpms not dropped it. Can someone give me their take on this setup he has sent me?? I just don't understand how less than 10000 rpms will get the 36 inch cat moving to compete, even with the tranny and a x457.

Input appreciated.

Curt

[Steven Vaccaro]

On either setup 1 to 1 with a x445 or 20% reduction and a x457 you will hit about the same 18-20mph speeds.
You can use the formula on this page.
http://www.offshoreelectrics.com/conversion.htm

Now somethings wrong with the picture. Both Chris and Don know what they are doing. Somethings missing.

[crrcboatz]

Let me be clear, Don did not recommend the tranny concept rather he just said a single motor setup for the first large boat was less stressful in setup and probably less costly. He just did not want me to go too far too quick. Many of you said the same thing. He said a good single motor setup could run the speeds of the twin I had posted here as my goal. Don is going to help me with the first runs of my boats. Plan to take a trip later this month to let him help me.

I just cannot see how Chris would recommend this when you look at the math.

[Fluid]

What has been done is to overdrive the motor. This allows a torquey motor like the Aveox to turn a useful rpm. Gear it up 2:1 and you'll see decent performance. An overdrive setup has been used to set SAW records so it is well proven. One of our club members runs a 42" mono with an overdriven Lehner, runs great.

Ths choice of the low Kv Aveox is rather strange....are you certain of the motor? My data shows a Kv of 670 rpm.


.

[crrcboatz]

What has been done is to overdrive the motor. This allows a torquey motor like the Aveox to turn a useful rpm. Gear it up 2:1 and you'll see decent performance. An overdrive setup has been used to set SAW records so it is well proven. One of our club members runs a 42" mono with an overdriven Lehner, runs great.

Ths choice of the low Kv Aveox is rather strange....are you certain of the motor? My data shows a Kv of 670 rpm.


.

670 was the was the older version an 18/17/2y I believe. The 46/43/2 is 737 according to Chris.
I agree with you that gearing that motor UP is correct. However Chris told me on the phone that he geared it down 20%. He said all trannys are used to gear down, never up

Have you known of people gearing up as well as down?

[Fluid]

Have you known of people gearing up as well as down?

Did you read my post? One guy holds the S Sport Hydro SAW record, another races his big mono regularly - both are overdriven.

Look here for the Kv of the 46/43/2 motor: http://www.parkjets.com/aveox.html

Chris must think you are running 10S, not 5S. He knows what is right - there is a communications breakdown somewhere. An x457 is really too big for a 36" mono, you may have terrible chine walk and hooking issues. A 45mm prop is plenty for my 33" 4S mono, which runs around 50 mph in oval races.


.

[NativePaul]

Chris isn't a boating noob so 3 scenarios come to mind
1, You misheard/misunderstood him.
2, He has recently suffered a blow to the head.
3, He is knowingly giving you bad advice in order to shift stock.

Either way, I would be inclined to ring Steven at offshore next time you need advice on a purchase.

[crrcboatz]

See post below.

[crrcboatz]

First let me say that I am aware of the level of experience that Chris has in fe rc boating. It is possible I misunderstood him. However, the thing that has me puzzled on this is the fact that when I expressed my lack of confidence an a setup that only produces 10000 rpms before hitting the water, he made the following analogy. He asked me if I had ever known a car transmission that geared up. He said all transmissions in FE gears down. Since I have no knowledge of an auto tranny I did not respond.
I do know this, I have NO use for a motor with a kv of 680 or what ever it is if the tranny thing won't produce the rpms I need for this hull. Don't want anything to do with hv projects right now. If the trans. concept doesn't have the numbers I need, I will expect a refund.

One additional comment the insinuation was just made that somehow I need to do business only with Steve. I have spent between 600-700 dollars on 2 motors and a hull in the last month with Steve. I respect him just as I do Chris. He will get continue to get a bunch of my business.

[Fluid]

With all due respect to Chris - whom I have known well for many years - some of his customers do indeed install his transmissons geared up. In his analogy about automotive transmisisons - is he not aware that most transmissions used in automobiles for the past 20 years include at least one OVERDRIVE gear ratio? My current auto has a six speed transmission, and both #5 and #6 are overdrives. So I guess know of at least 50 million auto transmissions that are geared up.

The motor you purchased is, as you discovered, useless for your application. Get a motor with a Kv between 1600 and 1900 rpm for 4S use.


.

[crrcboatz]

With all due respect to Chris - whom I have known well for many years - some of his customers do indeed install his transmissons geared up. In his analogy about automotive transmisisons - is he not aware that most transmissions used in automobiles for the past 20 years include at least one OVERDRIVE gear ratio? My current auto has a six speed transmission, and both #5 and #6 are overdrives. So I guess know of at least 50 million auto transmissions that are geared up.

The motor you purchased is, as you discovered, useless for your application. Get a motor with a Kv between 1600 and 1900 rpm for 4S use.


.

Thank you for those comments. I am sure he is a standup guy and I am counting on that to help me get this settled and behind me.