Graupner plastic geardrive assembly, very fragile! [Archive]

View Full Version : Careful! Graupner plastic geardrive assembly, very fragile!

Kmot

Jul 30, 2008, 03:07 PM

I have two Graupner gear drive assemblies. The housings are plastic. I just cracked both them, simply by lightly tightening the 3mm motor hold down screws. :mad:

It looks like one of these:

Hoghappy

Jul 30, 2008, 03:13 PM

Man that blows....I thought Graupner had fairly well built reliable products. Thanks for the heads up.

BTW...I cooked off another Titan 12T the other day....this time with 6 cells in a Crackerbox boat....they don't seem to like me either. :o

Capt. Crash

Kmot

Jul 30, 2008, 03:20 PM

You must have them way overpropped. I ran the Titan 12T in the bassboat without a hitch and now I run one in the Harbor Star without it getting overly warm.

Hoghappy

Jul 30, 2008, 03:26 PM

Gee...I was just running a little ole X632... :rolleyes:

The stock EP1 was faster with a X431 than the 12T with the same prop. I'm going to test the EP1 with the X632 next...I got a few of them laying around so what the hey.

Capt. Crash

patmat2350

Jul 30, 2008, 04:23 PM

Sounds like the same unit I panned here:
http://www.rcgroups.com/forums/attachment.php?attachmentid=1352989
but for different reasons! (Graupner Universal Marine Drive)

Kmot

Jul 30, 2008, 04:48 PM

Yeah, must be junk. Oh well, it is going in Project X, a suicide mission anyway. :p

avidjeepr

Jul 30, 2008, 05:24 PM

Same as these? just bought them last week.

Kmot

Jul 30, 2008, 06:06 PM

What you have there is a different unit than the one I am talking about.

patmat2350

Jul 30, 2008, 06:09 PM

That one is a nice unit for 400 size motors... also in my gear review!

toesup

Jul 30, 2008, 06:39 PM

The plastc that Graupner uses for all their boat propultion products seems to be fragile.
Their Z drives are fragile... now this... :(

woodybob

Jul 30, 2008, 07:07 PM

Me thinks you need a smaller screwing device. :eek:

Kmot

Jul 30, 2008, 07:32 PM

Smaller than this? :p

woodybob

Jul 30, 2008, 10:18 PM

That'll work; I thought maybe you were using something like this. :eek:

Kmot

Jul 31, 2008, 12:38 AM

Nice screwdriver! :p

For anyone who has one of these units, I think it would be a good idea to place a washer between the motor and the faceplate. Then insert and tighten the screw. I believe now that the motor does not sit flat on the plastic faceplate. Snugging down the screw causes the faceplate to distort leading to a crack. With a washer placed between the motor and faceplate, that space will be filled and the screw being tightened will not allow the plastic to distort.

Tugboat Andy

Jul 31, 2008, 12:50 AM

Good advice Kmot.

I have the multispeed 140 from a Graupner Pollux I tried to build years ago. It wasn't a bad drive unit for a beginner but I now see where it's weaknesses lie.

fgroza

Jul 31, 2008, 07:47 AM

Hoghappy

Jul 31, 2008, 07:56 AM

Don't use Locktight on them either. It attacks plastic with a vengence!. Found this out the hard way.
Oh yea, my titan 12T bit the dust without even hitting the water. Horizon is sending out a replacement. Must be a bad design......
Frank

What do ya mean Locktight attacks plastic? Does it deform it or what...I love that stuff but don't want to buy new parts because of it.

I'm going back to the stock EP1 in my bass boats because the Titan just don't cut it for me. I don't know what Tom is doing right with his or if he just got a good one or I got a bad batch or what....but on 6 cells with the stock prop the EP1 is much faster. On 7 cells the Titan cooks but then it cooks off...the EP1 just keeps on truckin! :) Hmmmm....I wonder what a monster motor would do the Batfisherman...think the gears could handle it?

Capt. Crash

Kmot

Jul 31, 2008, 11:33 AM

The Titan 12T is the motor that comes in all Traxxas Rustler and Stampede trucks so it certainly isn't a bad design or a bad motor. I'm sorry you guys are having trouble with yours.

Hoghappy

Jul 31, 2008, 12:46 PM

No problem here...I obviously ran the motors too hot....but it seems that they melt windings or whatever very quickly and at a low temp. I've run other motors hot...some many times (monster motor) and they keep on keeping on.

I just don't think the Titan 12T is a very durable product....comparatively speaking.

Now back to the subject at hand..I didn't mean to hijack the thread! :o

Capt. Crash

Shaun Hendricks

Jul 31, 2008, 01:21 PM

I would be very careful with any motor less than 17T running a boat prop of any significant size.

More turns = greater torque for fewer RPM per volt.

By lowering the turns you are upping the current the motor needs to try and spin the prop in it's 'happy RPM' range. If the motor cannot reach its 'happy RPM' range it starts to overheat. The prop is too big for the motor and it melts.

Tom is right about the Titan. It is used in trucks and cars, however it is going through a geared drivetrain where you can adjust the motor (using gears) for optimal performance. A simple change of 2 teeth in a spur or pinion gear can take the Stampede or Rustler from so-so, to WOW! It's a good motor.

My Stampede is an older model and came with a Scorpion 20T motor. That would probably be a better boat motor than the Titan for direct drive purposes. The Titan would probably do very well in a boat with the right gearing or a small enough prop.

In the end, you can't determine how good a motor is if it is being improperly configured to begin with. It's like saying, "GEE, the M1 Abrams is a terrible tank! It won't cross the Atlantic without sinking!" The battle-tank was never made to cross the Atlantic Ocean so it is an abuse of the vehicle.

I swear, I'm going to have to build a test tank and go to the prop companies to send me one each of their props to give specs for. That would go a long way to saving motors some headaches! :D

fgroza

Jul 31, 2008, 01:50 PM

The blue loctite cracks the plastic around the bolt hole. It has also caused chunks to fall off of my motor mount in the U-47. I had to clean the effected area and reinforce the mount with sheet abs. I don't know what causes it but something in the mix is bad for plastic.
It also has a tendency to soften the area of contact after awhile.
I don't use it around plastic mounts any more.
Frank

Hoghappy

Jul 31, 2008, 02:16 PM