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karooha MB

Super Stock Rz Issues

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I have picked up a used Super Stock RZ that I wish to run in my Monster Beetle. It goes well, fairly fast forwards, but it really struggles in reverse. It is binding in some way. Tried it on two MB's, one with LRP Esc, one with a Tamiya 101. Two very different acting ESC's gave the same results, slow reverse. When the motor is out of the car it feels stiff, very clunky, like going over humps when you turn it by hand. I assumed that is because it has more torque than a RS540 Sport Tuned, previously fitted, but now I am thinking there is something not right about it. I have never rebuilt a motor, although I am confident I could if required, as I have run silver cans or Sport tuned until now. Any advice is gratefully received. Peace.

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I have picked up a used Super Stock RZ that I wish to run in my Monster Beetle. It goes well, fairly fast forwards, but it really struggles in reverse. It is binding in some way. Tried it on two MB's, one with LRP Esc, one with a Tamiya 101. Two very different acting ESC's gave the same results, slow reverse. When the motor is out of the car it feels stiff, very clunky, like going over humps when you turn it by hand. I assumed that is because it has more torque than a RS540 Sport Tuned, previously fitted, but now I am thinking there is something not right about it. I have never rebuilt a motor, although I am confident I could if required, as I have run silver cans or Sport tuned until now. Any advice is gratefully received. Peace.

The RZ come stock with 'advanced timing' which gives you slightly more RPMs spinning forward, but at the sacrifice of reverse performance. Timing is adjusted by rotating the endbell around, and the timing 'degrees' are stamped into the steel motor housing to indicate what the timing 'angle' is. If you want equal forward and reverse performance, set the timing to '0' and there you go.

I may have oversimplified here, but the motor manual will explain the concept further. IIRC the SS motors only require a screwdriver to make the adjustment.

HTH!

-Steve

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The RZ come stock with 'advanced timing' which gives you slightly more RPMs spinning forward, but at the sacrifice of reverse performance. Timing is adjusted by rotating the endbell around, and the timing 'degrees' are stamped into the steel motor housing to indicate what the timing 'angle' is. If you want equal forward and reverse performance, set the timing to '0' and there you go.

I may have oversimplified here, but the motor manual will explain the concept further. IIRC the SS motors only require a screwdriver to make the adjustment.

HTH!

-Steve

Fantastic, thanks for that, I'll give it a try. I knew someone would know. :)

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Fantastic, thanks for that, I'll give it a try. I knew someone would know. :)

You can't set this motor to zero timing (without modifying it), nor would you want to as it kills performance. If the motor feels chunky when spinning by hand in reverse (but not forward), then something is wrong. It is my guess the commutator is shot and the brushes are hanging up on the segments. How long have you had this motor? How many runs on it? Have you ever overheated it? Do you oil the bushings? Have you ever serviced it (skimmed comm, replaced brushes, cleaned it, etc...)?

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You can't set this motor to zero timing (without modifying it), nor would you want to as it kills performance. If the motor feels chunky when spinning by hand in reverse (but not forward), then something is wrong. It is my guess the commutator is shot and the brushes are hanging up on the segments. How long have you had this motor? How many runs on it? Have you ever overheated it? Do you oil the bushings? Have you ever serviced it (skimmed comm, replaced brushes, cleaned it, etc...)?

The motor came with some second hand parts I picked up. I think its safe to assume it could do with a service. It is not grinding, but a symptom is that when I let off the accelorator it seems to want to lock the drive wheels, especially on dirt or concrete, not so bad on grass as the friction helps. The motor is also faily quiet. The black plastic piece is fairly worn, chewed even, around the centre pin. All contacts look ok, I'll pull the brushes out tomorrow and have a look.

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You can't set this motor to zero timing (without modifying it), nor would you want to as it kills performance. If the motor feels chunky when spinning by hand in reverse (but not forward), then something is wrong. It is my guess the commutator is shot and the brushes are hanging up on the segments. How long have you had this motor? How many runs on it? Have you ever overheated it? Do you oil the bushings? Have you ever serviced it (skimmed comm, replaced brushes, cleaned it, etc...)?

Sorry for the mis-info. I seem to have a habit of this :) For some reason I was convinced you could adjust the timing on these.

Anyhow, I did find this, if it helps any:

http://www.tamiyaclub.com/showroom_model.a...46&sid=1386

I run one of the TZ motors in my TB01, and I can verify that it feels very 'lumpy' when free spinning -- The rotors are very close to the magnets in these motors and they have very high 'rolling resistance'.

-Steve

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Sorry for the mis-info. I seem to have a habit of this :) For some reason I was convinced you could adjust the timing on these.

Anyhow, I did find this, if it helps any:

http://www.tamiyaclub.com/showroom_model.a...46&sid=1386

I run one of the TZ motors in my TB01, and I can verify that it feels very 'lumpy' when free spinning -- The rotors are very close to the magnets in these motors and they have very high 'rolling resistance'.

-Steve

Well yes the rotor should be hard to turn by hand, and cog very bad. That's typical with any brushed motor. This is a good sign of strong magnets and is very desirable. But you definitely shouldn't feel ANY physical blockage. Just the magnetic cogging. I would wager the OP's motor just needs a serious service. Cut the comm, replace the brushes, clean it thoroughly and oil the bushings. If you don't know how to do this stuff, ask for some help at the local hobby store. The comm must be turned on a lathe to to make it truly round again. This will make the motor run like new provided it hasn't already worn the copper segments too deep to save. Let us know how it goes...

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Excellent advice from you all, thank you. I have had a look at the motor. The brushes may benefit from a replacement, the Com "looks" ok. I am fairly satisfied the rolling resistance is as it should be, after reading what you all have to say. And it appears the motor timing has been advanced, which is why it will barely move backwards. So, if I'm right, by returning the timing to centre It will be equal (or there-abouts) forward and backward speed. This I dont want, but want to check. I want good forward speed, as I am using HPI paddle tyres on the MB in question, but require a little more power in reverse than currently available. You can see the MB (with a different motor) on youtube ;

There are some other vids there of my cars if you fancy it.

Thanks for your help everyone, I'll tinker this afternoon and let you all know how it goes.

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Right, Took it apart, it seems ok. I think the Brushes will need replacing, so I'll go source some, any suggestions? The Commutator, which if I am right is the piece that the brushes touch, looks ok, to the eye it seems round and is not excessively worn. The internals were lined with a black dust, I assume its from wear and tear, hope it wasn't a grease compound as I rubbed most of it out. I trimmed off the alignment tab on the plastic end cap so I can advance or retard the timing, whilst being careful to mark the original position just incase. Now that its all back together it seems to have slightly eased up on the resistance. Prior to being taken apartt it was locking up, no obvious reason why, but with a little nudge or 20 seconds rest it would move again. I will let you know if this has stopped happening.

I like the motor, it seems comfortable in the Monster Beetle, time will tell if the Gears and diff think the same.

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When you have to nudge a motor to get it going, it means the brushes are too short to provide enough spring pressure to seat the brush. Replace the brushes. The RZ uses any laydown style brush. I like the Finishline Racing "F" brush. These do need to be soldered on. Also, the Trinity 4499 "E" brush is good. They can be bought with and without eyelets to suit your skill level. The stock 53483 Tamiya laydown brushes are nothing special and I wouldn't hesitate to go with something else. Otherwise you can always find them on eBay as low as $6.50 shipped...

Don't forget to use a drop of oil on each bushing. If you don't have specialty bushing lube from the hobby store, you can always use a thin motor oil...

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Forgot to mention, it's always best to have the comm cut when replacing brushes. It may look round, but there will be very slight dips between each segment. This will cause the new brushes to bounce causing more arcing than normal. This, in turn, causes the brushes and comm to wear quicker than normal. Definitely see if your local hobby store has anybody who can do this for you...

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When you have to nudge a motor to get it going, it means the brushes are too short to provide enough spring pressure to seat the brush. Replace the brushes. The RZ uses any laydown style brush. I like the Finishline Racing "F" brush. These do need to be soldered on. Also, the Trinity 4499 "E" brush is good. They can be bought with and without eyelets to suit your skill level. The stock 53483 Tamiya laydown brushes are nothing special and I wouldn't hesitate to go with something else. Otherwise you can always find them on eBay as low as $6.50 shipped...

Don't forget to use a drop of oil on each bushing. If you don't have specialty bushing lube from the hobby store, you can always use a thin motor oil...

Hi 94eg,

Im about to change brushes on my SSBZ motor. What's the difference between the standard brushes and lay-down brushes of tamiya? Can the BZ use standard brushes? they're a bit cheaper than the lay down brushes.

Thanks.

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Hi 94eg,

Im about to change brushes on my SSBZ motor. What's the difference between the standard brushes and lay-down brushes of tamiya? Can the BZ use standard brushes? they're a bit cheaper than the lay down brushes.

Thanks.

A motor uses one type or the other. It really depends on what end-bell you use. The BZ uses standup brushes. If you installed a laydown brush end-bell, then you would have an RZ motor... B)

Here is an image of a motor that uses laydown brushes. Compare it to the endbell on your BZ motor. As you can see, the brush hoods are shaped so only a laydown brush can be inserted into the hole. If you turned a standup brush on it's side and stuck it in there, it would not make proper contact with the comm.

laydown%20brush.jpg

Standup Brush (ignore the dual shunts):

30514_small.jpg

Laydown Brush:

767.jpg

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A motor uses one type or the other. It really depends on what end-bell you use. The BZ uses standup brushes. If you installed a laydown brush end-bell, then you would have an RZ motor... :P

Here is an image of a motor that uses laydown brushes. Compare it to the endbell on your BZ motor. As you can see, the brush hoods are shaped so only a laydown brush can be inserted into the hole. If you turned a standup brush on it's side and stuck it in there, it would not make proper contact with the comm.

laydown%20brush.jpg

Standup Brush (ignore the dual shunts):

30514_small.jpg

Laydown Brush:

767.jpg

Thanks again 94eg!,

As always, your info is very informative and useful.

mix237

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Well, turns out the issue was too many washers inside the motor, it was getting jammed up! Works a treat now, punches my Monster Beetle along nicely. Thanks for the advice guys.

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