Tamiya Hornet accelerating issue.

[The_Hornet1778 3]

I have a Tamiya Hornet and am having a problem with power being cut off to the tires when I put it to max acceleration I have to jiggle the stick a bit then it goes top speed but my reverse works just fine.

[Frog Jumper 3661]

I had a similar issue when using old nimh batteries. After a few minutes, they would activate the low volt cutoff on my ESC, especially at max acceleration. Switching to LiPo fixed the issue for me.

YMMV…

Terry

[The_Hornet1778 3]

okay so it is just a battery issue, I am using a beat up Nikko Ultra Racing 7.2 1200mAh Ni-Cd battery 

[KEV THE REV 2319]

Is this hornet a vintage one with a manual speed controller ? , if it is the control arm needs adjusting with the handset throttle trim at neutral

[TurnipJF 9192]

Or the contacts need cleaning and the spring may need to be tightened. 

[The_Hornet1778 3]

23 hours ago, KEV THE REV said:

Is this hornet a vintage one with a manual speed controller ? , if it is the control arm needs adjusting with the handset throttle trim at neutral

It does not have a manual speed controller 

[The_Hornet1778 3]

22 hours ago, TurnipJF said:

Or the contacts need cleaning and the spring may need to be tightened. 

I am new to this, where are the contacts and how would you recommend cleaning them?

[TurnipJF 9192]

10 minutes ago, The_Hornet1778 said:

I am new to this, where are the contacts and how would you recommend cleaning them?

Hango on a minute and I'll circle them in red for you. Many electrical cleaning products exist, all doing pretty much the same thing. I use isopropyl alcohol in a spray can, agitated with an old toothbrush if necessary, but you can take your pick of whatever is available to you locally.

[KEV THE REV 2319]

You do have a manual speed controller . it is the 'square' looking board with the wiper arm on it . When you switch on the handset and then the car and you operate the throttle stick on your handset the arm will move across the contacts on the square board in one direction then the other as you move the stick foreward and back creating foreward and reverse on the car . The metal contact arm on the square board should be in the middle - kind of how it looks in your pic ( neutral) when the handset is turned on . If it isn't in the middle your car could run off in foreward or reverse , hence adjusting the throttle trim ( the small lever on your handset next to the throttle stick ) to middle and then seeing how the metal arm looks on the board ( hopefully middle = neutral ) . If it is not in the middle you need to adjust the set up , check these points first and report back . If all looks good you need to clean the contact with surgical spirit or similar , they are the metal arm and the arc style metal plates that the arm wipes over , don't forget to clean under the metal arm too .

[TurnipJF 9192]

The bits ringed in red are the MSC contacts that might need cleaning. The nut ringed in yellow is the one you would undo to take the mechanism apart.

[El Gecko 1344]

It could just be that the trim is set wrong on your transmitter, and the servo is pushing the MSC wiper arm past the contact point for full throttle. Mechanical Speed Controls like this can be finicky to set up. It's like adjusting the gearshift cables on a bicycle, or the throttle cable on a carburetor. The actuator rod could also be in the wrong hole in the servo arm, or the servo arm could have stripped splines or some other issue (I notice that there is no screw securing the arm to the servo).

The old AM radio gear is probably not helping the situation. The MSC wiper arm moves every time the servo does, so even if you're holding it at full throttle, any little electronic interference could cause the servos to glitch, causing the MSC to lose the connection between the battery and motor. A new radio set (transmitter and receiver) will help tons, and you can still use your old MSC or switch to an ESC (Electronic Speed Control) if you want more precise control.

[Aerobert 2144]

If the battery is as old as the Hornet I would replace it first. And give all a good clean. 

[rich_f 233]

The issue is neither the battery (you've said it works in reverse just fine), nor the 27MHz radio (I, and plenty of other people, used to race with the same radio and mechanical speed controller, and I still use 27MHz to race, albeit with an ESC). The problem is with the mechanical speed controller.  

As others have said, the contacts should first be cleaned (circled in red in the picture) and the connecting rod should be put into the hole on the servo arm that makes it such that when the throttle stick is at its maximum, the wiper arm does not go beyond the final metal contact, which will cause it to cut out. 

Moving the connecting rod one hole closer to the servo screw hole (you should really have a screw in that hole) so that the distance from the pivot point to the hole is the same on both the servo and the speed controller is the same might do it. 

You also might be suffering from too little spring pressure pressing the contacts together. This can happen if the nut on the top comes loose, or if the spring becomes a bit lax with age. It can be fixed by stripping it down, re-bending it and rebuilding. 

In summary, I don't think you need to buy anything new to get it to work properly - it just needs servicing and properly setting up. 

[Willy iine 18805]

On 7/5/2021 at 12:54 PM, KEV THE REV said:

Is this hornet a vintage one with a manual speed controller ? , if it is the control arm needs adjusting with the handset throttle trim at neutral

The_Hornet -  KEV THE REV has laid it out for you.    Your servo is probably over stroking the mechanical speed controller's large contact.  I would use the holes closer to the center of the servo arm to reduce the throw unless your radio has travel adjustment (EPA).  

As for cleaning the contacts I recommend some metal polish like Wenol and the like.  I remember back in the day I use to cut a balloon to cover the speed controller from dust.  

As others noted, you'll want to screw that servo arm in place.. GL!

[The_Hornet1778 3]

8 hours ago, KEV THE REV said:

You do have a manual speed controller . it is the 'square' looking board with the wiper arm on it . When you switch on the handset and then the car and you operate the throttle stick on your handset the arm will move across the contacts on the square board in one direction then the other as you move the stick foreward and back creating foreward and reverse on the car . The metal contact arm on the square board should be in the middle - kind of how it looks in your pic ( neutral) when the handset is turned on . If it isn't in the middle your car could run off in foreward or reverse , hence adjusting the throttle trim ( the small lever on your handset next to the throttle stick ) to middle and then seeing how the metal arm looks on the board ( hopefully middle = neutral ) . If it is not in the middle you need to adjust the set up , check these points first and report back . If all looks good you need to clean the contact with surgical spirit or similar , they are the metal arm and the arc style metal plates that the arm wipes over , don't forget to clean under the metal arm too .

Thank you! 

[The_Hornet1778 3]

5 hours ago, rich_f said:

The issue is neither the battery (you've said it works in reverse just fine), nor the 27MHz radio (I, and plenty of other people, used to race with the same radio and mechanical speed controller, and I still use 27MHz to race, albeit with an ESC). The problem is with the mechanical speed controller.  

As others have said, the contacts should first be cleaned (circled in red in the picture) and the connecting rod should be put into the hole on the servo arm that makes it such that when the throttle stick is at its maximum, the wiper arm does not go beyond the final metal contact, which will cause it to cut out. 

Moving the connecting rod one hole closer to the servo screw hole (you should really have a screw in that hole) so that the distance from the pivot point to the hole is the same on both the servo and the speed controller is the same might do it. 

You also might be suffering from too little spring pressure pressing the contacts together. This can happen if the nut on the top comes loose, or if the spring becomes a bit lax with age. It can be fixed by stripping it down, re-bending it and rebuilding. 

In summary, I don't think you need to buy anything new to get it to work properly - it just needs servicing and properly setting up. 

Thank you I will do all of that.

[Sir Crashalot 235]

It looks like you've got the antenna wire wrapped around the battery lead, too. Tidy that up by running it straight from the receiver to the antenna tube.

[Unknown Driver 262]

If you can get your hands on a copy (or pdf) of the original manual for the car (not the re-release) there is probably a section explaining how to setup the mechanical speedo. If you disconnect one motor wire you can play with the radio trims, servo arm, and linkage till your hearts content. You can also replace the solid link with an adjustable one if you really want to go nuts (look at an old Blackfoot or Monster Beetle for example) but that shouldn't be necessary if you have your servo horn and link position correct.

That's a true "vintage" car, so enjoy it but don't ruin it! You'll want something faster soon anyway

[Dakratfink 967]

I was going to chime in because I restored a vintage Hornet last year ( however I only restored the mechanical parts and used newer electronics). 
however, I have nothing to add because all the above advise you’ve been given so far is what I would have said. 

[Falcon#5 594]

TamiyaBase for a manual.

Click here>  Hornet

[The_Hornet1778 3]

 

21 hours ago, Unknown Driver said:

If you can get your hands on a copy (or pdf) of the original manual for the car (not the re-release) there is probably a section explaining how to setup the mechanical speedo. If you disconnect one motor wire you can play with the radio trims, servo arm, and linkage till your hearts content. You can also replace the solid link with an adjustable one if you really want to go nuts (look at an old Blackfoot or Monster Beetle for example) but that shouldn't be necessary if you have your servo horn and link position correct.

That's a true "vintage" car, so enjoy it but don't ruin it! You'll want something faster soon anyway

Yes it is definitely more enjoyable now that I got all my contacts cleaned. I was thinking that I would learn on the Hornet and when I get better Ill get a Super Hotshot 

[Unknown Driver 262]

You have expensive taste (Super Hotshot) but I approve! Glad to hear you're up and running!

[The_Hornet1778 3]

On 7/6/2021 at 1:15 PM, rich_f said:

The issue is neither the battery (you've said it works in reverse just fine), nor the 27MHz radio (I, and plenty of other people, used to race with the same radio and mechanical speed controller, and I still use 27MHz to race, albeit with an ESC). The problem is with the mechanical speed controller.  

As others have said, the contacts should first be cleaned (circled in red in the picture) and the connecting rod should be put into the hole on the servo arm that makes it such that when the throttle stick is at its maximum, the wiper arm does not go beyond the final metal contact, which will cause it to cut out. 

Moving the connecting rod one hole closer to the servo screw hole (you should really have a screw in that hole) so that the distance from the pivot point to the hole is the same on both the servo and the speed controller is the same might do it. 

You also might be suffering from too little spring pressure pressing the contacts together. This can happen if the nut on the top comes loose, or if the spring becomes a bit lax with age. It can be fixed by stripping it down, re-bending it and rebuilding. 

In summary, I don't think you need to buy anything new to get it to work properly - it just needs servicing and properly setting up. 

Thank you for all the advice I cleaned the contacts, moved the connecting rod and put a screw in the servo and It works!!  

[The_Hornet1778 3]

18 minutes ago, Unknown Driver said:

You have expensive taste (Super Hotshot) but I approve! Glad to hear you're up and running!

It caught my eye when I was scrolling. It is a bit pricey but I figured it's a more recent car (2012) so I would have a better chance at winning more races if I am a bit more up to date.

[Unknown Driver 262]

There are discussions on these forums about this - but if you're planning to do any racing do some homework first. At a minimum - know what the people you'll be racing against are driving. If "racing" means with buddies on a dirt track in someone's back yard, the Super Hotshot will be super fun. If it means racing at a club against modern cars (RC10B6, TLR 22 5.0, etc etc) you're going to be at a significant disadvantage. Just make sure whatever you get will work for what you're trying to do