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Old 01-13-2015, 02:48 AM   #31
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Hi all,


Is this the Rs4 Rally therapy group? I too have a problem... its costing me lots of money...

Having spent a huge amount of time searching the internet over the last few weeks and seeing these pages pop up, i thought i`d register on this forum. Some nice Rallys on here and good info too.

I`m based in the UK where HPI is one of the bigger brands but not as popular as the likes of Tamiya and Kyosho. Not as much of a following as in the US.

Pisc to follow, but i have a boxed RS4 Rally with the original Subaru body. Picked it up a couple of years ago on Ebay having hardly had any use. Complete with box, instructions, radio and even an edition of Radio Race Car that featured the car which the owner sent with it.

Having sold some of my other stuff in order to put money into the Rally, I am now in the process of sourcing as many spares as possible as well as grabbing upgrades when i find them. I have ordered the Slipper set so i can put in a Speed Passion brushless system. Should be quicker than the 17x4 Brushed item thats in there currently.

Does anyone know which MIP CVD units fit the front of these cars? I believe it may be the same as the RS4 200mm ones, but cant be sure. I thought i had found a set of the A513 universals, but sadly the store emailed to say they weren`t in stock when i placed the order.

Awesome cars. If only HPI did what Tamiya have done an re-released some of their older models. This would surely be a candidate along with the Super Nitro Rs4s.


Ant
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Old 01-13-2015, 07:01 PM   #32
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Hi all,


Is this the Rs4 Rally therapy group? I too have a problem... its costing me lots of money...

Having spent a huge amount of time searching the internet over the last few weeks and seeing these pages pop up, i thought i`d register on this forum. Some nice Rallys on here and good info too.

I`m based in the UK where HPI is one of the bigger brands but not as popular as the likes of Tamiya and Kyosho. Not as much of a following as in the US.

Pisc to follow, but i have a boxed RS4 Rally with the original Subaru body. Picked it up a couple of years ago on Ebay having hardly had any use. Complete with box, instructions, radio and even an edition of Radio Race Car that featured the car which the owner sent with it.

Having sold some of my other stuff in order to put money into the Rally, I am now in the process of sourcing as many spares as possible as well as grabbing upgrades when i find them. I have ordered the Slipper set so i can put in a Speed Passion brushless system. Should be quicker than the 17x4 Brushed item thats in there currently.

Does anyone know which MIP CVD units fit the front of these cars? I believe it may be the same as the RS4 200mm ones, but cant be sure. I thought i had found a set of the A513 universals, but sadly the store emailed to say they weren`t in stock when i placed the order.

Awesome cars. If only HPI did what Tamiya have done an re-released some of their older models. This would surely be a candidate along with the Super Nitro Rs4s.


Ant
The CVD's are the same as the 200mm ones. PN#80804 for the rear and 80803 for the front. I see the rears on eBay quite a bit, but the front's seem to be harder to come by. I agree that it would be cool if HPI re-released some of their older stuff. I'm a big fan of anything HPI from the late 90's-early 2000's. Some day I will have me a Proceed shelf queen as well.
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Old 01-15-2015, 01:46 PM   #33
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Thank you for confirming.

I did actually find some 80803 in a UK model store after an internet search. I asked them to measure them to confirm the length just to be sure before i ordered them..

I have fitted them this evening along with the bearing modification to the steering and put fresh oil in the dampers.

Here is a pic of mine. Body is not in the pic, but is pretty good although i have a new one in the packet along with spare wheels and tires. Im hoping to get some of the pirelli tyres as these seem to be the ones to use.

I also have two complete inner body sets although they could do with a lick of paint on the drivers.

I have a few upgrades including the springs and roll bars. I have a slipper clutch kit on its way too.

I was thinking of dropping down a few teeth on the pinion and going with a 10.5 Turn speed passion. Hopefully this will be a good compromise between speed and punch.
Another RS4 Rally thread?-rally.jpg


I have had so many HPI cars over the years. A couple of Nitro 2s, a few Nitro 3s. Always wanted the Super Nitro. I cant remember the last time i saw a Proceed for sale.

Interestingly, there are quite a few vintage HPI kits on ebay in the US. Shame shipping is so expensive to get them over here!
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Old 02-16-2015, 07:36 PM   #34
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i love these old guys .. but after collecting 8 solid chassis / 5 boxes / one rare unopened evo5/ almost every hop up hpi made/ and enough parts to rebuild everyone twice over/ oh and 2 2speed set ups with extra pinions ... i have decided to sell most of them .. iys good to see people still keeping these things alive like myself
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Old 05-12-2015, 08:18 PM   #35
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Had a rainy couple of weeks so I've been working on a project that I've been meaning to get to for a while. I was almost ready to sell this but decided to build it the way I wanted. It's brand new and I am only going to be putting other brand new parts on. It was all stock when I started.



It's killing me having this motor mount on there, but sourcing a new purple one is proving to be pretty tough.



I've got a new Rx and an almost new ESC. I'd still like to find a new in box ESC.

Not sure if I have the heart to bust the packaging on these. They're getting kinda rare.....
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Old 08-06-2015, 05:10 PM   #36
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Looky what I finally found!




Check out the sweet electronics install--


Probably just going to pull the two speed, clean up the wiring and sell this as a cheap runner on the 'bay. My Rally collection is starting to get out of hand again...
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Old 08-07-2015, 12:09 AM   #37
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Probably just going to pull the two speed,
I would be curious about your 2 speed experience.
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Old 08-07-2015, 12:20 AM   #38
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The problem with the 2-speed is that it allows the drivetrain to freewheel when coasting -- the engine just drops to idle as soon as you let off the throttle, so there's no engine-braking at all. You can adjust the brake linkage to provide some drag-brake when the throttle is in the neutral position, but that still leaves you with no proportional engine-braking when you just let-off the throttle a little bit instead of letting-off all the way.

Besides, if you're really running it in a rally context, on rough, loose surfaces, having a two-speed gearbox will mostly be just one more thing to break. The drivetrain will be suffering constant shocks and the shifting mechanism will be constantly disengaging and re-engaging.

I realize the vehicle posted above is electric, not nitro, but the power source doesn't affect how the gearbox behaves, so what I said still applies.
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Old 08-07-2015, 04:59 AM   #39
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The problem with the 2-speed is that it allows the drivetrain to freewheel when coasting -- the engine just drops to idle as soon as you let off the throttle, so there's no engine-braking at all. You can adjust the brake linkage to provide some drag-brake when the throttle is in the neutral position, but that still leaves you with no proportional engine-braking when you just let-off the throttle a little bit instead of letting-off all the way.

Besides, if you're really running it in a rally context, on rough, loose surfaces, having a two-speed gearbox will mostly be just one more thing to break. The drivetrain will be suffering constant shocks and the shifting mechanism will be constantly disengaging and re-engaging.

I realize the vehicle posted above is electric, not nitro, but the power source doesn't affect how the gearbox behaves, so what I said still applies.
I understand what you are saying, and I agree with it when it comes to nitro cars, but unlike nitro cars that have a completely seperate braking mechanism and servo, electric cars rely soley on the motors for braking.
I find it really hard to believe that HPI put out a device that not only increases your top speed but as a bonus completely eliminates a way to stop said bullet. Seems highly unlikely and dangerous.

I do not own one of these electric two speeds, so I can't say for certain that I know how they work, but my guess is it has a one-way bearing on the second gear going the opposite direction as the one-way bearing on the first gear. That means second gear is actually doing the braking. And when the car hits second gear the the centrifugal cam essentially "locks" the second gear to the shaft, so that second gear one-way is not doing anything at that point, but the first gear one-way is doing its job. I could be wrong, but it makes sense in my head, lol.

On the other hand if I am correct I'm now curious as to why nitro cars don't have this as an option? Seems like a nice feature to have a two speed without the free-wheeling effect. Or maybe it's only HPI's nitro two speeds that freewheel, and everybody else's don't?

Maybe if I do some digging around the Internet I can find a PDF of the installation instructions for one of these electric two-speeds and find out exactly how they work.
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Old 08-08-2015, 12:11 AM   #40
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Maybe if I do some digging around the Internet I can find a PDF of the installation instructions for one of these electric two-speeds and find out exactly how they work.


HPI A297 PDF
Ask and thee shall receive. I'm not sure how these things work, just picked this car up for the two speed, as they are kinda rare-ish and climbing in price. It will most likely never be ran, but rather cleaned up and installed on one of my shelf queens.
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Old 08-08-2015, 01:48 AM   #41
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I understand what you are saying, and I agree with it when it comes to nitro cars, but unlike nitro cars that have a completely seperate braking mechanism and servo, electric cars rely soley on the motors for braking.
I find it really hard to believe that HPI put out a device that not only increases your top speed but as a bonus completely eliminates a way to stop said bullet. Seems highly unlikely and dangerous.
It is entirely possible to have an electric car with mechanical brakes. The brake servo works the same as the brake/throttle servo on a nitro vehicle, except it's only connected to the brake lever since there is no throttle. Meanwhile, the ESC is set to forward-only with zero drag-brake. The throttle/brake signal is split so it can operate both the ESC and the brake servo. It's an uncommon setup, but much-preferred among a small subset of electric RCers.

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I do not own one of these electric two speeds, so I can't say for certain that I know how they work, but my guess is it has a one-way bearing on the second gear going the opposite direction as the one-way bearing on the first gear. That means second gear is actually doing the braking. And when the car hits second gear the the centrifugal cam essentially "locks" the second gear to the shaft, so that second gear one-way is not doing anything at that point, but the first gear one-way is doing its job. I could be wrong, but it makes sense in my head, lol.
What you're describing can't work. Second gear would be bound to the output shaft when braking, but it would freewheel when the motor tries to apply forward torque. Anyway, you'd still need a shifting mechanism, and the cheapest shifting mechanism is a centrifugal pawl -- which has the unfortunate side-effect of ratcheting when the vehicle is coasting. I think fancier shifting mechanisms that use centrifugal clutch shoes are capable of providing engine-braking since the clutch shoes can transfer force in both rotational directions, unlike a centrifugal pawl, but I've never actually driven a car with one of those fancier shifting mechanisms so I can't say with 100% certainty that it does allow engine braking.

The HPI R40 and the HB R10 both have the fancier type of shifting mechanism. Unfortunately I have no tracks anywhere near me, so there's no point for me to buy a car like that.
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Old 08-08-2015, 05:15 AM   #42
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Originally Posted by mountainman13 View Post
Maybe if I do some digging around the Internet I can find a PDF of the installation instructions for one of these electric two-speeds and find out exactly how they work.


HPI A297 PDF
Ask and thee shall receive. I'm not sure how these things work, just picked this car up for the two speed, as they are kinda rare-ish and climbing in price. It will most likely never be ran, but rather cleaned up and installed on one of my shelf queens.
Thanks mountainman13, that's what I was looking for. It's exactly how I thought it was and I'm thinking the A290 clutch bell has a one way bearing in it as well as the A292, although the instructions only mentions the one-way bearing in part A292.

Seems as how you have one of these on hand, can you just slide the A290 part on the shaft and see if it is in fact a one-way bearing, or does it rotate both directions? If it's just a regular bearing and spins both directions, then this two-speed definitely has me baffled as it has no brakes at all.
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Old 08-08-2015, 05:43 AM   #43
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It is entirely possible to have an electric car with mechanical brakes. The brake servo works the same as the brake/throttle servo on a nitro vehicle, except it's only connected to the brake lever since there is no throttle. Meanwhile, the ESC is set to forward-only with zero drag-brake. The throttle/brake signal is split so it can operate both the ESC and the brake servo. It's an uncommon setup, but much-preferred among a small subset of electric RCers.
I mean, I agree that you can add servos/brake mechanisms etc. to and electric car, but that's not really the point I was trying to make. I thought we were discussing this HPI option two-speed. They are meant to be run as a direct bolt on option part with nothing else needed. Which is why I'm trying to figure out if it in fact does have some way of allowing braking built into it that the nitro two-speeds don't have.

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What you're describing can't work. Second gear would be bound to the output shaft when braking, but it would freewheel when the motor tries to apply forward torque. Anyway, you'd still need a shifting mechanism, and the cheapest shifting mechanism is a centrifugal pawl -- which has the unfortunate side-effect of ratcheting when the vehicle is coasting. I think fancier shifting mechanisms that use centrifugal clutch shoes are capable of providing engine-braking since the clutch shoes can transfer force in both rotational directions, unlike a centrifugal pawl, but I've never actually driven a car with one of those fancier shifting mechanisms so I can't say with 100% certainty that it does allow engine braking.
I think what I'm describing is exactly how a two-speed works already, I'm just replacing a normal bearing with a one-way bearing in the second gear clutch bell (HPI part# A290). Second gear is meant to freewheel until the second gear clutch engages and then "binds" second gear to the shaft, and the first gear then freewheels via it's one-way bearing. Adding a second one-way bearing still makes everything function exactly the same, except you would get braking via the second gear one-way instead of no brakes you would get with a typical bearing.
Again, I'm describing all of this in context to the HPI two-speed that mountainman13 posted. He also posted up the PDF instructions for us to look at, so hopefully we can find out if this thing has brakes or not.
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Old 08-08-2015, 11:02 PM   #44
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I don't see a second OWB in the diagram Mountainman posted.

I think I understand what you're saying, though. If the second gear rotated on a reverse-direction OWB but still had a centrifugal pawl to lock it onto the output shaft at high speed, then the reverse-direction OWB could transfer reverse torque to provide braking when the centrifugal pawl would normally start ratcheting instead. That seems like a plausible setup, though I don't know how long the OWB would last before wearing out. Ideally OWBs should always be used in combination with ball-bearings to support lateral loads and to keep the OWB perfectly centered on the shaft, but that doesn't seem to be how RC companies use them.
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Old 08-09-2015, 05:00 AM   #45
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I don't see a second OWB in the diagram Mountainman posted.

I think I understand what you're saying, though. If the second gear rotated on a reverse-direction OWB but still had a centrifugal pawl to lock it onto the output shaft at high speed, then the reverse-direction OWB could transfer reverse torque to provide braking when the centrifugal pawl would normally start ratcheting instead. That seems like a plausible setup, though I don't know how long the OWB would last before wearing out. Ideally OWBs should always be used in combination with ball-bearings to support lateral loads and to keep the OWB perfectly centered on the shaft, but that doesn't seem to be how RC companies use them.
Yeah, I didn't see a second OWB in the diagram either, plus they say to oil the OWB so if there was two I would have expected them to say to oil the other one as well, but they don't.

You are correct though, that is how I was intending it to work. Seemed plausible in my head, lol. You make a good point on wear, I don't think this is how these bearings were ever designed to be used. I know the one in my nitro two-speed sometimes give me issues randomly. I'd imagine these OWB wouldn't last to long during this type of use, or at the very least I'd hate to lose consistency in my brakes suddenly.

It's sounding more and more likely that this particular two-speed is just like most other two-speeds and in fact does not have brakes, seems so crazy to me that they would ever make such a part.
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