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Old 04-27-2012, 03:05 PM   #31
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Here's a pic of the J Pro.



Notice that the top deck on the J Pro only attaches to motor bulkhead in the rear via the chassis spring. The M2 Pro has two additional attachment points on the chassis on both sides of the bulkhead.

Also note the J Pro has two sets of holes on the motor bulkhead to allow mounting the layshaft both in the upper position (for stick packs) and the lower position (for saddle packs). The M2 Pro only allowed for mounting in the upper position and was anodized in blue. The J Pro only had clear anodizing.
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Old 04-27-2012, 08:00 PM   #32
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Originally Posted by YR4Dude View Post
Not sure what your budget or priorities are. If you can afford the TC6.1 or the latest from XRay or Tamiya, go for it.

Regarding your YR, I had an M2 Pro from when it was first released. At that time, it was an upgrade to change the motor bulkhead to J Pro spec. With the layshaft in the lower position, it eliminated the belt tensioner for the rear belt which made the transmission more free. Also because of the layshaft being lower, the front belt would also be lower hence you could only use saddle packs.

However with the layshaft in the upper position and an additional belt tensioner for the front, it would allow you to use stick packs. So maybe its good you have the M2Pro bulkhead so now you can run a lipo pack crosswise in the middel of the chassis.
Gosh you're very knowledgeable about this car. You are well worth your name I guess.
I think I made you confused a bit. Or maybe I'm not still in 100% of understanding of what you say. Anyway, mine has a belt tensioner on the lower chassis. And the rear belt has small ring of belt tensioner too. The purpose of the rear tensioner is seemingly not to tense the belt but to avoid contact to pinion gear.
My point is it seems that I can run the stick battery across but I didn't want to do that because of possible contact. So I put that longitudinally. I made some modification to hold the battery by using TCX batter holder
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anyone still drive the yokomo YR4-M2 pro?-p6233416.jpg  
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Old 04-27-2012, 08:58 PM   #33
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Gosh you're very knowledgeable about this car. You are well worth your name I guess.
I think I made you confused a bit. Or maybe I'm not still in 100% of understanding of what you say. Anyway, mine has a belt tensioner on the lower chassis. And the rear belt has small ring of belt tensioner too. The purpose of the rear tensioner is seemingly not to tense the belt but to avoid contact to pinion gear.
My point is it seems that I can run the stick battery across but I didn't want to do that because of possible contact. So I put that longitudinally. I made some modification to hold the battery by using TCX batter holder
Back in the days of brushed motor racing, any bit of resistance from the use of a belt tensioner had a serious affect on speed. Especially for me because I was racing 27T brushed stock at that time. Nowadays with lipo power and brushless motors, that resistance in minimal.

You should try to put the battery crosswise. It may help balance the car better. Depending on what battery you use, you may have to shim the mounting posts for the top plate to clear the lipo. If you have one of the older Orion 3200 lipos those may be able to fit because they're lower in profile compared to the 5000's.
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Old 04-27-2012, 09:22 PM   #34
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Originally Posted by YR4Dude View Post
Here's a pic of the J Pro.



Notice that the top deck on the J Pro only attaches to motor bulkhead in the rear via the chassis spring. The M2 Pro has two additional attachment points on the chassis on both sides of the bulkhead.

Also note the J Pro has two sets of holes on the motor bulkhead to allow mounting the layshaft both in the upper position (for stick packs) and the lower position (for saddle packs). The M2 Pro only allowed for mounting in the upper position and was anodized in blue. The J Pro only had clear anodizing.
Well exactly same as mine. I can't really see the motor mount but there are two versions. One of them is optional and you can only use stick packs with the optional part. I'm positive that mine is YR4 M2 type J pro. Type J pro has a distinguishing part which is upper deck. It's Y shaped and it differentiates it from the other versions. I just found out M2 pro is same as M2 type J. There is no M2 USA pro. Am I wrong?
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Old 04-28-2012, 12:34 PM   #35
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M2 USA Pro had the Y type top deck like the one you have. It also had a blue anodized motor bulkhead that only had the one hole for the layshaft in the upper position for stick packs.

The J Pro (Japanese version) had the narrow top deck and the clear anodized motor bulkhead with the two positions for the layshaft.

There was an optional blue motor bulkhead for the M2 USA Pro that allowed it to run the layshaft in the lower position only.
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Old 04-29-2012, 07:35 AM   #36
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I have a J pro too, and I raced it on foams outdoors. It was a very good car, very easy to set up and it went like stink. For today's racing it is a bit on the heavy side, but I think with some effort it can be competitive. This is the car that convinced me all those adjustments we now have are not really necessary (think large, fast outdoor tracks). It is built like a tank, except the suspension arms which are too hard and break if hit. if the arms don't take the hit, nothing breaks. I have both narrow and wide (Y-end) top decks, don't see much difference.

If I was running it again, I would try it in stock (17.5) with a front spool and CVDs, and I would run saddle pack lipos. There are endless upgrades for it including a two-speed trnasmission (like a nitro car) with special double pinions and centrifugal clutch spur holder. Useless in my opinion.

By the way, the car in the pictures above has a rear BLUE aluminium bulkhead. AFAIK this is not a Yokomo item (original was plastic, upgrade was silver magnesium), any idea what it is?

One major advantage I see in this car's design (and the reason I didn't ever sell mine) is its side-to-side balance due to the centralised positioning of its motor/transmission/battery (if saddle packs are used) and the equal flex of its chassis due to its perfect symmetry. Kinda like the first Xrays. I would really like to see this design further explored, and I guess it will come back at some point. This car is one of the better examples of this design.
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Last edited by niznai; 04-29-2012 at 07:53 AM.
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Old 04-29-2012, 08:09 AM   #37
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Quote:
Originally Posted by niznai View Post
One major advantage I see in this car's design (and the reason I didn't ever sell mine) is its side-to-side balance due to the centralised positioning of its motor/transmission/battery (if saddle packs are used) and the equal flex of its chassis due to its perfect symmetry. Kinda like the first Xrays. I would really like to see this design further explored, and I guess it will come back at some point. This car is one of the better examples of this design.
i think you are wong there, the motor is not placed in the center. its offset to the left becuase the layshaft and spur is low, not over the motor like the
T1s.
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Old 04-29-2012, 08:36 AM   #38
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i think you are wong there, the motor is not placed in the center. its offset to the left becuase the layshaft and spur is low, not over the motor like the
T1s.
True, the motor is not dead centre, but close enough. The reason the layshaft is low is because it is in front of the motor so the front belt doesn't have to clear the motor and the rear belt is running alongside the bulkhead. it hink this is a good compromise, but that being said, I am not convinced the height of the layshaft is a bad thing as it is made out to be.
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Old 04-29-2012, 01:52 PM   #39
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Originally Posted by niznai View Post
By the way, the car in the pictures above has a rear BLUE aluminium bulkhead. AFAIK this is not a Yokomo item (original was plastic, upgrade was silver magnesium), any idea what it is?

One major advantage I see in this car's design (and the reason I didn't ever sell mine) is its side-to-side balance due to the centralised positioning of its motor/transmission/battery (if saddle packs are used) and the equal flex of its chassis due to its perfect symmetry. Kinda like the first Xrays. I would really like to see this design further explored, and I guess it will come back at some point. This car is one of the better examples of this design.
That light blue rear bulkhead is mots likely GPM because they made many aluminum upgrades for Yokomos at the time.

As for the motor, it was never centered. Hence the need for the 4x2 battery packs that some used to maintain proper balance. Yokomo's attempt at flex adjustment then was the use of their center spring on the top deck and optional posts for the top deck. As well as the rear post held with a body clip (don't know why). It was innovative then but even the most basic of kit cars nowadays have more adjustment now than the YR. (ie droop, roll center, anti-dive, anti-squat).

As enthusiastic as I am or was about the YR, its only good for nostalgic reasons. Its cheaper and easier to pick up something like a Sakura Zero S to go racing.
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Old 04-30-2012, 12:03 AM   #40
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That's true, the motor is not really centred, but still, closer tot he centreline than today's cars.

As for droop, it can be adjusted the old school way, and roll centre has some adjustability too by virtue of the upper suspension arms (IIRC). At any rate, I didn't feel these were holding me back back in the day. Nor do I think they really make a difference for a good driver today (perhaps at the top world competitions would).

But I think some of these can be engineered given some patience and effort put into the car. There are so many combinations of suspension arms/driveshafts/transmission parts it is almost impossible to not find something that works to upgrade the car. I have a vast collection of cars and more often than not I find bits of today fit cars of yore with minimal effort if any. Viceversa is true too, but most of the time this isn't an upgrade.
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Old 04-30-2012, 12:23 AM   #41
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Originally Posted by niznai View Post
I have a J pro too, and I raced it on foams outdoors. It was a very good car, very easy to set up and it went like stink. For today's racing it is a bit on the heavy side, but I think with some effort it can be competitive. This is the car that convinced me all those adjustments we now have are not really necessary (think large, fast outdoor tracks). It is built like a tank, except the suspension arms which are too hard and break if hit. if the arms don't take the hit, nothing breaks. I have both narrow and wide (Y-end) top decks, don't see much difference.

If I was running it again, I would try it in stock (17.5) with a front spool and CVDs, and I would run saddle pack lipos. There are endless upgrades for it including a two-speed trnasmission (like a nitro car) with special double pinions and centrifugal clutch spur holder. Useless in my opinion.

By the way, the car in the pictures above has a rear BLUE aluminium bulkhead. AFAIK this is not a Yokomo item (original was plastic, upgrade was silver magnesium), any idea what it is?

One major advantage I see in this car's design (and the reason I didn't ever sell mine) is its side-to-side balance due to the centralised positioning of its motor/transmission/battery (if saddle packs are used) and the equal flex of its chassis due to its perfect symmetry. Kinda like the first Xrays. I would really like to see this design further explored, and I guess it will come back at some point. This car is one of the better examples of this design.
Is there any way to change the one way diff to solid axle? I can't seem to get hold of the part. What is CVD??
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Old 04-30-2012, 01:52 AM   #42
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Is there any way to change the one way diff to solid axle? I can't seem to get hold of the part. What is CVD??
I am pretty sure there would be if you looked into it. The aluminium one-ay housing is very easy to change into a spool, the main difficulty would be to find outdrives to work there. I would try some of the new gear diff outdrives because they come with pin holes and use a "core" turned out of aluminium to reduce the internal diameter of the one-way housing.

I remember last time I measured the bearing shoulders for the YR are not far off from those of modern cars, so there might be something that just drops in.

CVD stands for constant velocity drive (articulated driveshafts have these joints which are not always exactly CVD).
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Old 04-30-2012, 08:04 AM   #43
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Originally Posted by niznai View Post
That's true, the motor is not really centred, but still, closer tot he centreline than today's cars.

As for droop, it can be adjusted the old school way, and roll centre has some adjustability too by virtue of the upper suspension arms (IIRC). At any rate, I didn't feel these were holding me back back in the day. Nor do I think they really make a difference for a good driver today (perhaps at the top world competitions would).

But I think some of these can be engineered given some patience and effort put into the car. There are so many combinations of suspension arms/driveshafts/transmission parts it is almost impossible to not find something that works to upgrade the car. I have a vast collection of cars and more often than not I find bits of today fit cars of yore with minimal effort if any. Viceversa is true too, but most of the time this isn't an upgrade.
problem is while newer arms may fit, they may make the car too wide. keep in mind the spacing for the suspension arms of todays cars and the old cars are different. you may end up with a car that is too wide and not legal for racing.
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Old 04-30-2012, 10:33 PM   #44
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I am pretty sure there would be if you looked into it. The aluminium one-ay housing is very easy to change into a spool, the main difficulty would be to find outdrives to work there. I would try some of the new gear diff outdrives because they come with pin holes and use a "core" turned out of aluminium to reduce the internal diameter of the one-way housing.

I remember last time I measured the bearing shoulders for the YR are not far off from those of modern cars, so there might be something that just drops in.

CVD stands for constant velocity drive (articulated driveshafts have these joints which are not always exactly CVD).
So Is CVD same/similar to universal shaft?
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Old 05-01-2012, 12:01 AM   #45
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The terminology is rather loose, contrary to what you see around here. I think here, universal joint is considered a single cardanic joint whereas a CV joint needs two cardanic joints to compensate for the uneven angle sweep of a single. The double cardanic joints are true CVD joints and most top R/C companies offer them these days.

Another option not using cardanic joints is the ball and channel joint as used in modern FWD (real) cars. There is a company floating about that makes these for us, R/C folk, but having bought a few pairs, I would say the technology is yet to settle here.
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