YR-4 custom buggy conversion

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AllenB.5979
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YR-4 custom buggy conversion

Post by AllenB.5979 »

This isn't really going to be a build thread. More of a questions and comments section. When I built this car I had never intended to post it. I actually wasn't even a member of rc10talk. Well now I am and let the sharing begin :lol:
I do have a few pictures of the car as it went through a couple of different iterations. I'll try to cover everything I've done. It's not one of the most involved customs in terms of fabrication but that wasn't really my goal. I wanted to build a car that was based on the Yr-4 / Yz10 platform that is tough, modern and inexpensively rebuildable. My first intentions were to have a runner that could keep up with some of the newer cars but still be vintage at heart. I think I've come close to that goal however given how nice it came out... I'm reconsidering the runner part.

Ok. Let's get into it. Haters welcome. Everyone's opinion counts. It might be wrong but hey, it still counts! :D
They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

So here's the car as it sits now. Yes I went with an Egress body. The under pan fit well and I love the Egress. Imo Tamiya makes some of the coolest bodies out there.

Please keep in mind that this car is not 100% finished yet and I still intend to change some things. Take the front bumper for example. That needs to be switched over to a Yz10 piece.

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They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

So back to the beginning. This car started out as a Yr-4 I bought from my great friend Mimi at The Track in Gaithersburg, MD back in I want to say 93' Ish maybe 94'. This was when she had a carpet oval with a road section in the infield. It was my first touring car having come from oval pan car racing and dirt oval. I believe at some point I converted to the SP chassis or I may have got the kit with that chassis. It's been a long time and my memory is hazy. At any rate I see very few cars with this chassis so I'm glad I didn't beat it up.

I moved around and away from MD and my favorite place on earth, The Track. Not to mention I got sidetracked by 1/24th an 1/32nd slot cars for many years. Mimi has an awesome track for those as well but that's another story. The car sat unused for a very long time. Now, having returned to the area and deciding (after selling my entire collection like an idiot) to return to RC I figured let's pull out what I have left and see what we can do. Having in 89' started racing buggies off-road and now that The Track has switched from carpet to clay I chose to head in that direction.

I thought to my self... well, a Yr-4 isn't that different from a Yz10 (at least the early models) let me see if I can build a modern take on a Yz10.
They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

This was my first iteration. Using HSP touring car arms and HPI hub assemblies I was heading in the right direction but I thought even though it was much wider than with the standard Yr-4 arms I could still do better.

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The wheels were never intended to stay. They are just some alloy touring wheels I used for size reference. I didn't even have any buggy wheels at this point to test with. Sad, I know.
They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

At this point I hadn't worked out the drivetrain. The front and rear diff pulleys were shot as we're the super old belts.

I did have a rear stabilizer bar set up which came out well but unfortunately this did not fit when I went to the longer arms. That's something I still intend to sort out with the current set up.

Here it was still sporting the Yr-4 shock towers. Didn't know what my plan was going to be as far as dampers and towers yet.
They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

Early body test fitting. Lucked out here. Very little body chopping had to be done. The under pan needed some work but it came out great. I used a couple of early Tamiya aluminum body posts turned down to the proper length. The front was put in place of the plastic nub on the front bulkhead cover. I shaved that off and opened up the hole on the upper plate to make a nice tight fit. It actually fits much better than the factory hole and plastic nub. Bonus! Less chassis flex. The rear was mounted to the rear belt tensioner link which I added earlier. I'll talk more about the tensioner later.

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Just some different angles.

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The wing isn't actually mounted yet. Just set on to get an idea of what it will look like.

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They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

In this set I was a little further along. I had ordered a couple different sets of diff pulleys. M2 and M3 pitch along with the belts to go with them. Hadn't got them yet as they came from Spain and it took weeks. You can see the custom idler pulleys I made (again from vintage Tamiya bits). I could have bought some on Ebay but where's the fun in that?

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I chose to go with shock towers from a 1st gen. Yokomo Yz10 870c reproduced in carbon fiber. I got these from a great guy on Ebay by the username rcwingsnwheels.

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This is a good shot of the motor mount. This was a vintage part I put on the car many years ago. If I remember correctly this was a GPM part. It used to be anodized red. Sad to say though over the years it had turned more of an ugly shade of pink. After lots of careful wet sanding I baked on a wrinkle finish that came out just great. There is a removable motor plate that is not pictured here but it got the same treatment.

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They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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Re: YR-4 custom buggy conversion

Post by Mr. ED »

Check out my gallery. I made a kind of hot dog about 9 years ago after trying to sell a nib yr4. It got outfitted with a baldre body.
I also bought some spares: Second hand runners. And ran in the tc class with the same chassis you have. The links to the build treads are in the gallery too.

Please find us some modern arms that work. I'd like to build another one but don't like the pricing on 91 works arms.

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

Mr. ED wrote: Fri Jan 20, 2017 2:16 pm Check out my gallery. I made a kind of hot dog about 9 years ago after trying to sell a nib yr4. It got outfitted with a baldre body.
I also bought some spares: Second hand runners. And ran in the tc class with the same chassis you have. The links to the build treads are in the gallery too.

Please find us some modern arms that work. I'd like to build another one but don't like the pricing on 91 works arms.
Man, your cars are awesome! Just spent 30 minutes looking over your gallery. I'm with you about the arms! I found some original pieces for 50$ and up. I definitely didn't want a botched jump to cost me 50$. Besides I figure I'll leave the original parts out there for the guys doing restorations. As far as a substitute the best I've come up with so far is an HPI MT2 set. They fit with just a couple spacers but the are really long (longer than ROAR allows) and require 91mm dog bones. Those are hard to come by. I had to pay a fortune for a set from England and the only manufacturer that has them is in Australia. These are the arms on the car in the pictures at the top of the thread. I will be posting more this evening. I will detail the arms and drivetrain.
They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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Re: YR-4 custom buggy conversion

Post by jwscab »

i believe I have seen arms from dynotech made of machined white nylon that could likely be purchased. They would be extremely difficult to break. I'm not sure they are in the catalog but an email might help.

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

jwscab wrote: Fri Jan 20, 2017 4:35 pm i believe I have seen arms from dynotech made of machined white nylon that could likely be purchased. They would be extremely difficult to break. I'm not sure they are in the catalog but an email might help.
Thanks for the heads up. I'll look into it.
They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

So this is the latest version of my creation.

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They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

Here is a close shot of the rear belt tensioner. This is an idea stolen from the late 90's Yz10 cars. A common upgrade I'm sure everyone here is familiar with. Accomplished with an adjustable linkage and some Tamiya aluminum bits turned down to the correct sizes.

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Also here we have a Yokomo Yz10 spur and rear pulley combo with an M2 rear drive pitch and a one way bearing hub. I chose the M2 pitch for the rear drive because it's smoother than the M3 and since it's a short run slipping due to belt stretch isn't really an issue. I do plan to add a slipper clutch eventually to handle brushless power.
They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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AllenB.5979
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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

The view from the motor side. Here is the removable motor plate finished with bake on wrinkle coat to match the center drive block.
You can also see the difference between the M2 pitch rear belt and M3 pitch front drive belt. Went with the M3 up front because of the long run where belt stretch could cause slippage issues using the M2 pitch. It also simplifies belt tensioning as the M3 isn't as finicky as the M2. If you are going to do a mixed set up like this make sure to do your math! Don't want your ratios messed up. I didn't but if you are using different diff pulleys from other cars you can mess things up easily.

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They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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Re: YR-4 custom buggy conversion

Post by AllenB.5979 »

Her are a couple shots of the front suspension. These are HPI Mt2 suspension arms with a set of HPI Rs4-3 C hubs and hub carriers. This makes all the parts that stick out inexpensive to replace. I am however still looking for something modern that is in between the HSP arms I started with and these. Although these are a great fit only using some spacers and HPI hinge pins they are a little long. ROAR rules say max with for a buggy is 250mm and these blow that away by almost 20mm. Not so great if you wish to do any regulation racing. Not to mention the required Colt s7045 6 × 91mm drive shafts. Sourcing these can get expensive due to shipping. I think I bought the only set available outside of Australia.

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Here you can see how I had to trim the top of the C hub where the top linkage attaches and the hub carrier where the steering linkage attaches. This was the only way to get a modern buggy wheel to fit over the hub assembly and not rub. No worries though, the steering still has plenty of travel and I was able to keep the upper linkages parallel to the suspension arms for good geometry.

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They asked me what I was thinking!? I simply told them... I wasn't. :roll:

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