Going Slideways - MST RMX Build

[OSRC]

Been watching Hyperdrive on Netflix, and though it's a bit over produced, it's a pretty cool show. Got me all fired up to finally build a real drift car. I've dabbled around with drifting a bit in the past - mostly bolting drift wheels on touring cars, but this is my first real drift car. Skipping any kind of learning curve whatsoever, I jumped right into a RWD car..

Going back in time, this is as close as I've got to building a drift car. My drift build for Scale 4x4's build off... My TA02 hardbody Porsche 959.


Wow....10 years ago! Holy cow!

So anyway, let's get going with something based in this decade.... Started with an RMX kit, a few wheels and tires, 17t BL to start, and a Vaterra Camaro body (since I think a drift version would look sick!)

I was going back and forth with an MST or Yokomo. I've never built a Yoko ever, and I've built a few MST's but after reading some reviews and checking the aftermarket, I thought the MST would be the best bet.


Tiny box... looks like 10 bags of goodies. I'll post up bag by bag as I go through the kit.


Bag 1.. Suspension arms and mounts. Nothing notable here, though I did have to shim the front arms as there was quite a bit of slop. Kinda unexpected from MST as the CMX/CFX kits have been pretty precise. I used a silver sharpie to highlight the chassis... it was awful black! Kinda weird seeing giant rod ends as lower front arms.


I did buy the rear suspension upgrade for more adjustability, though for now I decided to build it stock and swap it on later.

[OSRC]

Bag 2...front bulkhead and steering. These front inserts are indexed and have to go in a certain way...my old eyes had to break out the magnifying glass to see them... lol. There's arrows on there...somewhere.


Upper arms and bulkhead assembled.


Kind of a crappy design here imo. Steering rack pivots on brass bushings - no big deal, but they pivot on threaded screws. That will chew up the brass quickly! I could have bought some bearings, but I didn't feel like holding up the build. So I found some stepped screws where the bushings would ride on the stepped part and cut them down to fit. With a bit of grease, it's slop free and super smooth.


Mounted up and sliding smooth!! Hopefully a good omen for this build.


You can build the kit in one of two ways - motor up top or down on the chassis. Big selling point, on the website and also all over the box. However, MST for some reason only includes all the steering parts for the motor in the down position. The rod ends are included for the upper position, but NOT the turnbuckle. Are you kidding? Why would you only include HALF of the parts? Cheap and ridiculous. C'mon MST, that's way stupid. I used a Tamiya threaded rod I had in my stash to made it work.


Mounted on the chassis with a drift specific servo I had.... sorry for the blurry pic, ever since I went to LED lighting, sometimes my camera has fits and refuses to focus. Not sure why. Kinda like my 44 year old eyes can't focus on anything either.

[BIGW0RM]

NICE! My RTR kit didnt include that turnbuckle either.

Curious, why did you mount your servo that way anyhow? Just curious. Mine came setup the other direction.

Also, the red aluminum steering parts they sell (3 separate PCS needed) REALLY took out most of the slop up front. Just in case your eyeballing that stuff. Its worth it!

[OSRC]

That's what the manual says for the motor in the upper position...I dunno, I follow what the manual says! Odd they have you build it that way, but don't include the part you need.

We'll see how I like it before dumping some more $$ into it.... (never stopped me with my crawlers, but you know...)

[BIGW0RM]

Originally Posted by OSRC

That's what the manual says for the motor in the upper position...I dunno, I follow what the manual says! Odd they have you build it that way, but don't include the part you need.

We'll see how I like it before dumping some more $$ into it.... (never stopped me with my crawlers, but you know...)

Oh, I did not know that. Mine was an RTR that came with the servo the other way. Your way looks a lot easier to dial the servo in though!

I moved my motor to the upward position, but left my servo where it was. I wonder what the difference is.

Well, I hope you enjoy it as much as I do. I can only slow crawl so much. I tried an Arma granite 3S and thats just NUTS. Thats way too fast for me. Bashing isnt for me.

I like the the drift car. Endless tuning possibilities. Lots of options. Cheap wheels and its fast enough sliding sideways, but not fast enough to break stuff every other run. And you dont need much room!

Hopefully you will like it. Now get it done and lets hear about it!

[JatoTheRipper]

You drifted with the 959 body?! Isn't that unobtanium now?

Looks like a fun build. Very, very odd they didn't include the required links. I expected better from MST. I suspect the quality of materials is very high though.

[c0bra]

Originally Posted by OSRC

That's what the manual says for the motor in the upper position...I dunno, I follow what the manual says! Odd they have you build it that way, but don't include the part you need.

We'll see how I like it before dumping some more $$ into it.... (never stopped me with my crawlers, but you know...)

A lot of seasoned drifters seam to like the motor mounted higher up in the chassis as it’s supposed to give more weight transfer.

You shouldn’t need any parts to put the motor in the higher position. On my rmx rtr it just requires that you rotate the motor mount. Now if you convert it to a rrx (flipped transmission) then you will need I think only rear suspension parts


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[BIGW0RM]

Hows the build going OSRC?

I also wanted to ask you if your front lower control arms have any front to back play in them? Mine seem to have 1-1.5mm of slop front to back. Since mine is an RTR, Im left wondering if this is normal or if I need to shim them.

This is what Im talking about.

[OSRC]

Its going... I've been slacking with updates.

Yes, lower arms had a bunch of slop....more than I expected from MST anyway... I shimmed them with some Tamiya 3mm shims I had laying around.

[BIGW0RM]

Originally Posted by OSRC

Its going... I've been slacking with updates.

Yes, lower arms had a bunch of slop....more than I expected from MST anyway... I shimmed them with some Tamiya 3mm shims I had laying around.

Oh cool! Keep it up.

And thank you for the confirmation. I wasn’t sure if that was meant to be there. With all the other parts being very rigid, I was confused.




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[OSRC]

Moving right along, this kit goes quick.

Step 4 is to top chassis rails and gyro mount. The gyro I have has a slick separate mount that gets bolted to the chassis, and then the gyro slides in.


Step 5: Ball diff... such a pain! The thrust washer has to be assembled and those tiny little balls are murder on my old eyes! I put a lot of grease on my Xacto and used it to pick up the balls and hold them in. Worked pretty well! I lost one under the workbench, but I got enough in there. Diff is nice and smooth.



Gearbox uses a set of bevel gears to connect the top layshaft to the diff. Kinda odd but it seems to work.


The gearbox was SUPER notchy. I played around with it for quite a while before I got it to run smooth. I sanded the back of the spur off a bit and did some shimming on the layshaft... finally it turns nice and free.


Set up the gearbox in the motor up position and mounted to the chassis rails....


Finally the entire thing gets bolted to the lower chassis... finally starting to look like something here!

[OSRC]

Step 6: simple shock towers and upper links.... I should have splurged on the carbon ones here, but the stock plastic seems plenty strong enough.



Step 7: Fun stuff!! Hubs, CVD's and axles. Love the brakes, one of the features of the chassis that sold me on it.


Ouch! One of the CVD's was badly bent out of the box...debated contacting MST but I managed to get it straightened out on my vice. Mostly...we'll see how it does.


And a few pics of the chassis... Again, love the brakes!!




Step 8: Shocks.. pretty basic plastic shocks, but they are nice and smooth and build well.





Step 9: Battery wings.... set up for a full size pack.


And finally, step 10...front bumper and body mounts. Surprised there's no foam bumper - seems like a cheap omission to me.


Mounted up my wheels - they just clear the brakes!


Steering angle is just crazy! Wow!


Need to set up the electronics and tidy up a few loose ends, but the chassis is done. On to the body!

[BIGW0RM]

Originally Posted by OSRC

Moving right along, this kit goes quick.

Step 4 is to top chassis rails and gyro mount. The gyro I have has a slick separate mount that gets bolted to the chassis, and then the gyro slides in.


Step 5: Ball diff... such a pain! The thrust washer has to be assembled and those tiny little balls are murder on my old eyes! I put a lot of grease on my Xacto and used it to pick up the balls and hold them in. Worked pretty well! I lost one under the workbench, but I got enough in there. Diff is nice and smooth.



Gearbox uses a set of bevel gears to connect the top layshaft to the diff. Kinda odd but it seems to work.


The gearbox was SUPER notchy. I played around with it for quite a while before I got it to run smooth. I sanded the back of the spur off a bit and did some shimming on the layshaft... finally it turns nice and free.


Set up the gearbox in the motor up position and mounted to the chassis rails....


Finally the entire thing gets bolted to the lower chassis... finally starting to look like something here!

I was wondering if you had a ball diff or spool. Mine came with a ball diff, but it’s so tight that it seems to act like a spool. I bought the red MST spool gear as a replacement for the ball diff but Since my ball diff Is damn near locked I haven’t bothered.

Plus the transmission design looks challenging to mesh. Seems complicated.

Great job! Thanks for sharing!


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[OSRC]

Just a few pics of the Vaterra body... love the idea of an old school muscle car drifter. Body has pre-drilled holes which sucks, but suprisingly the front posts almost match - close enough that they can be used. Win! Debating on a color scheme.



The body has an odd cut in the front...no idea why.

[HumboldtEF]

Nice body choice!

I also picked up a RWD RMX 2.0 a while back, I struggled with the gyro. Tried another gyro and decided to remove it all together. With all those changes I never got it to where I felt fully in control.

Anyway I'd be curious to hear how you make out regarding the gyro.

[OSRC]

I have no doubt I'll be out of control most of the time. This gyro ties into Ch3 and you can adjust the amount of gain remotely, seems like a pretty cool unit.

I have no idea what to expect, I wasn't very good at whipping around an AWD car, RWD might be a disaster, who knows!

[BIGW0RM]

Originally Posted by OSRC

I have no doubt I'll be out of control most of the time. This gyro ties into Ch3 and you can adjust the amount of gain remotely, seems like a pretty cool unit.

I have no idea what to expect, I wasn't very good at whipping around an AWD car, RWD might be a disaster, who knows!

OSRC,

Does your ball diff act like a spool diff? Mine came with a ball diff, but its "locked" from what I can tell. My rear wheels both turn the same way if I turn one or the other.

Since you built your ball diff. How tight is yours? Because mine appears to be locked unless it works differently than what Im use to seeing on a ball diff.

[OSRC]

I tightened mine so that it has diff action, but it is on the tight side for sure. You can certainly loosen it up a bit, though I don't know what effect that has on performance.

[HumboldtEF]

Originally Posted by BIGW0RM

OSRC,

Does your ball diff act like a spool diff? Mine came with a ball diff, but its "locked" from what I can tell. My rear wheels both turn the same way if I turn one or the other.

Since you built your ball diff. How tight is yours? Because mine appears to be locked unless it works differently than what Im use to seeing on a ball diff.

My ball diff was definitely open, I didn't like it much so I ordered a spool. Probably could have just tightened it up.

[BIGW0RM]

Originally Posted by OSRC

I tightened mine so that it has diff action, but it is on the tight side for sure. You can certainly loosen it up a bit, though I don't know what effect that has on performance.

Thank you. Mine must be very tight but it drifts just fine to me. Maybe I’m a spool guy and don’t know it. lol.


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