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Converting M05 to rally car

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Hey everyone,

 

Well, after tearing apart my M-05 to clean and replace a stripped gear, I’ve thought about converting it to a rally car. So far, the only ‘part’ I’ve purchased are the Tamiya 60D rally block tires. From what I’ve read they have roughly a 10% larger diameter with the treads, so I’m hoping it will give enough ground clearance for relatively tame off roading. I know that I’ll also definitely need a skid plate and shield so the chassis doesn’t fill up with dirt and stones. I could fabricate my own skid plate out of aluminum but don’t see how I can properly attach it. I’ve read other people buying the M05 rally edition suspension parts, but am wondering if that’s really necessary…I don’t want to shell out too much money on longer shocks too (and the car has seen better days). Right now I’m using an Arrma 15T motor which realistically is too fast for this chassis, I may just set my throttle end point down to 75% on dirt. Anyways, has anybody had any success doing this without adding the rally edition parts and longer shocks?

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You don't need to buy longer shocks if you have tamiya CVA oil filled shocks. If you do they are currently built at 55mm length using internal spacers to limit travel. You can open them up and remove one or both of the spacers to get up to 64mm length and 9mm more shock stroke. Not sure if they will fit at that length but you could certainly remove one of the spacers in there to get a few more mm ride height and shock travel.

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I'd recommend upgrading the F parts on a rally conversion, the "ra" F parts have 2 sets of holes to allow you to use a standard or higher ride height, and it is useful have the extra ground clearance in a rally car.

I've got a couple of M chassis cars, and all have been changed to the M-05Ra parts to give me the choice in the future.

Here's a handy link: https://www.ebay.co.uk/itm/Tamiya-51425-M-05Ra-F-Parts-Upright-M05Ra-Swift-Alpine-A110-Renault-5-NIP-/391767748615

 

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Thanks, I think I forgot to mention that I’m using the Yeah Racing aluminum shocks…I don’t think there are any spacers that I can remove to give additional travel. I am hoping that the rally tires give me a few more millimeters of space under the chassis. I believe I’ve seen youtube videos of people using completely stock set ups on a baseball field. I will be fabricating a lightweight skid plate for the front probably out of a soda can, if it doesn’t hold up then I’ll maybe go to a hardware store and get some stronger grade metal to mount. I also plan on using something like hot glue or putty to plug the unused pinion holes and maybe using a piece of tape to cover up the slight gap between the two chassis halves.

 

 I’ve ran the heck out of the car for about 5 years now, so the chassis is pretty beat up at this point.

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You can either use longer shocks on the stock uprights, or short shocks on the RA uprights. You can’t do both as the RA uprights put the dogbone lower and then you can’t drop the arm without the dogbone fouling, hence longer shock and ra uprights doesn’t work. I prefer longer shocks, as you gain suspension travel. The ra uprights you gain ground clearance but not suspension travel due to droop limitation. 

I’d lock the diff too, or you’ll be bogged most of the time. 

 

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Thanks, I'm still waiting for my rally tires. I have it completely rebuilt (with new gears, no grease) and sealed the unused pinion holes with rubber cement. I ran it last night and after a bit of a front end alignment, it runs beautifully. I also added kind of a skid plate I made out of a soda can to protect the gearbox and plastic underneath. 

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On 8/7/2018 at 1:15 PM, Pteppic said:

I'd recommend upgrading the F parts on a rally conversion, the "ra" F parts have 2 sets of holes to allow you to use a standard or higher ride height, and it is useful have the extra ground clearance in a rally car.

I've got a couple of M chassis cars, and all have been changed to the M-05Ra parts to give me the choice in the future.

Here's a handy link: https://www.ebay.co.uk/itm/Tamiya-51425-M-05Ra-F-Parts-Upright-M05Ra-Swift-Alpine-A110-Renault-5-NIP-/391767748615

Thanks, I went ahead and ordered the Ra 'F' parts. I'm going to keep the Yeah racing short shocks I currently have, they're pretty nice and still in decent shape...I think ground clearance is the big issue with taking the M-05 off-road. Still waiting on the rally tires to arrive. 

 

So, once I get everything put together, I'll have a skid plate I made to fit over the bumper and the bottom of the gearbox, Tamiya 60d block rally tires and extra ground clearance. Is there anything else that I need to worry about?

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So, I finally got the M05 RA parts and went ahead and installed them. It adds quite a bit of gound clearance, in conjunction with the block tires. I took it to a local baseball diamond that was relatively flat to try it out. Holy cow, what a blast this thing is on dirt! I couldn't believe how well the tiny wheels gripped. Now, I did end up stripping the spur gear because apparently I didn't set the pinion correctly. I've torn the car apart so many times now, that it wasn't a big deal to replace. I think part of the problem was I'm using a 15T motor, which really is way too hot for this model. I ran it again tonight and set the throttle end point to 70% and no break-downs. I even was able to keep pace with my wifes Kyosho Tomahawk in the dirt! As another poster pointed out, I did notice it tends to slow down quite a bit (diff out) on the turns but still great fun. Since I also run it on tarmac, I probably will just keep the differential as is.

 

Overall, very happy to have done this conversion. What's cool is that I can just throw the slicks back on it to run on the street. It's like 2 cars in one! :D

 

 

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Pleased it's all worked out for you!

Did you get the underbody protection sorted? Tamiya's official solution is part number 51426, they have to be cut and sprayed, but protect the front and the battery from flying rocks.  https://www.tamiyausa.com/shop/tamiya-goods/rc-m05ra-front-skid-plate/

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You can use some ride diff putty in the diff to get a fairly good LSD type action, once broken in with this putty it tends to let the diff rotate about once then starts to lock up in an almost elastic kind of fashion which means you still get initial turn in. Assuming you don't overdo it with the putty, downside is you must remove the grease in there first or the putty just slips off the gears.

The putty was designed with FWD M Chassis in mind. just be careful with it you don't need much, the 45 weight is heavy enough for 99% of applications.

in this picture there probably is a bit much for a M diff, about half that would suffice, takes a pack or 2 for it to bed in properly so you know how stiff it is. It'll seem nearly locked initially.

 47850F7B-9E2B-4FC3-B83E-8C9730DA1CB1.thumb.jpeg.511dbfb5f50e715caa5eac4d2c146c5f.jpeg

Juls

 

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Thanks everyone. I ended up not getting the underbody cover and it definitely fills up with dirt. I did use electrical tape on the bottom of the two chassis halves and unused motor mounting holes to prevent dirt from getting into the gear box. Unfortunately, some dirt does get in there through the motor vents and the gap where it mounts to the chassis. I’m running the gears dry as not to attract even more dirt, it also makes it easier to use compressed air to clean. Grease + dirt and sand = very bad

 

After I put the car up for the day, I take my air compressor and clean it the best I can.

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Glad it’s working out, RC rally is a lot of fun. Start saving your penny’s for a xv-01 now so you can pull off spectacular opposite lock  gravel drifts, it’s the only chassis that really handles just like you’d expect/want it to in that application. All the other 4wd layouts are boring by comparison. 

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Those look like cool little cars. Its a shame the price of tamiyas here has skyrocketed though...

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On 8/8/2018 at 10:45 AM, Juls1 said:

You can either use longer shocks on the stock uprights, or short shocks on the RA uprights. You can’t do both as the RA uprights put the dogbone lower and then you can’t drop the arm without the dogbone fouling, hence longer shock and ra uprights doesn’t work. I prefer longer shocks, as you gain suspension travel. The ra uprights you gain ground clearance but not suspension travel due to droop limitation. 

I’d lock the diff too, or you’ll be bogged most of the time. 

 

Could you explain how this works a little please?

I have some mini CVA shocks that are too long for my M-05RA but after reading your post I got the impression they might work if I switched to the standard uprights so I ordered some but the shocks are still too long. With the standard arms and CVA mini, the travel is worse in both directions!

ZQuLvZN.jpg

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6 hours ago, nowinaminute said:

Could you explain how this works a little please?

I have some mini CVA shocks that are too long for my M-05RA but after reading your post I got the impression they might work if I switched to the standard uprights so I ordered some but the shocks are still too long. With the standard arms and CVA mini, the travel is worse in both directions!

ZQuLvZN.jpg

Sorry I should have expanded,

you'll need to get the dremel out and relieve the C hubs from the arm to allow for more

However I used CVA Mini without the long eyelets fitted, the shock in the picture you've provided has long eyelets on it. Using the shorter eyelets will shorten the length by about 4mm so the extra travel of the CVA Mini can be used.I may have used different spring cups i don't remember.

I may also have used Tamiya 54583 which gives you a hinge pin point to connect the shock allowing for a longer shock.

Juls

 

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On 7/15/2020 at 3:24 PM, Juls1 said:

Sorry I should have expanded,

you'll need to get the dremel out and relieve the C hubs from the arm to allow for more

However I used CVA Mini without the long eyelets fitted, the shock in the picture you've provided has long eyelets on it. Using the shorter eyelets will shorten the length by about 4mm so the extra travel of the CVA Mini can be used.I may have used different spring cups i don't remember.

I may also have used Tamiya 54583 which gives you a hinge pin point to connect the shock allowing for a longer shock.

Juls

 

I'm currently building a M05 Kit, Street and Dirt, much like the OP did...

I was just going to get M05 RA F parts, but your method apparently gives more overall travel. 👍👍

Do you happen to have any pics showing how you modified the Chubs? Or is it just a matter of common sense grinding, until reaching the desired results? Also, wouldn't it be safer to grind on the A Arms? 

Sorry so many questions! Although I've been in the Hobby since early 1984... This is my first M05, and I'm here to learn its ins and outs. 😉

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4 hours ago, Carmine A said:

I'm currently building a M05 Kit, Street and Dirt, much like the OP did...

I was just going to get M05 RA F parts, but your method apparently gives more overall travel. 👍👍

Do you happen to have any pics showing how you modified the Chubs? Or is it just a matter of common sense grinding, until reaching the desired results? Also, wouldn't it be safer to grind on the A Arms? 

Sorry so many questions! Although I've been in the Hobby since early 1984... This is my first M05, and I'm here to learn its ins and outs. 😉

It's been awhile since I did it, you just need to look at where the restriction is in terms of getting droop, if you take the shock off and let it fall, you can see where the hub and arm touch each other, then you just take a bit off, if you have a really sharp knife you can slice some off, but you may cut yourself in the process. 
you might need to take a tiny bit off the upper part to let the dogbone through at the front. 

You'd also want a set of CVA Mini there built up to make sure you don't grind off further than you really need, all your trying to do it get a bit more droop to give you that extra clearance. At the end of the day though, the car is still darn close to the ground and has tiny little wheels, so you need to be realistic about your running surfaces.

for M05 I recommend either locking the front diff, or running some fairly stiff diff putty, if you run open diff you'll spend your whole life bogged. 

The M05RA uprights are a just bolt on job done situation, but they lower the dogbone in the arm so it restricts you from having more travel, the advantage of doing slight grinding and using Mini CVA as opposed to the stock super mini is that you also gain a little bit more travel which is welcome on a rally car.

Juls

 

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On 7/19/2020 at 2:13 AM, Juls1 said:

It's been awhile since I did it, you just need to look at where the restriction is in terms of getting droop, if you take the shock off and let it fall, you can see where the hub and arm touch each other, then you just take a bit off, if you have a really sharp knife you can slice some off, but you may cut yourself in the process. 
you might need to take a tiny bit off the upper part to let the dogbone through at the front. 

You'd also want a set of CVA Mini there built up to make sure you don't grind off further than you really need, all your trying to do it get a bit more droop to give you that extra clearance. At the end of the day though, the car is still darn close to the ground and has tiny little wheels, so you need to be realistic about your running surfaces.

for M05 I recommend either locking the front diff, or running some fairly stiff diff putty, if you run open diff you'll spend your whole life bogged. 

The M05RA uprights are a just bolt on job done situation, but they lower the dogbone in the arm so it restricts you from having more travel, the advantage of doing slight grinding and using Mini CVA as opposed to the stock super mini is that you also gain a little bit more travel which is welcome on a rally car.

Juls

Thank you!! I will be running CVDs. Hopefully that will allow as much travel as I can eek out of it. I had heard about the M05 RA limitations, which is why I was searching for a solution using the standard M05 Parts.

I'm looking for an affordable Diff Putty - that's IN stock. Don't want to lock it, as it will be an on-Roader as well. That brings me to the concern you mentioned... 

I'm absolutely aware that the performance of this platform will be seriously limited. I've got SCX10 IIs for my serious off-road needs! 😉

Isn't it interesting that Tamiya didn't figure out that in creating the RA, they actually ADDED restrictions to the suspension...

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Alot of people who race M03/05 run locked front diffs on the race track, I doubt it'd be a issue on the road, unless you where running Type A slicks or something equally sticky.

The M05RA parts, don't alter the stock suspension, but instantly give you 3-4mm more ride height, so it's more of a "bolt on" job done kind of situation.

Remember that M05 stock doesn't come with oil shocks, simply adding longer shocks doesn't work without physical modification, so from Tamiyas perspective those uprights made alot of sense, 

this being said while the RA uprights prevent you from getting more droop (arms going lower) the limitation of more travel is as much to do with the shock towers position, if the shock tower was taller then you could squeeze a longer shock in there for more up travel. But alas no such part exist. 

Juls

 

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16 hours ago, Juls1 said:

Alot of people who race M03/05 run locked front diffs on the race track, I doubt it'd be a issue on the road, unless you where running Type A slicks or something equally sticky.

The M05RA parts, don't alter the stock suspension, but instantly give you 3-4mm more ride height, so it's more of a "bolt on" job done kind of situation.

Remember that M05 stock doesn't come with oil shocks, simply adding longer shocks doesn't work without physical modification, so from Tamiyas perspective those uprights made alot of sense, 

this being said while the RA uprights prevent you from getting more droop (arms going lower) the limitation of more travel is as much to do with the shock towers position, if the shock tower was taller then you could squeeze a longer shock in there for more up travel. But alas no such part exist. 

Juls

AGAIN, very useful information Juls!! 👍👍

I suppose that Shock Tower Extensions could be fabricated... provided it still clears under the Body. I have a set of Yeah Racing 65mm Aluminum Shocks. IF I can fit them, that SHOULD improve Droop AND Compression, and provide better damping. 😉

As a Retired Auto Mechanic, I often apply 1:1 theories to 1/10th Scale. That said, a locked Diff in a FWD Car, would cause excessive Scrub Steer. Also, because one Front Wheel would HAVE to slip in a Turn.... it would certainly Increase Understeer. Something that FWD Cars already have too much of! 😲

I'm trying an experiment... reversible if it's a total FAIL. 

I've already done this on 5 other RWD and AWD Tamiya Cars. I cut pieces of Paper, just large enough to fit inside the Diff Housing.

I cut out the holes where the Output Shafts attach to the Diff Bevel Gears...

I then assemble the Diff as normal, but using a generous amount of Marine Grease inside. 

WHAT THIS DOES, is not only keep light pressure on the Diff Bevel and Spider Gears, but the Paper itself acts like Clutch Plates. It still allows one Wheel to spin faster than the other, but it will never let one Wheel spin like mad - whilst the other just sits still!! 😉 Similar to how a Positraction Diff is built in 1:1. I'm not 100% sure, yet.... but it's a sound modification, without consequences. It will definitely prevent getting stuck - simply because one Wheel is slightly off the Ground on an uneven Dirt Path!! 😜👌

I'm definitely avoiding the RA parts swap, for the reasons you stated. I've got the Front End assembled. With the CVDs, I've got a SIGNIFICANT increase in Droop! 

Shock selection, Tower modification/fabrication is next. 

I'm DOA, and cannot go any further, because I don't have D-Slot Dogbone Outputs to attach the CVDs TO.... And more critically, I don't have EITHER 5mm Shafts that fix the two Transmission Gears in place!! 😭😭

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Sounds like your having fun, the customization or mechanical improvements is ready makes Tamiya kits fun to work with. Especially when many parts swap between different chassis even when they are not included in a that particular chassis. 
 

the diff idea sounds good. I guess a wax paper might be the go for greater longevity? Just watch that heavy grease doesn’t escape into the gearbox and slow the whole gearbox down and potentially overheating your motor. 
 

not to mention making a mess in the gearbox. 
 

Juls

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Thanks so much @Juls1 😉

I'm definitely enjoying this one!!! I don't think I've built a Kit, Box Stock, in Decades! I really enjoy this aspect of the Hobby. Also, I battle with a lot of Disabling Injuries.... The act of Building Kits when I cannot get outside, I Work on my Rigs. By that act, RC actually keep me SANE!! 😲😞

I still can't believe that I'm completely STALLED, because of a few SMALL bits!!! 😖😠😠😠 I either can't afford them - or can not FIND them. 😞

On that note... I have an important question to ask, of all of you

My M05 front Driveline is bogged because I can't get the Diff Drive Cups! They are an odd size, what goes into the Diff is either an Oval - or a Circle, with a slice out of the top and bottom......

I'm not 100% sure how to describe it. NOW - the only other vehicle I've seen with these Diff Cups is, the XV-01. VERY scarce Parts resources...

The next closer is the TT-01 - but the Dogbone Cups are grotesquely oversized. They're made for those chunky Plastic Dogbones.

SO..... The OTHER type of Diff Drive Cup, with SPLINED Input Shafts, fit nearly 85% of all Tamiya Vehicles, w6

ith a Gear Diff.

THE QUESTION, WOULD  the Splined Diff Gears in my CC-01, just the Gears, fit in the M05's Diff Case/Drive Sprocket?? 😲

The Splined Drive Cups are SO MUCH EASIER to get than the ones I need for this M05 -  and Significantly easier to find. Someone MAY even have a spare set in their Tool Box!!😉😁😁 I really, REALLY need these

I also desperately NEED the two Rods that support the Bearings and the two Gears in the Transmission.

I hope that someone will be able to Help me! 😉

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Very likely, yes. Tamiya seem to use the same metal diff internals in a wide variety of cars. Certainly worth a try!

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13 minutes ago, TurnipJF said:

Very likely, yes. Tamiya seem to use the same metal diff internals in a wide variety of cars. Certainly worth a try!

Since I've got a CC-01 right here..... That would be an absolute dream solution!!! 😁👍👍  Thank you so much!

..... If only getting those two Transmission Rods was that easy. 😲  That one's been very frustrating! 😖😡😠

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