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Badcrumble

M Chassis Damper set-up

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I recently bought some 50746 CVA Super Mini shocks to go on my M chassis cars and am preparing for an M05-RA build.

Oil shocks bring three variables to consider – oil, pistons and springs.

The pack comes with oil (I haven’t checked the weight of it)– given that these are for the M chassis / TT cars, I see no reason to use anything else.

How about pistons and springs?

My default would be 2 hole pistons (but my random googling suggested that three holes theoretically gives more balanced damping) and the kit springs?

Or should I be looking at soft springs form  Tamiya 53333 spring tuning set (short)?

I am not a racer, these will only be run on asphalt or loose gravel.

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When in doubt, I always go for the softest.  (M-Chassis require different settings, front and back)

Since M05 has no weight at the back, I'd set the rear softest. Then a step harder for the front.  This often means no-oil for the rear. (Just because it's there doesn't mean that it's best to use it)  My Hornet uses just one O-ring for damping for the front, and that's enough.  Oil shocks have an O-ring, and for the light rear of M05, that's enough.  Even so, I chose 4 holes for easier air movement.  I use 4 holes for the front, and often use supplied oil to start.  Then the test begins.  I drive over a little bump in the kitchen.  First, I'd back up, to see how the rear jumps. 

With oil, it jumped too high.  It wasn't absorbing enough shocks; meaning it's too stiff.  After draining the oil, it jumped only half as much.  (If I had softer springs, I might have tested them)  Then, I drove the right way to test the front.  The front didn't jump much.  It absorbed enough, but bounced in a wobbly fashion once it landed.  It was too soft.  I forgot if I used harder oil or pistons with less holes.  At any rate, the front and rear jumps about the same now, forward and backward.  This was with 55mm Yeah Racing shocks, so it might be different with Tamiya mini. Also M05-Ra has cushier tires, so that might change things, but the principle should be the same.  Shock absorbers should absorb the shocks, not repel the shocks.   

Bump test works good for the gravel.  If I were to use it exclusively on-road, the bump test gets you only to the ball park. 

Springs, I think stock springs work the best.  

 

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M05 RA can be a great little rallye machine. The onroad tuned springs are a little too hard, if you want to go slightly offroad and soak up some bumps . I used the M04/M08 front springs for my M05 RA Renault 5, which have a golden color. M08 reuses it now even for the rear axle. These are even softer than the red ones coming with the 53333 set. Then I would use 3 hole pistons, and a soft oil, like Tamiya 200 or 300, something in that range. And there is a difference between friction damping and oil damping. The Tamiya CVA´s can be really built to work buttersmooth by using higher quality O-rings, like the Tamiya clear ones or something comparable from other parties. With only friction, you do not catch the chassis movement when doing bigger jumps, and you prevent the axle from starting to move initially. You don´t want a stick slip effect, but instead being able to move the piston rod slowly with minimal force. If you move the piston rod quicker, the oil and the pistons increase the force automatically. Doesn´t make sense to me, to run the good CVA´s without oil. I don´t say that Superluminal is wrong, I think he just couldn´t adjust the Yeah Racing Shocks weak enough for the chassis weight. There´s still the option, to enlarge the holes in the piston and find thinner oil, so to say. 

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Thank you @Juggular and @ruebiracer, whilst your methods are slightly different, I think you both agree that soft is the way to go with more, rather than less, piston holes.

I had found a more on-road set-up guide for the M05

https://www.thercracer.com/2017/07/tamiya-m05-v2-guide-mods-tuning-and.html?m=0

and I would say that your method, @ruebiracer, takes the asphalt set-up sheet and moves it in a more rally direction, for loose rough stuff rather than the road.

When you mentioned the gold M04 springs, I take it that they go on the front of the RA, the motor laden end as the red go on the set-up sheet?

As I have a couple of damper sets, I am tempted to build them slightly differently (perhaps different oil weights) and run progressively softer set ups to see if I can tell the difference. 

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9 hours ago, ruebiracer said:

You don´t want a stick slip effect, but instead being able to move the piston rod slowly with minimal force

I agree.  

I forgot to add "leaving a drop of oil." (as I did in other posts)  You are right, you never want the rod to stick to the o-rings.  With a drop of oil, it will move smoother than cylinder full of oil because no oil is thinner than air.  CVA has 2 o-rings per cylinder.  With a drop of oil, those should give enough friction for the lighter side of M05.  I'd put in a drop of oil to see how it bottoms out.  Usually, it'd be several inches.  If you are going to jump beyond that, you'd want oil.  Widening holes on the piston is also a good idea.  

 

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13 hours ago, Badcrumble said:

Thank you @Juggular and @ruebiracer, whilst your methods are slightly different, I think you both agree that soft is the way to go with more, rather than less, piston holes.

I had found a more on-road set-up guide for the M05

https://www.thercracer.com/2017/07/tamiya-m05-v2-guide-mods-tuning-and.html?m=0

and I would say that your method, @ruebiracer, takes the asphalt set-up sheet and moves it in a more rally direction, for loose rough stuff rather than the road.

When you mentioned the gold M04 springs, I take it that they go on the front of the RA, the motor laden end as the red go on the set-up sheet?

As I have a couple of damper sets, I am tempted to build them slightly differently (perhaps different oil weights) and run progressively softer set ups to see if I can tell the difference. 

Yes, you´re right! As I bought my first M05 it was the R5 RA spec, and I used it as a sunday racer on rougher Terrain or normal streets, as the intention of the Rally cars is. If I remeber right, I put the gold spring front and rear, but you can for sure mix with the red one, to change the handling. I´ve adapted mine later on to onroad spec, as we started our M-Chassis racing class some years ago. I often liked the harder spring in rear, as it gives more steering in front. So you don´t have to focus strictly on the old rule "stiffer spring to the heavier side of the car". On a FWD, everything is a little different tuningwise. Just try out, what is the best compromise for you on bumps, steering feel, and driving fun.;) And the most important thing: Try getting an oil filled gear diff, e.g. the 3-Racing one for M05/M06. Bombproof, Aluminum outdrives with plastic blades. Fill with 20k oil, which will give you a decent limited slip effect. Car will be more stable on braking,  acceleration will improve drastically out of corners. Especially on low grip Rallye tracks. Every modern FWD Rc Car uses such type off differentials for serious racing. Best thing is: It´s very reliable. During my mini racing Seasons with my M05, I only refilled a slight amount of oil before the start of the new season.

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GreenSlime your 'Os before inserting the shaft fellas!

yokomo-c-1105a-green-slime-by-associated

Don't do the deed without the proper lube.

 

 

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4 hours ago, ruebiracer said:

.;) And the most important thing: Try getting an oil filled gear diff, e.g. the 3-Racing one for M05/M06. Bombproof, Aluminum outdrives with plastic blades. Fill with 20k oil, which will give you a decent limited slip effect. Car will be more stable on braking,  acceleration will improve drastically out of corners. Especially on low grip Rallye tracks. Every modern FWD Rc Car uses such type off differentials for serious racing. Best thing is: It´s very reliable. During my mini racing Seasons with my M05, I only refilled a slight amount of oil before the start of the new season.

Thank you for that, I will investigate...

@WillyChang, I have some SRAM butter which should do the same job - it is meant for MTB fork seals. Has worked on my CVSs so far (not that they get much use!).

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I've been running 3 holes with the yellow oil. I also use the #53333 spring set. Yellow spring on the heavy end of the car and red on the light end. Good enough for playing around in the street which is pretty rough.

I have to try out the Associated Green Slime. Gets a lot of positive reviews.

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1 hour ago, Otis311 said:

I have to try out the Associated Green Slime

I found that Green Slime makes it sticky.  O-rings do seal better.  For heavier off-roaders with vintage o-rings, that's what you'd want.  But for on-roaders, I'm not a fan. It would make the piston rod stick to o-rings.  

 

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6 hours ago, ruebiracer said:

I often liked the harder spring in rear, as it gives more steering in front. So you don´t have to focus strictly on the old rule "stiffer spring to the heavier side of the car".

Good thing you brought up.  Once again, I agree.  

In my opinion, off-road setting should be softer (up to the point where bottoming out becomes a problem).  Generally, stiffer suspensions produce sharper steering.  But softer suspension turns better off-road because it allows the tires to stay in contact with the surface longer.  On road, tires are basically guaranteed to stay in contact, so you can afford to make the suspension harder.  But if off-road suspension is too hard, the tires just bounce off the surface. That gives less contact-time, thus erratic steering.  

 

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4 minutes ago, Juggular said:

Good thing you brought up.  Once again, I agree.  

In my opinion, off-road setting should be softer (up to the point where bottoming out becomes a problem).  Generally, stiffer suspensions produce sharper steering.  But softer suspension turns better off-road because it allows the tires to stay in contact with the surface longer.  On road, tires are basically guaranteed to stay in contact, so you can afford to make the suspension harder.  But if off-road suspension is too hard, the tires just bounce off the surface. That gives less contact-time, thus erratic steering.  

 

Totally on your side, Juggular, good Explanation!

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When I was younger I thought I needed to run my shocks as hard as possible. All I was thinking about was hitting little jumps and bottoming out. I finally saw the light when I set up my Blitzer Beetle as soft as possible. The thing flies across my stone driveway with its tires shooting up and down but the body barely moves. What a beautiful sight.

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27 minutes ago, Otis311 said:

When I was younger I thought I needed to run my shocks as hard as possible. All I was thinking about was hitting little jumps and bottoming out. I finally saw the light when I set up my Blitzer Beetle as soft as possible. The thing flies across my stone driveway with its tires shooting up and down but the body barely moves. What a beautiful sight.

Same for me! As a kid I also raked my buggies as high as possible to get clearance and try to prevent bottoming out. But as you say, the car needs stroke in both directions to be settled, and sometimes it´s better to just let it bottom out.

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3 hours ago, Badcrumble said:

Thank you for that, I will investigate...

@WillyChang, I have some SRAM butter which should do the same job - it is meant for MTB fork seals. Has worked on my CVSs so far (not that they get much use!).

If you want, you can also built such a diff for M05/M06 from Tamiya parts. But it´s more expensive than getting one from e.g. 3 Racing:

https://www.tamiyaclub.com/showroom_model.asp?cid=130513&id=34024

Displayed for M06, but M05 is identical regarding gearbox internals.

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