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bugster_man

M06 brake lock-up and right spin

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Hi guys,

I do have a Tamiya beetle with the M06 chassis. I bought that one used and it had been a shelf-queen all of its life. All my cars do run, so I installed all needed to drive it. But it has one issue since the time I had it and I hope you can enlighten me on a solution:
whenever I drive higher speeds and do braking, it makes a hefty right turn and completely turns around by 180 degrees. This makes the car uncontrollable and hence it simply is zero fun driving it.

What I have done so far:
- bought new tyres to avoid they would have a flat sport from standing on the shelf for years
- bought new wheels to avoid they are un-balanced
- dis-assemlbed and re-assembled the wohl chassis front and rear and carefully re-assembled everything double and triple checking every measurement
- installed a bag of M10 nuts on various positions of the car to pack some weight and see if that creates a counter momentum
- installed Tamiya aluminum hop-up dampers. 
- changed damper oil front soft, hard rear and vice versa
- toyed around with spring options (hard / soft)
- installed YEAH Racing aluminum long wishbone upgrade

Zero change. Whatever I do, I get the same effect. It drives me nuts.

 

 

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I feel your pain! 😁 The M-06 definitely takes a little finesse to get the most out of it. Being rwd as soon as you hit the brakes it's like pulling on a handbrake which is magnified by any toe you have set in the front wheels (angle off center). I found mine best with completely neutral steering, soft rear springs and light oil, harder front springs and heavier oil plus soft initial brakes on the speedo. Neutral steering minimises any spin, soft rear allows the back to roll and grip, a stiffer front alleviates the pitch forwards and lightening of the rear keeping weight transfer to a minimum. Once you have the hand of it they're ace to drift about. 

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Hi,

thank you so much.

I'll definitly will follow your advice especially going hard front and soft rear to keep weight distribution to a minimum. I'll try, but what puzzles me is, it always turns right. If the problem is the wieght distribution and loosing grip on the rear axle under braking, I would have expected it turns sometimes right sometimes left depending on street surface conditions. 

Adjustiung the steering is a good proposal too. So far I had it setup completely as the build instructions of the M06 suggested. I'll toy around with it altough I have to admit I'm comparibly new to RC cars and have limited to no experience in making sure the measures are correct. We'll see how that works out

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So this is transfer of power under braking, effectively, above all else. The only real component there is the differential itself. Are you running with the kit gear-diff? Is it just greased as standard, or have you tried a heavier grease?

I'm thinking what's happening is a bit like the opposite effect you get from an open diff when accelerating hard - ie. a single-tyre-fire where it sends all the power to one wheel only through the path of least resistance - usually the inside wheel. 

In my head at least this makes sense. Try packing the standard diff with some heavier grease or gear diff putty (don't bother buying the latter if you don't already have it - it's basically no better than using blu-tac!).

If that doesn't work, perhaps a ball differential could be your next hop-up?

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A programmable ESC will definitely help, as mentioned above.

Set a 10% drag brake, then full brakes at 25%. This should help you stop in a straight line. 

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24 minutes ago, ChrisRx718 said:

So this is transfer of power under braking, effectively, above all else. The only real component there is the differential itself. Are you running with the kit gear-diff? Is it just greased as standard, or have you tried a heavier grease?

I'm thinking what's happening is a bit like the opposite effect you get from an open diff when accelerating hard - ie. a single-tyre-fire where it sends all the power to one wheel only through the path of least resistance - usually the inside wheel. 

In my head at least this makes sense. Try packing the standard diff with some heavier grease or gear diff putty (don't bother buying the latter if you don't already have it - it's basically no better than using blu-tac!).

If that doesn't work, perhaps a ball differential could be your next hop-up?

good one ! I'm running the standard diff from the kit but have no idea what grease it runs. I'll give it a shot, as this reminds of some other effect, which isn't critical: if I run the car inside on the wooden floor (no tarmac, no carpet) it also turns right. This means under acceleration it transfers most / all torque to the left rear wheel, under braking more torque goes to the right wheel. Sounds like a diff issue. I'll check. All of that still with the standard motor that comes with the kit. 

But honestly: I'm not too happy to spend more money on more hop-up options on the diff. If I can't solve it on this chassis, it might be better off buying a real race chassis, create some body fixtures for th beetle body and then run brushless. And then invest in a proper ESC.

 

 

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M-06 is notoriously difficult to set-up, as was the M-04 before it.

If you get a ball diff and have an interest in M-chassis cars, I believe I'm right in saying that it should have the same 39(?) tooth diff which will be transferable to an M-05/M-07 Front-Wheel drive chassis. I think.

I also really hate working on my M-06. It's my least-favourite Tamiya, everything feels like an afterthought (threading the servo wiring under the battery via a recess in the chassis - Whats that all about then??! And the amount of screws requiring removal in order to adjust the slightest thing). 

An M-04 is resplendent in its' simplicity compared to an M-06!

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8 minutes ago, ChrisRx718 said:

M-06 is notoriously difficult to set-up, as was the M-04 before it.

If you get a ball diff and have an interest in M-chassis cars, I believe I'm right in saying that it should have the same 39(?) tooth diff which will be transferable to an M-05/M-07 Front-Wheel drive chassis. I think.

I also really hate working on my M-06. It's my least-favourite Tamiya, everything feels like an afterthought (threading the servo wiring under the battery via a recess in the chassis - Whats that all about then??! And the amount of screws requiring removal in order to adjust the slightest thing). 

An M-04 is resplendent in its' simplicity compared to an M-06!

I can't agree more ! Although I have no experience in M-chassis other than the M06. I'm coming from the real beetles (having a bunch of them) so hence I like the really well designed Tamiya Beetle bodied RC cars, as they look really cool. Therefore I like the M06 with th ebeetle body a lot, as it has, like the real car rear engine and RWD. And as this car had been painted in exactly the same colour like one of my real beetles, being cheap, being in my neighbour village and never been driven, I just had to have it. So here I am with the M06 :-)

But compared to my Blitzer Beetle running brushless, the M06 feels like a POS (sorry for the wording). The Blitzer has zero problems with all of that once roughly adjusted

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Before you give up with it try much stickier rear tyres than the front.. I really like mine, it's one of my favourites! Still, different strokes for different folks and all that 😁

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It might also be that the chassis just "wants" to be used differently.

I have both an M-04 and M-06 in my fleet. Both were really difficult to drive in on-road configuration no matter how much I fiddled with setup. However the M-04 makes a brilliant miniature stadium truck, and the M-06 is an outstanding rally car. Maybe your Beetle just wants to follow the example set by its full size Baja brethren, and go off-road?

 

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ok, I took it apart, changed the grease from molybdenum to Tamiya ceramic grease, switched the diff left to right, double and triple checked all components, interchanged the bearings, changed damper oil on the rear to Tamiya 200 (softest I have), changed spings to soft, adjusted the chassis best I could. What should I say: spins to the right.

I'm close to speechless. Now I changed spings soft on the left sid, hard on the right side. Still same effect.

When I toy around with the trim and make it turn left when it's supposed to go straight, it seems easier to handle and seems to do this right spinning much less. But then again, it's not running in a straight line

Looks like there is a reason why this vehicle had been a shelf queen all its life. So eventually will end up as shelf queen on my shelf also.

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Wow, that doesn't sound right! One last thing to check. Place the car on a flat surface and look at it from the rear at eye level. Check that the wheels both leave the ground at the same time if you slowly lift it from the middle at the back. A pencil under the motor is good for this. Your looking to see if the chassis is "tweaked" or if one wheel drops / drops lower than the other. I'm sure on one side of the M-06 the upper suspension arm can catch on the chassis at full extension limiting wheel travel on that side. If so just add a small washer or two internally on the rear damper shaft so that they both extend the same. 

If that's not it, crack open the polish, buff it up and sling it on the shelf! 😁

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Do you mean it goes right even if you're going in a completely straight line and then brake hard? I guess you've ruled out any issues with the electronics? (eg unplug steering servo and make sure it's not doing something strange on braking).

Otherwise Grotty Otty's idea to check chassis and suspension travel makes some sense, but with a fairly open diff I'd have thought that even if one wheel lifted clear of the ground, it'd be braking fairly evenly on both sides... If the diff is relatively stiff then the left wheel lifting more, and so gripping less, as the rear suspension lifts could cause it to brake on the right rear and veer right.

My only other thought is to check that the wheels are both turning completely freely as the suspension lifts. Could a driveshaft be catching or something? Or could anything (a wire or anything) be moving forwards under braking and catching or rubbing on a wheel or driveshaft?

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Hi,

thank you! I'll definitely try the suggestion of disconnecting the servo and trying to see if both wheels lift the ground at the same time.

In any case I gave it some hefty toe-in on the front and that does seem to heavily improve things !

i checked of course first if it runs in a straight line. The trim at the remote is set to 0 and it does run in a straight line. With strong toe-in then things improved. This is definitely much more toe in, than it would have being build according to build instructions, but hey, if it does the trick, then I'm all in for it.

In terms of wheel travel being free: yes they do travel free. I had to check everything to make the YEAH Racing axles realy travel free. If you mount that kit accoring to instructions, it will touch in many spots; e.g. ball pins on the front will touch at the body mount bracket so I needed to cut some at th ebracket etc. No it moves completely free with the stop / limit of travel being the dampers. 

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Hi Bugster,

I´m on the same route and have a real (aircooled) beetle and the Tamiya ones since M02.;)

First, you cannot really compare a Blitzer to an M-Chassis. Track width, Tire sizes and  wheelbase are much bigger, so everything is slowed down on the big beetle. M-Chassis are small and have usually to deal with the same engines in a much more smaller chassis. M06 is one of the best RWD M-chassis Tamiya ever made, and I much prefer it drivewise over my M04 and M02. Grip conditions are really important. On a well prepped carpet track, the M06 can be a beast. On low grip conditions like on dusty, public roads, it can be a nightmare to drive, as every RWD chassis that lacks grip. Remember, you don´t have front braking on this size cars. I usually reduce my brakes on the Speedo and the Transmitter to be able to do some emergency braking, which means reducing speed in a straight line, depending on the conditions I run on. Modern Electronics leave you many choices like ABS and reducing maximum brake power. Even if you cannot reduce speed as effective as with a FWD (or 4WD) car, you don´t have to be afraid to loose the rear under braking. Always try to go as straight as possible, when you hit the brakes. Braking in curves will let the car turn in more, and will end up in a 360° when grip is too low. (Of course you noticed already)

I fully agree with you, that your car has a problem always wanting to turn in right. The diff itself will deliver power equally left right on the outdrives with the standard design. So you could further check, if the bearings left to right have an equal resistance on the rear axle, or slow down one side more than the other. Replacing moly grease with the Tamiya ceramic grease makes the diff resistance even more "open", that was the opposite you aimed for braking wise. I propose to use the Tamiya Anti wear grease. (clean out all the light grease before applying). A modern M-Chassis needs a oil filled gear diff in my eyes, which can be locked by using silicone oil. That gives you a constant working diff over a long time period without maintenance. Even Tamiya came to that conclusion and M07 and M08 use the FF03 diff now. I have it on my M06 as well, it´s one of the real useful tuning parts, that make sense. Leave out the blue alloy bling parts all around that often do nothing as reduce your wallet.

Probably you have no equal static weight distribution or a tweak by uneven damper lengthes or spring preloads. A corner weight scale would identify that if used properly. Lifting the axles as explained before is cheaper and does the same. Do you have any pics of your chassis? And what electronics and motor you use? For the tires, I would propose to stay with the S-Grips on rear and the radials on front, if you still have the kit tires. Profile is the same, just check the lettering on the side. (Just saying, as you say you bought it used and it was a shelf queen. Maybe tires are some display stuff.

If you want a good diff, I can recommend the 3 Racing one for price and reliability (even has aluminum outdrives with plastic shoes for the drive shafts), or you checkout my tutorial for Building a oil filled gear diff from Tamiya parts. (more expensive).

Have fun with your big and small beetle,

Aircooled greets,

Matthias

 

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Hi folks,

I have it under control and it works now. So thank you all for the valuable tips and even more giving me th emotivation to keep hanging in there.

Reason for the strange behavior: all of the above and more. Really.
(1) diff seemed to lock up
(2) left wheel left ground (table) much earlier than right wheel
(3) Yeah Racing studs for the ball head are too long and start scratching the outer drives leading to uneven torque distribution left/right
(4) 2 akku packs of adjusting front axle settings for toe-in and camber
(5) Steering servo did seemingly have a problem. Installed a Futaba 3010 now
(6) fiddling around with the settings on my remote (FS-it4s clone), as it allows me to have softer torque build-up of the motor 

And while test driving, I did hear a knackering sound from the gearbox internals. Not good. Main gear had one tooth heavily damaged so installed new now. And I fancy I'll follow your advices on installing an aftermarket diff. Because now with all the mods, the performance is simply stunning. Even at full speed, you can turn in and it very easily follows. If only I would be a better driver, I'd imagine this to be really good fun when going fast.

 

@Matthias: sounds like a partner in crime :-) What kind of real-deal VW do you have?

 

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16 hours ago, bugster_man said:

Hi folks,

I have it under control and it works now.

Reason for the strange behavior: all of the above and more. Really.
(1) diff seemed to lock up
(2) left wheel left ground (table) much earlier than right wheel
(3) Yeah Racing studs for the ball head are too long and start scratching the outer drives leading to uneven torque distribution left/right
(4) 2 akku packs of adjusting front axle settings for toe-in and camber
(5) Steering servo did seemingly have a problem. Installed a Futaba 3010 now
(6) fiddling around with the settings on my remote (FS-it4s clone), as it allows me to have softer torque build-up of the motor 

And while test driving, I did hear a knackering sound from the gearbox internals. Not good. Main gear had one tooth heavily damaged so installed new now. And I fancy I'll follow your advices on installing an aftermarket diff. Because now with all the mods, the performance is simply stunning. Even at full speed, you can turn in and it very easily follows. If only I would be a better driver, I'd imagine this to be really good fun when going fast.

 

@Matthias: sounds like a partner in crime :-) What kind of real-deal VW do you have?

 

Great News Bugster Man!

I knew you would find the issue, usually beetle drivers nowadays have a good hand for technical things, too.:D

For your main gear problem, this can happen also during a hard crash, if the wheels cannot slip enough. With the rear Motor, M06 offers very good traction. I killed one or 2 Spur gears during races since 2010. Have an eye on the adjustment of the pinion clearance from time to time, that´s all you can do. I´m still not really sure, if the black reinforced gear set is really stronger than the yellowish original set. But for sure it should be no Downgrade, if you order a new one.

My real beetle is a 1974 "Jeans bug", which I bought 1996 from the girlfriend of my mother. So I restored it with my dad until 1998, and did some Upgrades over the years. Today I finished my rework of the engine, which I had to tear down 2017, because I got some friction in the crankshaft somehow. I have new TÜV since today and am quite happy to have my Little friend back. Due to Corona regulations in Bavaria, there´s no driving around for fun allowed, so I have to make my run in turns and adjustments driving to shopping, refuelling etc. Strange times!

I´ve one pic of my beetle in my showroom:

https://www.tamiyaclub.com/showroom_model.asp?cid=120588&id=34024

And what is you aircooled baby? Some oldschool 60`s bug maybe, like the Tamiya model? Just guessing. Have to admit, that I like all beetles from split window to the late 1303`s. I´m in a beetle club since 1996, so we have cars of nearly every model year in our club!

Stay healthy,

and great to have a "partner in crime" here on TC,

Matthias

 

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Glad to hear you got it sorted out!  It’s a fun chassis if you spend some time with it.  I’ve given my M06 the treatment and while it definitely isn’t as simple to drive as something like the M05, it’s much more rewarding when you get it right.  I also appreciate Tamiya releasing the Karmann Ghia and Bus to add to my RR Arsenal.  
 

I am probably alone in this, but M06 is my 2nd favorite Tamiya chassis (SRB being #1).

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