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TurnipJF

Stiff diff - how best to drive with it?

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As those of you who frequent the build section will know, I have recently finished putting together an M-07. It has a sealed gear diff filled with thick oil, which is a fair bit stiffer than the unsealed AW greased M-05 diff that I am used to.

At first I thought I could set the new car up to act like it's predecessor, but that is clearly a non-starter due to the very different diff actions that they possess.

I know stiff diffs are meant to give an advantage in a front wheel drive car, as some people go as far as fitting spools. Does anybody have any tips as to how to get the best out of the M-07 diff arrangement?

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I've got no answer.  I was looking to get a cheap M05.  Now I want M07!  It looks very good.  Why, oh why must you do this to me, Turnip?  

Would you be so kind as to tell me M07 is horrible when compared to M05? (So I could settle with cheaper M05?) 

(Or you could tell me that it is worth every penny.  In which case, I must go with M07.) 

5OXsZIf.jpg

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@Juggular you know the answer, get both and compare yourself!

I run 1M oil upfront in my TA07 and find I can just drive out of corners, no wheelspin at all. It just works. In saying that I have tried 7k, 3k, 2k and 1k in the rear diff and that made a big difference. I settled on 2k I think in the end. I assume the rear of the M07 just follows the front though so thats irrelevant.

How does your M07 drive? Any wheelspin? What weight oil did you use?

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@Juggular

I cannot tell you that the M-07 is a terrible car, but I can't really tell you that it is a great one either quite yet. I still need to learn how to set it up before I can get the best out of it. It looks like it has massive potential though, sharing design ideas and materials with the latest TA and TB touring cars.

I can however say that the M-05 is a lovely little car to drive once you have it set up properly. It has a few quirks, such as the multi-part chassis needing a good few laps to settle down before it can be set up without tweaking, and of course it benefits from the usual Tamiya upgrades such as bearings and oil shocks, both of which come as standard with the M-07.

Either way I don't think you will be disappointed. If you want something fun and cheerful that can also be raced at club level, go for the M-05. If you want to take racing quite seriously, go for the M-07.

 

@Jonathon Gillham

The M-07 can easily be made to take off with a bit of wheel spin, as is to be expected from a front wheel drive car on 13.5t and I don't think that this can be avoided through set up. I simply need to be careful with my throttle finger.

It doesn't "diff out" though. When the wheels spin, it is both of them.

I am using the stock diff oil which I believe is 5k or thereabouts.

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Here are my experiences with the m-07. I run the M-07 last year in our club championship in the class m-chassis 2wd and became club champion.The plastic differential gears lasted until the second race, then they were broken. I replaced them with the available steel gears and also replaced the differential cover with the one made of aluminum to improve the sealing, because half of the diff oil was in the gearcase. I used the kit oil in the diff. As motors were 23t brushed mandatory (carson cup machine) and i used the robitronic iCube esc, as this offers the possibility of the function auto-roll, which eliminates the braking torque of the motor when you lift the throttle, because the car oversteered heavily at initial turn in and auto-roll has eliminated that. Springs front hard and rear very soft, tires sweep 40 in front and sweep 33 or 25 rear . Track was black ets carpet with different layouts. Stabilizer front only, heatsink and a 25x25 fan between motor and battery were there is a special place made for it. No gear case covers or plugs, i closed all holes in the gear case, bottom and side with reinforced tape.
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The M07 is in a totally different league to the M05 for onroad racing.

the stiffer front differential will make the car have even more understeer into the corner. However you will get a huge amount of benefit out of the corner.

 

So just ensure the front suspension is not set to me initially harder than the rear, and check the roll centre. 

 

Also yoir droop settings will make a huge difference on corner entry and initial launch. 

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3 hours ago, qatmix said:

The M07 is in a totally different league to the M05 for onroad racing.

the stiffer front differential will make the car have even more understeer into the corner. However you will get a huge amount of benefit out of the corner.

 

So just ensure the front suspension is not set to me initially harder than the rear, and check the roll centre. 

 

Also yoir droop settings will make a huge difference on corner entry and initial launch. 

Interesting. Thanks for the info!

At the moment I have yellow springs at the back and blue at the front. I was thinking of going for red at the back. But you say I shouldn't have the front harder than the back? Should I perhaps swap the front and rear springs?

Also what would you suggest I do to the droop settings? Minimal droop I'm guessing?

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6 hours ago, a.w.k. said:
Here are my experiences with the m-07. I run the M-07 last year in our club championship in the class m-chassis 2wd and became club champion.The plastic differential gears lasted until the second race, then they were broken. I replaced them with the available steel gears and also replaced the differential cover with the one made of aluminum to improve the sealing, because half of the diff oil was in the gearcase. I used the kit oil in the diff. As motors were 23t brushed mandatory (carson cup machine) and i used the robitronic iCube esc, as this offers the possibility of the function auto-roll, which eliminates the braking torque of the motor when you lift the throttle, because the car oversteered heavily at initial turn in and auto-roll has eliminated that. Springs front hard and rear very soft, tires sweep 40 in front and sweep 33 or 25 rear . Track was black ets carpet with different layouts. Stabilizer front only, heatsink and a 25x25 fan between motor and battery were there is a special place made for it. No gear case covers or plugs, i closed all holes in the gear case, bottom and side with reinforced tape.

Thanks for the tips!

At the moment I have a bit of drag brake set on my ESC. Your comment regarding auto-roll suggests that I should turn it off? 

Which stabilizer did you use at the front?

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hmm... oversteer, understeer, front hard, not hard... I'm getting conflicting information.  

Could this mean that M07 is highly adjustable?  

 

 

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It is certainly the most adjustable M chassis Tamiya have released so far, which can be a bit bewildering to those of us used to M-03s and M-05s...

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8 hours ago, TurnipJF said:

At the moment I have a bit of drag brake set on my ESC. Your comment regarding auto-roll suggests that I should turn it off?  

Which stabilizer did you use at the front?

First i have say that these are my experiences with the M-07 and maybe they are conflicting with other racers opinions, but this worked for me last season.

I think you should try to turn the drag brake off, but as you use a brushless setup you don't rely on to keep the speed through the corner as much as a low power brushed setup that has to keep the momentum through the corners and brake as little as possible.

Maybe the oversteer in my car has had something to do with the body i used, the ride Subaru BRZ, with its massive frontlip causing downforce infront. But it was the fastest body on the straight. Front springs i used were he yellow ones from #49382 and rear springs the red ones from #42168, that were used with the CVA shocks. Front stabilizer i settled for the blue one and the rear got disengaged. We had to run 55mm tires.

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Yellow at the front and red at the back is the spring combination I use on my M-05, and it drives superbly. However that is contrary to qatmix's recommendation of avoiding a harder front. Interesting...

Perhaps the two of you have very different driving styles? How do you typically approach a corner, how much throttle do you hold and when do you start accelerating again?

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Yeah, that would be possible. I like racing with low power equalized racing cars and some of my fellow racers stated that i am on a different line around the circuit ^_^. I try to brake as little as possible and to keep as much as possible momentum through the corners. My goal is to keep the biggest radius possible through the corner, approaching as much on the outside as possible, then passing the apex as near as possible and accellerate. Like those old tables in the guidebooks suggested it....:)

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The shell will make a lot of difference. I would first move the shock positions and then make the springs softer.

I would not run softer springs on the front than the rear, but would go to running the same front and rear. 

Droop, I would go for 1mm more downstop value at the front than the rear. Usually 5 front and 4 rear is a good starting point. This will give you less weight going forward when off power, you can then tweak it to help make the car feel responsive.

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12 hours ago, qatmix said:

The shell will make a lot of difference. I would first move the shock positions and then make the springs softer.

I would not run softer springs on the front than the rear, but would go to running the same front and rear. 

Droop, I would go for 1mm more downstop value at the front than the rear. Usually 5 front and 4 rear is a good starting point. This will give you less weight going forward when off power, you can then tweak it to help make the car feel responsive.

I will try out your suggestions for sure, because you have much more expertise in car setups than me, whenever i build a car, i go to thercracer.com to get tips for setup and build. I have seen the M07 is in the queue, so i am looking forward to the report.

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M07 is a great chassis, although I tend to say that M05 cannot   compete with it when having a good setup and a proper oil filled gear diff. Nevertheless, build and Plastics quality is higher, and the kit Equipment is more luxury. You can go racing out of the box. And me and my fellow racers agree in the meaning, that it is easier to drive consistent, let´s call it "easy driving". :lol:

The kit  diff oil is 100.000, but do not take that too serious. the locking effect depending a lot on the design off the diff as internal gear sizes, stiffness of sealings, filling amount and so on. If in doubt, turn one front wheel and feel the resistance. On my M05´s, I ended up often with 20.000 oil in a 3 racing diff, which feels quite similar to my M07 diff with 100k, as the internal gears are much finer on M07. In 2 years of M07 racing, the diff is oil tight as no Tamiya diff I had before, using the orange o-rings and the optional aluminum outdrives. You get blades and minimal wear on the outdrives. Setupwise, there is no mandatory way I think nowadays. Many of my Mini friends use quite different spring or stabilizer combos. My favourite setting is red (black) spring front, sometimes yellow, and blue in the rear. So hardest on the back, but the softer spring set as it Comes in the kits of M06 Pro/R, M05 R and M07. This with LWB and my VW beetle shell. On a Mini with 2WD, body is not as important as on a 4WD top racing car in my eyes. It just has to fit to the setup. (But we forbid real Mini race bodies, only Tamiya and scale looking ones from other manufacturers). 

For driving style with a more locked front diff, you have to back off earlier before the turn, to not come into off power understeer too much and lose ground by going too wide, but then go earlier on the throttle as the car will have a lot more turn in on power and pull you into the desired direction. You will learn that driving style easily after some batteries. But that is also required on a M05 or M03 with locked diff, nothing M07 "special".

Most important Thing on Mini is fun and scale Looks for me and my Friends. It is intended to be an opposite to the other race classes we compete in.;)

If you want to buy a new Mini this days, I Always recommend the M07, especially for beginners. It takes square batteries, has the oil filled diff, cardans, oil Shocks and adjustable camber and toe. And the kit setup is very forgiving for beginners. 

Br,

Matthias

Edited by ruebiracer
wrong meaning
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16 hours ago, qatmix said:

Droop, I would go for 1mm more downstop value at the front than the rear. Usually 5 front and 4 rear is a good starting point. This will give you less weight going forward when off power, you can then tweak it to help make the car feel responsive.

Just to be clear, does that mean 1mm less down travel at the front?

I started out with the stock settings from the manual, and have since adjusted the downstops so that the lower arms are parallel at maximum droop.

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1 hour ago, ruebiracer said:

For driving style with a more locked front diff, you have to back off earlier before the turn, to not come into off power understeer too much and lose ground by going too wide, but then go earlier on the throttle as the car will have a lot more turn in on power and pull you into the desired direction. You will learn that driving style easily after some batteries. But that is also required on a M05 or M03 with locked diff, nothing M07 "special".

That sounds very different to how I currently drive my M-05 with its AW greased stock diff. With the M-05 I approach the corner at full throttle, point it at the apex at full throttle, steer round the corner at full throttle and accelerate towards the next corner at full throttle. :)

I think I need to stop thinking about it as a more advanced M-05, and instead consider it in the same vein as my F1s and TB-03, namely as a race chassis which demands thought and careful control throughout the lap, rather than the "throw it at a corner and see what happens" approach which my M-05 seems to enjoy. 

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2 minutes ago, TurnipJF said:

That sounds very different to how I currently drive my M-05 with its AW greased stock diff. With the M-05 I approach the corner at full throttle, point it at the apex at full throttle, steer round the corner at full throttle and accelerate towards the next corner at full throttle. :)

I think I need to stop thinking about it as a more advanced M-05, and instead consider it in the same vein as my F1s and TB-03, namely as a race chassis which demands thought and careful control throughout the lap, rather than the "throw it at a corner and see what happens" approach which my M-05 seems to enjoy. 

Quite depending on the Motor power, if you can go full throttle all the time!:lol: If you like your driving style of the M05 a lot, just go with 5000 oil in your M07 diff or something that reflects your resistance with the AW grease in your M05. So you can compare your favorite driving style on both chassis with similar Basic settings. 

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3 hours ago, TurnipJF said:

That sounds very different to how I currently drive my M-05 with its AW greased stock diff. With the M-05 I approach the corner at full throttle, point it at the apex at full throttle, steer round the corner at full throttle and accelerate towards the next corner at full throttle. :)

That made me laugh. The first time I took my nitro buggy out my only experience and reference points were with 17.5T blinky buggies, so i drove the same way as you described which is how you have to drive the stock buggies. Except straight into the wall at the end of the straight. It took ages to come to grips with using brakes, needing to give a nitro a little bit of time to gain revs etc. 

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On 1/10/2019 at 12:56 PM, Juggular said:

I've got no answer.  I was looking to get a cheap M05.  Now I want M07!  It looks very good.  Why, oh why must you do this to me, Turnip?  

Would you be so kind as to tell me M07 is horrible when compared to M05? (So I could settle with cheaper M05?) 

(Or you could tell me that it is worth every penny.  In which case, I must go with M07.) 

5OXsZIf.jpg

What differential is that and can I run it in a top force?

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47 minutes ago, GTodd said:

What differential is that and can I run it in a top force?

I counted teeth on the Top Force manual.  It's far less than 52t of M07, so my guess is probably not compatible.  

 

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16 hours ago, Juggular said:

I counted teeth on the Top Force manual.  It's far less than 52t of M07, so my guess is probably not compatible.  

 

Not the M07 diff, but oil filled M05/M06 diffs would fit the Top force, if there wasn´t the difference in bearing size. The oil filled diffs use 1510 bearings, while the Manta Ray gear boxes need the good old 1150 Tamiya std. bearing. So to fit these diffs, the bearing seats in the gear boxes would need machining to 12mm diameter to take an 1280 bearing with 12 mm outer diameter. Then a modded diff with 1280 bearings could be used. I did this in principle on my M03 in my showroom and the "1280 trick" tutorial "How to have oil filled gear diff in an M03". I thought about applying this trick to my Top force gear boxes already, but I haven´t found a good tooling to enlarge the bearing seats, as the Top force gear boxes are separated into a front and rear section, while the M03 is separated longitudinal. (easier to drill this design)

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